properties and testing of concrete materials

Properties and Testing of Concrete Materials 6/7/2008 - 17/7/2008

Prepared by Balsam J. Farid 1

الجماهيرية العربية الليبية الشعبية االشتراآية العظمى

آلية الهندسة جامعة التحدي

:دورة تدريبية في

خواص وفحوصات مواد الخرســانةProperties and Testing of Concrete Materials

جاسم محمد فريدبلسم . أ: مشرف الدورة

ف2008/ 17/7ف إلى 6/7/2008



Properties and Testing of Concrete Materials

The Theoretical Part: Content Subject Page 1-Introduction and Definitions …………………………………..…2 2-Aggregate: a - Classification as to: Shape, Size, Surface Texture, Source and Unit weight. …………………………………......3 b - Properties of aggregate i- Main Properties required for compliance with specifications.…..6 ii- Properties required for choosing mix proportions ……… .…9 c- Moisture conditions. ……………………………………..….11 d- Deleterious materials ………………………………………11 e- Sampling and testing. …………………………………….…12 3-Cement: a- Introduction and manufacture. …………………………13 b-The properties and composition of cement ………………..14 c- The hydration process …………………………..…….15 d- Types of cement. …………………………………………..16 e- Physical properties of cement. …………………………….18 4- Water: a- Mixing water ……………………………………………….20 b-Curing water. ……………………………………………….21



Introduction and Definitions Concrete: is a word of Latin derivation ( con – together ) ( crete – to grow ) and its history can be charted from 5000 BC. It is a composite material that consists essentially of a binding medium within which are embedded particles or fragments of aggregate. In hydraulic cement concrete the binder is formed from a mixture of hydraulic cement and water. Concrete composites of :- 1- cement 2- Aggregates 3- Water 4- Admixtures Cement: an organic material or a mixture of inorganic materials that sets and develops strength by chemical reaction with water by formation of hydrates and is capable of doing so under water. Aggregates: Granular materials, such as sand, gravel, crushed stone, or iron blast- furnace slag, used with cementing medium to form concrete or mortar. Aggregates act as a relatively inexpensive inert filler, providing stability against volume changes and influencing strength and stiffness. Water: It reacts with the cement and also lubricates the fresh concrete enabling it to be placed into position and compacted. Admixtures: They are chemicals that can be added to the concrete immediately before or during mixing and significantly change its fresh, early age or hardened state to economic or physical advantage.



Aggregates

The mineral aggregates comprise the relatively inert filler materials in a Portland-cement concrete. As the aggregate usually occupies from 70 to 75 percent of the total volume of a mass of concrete, its selection and proportioning should be given careful attention in order to control the quality of the concrete structure. Classification of aggregates: Aggregates can be classified as to :

1- Size: a- Fine aggregate: Aggregate smaller than (5 or 4.75 mm) in diameter is classified as fine aggregate or sand. b-Coarse aggregate: Aggregate larger than (5 or 4.75mm) in diameter is classified as coarse aggregate.

2- Source: a- Natural aggregate: The natural sands and gravels are the product of weathering

and the action of running water, while the stone sands and crushed stones are reduced from natural rock by crushing and screening of quarried material.

b- Artificial aggregate: are usually produced for some special purposes, for example: burned expanded clay aggregate for making lightweight concrete. Some artificial aggregates are a by-product of industrial process such as blast furnace slag.

3- Unit weight:

a- Normal weight aggregate: It is usually the natural aggregate for which the unit weight is between (1500 to1800) kg/m3.



Normal weight aggregate Lightweight aggregate (Pumic) b- Lightweight aggregate: It can be artificial or natural.

The artificial lightweight aggregates are produced as both coarse and fine materials. They have a lower density due to increase in porosity which results in an overall lowering of the concrete strength ceiling. Lightweight aggregates are not as dense as normal weight aggregates ( unit weight less than 1000 kg/m3) and because their elastic modulus is lower, produce concrete with a lower elastic modulus and a higher creep and shrinkage. Lightweight aggregates can be of natural sources such as Pumic ( a volcanic rock).

c- Heavyweight aggregate: Where concrete of a high density is required, in radiation shielding for example, heavyweight aggregates can be used. The unit weight can be larger than 1800 kg/m3. Concrete densities of 3500-4500 kg/rn3 are obtained by using Barytes (a barium sulphate ore). Even greater concrete densities are obtained using lead shot - around 7000 kg/m3.



4- Particle Shape: The particle shape is important in that it affects the workability of the plastic concrete. The more rounded an aggregate the lower the inter particle friction, the smaller the surface/unit volume and therefore less water is required for a given workability. Therefore, a potentially higher strength is possible. Crushed aggregates can be used to produce higher strength concrete ( greater than about 80 N/mm2 ) as a greater bond strength can be achieved between the aggregate and the paste due to the rough angular texture of the aggregate surface. Natural gravels and sands tend to have a more rounded shape as a result of attrition water, whereas crushes rock aggregates tend to be more angular in shape. Aggregates can be classified as to shape into:

Note: Rounded, Irregular and Angular particles are more suitable for concrete mixes.

5- Surface Texture

Smother particles tend to produce a more workable concrete. The bond strength is, however likely to be higher with rough textured materials. The particles can be Glassy, smooth, granular, rough, crystalline or honeycombed.

Properties of Aggregate In fact, aggregate is not truly inert because its physical, thermal and, sometimes, chemical properties influence the performance of the concrete, for example, by improving its volume stability and durability over that of the cement paste. Generally Specifications require certain properties of aggregate to be tested to accept the using of aggregate in the concrete mixes. Other properties can be required for calculating concrete mix proportions.



A-Main Properties required for compliance with specifications: 1- Particle size distribution. 2- Resistance to degradation of coarse aggregate by abrasion. 3- Presence of Materials finer than 75µm. 4- Presence of Clay lumps 5- Soundness. 6- Presence of sulfate or chloride ions in aggregates. 7- Flakiness or Elongation of the aggregate particles. 8- Presence of Organic Impurities in Fine Aggregates.

B- Properties required for choosing mix proportions

1- Specific gravity and absorption. 2- Moisture content. 3- Loose or rodded unit weight of aggregates. 4- Nominal maximum size of aggregate and fineness modulus.

There may be other properties needed for special uses or conditions. The above properties will be discussed here shortly before talking about the laboratory tests used to determine these properties.

A-Main Properties required for compliance with specifications: 1- Particle size distribution: The actual size of the aggregate particles influence the concrete mix. In practice it is desirable to have particles of different sizes. The aggregate is usually split into at least two different portions for ease of batching: The common dividing point is 5mm ( or 4.75mm). Material larger than 5mm is termed coarse aggregate or gravel and the material smaller than 5mm is termed fine aggregate, fines or sand.

The distribution of the different sizes of particles in the coarse or fine aggregates is termed grading. The grading may be coarse or fine depending on the distribution of the particles and may be continuous (particles of different sizes) or single sized (particles of predominantly one size). The particle size distribution is extremely important in the design of any concrete mix. For most practical concretes it is desirable to have the particle sizes evenly distributed from the maximum size of coarse aggregate down to the smallest sand particles. This will enable the aggregate to compact in the densest form leaving the minimum number of voids to be filled



by the more expensive cement paste. It will also minimize the risk of segregation of the plastic concrete during handling & placing.

The test method covers the determination of the particle size distribution of fine and coarse aggregates by sieving, is Sieve Analysis of Fine and Coarse Aggregates, (ASTMC 136 – 96a) or (BS 812-103.1).

2-Resistance to degradation of coarse aggregate Hardness is the resistance of an aggregate to wear and is normally determined by an abrasion test, while the toughness of an aggregate is defined as its resistance to failure by impact. Hardness and toughness are particularly important when aggregates are to be used in a concrete road pavement or heavy duty wearing surfaces. A test used as a measure of degradation of mineral aggregates of standard grading resulting from a combination of actions including abrasion or attrition, impact, and grinding is "Resistance to Degradation of Small-Size Coarse Aggregate by Abrasion and Impact in the Los Angeles Machine" ASTM C 131 – 96). Another test used for the determination of the aggregate crushing value (ACV) which gives a relative measure of the resistance of an aggregate to crushing under a gradually applied compressive load is "Methods for determination of aggregate crushing value (ACV)" (BS 812-110) 3&4-Presence of Clay lumps and materials finer than 75µm Clay may be present in aggregate in the form of surface coatings which interfere with the bond between the aggregate and the cement paste. In addition, silt and crusher dust may be present either as surface coatings or as loose material. Even in the latter form. Silt and free dust should not be present in large quantities because, owing to their fineness and therefore large surface area, they increase the amount of water necessary to wet all the particles in the mix. Material finer than the 75-μm (No. 200) sieve can be separated from larger particles much more efficiently and completely by wet sieving than through the use of dry sieving. Therefore, accurate determinations of material finer than 75 μm in fine or coarse aggregate are desired. Materials Finer than 75-μm (No. 200) Sieve in Mineral Aggregates by Washing (ASTM C 117 – 95) and for clay lumps, the test is "Clay Lumps and Friable Particles in Aggregates" (ASTM C 142 – 97)



5-Soundness. The soundness of an aggregate is a measure of its durability. which is defined as: “The ability of individual particles to retain their integrity and not suffer physical. mechanical or chemical changes to extents which could adversely affect the properties of the concrete in either engineering or aesthetic respects.” The physical causes of large or permanent volume changes of aggregate are freezing and thawing, thermal changes at temperatures above freezing, and alternating wetting and drying. If the aggregate is unsound such changes in physical conditions result in a deterioration of the concrete in the form of local scaling, so called pop-outs, and even extensive surface cracking. Unsoundness is exhibited by porous flints and cherts, especially lightweight ones with a fine-textured pore structured pore structure, by some shales, and by other particles containing clay minerals. The degree of unsoundness is expressed by the reduction in particle size after a specified number of cycles. A test method covers the testing of aggregates to estimate their soundness when subjected to weathering action in concrete or other applications. This is accomplished repeated immersion in saturated solutions of sodium or magnesium sulfate followed by oven drying to partially or completely dehydrate the salt precipitated in permeable pore spaces. The internal expansive force, derived from the rehydration of the salt upon re-immersion, simulates the expansion of water on freezing. "Soundness of Aggregates by Use of Sodium Sulfate or Magnesium Sulfate"(ASTM C 88 – 99a) 6-Presence of sulfate or chloride ions in aggregates. Because of the danger of chloride- induced corrosion of steel reinforcement, the BS specifications specifies the maximum total chloride content in the mix. The chlorides may arise from all ingredient of the mix. Apart of the danger of corrosion of steel reinforcement, if salt is not removed, it will absorb moisture from the air and cause efflorescence- unsightly white deposits on the surface of the concrete. The presence of Sulphates will cause low ultimate strength and disintegration due to expansion. "Methods for determination of sulphate content"(BS 812-118) For chloride ions: "Method for determination of water-soluble chloride salts" (BS 812-117) 7- Flakiness or Elongation of the aggregate particles. The particle shape is of importance with regard to the properties of fresh and hardened concrete. Particles with high ratio of surface area to volume are of particular interest as they lower the workability of the mix. Elongated and flaky particles are of this type. The latter can also adversely affect the durability of concrete as they tend to oriented in one plane, with water and air voids forming underneath. The presence of elongated or flaky particles in excess of 10 to per cent of the mass of coarse aggregate is generally considered undesirable, although no recognized limits are laid down. Methods for determination of particle shape (BS 812-105.1) for Flakiness index and (BS 812-105.2) for Elongation index of coarse Aggregate. 8- Presence of Organic Impurities in Fine Aggregates. Natural aggregates may be sufficiently strong and resistant to wear and yet may not be satisfactory for concrete-making if they contain organic impurities which interfere with the hydration process. The organic matter consists of products of decay of vegetable matter in the form of human or organic loam, which is usually present in sand rather than in coarse aggregate, and is easily removed by washing. A test method used for that is "Organic Impurities in Fine Aggregates for Concrete" (ASTM C 40 – 99)



B- Properties required for choosing mix proportions 1- Absorption and Specific gravity. The following definitions can be useful: Absorption—the increase in the weight of aggregate due to water in the pores of the material, but not including water adhering to the outside surface of the particles, expressed as a percentage of the dry weight. The aggregate is considered “dry” when it has been maintained at a temperature of 110 + 5°C for sufficient time to remove all uncombined water Specific Gravity—the ratio of the mass (or weight in air) of a unit volume of a material to the mass of the same volume of water at stated temperatures. Values are dimensionless. Apparent Specific Gravity—the ratio of the weight in air of a unit volume of the impermeable portion of aggregate at a stated temperature to the weight in air of an equal volume of gas-free distilled water at a stated temperature. Bulk Specific Gravity—the ratio of the weight in air of a unit volume of aggregate (including the permeable and impermeable voids in the particles, but not including the voids between particles) at a stated temperature to the weight in air of an equal volume of gas-free distilled water at a stated temperature. Bulk Specific Gravity (SSD)—the ratio of the weight in air of a unit volume of aggregate, including the weight of water within the voids filled to the extent achieved by submerging in water for approximately 24 h (but not including the voids between particles) at a stated temperature, compared to the weight in air of an equal volume of gas-free distilled water at a stated temperature.

Significance and Use 1 Bulk specific gravity is the characteristic generally used for calculation of the volume occupied by the aggregate in various mixtures containing aggregate, including Portland cement concrete, bituminous concrete, and other mixtures that are proportioned or analyzed on an absolute volume basis. Bulk specific gravity is also used in the computation of voids in aggregate in the unit weight test. 2 Bulk specific gravity (SSD) is used if the aggregate is wet, that is, if its absorption has been satisfied. Conversely, the bulk specific gravity (oven-dry) is used for computations when the aggregate is dry or assumed to be dry. 3 Apparent specific gravity pertains to the relative density of the solid material making up the constituent particles not including the pore space within the particles which is accessible to water. 4 Absorption values are used to calculate the change in the weight of an aggregate due to water absorbed in the pore spaces within the constituent particles, compared to the dry condition, when it is deemed that the aggregate has been in contact with water long enough to satisfy most of the absorption potential. The laboratory standard for absorption is that obtained after submerging dry aggregate for approximately 24h in water. Aggregates mined from below the water table may have a higher absorption, when used, if not allowed to dry. Conversely, some aggregates when used may contain an amount of absorbed moisture less than the 24-h soaked condition. For an aggregate that has been in contact with water and that has free moisture on the particle surfaces, the percentage of free moisture can be determined



by deducting the absorption from the total moisture content determined The test method used for calculating the specific gravities and absorption is (ASTM C127&128-88) 2-Moisture content. One of the properties of the aggregates which should be known to design a concrete mix is its moisture content. It is necessary in order to determine the net water -cement ratio in a batch of concrete and to adjust batch quantities of ingredients for concrete. The test method used for that is “Moisture Content of Concrete Aggregate” (ASTM C-566- 84) 3-Loose or rodded unit weight of aggregates The following definitions can be useful: Bulk density, of aggregate, the mass of a unit volume of bulk aggregate material, in which the volume includes the volume of the individual particles and the volume of the voids between the particles. Expressed in [kg/m3]. Unit weight, weight (mass) per unit volume. (Deprecated term–used preferred term bulk density.) Voids, in unit volume of aggregate, the space between particles in an aggregate mass not occupied by solid mineral matter. Note: Voids within particles, either permeable or impermeable, are not included. Bulk density values are necessary for use for many methods of selecting proportions for concrete mixtures. The test method : “Unit Weight and Voids in Aggregate in its compacted or loose condition” (ASTM C 29 – 89) is used to determine bulk density values that are necessary for use for many methods of selecting proportions for concrete mixtures. 4-Nominal maximum size of aggregate and fineness modulus Nominal Maximum Size (of aggregate), in specifications for, or description of aggregate, the smallest sieve opening through which the entire amount of the aggregate is permitted to pass. Specifications on aggregates usually stipulate a sieve opening through which all of the aggregate may, but need not, pass so that a stated maximum proportion of the aggregate may be retained on that sieve. A sieve opening so designated is the nominal maximum size of the aggregate. The larger the aggregate particle the smaller the surface area to be wetted per unit mass( specific surface). Thus, extending the grading of aggregate to a larger maximum size lowers the water requirement of the mix so that, for specified workability and richness of the mix, the water/cement ratio can be reduced a consequent increase in strength. However, there is a limit of maximum size of aggregate. Fineness Modulus, a factor obtained by adding the percentages of material in the sample that is coarser than each of the following sieves (cumulative percentages retained), and dividing the sum by 100: 150-μm (No. 100), 300-μm (No. 50), 600-μm (No. 30), 1.18-mm (No. 16), 2.36-mm (No. 8), 4.75-mm (No. 4), 9.5-mm (3⁄8-in.), 19.0-mm (3⁄4-in.), 37.5-mm (11⁄2-in.), 75-mm (3-in.), 150-mm (6-in.). Usually, the fineness modulus is calculated for the fine aggregate rather than for coarse aggregate. Typical values range from 2.3 and 3.0, a higher value indicating a coarser grading. The usefulness of the fineness modulus lies in detecting slight variations in the aggregate from the same source, which could affect the workability of the fresh concrete.



Moisture Conditions of aggregate The porosity, permeability and absorption of aggregate influence the bond between it and the cement paste, the resistance of concrete to freezing and thawing, as well as chemical stability, resistance to abrasion, and specific gravity. When all the pores in the aggregate are full, it is said to be saturated and surface-dry. If this aggregate is allowed to stand free in dry air, some water will evaporate so that the aggregate is air-dry. Drying in an oven will remove the moisture; the aggregate is now oven dry. The aggregate can be also moist or wet when all voids are full of water and the surface is wet also.

Moisture conditions of aggregate. Deleterious Materials These are materials that can prove harmful to the concrete if present in sufficient quantity. Some impurities can be removed by careful washing and screening at the aggregate production plant.



Sampling and testing Two things to remember when performing a test on any material are: 1. The test must be performed in exactly the same way each time so that any change in the result is only indicative of a change in the property being measured. 2. The sample being tested must be truly representative of the total quantity. When testing aggregates the total weight of the sample being tested is no more than a few kilogram's yet it has to be representative of a stockpile of several tonnes. Sampling aggregates for concrete is usually based on random selection with each part of the stock pile having an equal chance of being sampled. The first requirement is to define the batch or stockpile quantity to be sampled, then to take a number of scoopfuls which are then combined into a representative sample to be reduced into one or more laboratory samples. At the laboratory, the sample is reduced to an appropriate size using a riffle box or a quartering board. Details of tests are shown in the laboratory manual ( see Appendix )



The cement

When all the ingredients are mixed, the cement and water react together and the resulting reaction products bind the sand and coarse aggregate together to form concrete. This reaction process is known as hydration and it continues throughout the life of the concrete, providing the temperature is high enough and moisture is present. It is important to realize that the reaction is a chemical one and not a drying out process as is commonly thought. The manufacturing process can be summarized in the following figure:

Manufacture steps of cement INGREDIENTS The essential ingredients of cement are lime and silica. Limestone has a high lime content, while the clay contains the silica. CRUSHING and MILLING The raw materials are crushed and reduced to a size or less (0.075 mm). of approximately 75 microns BLENDING There are two alternative ways of blending the materials together. In the wet process the ingredients are mixed in a slurry, while in the dry process the particles are transported in an air stream to the kiln. The dry process being the least energy intensive is now the preferred method.



HEAT EXCHANGE - Stage I The blend is fed into a slightly inclined rotary kiln where the initial temperature is sufficient to drive off any water. The dimensions of the kiln can be up to 230m long, land 7m diameter and the temperature gradually increases along its length. HEAT EXCHANGE - Stage 2 The second stage heats the mix to approximately 600 °C, when the calcium carbonate and chalk decompose to produce quicklime. HEAT EXCHANGE - Stage 3 The temperature in this zone is approximately 1500 °C and 20-30% of the material becomes a liquid flux. The mass of lime, silica and alumina then fuse into balls of hard clinker. DUST EXTRACTION This is necessary to prevent harmful particles being discharged into the atmosphere. CLI NKER The clinker drops into coolers, and the heat that is exchanged is used to raise the temperature of the air going into the kiln. At this stage, the size of the clinker particles is in the order of 2-25 mm. CLINKER GRINDING The clinker/gypsum mix is ground to produce the cement The grinding continues until the particle sizes are between 2 to 80 microns (0.002 to 0.080 mm). GYPSUM Gypsum (calcium sulphate), is added to the clinker to prevent rapid setting of the cement when water is added. Properties of Portland Cement There are many different types of cement available, the most common of which is Portland cement (PC). The properties of PC will now be discussed in detail and reference will be made later to the other types of cements.

Portland cement is a fine powder that when mixed with water becomes the glue that holds aggregates together in concrete.



Cement Composition. In the kiln the raw materials fuse together to form the cement clinker. This clinker is composed of four primary compounds - each playing a different part in the hydration reaction. Tricalcium Dicalcium Tricalcium Tetracalcium Silicate Silicate Aluminate Alumino-ferrite C3S C2S C3A C4AF The properties of the cement depend upon the proportions in which these compounds exist Variations in compound composition can lead to significant variations in the properties of the cement. Hydration - The Chemical Reactions When the water and cement are mixed a number of chemical reactions begin involving the silicates and aluminates in the cement. These combine with the water producing the hydration products which in time form the hardened cement paste (HCP). The first reaction between C3A and the water is the most rapid of all. It needs to be controlled to avoid “flash-setting”, this is achieved by the addition of gypsum The formation of ettringite slows down the hydration of C3A by creating a barrier around the cement grains. This dormant period is extremely important since it allows time for the cement to be transported to site and compacted After a certain proportion of the sulphate has been consumed, the ettringite coating becomes broken and a second reaction begins to take place It is not until this second reaction occurs that the paste begins to stiffen significantly and workability begins to drop. Shortly we can say: Tricalcium Silicate, C3S, hydrates and hardens rapidly and is largely responsible for initial set and early strength. In general, the early strength of Portland cement concrete is higher with increased percentages of C3S. Dicalcium Silicate, C2S, hydrates and hardens slowly and contributes largely to strength increase at ages beyond one week. Tricalcium Aluminate, C3A, liberates a large amount of heat during the first few days of hydration and hardening. It also contributes slightly to early strength development. Cements with low percentages of C3A are more resistant to soils and waters containing sulfates. Tetracalcium Aluminoferrite, C4AF, is the product resulting from the use of iron and aluminum raw materials to reduce the clinkering temperature during cement manufacture. It contributes little to strength. Most color effects that make cement gray are due to C4AF and its hydrates. Calcium Sulfate, as anhydrite (anhydrous calcium sulfate), gypsum (calcium sulfate dihydrate), or hemihydrate, often called plaster of paris or bassanite (calcium sulfate hemihydrate) is added to cement during final grinding to provide sulfate to react with C3Ato form ettringite (calcium trisulfoaluminate). This controls the hydration of C3A. Without sulfate, a cement would set rapidly. In addition to controlling setting and early strength gain, the sulfate also helps control drying shrinkage and can influence strength through 28 days.



Strength Contribution Providing moisture is present, the cement can continue to hydrate for many years. However, after about one year the rate of hydration is so slow that it is assumed to be fully hydrated and therefore at full strength. During this period each compound contributes a different amount to the strength of the cement. This is best described by the diagram on the left. Heat Evolution During hydration the four main compounds generate different amounts of heat as shown in the graph on the right. TYPES OF PORTLAND CEMENT Different types of Portland cement are manufactured to meet various normal physical and chemical requirements for specific purposes. Portland cements are manufactured to meet the specifications of ASTM C 150, AASHTO M 85, or ASTM C 1157. ASTM C 150, Standard Specification for Portland Cement, provides for eight types of Portland cement using Roman numeral designations as follows: Type I Normal Type IA Normal, air-entraining Type II Moderate sulfate resistance Type IIA Moderate sulfate resistance, air-entraining Type III High early strength Type IIIA High early strength, air-entraining Type IV Low heat of hydration Type V High sulfate resistance Type I Portland cement is a general-purpose cement suitable for all uses where the special properties of other types are not required. Its uses in concrete include pavements, floors, reinforced concrete buildings, bridges, tanks, reservoirs, pipe, masonry units, and precast concrete products



Type II Portland cement is used where precaution against moderate sulfate attack is important. It is used in normal structures or elements exposed to soil or ground waters where sulfate concentrations are higher than normal but not unusually severe. Type II cement has moderate sulfate resistant properties because it contains no more than 8% tricalcium aluminate (C3A). Type III portland cement provides strength at an early period, usually a week or less. It is chemically and physically similar to Type I cement, except that its particles have been ground finer. It is used when forms need to be removed as soon as possible or when the structure must be put into service quickly. In cold weather its use permits a reduction in the length of the curing period. Although higher-cement content mixes of Type I cement can be used to gain high early strength, Type III may provide it easier and more economically. Type IV Portland cement is used where the rate and amount of heat generated from hydration must be minimized. It develops strength at a slower rate than other cement types. Type IV cement is intended for use in massive concrete structures, such as large gravity dams, where the temperature rise resulting from heat generated during hardening must be minimized. Type IV cement is rarely available. Type V Portland cement is used in concrete exposed to severe sulfate action—principally where soils or ground waters have a high sulfate content. It gains strength more slowly than Type I cement. The high sulfate resistance of Type V cement is attributed to a low tricalcium aluminate content, not more than 5%. Use of a low water to cementitious materials ratio and low permeability are critical to the performance of any concrete exposed to sulfates. Even Type V cement concrete cannot withstand a severe sulfate exposure if the concrete has a high water to cementitious materials ratio. Type V cement, like other Portland cements, is not resistant to acids and other highly corrosive substances. Air-Entraining Portland Cements Specifications for three types of air-entraining Portland cement (Types IA, IIA, and IIIA) are given in ASTM C 150 and AASHTO M 85. They correspond in composition to ASTM Types I, II, and III, respectively, except that small quantities of air-entraining material are interground with the clinker during manufacture. These cements produce concrete with improved resistance to freezing and thawing. Such concrete contains minute, well-distributed, and completely separated air bubbles. Air entrainment for most concretes is achieved through the use of an air-entraining admixture, rather than through the use of air-entraining cements. Air-entraining cements are available only in certain areas. White Portland Cements White Portland cement is a true Portland cement that differs from gray cement chiefly in color. It is made to conform to the specifications of ASTM C 150, usually Type I or Type III; the manufacturing process is controlled so that the finished product will be white. White Portland cement is made of selected raw materials containing negligible amounts of iron and magnesium oxides—the substances that give cement its gray color. White Portland cement is used primarily for architectural purposes in structural walls, precast and glass fiber reinforced concrete (GFRC) facing panels, terrazzo surfaces, stucco, cement paint, tile grout, and decorative concrete. Its use is recommended wherever white or colored concrete, grout, or mortar is desired. White Portland cement should be specified as: white Portland cement meeting the specifications of ASTM C 150, Type [I, II, III, or V]. White cement is also used



to manufacture white masonry cement meeting ASTM C 91 and white plastic cement meeting ASTM C 1328. White cement was first manufactured in the United States in York, Pennsylvania in 1907. Physical Properties of Cement Specifications for cement place limits on both its physical properties and often chemical composition. An understanding of the significance of some of the physical properties is helpful in interpreting results of cement tests. Tests of the physical properties of the cements should be used to evaluate the properties of the cement, rather than the concrete. Cement specifications limit the properties with respect to the type of cement. Cement should be sampled in accordance with ASTM C 183 (AASHTO T 127). During manufacture, cement is continuously monitored for its chemistry and the following properties: The fineness of cement affects heat released and the rate of hydration. Greater cement fineness (smaller particle size) increases the rate at which cement hydrates and thus accelerates strength development. The effects of greater fineness on paste strength are manifested principally during the first seven days In the early 1900s, cement fineness was expressed as The Wagner turbidimeter test (ASTM C 115 or AASHTO T 98—Fig. 2-32), the 45 micrometer (No. 325) sieve (ASTM C 430 or AASHTO T 192—Fig. 2-33) or the 150-μm (No. 100) and 75-μm (No. 200) sieve (ASTM C 184 or AASHTO T 128), and the electronic (x-ray or laser) particle size analyzer can also be used to test fineness. Soundness Soundness refers to the ability of a hardened paste to retain its volume. Lack of soundness or delayed destructive expansion can be caused by excessive amounts of hard burned free lime or magnesia. Most specifications for Portland cement limit the magnesia (periclase) content and the maximum expansion as measured by the autoclave-expansion test. Since adoption of the autoclave-expansion test (ASTM C 151 or AASHTO T 107) in 1943, there have been exceedingly few cases of abnormal expansion attributed to unsound cement. Consistency Consistency refers to the relative mobility of a freshly mixed cement paste or mortar or to its ability to flow. During cement testing, pastes are mixed to normal consistency as defined by a penetration of 10 ± 1 mm of the Vicat plunger (see ASTM C 187 or AASHTO T 129) Setting Time The object of the setting time test is to determine (1) the time that elapses from the moment water is added until the paste ceases to be fluid and plastic (called initial set) and (2) the time required for the paste to acquire a certain degree of hardness (called final set). To determine if a cement sets according to the time limits specified in cement specifications, tests are performed using either the Vicat apparatus (ASTM C 191 or AASHTO T 131) or the Gillmore needle (ASTM C 266 or AASHTO T 154 ). The Vicat test governs if no test method is specified by the purchaser. Initial set of cement paste must not occur too early and final set must not occur too late. The setting times indicate that a paste is or is not undergoing normal hydra- Compressive Strength Compressive strength as specified by ASTM cement standards is that obtained from tests of 50-mm (2-in.) mortar cubes tested in accordance with ASTM C 109 (AASHTO T 106)



These cubes are made and cured in a prescribed manner using a standard sand. Compressive strength is influenced by the cement Density and Relative Density (Specific Gravity) The density of cement is defined as the mass of a unit volume of the solids or particles, excluding air between particles. It is reported as mega grams per cubic meter or grams per cubic centimeter (the numeric value is the same for both units). The particle density of Portland cement ranges from 3.10 to 3.25, averaging 3.15 Mg/

Mixing Water for Concrete

Water that is safe to drink is safe to use in concrete.

Water is mixed with the cement powder to form a paste which holds the aggregates together like glue. Almost any natural water that is drinkable and has no pronounced taste or odor can be used as mixing water for making concrete. However, some waters that are not fit for drinking may be suitable for use in concrete. Water of questionable suitability can be used for making concrete if mortar cubes (ASTM C 109 or AASHTO T 106) made with it have 7-day strengths equal to at least 90% of companion specimens made with drinkable or distilled water. In addition, ASTM C 191 (AASHTO T 131) tests should be made to ensure that impurities in the mixing water do not adversely shorten or extend the setting time of the cement. Acceptable criteria for water to be used in concrete are given in ASTM C 94 (AASHTO M 157) and AASHTO T 26. Excessive impurities in mixing water not only may affect setting time and concrete strength, but also may cause efflorescence, staining, corrosion of reinforcement, volume instability, and reduced durability. Therefore, certain optional limits may be set on chlorides, sulfates, acid alkalies, and solids in the mixing water or appropriate tests can be performed to determine the effect the impurity has on various properties. Some impurities may have little effect on strength and setting time, yet they can adversely affect durability and other properties. Water containing less than 2000 parts per million (ppm) of total dissolved solids can generally be used satisfactorily for making concrete. Water containing more than 2000 ppm of dissolved solids should be tested for its effect on strength and time of set.



Acceptance Criteria for Questionable Water Supplies (ASTM C 94 or AASHTO M 157) Limits Test method

Compressive strength, minimum percentage of 90 C 109* or T 106

control at 7 days

90 C 109* or T 106

Time of set, deviation from control, hr: min

from 1:00 earlier to 1:30 later

C 191* or T 131

Curing water for concrete

Lawn sprinklers saturating burlap with water keep the concrete continuously moist.

Generally, water satisfactory for mixing is also suitable for curing purpose. However, iron or organic matter may cause staining, particularly if water flows slowly over concrete and evaporates rapidly. In some cases, discolorationis of no significance, and any water suitable for mixing, or even slightly inferior in quality, is aacceptable for curing. However, it is essential that curing water be free from substances that attack hardened concrete. For example, concrete is attacked by water containing free CO2. Flowing pure water, formed by melting ice or by condensation, and containing little CO2, dissolves (CaOH)2 and causes surface erosion. Curing with sea water may lead to attack of reinforcment.



Appendix

Building Materials Laboratory Manual

A- The aggregate tests: 1- Reducing Field Sample of Aggregate to Test Sample 2- Moisture Content of Concrete Aggregate. 3- Specific Gravity and Absorption of Coarse Aggregate. 4- Specific Gravity and Absorption of fine Aggregate. 5- Resistance to Degradation of Small-size coarse Aggregate by Abrasion in the Los Angeles Machine.

6- Sieve Analysis of fine and coarse aggregates. 7- Unit Weight and Voids in Aggregate. 8- Materials Finer than 75µm (No. 200) Sieve in Mineral aggregate. 9- Method of determination of particle shape " Flakiness index"

10- Method of determination of particle shape " Elongation index" 11- Method for determination of water-soluble chloride salts 12- Methods for determination of sulphate content 13- Organic Impurities in Fine Aggregates for Concrete 14- Soundness of Aggregates by Use of Sodium Sulfate or Magnesium Sulfate B- The cement tests: 1- Fineness of cement. 2- Normal consistency. 3- Initial and final time of setting. 4- Density and specific gravity. 5- Compressive strength of cement mortar. 6- Tensile strength of cement mortar.



Reducing Field Sample of Aggregate to Test Sample ASTM C 702, D75

Purpose: To obtain laboratory samples of aggregates from stockpiles. Equipment: Shovel, scoop , boom.

:Procedure

1-Obtain a sample of aggregate (about 50 kg) from three places in the stockpile: from the top third, at the midpoint, and from the bottom third

of the volume of the pile. 2- Place the field sample on a hard, clean level surface. 3- Mix the material thoroughly by turning the entire sample three times. 4- Shovel the entire sample into a conical pile. 5- Carefully flatten the conical to a uniform thickness and diameter by pressing down the apex with a shovel. ( The diameter should be approximately four to eight times the thickness). 6- Divide the flattened mass into four equal quarters with a shovel. 7- Remove two diagonally opposite quarters. Brush the cleared spaces clean. 8-Mix and quarter the remaining materials until the sample is reduced to the desired size. Note The sample splitters can be used instead of flattening the mass on a level surface.



Fig. (1) The sample splitters for fine &coarse aggregates

Fig.(2) Reducing Field Sample of Aggregate to Test Sample



Aggregate Tests :1.Test No

“Moisture Content of Concrete Aggregate” ( ASTM C-566- 84)

: Scope of test

One of the properties of the aggregates which should be known to design a concrete mix is its moisture content. It is necessary in order to determine the net water -cement ratio in a batch of concrete made with job aggregate.

:Materials The amount of materials depends on the nominal maximum size of aggregate as follows:

Weight of Sample N.M.S

)kg( )mm (

0.5 4.75 1.5 9.5

2 12.5 3 19 4 25

6 37.5

: Apparatus 1. A balance sensitive to 0.5gm. 2. Electrical oven at temperature 105 °C. 3. Container with a cover. 4. Sample splitter.

: Procedure 1- Prepare the container clean, record its empty weight (A).

2- Weigh the suitable sample of aggregate and keep it in a container, put the cover on. 3-The weight of the container with the cover and the gravel is (B). 4-Remove the cover, then put the sample in the oven at 105 °C for 24 hours. 5-Remove the sample forms the oven and put the cover on it, then leaves it for half an hour, and then weigh it (D). 6- Repeat the same steps for the sand sample.



:Calculations and Results

Moisture Content % = [ ( B – D ) / ( D – A )] x 100

Discussion: 1- Comment on the results you get. 2- Do you think that your results are affected by the weather conditions?



: 2Test

“Specific Gravity and Absorption of Coarse Aggregate”

(ASTM C 127 – 88)

: Scope This test method covers the determination of Specific Gravity and Absorption of coarse aggregate. The specific gravity may be expressed as bulk specific gravity, bulk specific gravity SSD or apparent specific gravity. The bulk specific gravity and absorption are based on aggregate after 24hour soaking in water.

:Materials

1- Coarse aggregate , must be sampled using sample splitter. 2- The weight of the sample depends on nominal maximum size (NMS) of the aggregate as follows.

Minimum Weight of Sample N.M.S

)kg( )mm ( 12.5 or less 2

3 19 4 25

5 37.5 8 50

: Apparatus

1-A weighing balance sensitive, readable and accurate to 0.5gm. 2-The balance shall be equipped with suitable apparatus for suspending the sample container in water. 3.Sample container (A wire basket) [20cm diameter& 20cm in height]. 4.Water tank; a watertight tank into which the sample container may be placed while suspended below the balance. 5-Sieves; 4.75mm (No.4) or other sizes as needed

Procedure:

1- Take the sample of coarse aggregate using the sample splitter. 2-Sieve the sample with 4.75mm sieves and ignore the materials passing through No.4.75 sieve. - 3- Wash the sample to remove dust.. 4- Put the sample in the oven at 105°C for 24hours. 5- Get the sample out of the oven, leave it to cool then determine its weight. 6- Submerge the sample in water for 24hours. 7- Remove the sample from the water and roll it in a large absorbent cloth until all



visible films of water are removed .Wipe the larger particles individually. Take care to avoid evaporation of water from aggregate pores during the operation of surface- drying. 8- Take the required weight of the sample in its (S.S.D) (saturated surface dry) condition. 9-After weighing, immediately place the S.S.D sample in the sample container and determine its weight in water at 23±1°C.Take care to remove all entrapped air before weighing by shaking the container while immersed. 10-Dry the test sample to constant weight at a temperature of 110±5°C, Cool in air at room temperature 1 to 3 hours, or until the aggregate has cooled to a temperature that is comfortable to handle, and weigh.

Calculations :-

1-Specific Gravity:-

a. Bulk specific gravity: - Calculate the bulk specific gravity as follow :

Bulk Specific Gravity = A /(B-C) Where: A=Weight of oven-dry test sample in air,(gm). B= Weight of S.S.D. sample in air,(gm). C=Weight of saturated sample in water,(gm).

b- Bulk Specific Gravity (SSD) = B / (B-C)

c-Apparent Specific gravity: - Calculate the apparent sp. gr. As follows:

Apparent Specific Gravity = A / (A - C)

2- Absorption:-

Calculate the percentage of absorption as follows:

Absorption% = [(B – A) / A ]x100



Discussion: 1-Comment on the results. 2- Compare the results with the typical values. 3- How can the percentage of absorption affect on a concrete mix?

Fig.(3) A balance with suitable apparatus for suspending the sample container in water.



Test No.3

“Specific Gravity and Absorption of fine Aggregate”

(ASTM C 128 – 88)

Scope:. This test method covers the determination of Bulk and Apparent Specific Gravity and Absorption of fine aggregate.

Materials:- l kg of sand is used using sample splitter.

Apparatus:

1-A balance having capacity of 1kg or more sensitive to 0.1gm 2- Pycnometer: A flask or other suitable container into which the fine aggregate sample can be introduced .It is usually of 500cm3 capacity. 3-Mold: a metal mold in the form of a frustum of a cone with dimensions as follows: 37mm inside diameter at the top, 90mm inside diameter at the bottom and 75mm in height. 4-Tamper: A metal tamper weighing 340±15gm and having a flat circular tamping face 25mm in diameter. 5- Electrical Oven. 6- A container suitable to submerge the sample with water.

Preparation of the test Specimen:- 1-Obtain approximately 1kg of the fine aggregate using sample splitter. 2- Dry it in a suitable pan or vessel to constant weight at 110°C. Allow it to cool to a comfortable handling temperature, cover with water by immersion and permit to stand for 24 hours. 3- Decant excess water with care to avoid loss of fines, spread the sample on a flat nonabsorbent surface exposed to a gently moving current of warm air. 4- Stir frequently to get homogeneous drying until achieving the saturated surface dry condition. Use cone test for surface moisture. 5- Hold the mold firmly on a smooth nonabsorbent surface with the large diameter down. Place a portion of partially dried fine aggregate loosely in the mold by filling it to over following and heaping additional materials above the top of the mold. 6- Lightly tamp the sand into the mold with 25 light drops of the tamper. Each drop should start about 5mm above the top surface of the sand. Permit the tamper to fall freely under gravitational attraction on each drop. 7- Adjust the surface, remove loose sand from the base and lift the mold vertically. If surface moisture is still present the sand will retain the molded shape. When the sand slumps slightly, it indicates that it has reached S.S.D condition.



Procedure:- 1 -Weigh 500gm of the S.S.D sample. 2- Partially fill the pycnometer with water. Immediately put into the pycnometer 500gm saturated surface dry aggregate. 3- Then fill with additional water to approximately 90%of capacity. 4- Roll; invert the pycnometer to eliminate all air bubbles. 5-Adjust its temperature to 23±1.7 °C by putting the pycnometer in a water bath for an hour. 6-Bring the water level in the pycuometer to its calibrated capacity. 7- Determine the total weight of the pycnometer, specimen and water. 8- Remove the fine aggregate from the pycnometer, dry to constant weight at temp. 110±5 oC, cool in air at room temperature for one hour, and weigh. 9- Determine the weight of the pycnometer filled to its capacity with water at 23 oC

Calculations:

1-Calculat the bulk specific gravity as follows:-

Bulk sp. gr. = A / ( B + S – C )

Where: A: Weight of oven —dry specimen in air, (gm). B: Weight of pycnometer filled with water, (gm) S: Weight of the saturated surface-dry specimen. (500 gm) C: Weight of pycnometer with specimen and water to calibration mark, (gm).

1-Calculat the bulk specific gravity (SSD) as follows:

Bulk sp. gr.(SSD) = S / ( B + S – C )

3- Calculate the apparent Specific Gravity as follows:-

Apparent sp. gr=. A / ( B + A - C )

3-Calculate the percentage of absorption as follows:-

Absorption = [ ( S – A) / A x] 100

Discussion:

1- Comment on the results. 2- Compare the results with the typical values. 3- How can the percentage of absorption affect on a concrete mix?



Fig.(4) Exposing the fine aggregate to a gently moving current of warm air.

Fig.(5) The fine aggregate is still damp. Fig.(6) The fine aggregate is in SSD condition.



Test No.4

“Resistance to Degradation of Small-size coarse Aggregate

by Abrasion in the Los Angeles Machine.”

ASTM C 131-81(1987)

Scope of test: This test method cover testing sizes of coarse of (12.5mm) for resistance to degradation using the Los Angeles testing machine.

Summary of test:

The Los Angeles test is a measure of degradation of mineral aggregates of standard grading resulting form a combination of actions including abrasion or attrition, impact, and grinding in a rotating steel drum containing a specified number of steel spheres, the number depending upon the grading of the test sample. As the drum rotates a shelf plate picks up the sample and the steel spheres, carrying them around until they are dropped to the opposite side of the drum, creating an impact- crushing effect. The contents then roll within the drum with an abrading and grinding action until the shelf plate impacts and the cycle is repeated. After the prescribed number of revolutions, the content is removed from the drum and the aggregate portion is sieved to measure the degradation as percent loss.

Materials: The test sample shall be washed and oven-dried at (105-110) CO and separated into individual size fractions and recombined to the grading of table (1) most nearly corresponding to the range of sizes in the aggregate as furnished for the work. Apparatus:- 1. Los Angeles Machine. 2. Sieves. 3. Balance accurate to 0.5 gm. 4. Oven. and containers. 5. Charge – The Charge must consist of steel spheres averaging (46.8mm) in diameter and each weighing between 390 to 445gm. The charge, depending upon the grading of the test sample as follows:



Grading No: of spheres Wt of charge (gm)

A 12 5000+25

B 11 4584+25

C 8 3330+20

D 6 2500+15

Procedure:

1. Put the sample of coarse aggregate in an oven at 105°C to get oven-dry sample. 2. Prepare the sample, then Weigh and record its weight to the nearest 1gm. 3.Placc the test sample and charge in the Los Angeles testing machine and rotate the machine at 30to33 round/min for 500 revolutions. 4. Discharge the material from the machine and make preliminary separation of the sample a sieve coarser then (1.7mm).The finer portion shall then be sieved on a 1.7mm sieve. 5. The material coarser then the 1.7mm sieve shall be washed, oven dried at 105 oC to substantially constant weight, and weighed to the nearest 5gm.

Calculations:

%Abrasion = (wt of the initial sample- wt of retained of 1.7mm sieve) x 100 Wt of initial sample

or = wt of passing sieve (1.7mm) x 100

Wt. of initial sample

Note:

ASTM Specifications C33-86 requires that the abrasion percent should not exceed 50% for coarse aggregate used in concrete mixes.



Table (1): Grading of test samples:

Weight of indicated sizes (gm) Grading

Sieve size (mm)

D C B A Retained on

Passing

- - - 25+1250 25 37.5 - - - 25+1250 19 25 - - 10+2500 10+1250 12.5 19 - - 10+2500 10+1250 9.5 12.5 - 10+2500 - - 6.3 9.5 - 10+2500 - - 4.75 6.3

10+5000 - - - 2.36 4.75 10+5000 10+0050 10+0500 10+5000 Total

Fig. (7) The Los Angeles Machine.



Test No.5

“Unit Weight and Voids in Aggregate in its Compacted

or Loose condition”

(ASTM C 29 – 89)

Scope: This test method covers the determination of unit weight in a compacted or loose condition and calculation of voids in fine and coarse aggregates. This test method is applicable to aggregates not exceeding (100mm) in N.M.S.

Materials: Sample of, preferably, oven dry fine aggregate and an other of oven-dry coarse aggregate.

Apparatus:- 1. A balance accurate to 0.5gm. 2. Measure: A cylindrical metal measure preferably provided with handles. Its capacity shall conform to the limits below:

N.M.S (mm) Capacity of measure (m3)

12.5 0.0028

25 0.0093

37.5 0.014

100 0.028

Note: - The indicated size measure may be used to test aggregate of N.M.S equal to or smaller than that listed.

3. Tamping Rod (A round, straight steel rod (l6mm) in diameter and approximately 600mm in length with a rounded to a hemispherical tip. 4. Containers and shovel or scoop.



Procedure:

A- Calibration of the measure:

1- Fill the measure with water at room temperature and cover with a piece of plate glass in such away as to eliminate bubbles and excess water. 2- Determine the weight of the water in the measure.

3-Measure the temperature of water and determine its density from table below:-

Density of water

Temperature (0C) Density (kg/m3)

15.6 999.01

18.3 998.54

21.1 997.97

23 997.54

23.9 997.32

26.7 996.59

29.4 995.83

Note: Use interpolating if necessary.

4- Calculate the volume, V of the measure by dividing the weight of water required to fill the measure by its density.

B- Procedure of the test:-

1. Weigh the cylinder (empty).

2. Fill the cylinder to overflowing by means of a shovel or scoop, discharging the aggregate from a height not to exceed 50mm above the top the cylinder edge. Exercise care to prevent, so far as possible, segregation of the particle sizes of which the sample in composed. Level the surface of the aggregate with the fingers or straight edge in such way that any slight projections of the larger pieces of the coarse aggregate approximately balance the larger voids in the surface below the top of the cylinder

3. Determine the weight of the measure plus its contents, and calculate the weight of the aggregate by subtracting the empty weight of the cylinder.

4. Empty the cylinder and refill it again to one third of its height and rod the layer of aggregate with (25) strokes of the tamping rod evenly distributed over the surface. Fill



the cylinder two-thirds full and again level and rod as previous. Finally, of the cylinder to overflowing and rod again in the manner previously mentioned. Level the surface of the aggregate with the fingers or a straight edge in such away as that mentioned in (step 3).

5. In Roding the first layer, do not allow the rod to strike the bottom of the measure forcibly. In Roding the second layer and third layer, use only enough force to cause the tamping rod to penetrate the previous layer of aggregate.

6. Determine the weight of the measure plus its contents and calculate the wt. Of aggregate.

7. Repeat the same procedure for the fine aggregate sample.

Calculations:

1-Unit weight: calculate the unit weight for the rodding or shoveling procedure

follows:- M = ( G-T )/ V Where :- M= unit weight of the aggregate (kg/m3) G= Weight of the aggregate plus the cylinder (kg) T= Weight of the empty cylinder (kg) V= Volume of the cylinder (m3)

Note: The unit weight determined by this test method is for aggregate in an oven- dry condition.

2-Void content:- Calculate the void content in the aggregate using the unit weight determined by either the rodding or shoveling procedure as follows:

%void= (S )(W) – (M) x100 ( S) (W)

Where S= bulk specific gravity (from tests 2+3) W= density of water (1000kg/m3 )



3-Put your results in a table like that shown below.

Fine Aggregate Coarse Aggregate

Compacted Loose Compacted Loose Unit weight

kg/m3

Voids%

:Note Normal-Weight aggregate density: (1280-1920) kg/m3

Fig.(8) The cylindrical metal measures for the fine and coarse aggregates



Test No.6

“Sieve Analysis of fine and coarse aggregates"

(ASTM C136 – 84a)

Scope: This method covers the determination of the particle size distribution the fine and coarse aggregate by sieving.

Materials: 1. The weight of test sample of fine aggregate shall be, after drying, approximately (500 gm). 2. The weight of test sample of coarse aggregate shall conform with the following:

N.M.S (mm) Minimum Weight (kg)

9.5 1

12.5 2

19 5

25 10

37.5 15

Apparatus:

1. Balance: For fine aggregate accurate for 0.5gm. For coarse aggregate accurate for 0.5gm. 2. Containers to carry the sample. 3. Oven. 4. Mechanical Sieve shaker. 5. Two sets of sieve:-For fine aggregate [ No.4 , No.8, No.16 , No.30 , No.50, No.100] For coarse aggregate [37.5mm , 19mm ,9.5mm, No.4 , No.8]

In addition to a pan and a cover for each set.

Procedure: 1- Put the sample in the oven at 110°C. 2-Determine the empty weight for each sieve and record. 3-Nest the sieve in order of decreasing size of opening from top to bottom place the sample on the top sieve. 4- Agitate (shake) the sieve by placing the set on the mechanical shaker for 10min.



5- Open the set of sieve carefully so that no loosing of materials is expected. 6-Weigh each sieve with the residue record its weight. 7- Tabulate your data in a suitable shape. 8. Make sure that the summation of the residue weights equals to the original sample weight with a difference not more than 1% of the original weight. 9-The table should contain:-

No. of sieve

Sieve empty Wt

Sieve +residue Wt

Residue Wt

Residue %

% Cum

Residue

%

Passing

10-Fineness Modulus for fine aggregate can be determined as: - F.M. = Σ cumulative residue percentage 100

It must be within-(2.6 - 3.1) for sand.

: Notes

1-The sieves dimensions are:

1.5'' 1'' 3/4'' 1/2''3/8''481630 50100No. of sieve

37.5 25.4 19 12.5 9.5 4.75 2.36 1.18 0.6 0.3 0.150Size of opening (mm)

2- The results must be compared with ASTM Specification [C33-99a] a- For Fine aggregate:

% Passing Sieve size

mm Sieve No.

100 9.5 3/8'' 95-100 4.75 No.4 80-100 2.36 No.8 50-85 1.18 No.16 25-60 0.600 No.30 5-30 0.300 No.50 0-10 0.150 No.100

b- For Coarse aggregate: See table (1).



Fig. (9) The Mechanical Sieve Shaker.

\



7.Test No

“Materials Finer than 75µm (No. 200) Sieve in Mineral

Aggregate by Washing ”

(ASTM C117-87)

Scope: This test method covers determination of the amount of materials finer than a 75µm (N0.200) sieve in aggregate by washing. Clay particles and other aggregate particles that are dispersed by the wash water, as well as water –soluble materials, will be removed from the aggregate during the test.

Materials :

the mass of the test sample, after drying , shall conform with the following:

Minimum Mass (gm) Nominal Max. Size

300 4.5mm or smaller 1000 9.5mm 2500 19mm 5000 37.5mm or larger

:ratus Appa 1- Balance accurate to 0.1g or 0.1% of the test mass , whichever greater. 2- Sieves: 75µm (No.200) sieve + 1.18mm (No.16) sieve . 3- Container. 4- Oven.

:Procedure

5 Co± 1- Dry the test sample to constant mass at a temperature of 110 CO

Determine the mass to the nearest 0.1gm of the test sample. 2- Place the test sample in the container and add sufficient water to cover it. Agitate the sample to result in complete separation of all particles finer than the 75µm (No.200) sieve from the coarser particles, and to bring the fine materials into suspension. immediately pour the wash water containing the suspended and dissolved solids over the nested sieves, arranged with the coarser sieve on top . 3- Add a second charge of water to the sample in the container, agitate , and decant as before. Repeat this operation until the wash water is clear.



4- Return all materials retained on the nested sieve by flushing to the washed sample . Dry the washed sample to constant mass at a temp. of 110 + 5 Co and determine the

mass to the nearest 0.1% of the original mass of the sample . 5- Calculate the amount of materials passing 75µm (No.200) sieve by washing as follows:

100× B

C-B A =

Where : A = percentage of material finer than 75µm sieve by washing . B = Original dry mass of sample .(gm) C = Dry mass of sample after washing.(gm)

:eNot

According to [C33-99a] ASTM. [A] must be not more than (3%), in fine aggregate for concrete, and not more than (1%), in coarse aggregate.



Test No.8

Method of determination of particle shape "Flakiness index"

BS 812-105.1:1989

Scope: The test describes the method for determining the flakiness index of coarse aggregate. Principle Aggregate particles are classified as flaky when they have a thickness (smallest dimension) of less than 0.6 of their mean sieve size. The flakiness index of an aggregate sample is found by separating the flaky particles and expressing their mass as a percentage of the mass tested. The test is not applicable to material passing a 6.30mm BS test sieve or retained on a 63.0 mm BS test sieve. Apparatus

1- A sample divider 2- A ventilated oven. 3- A balance accurate to 0.1% of the mass of the test portion. 4- Test sieves. 5- A mechanical sieve shaker. 6- Trays of suitable size. 7- A metal thickness gauge ( see figure).

Preparation of test sample 1- Reduce the sample using sample splitter to produce a test portion that complies with

table 2 with due allowance fo the later rejection of particles retained on a 63.0 mm test sieve and passing a 6.30 mm test sieve.

2- Dry the test portion by heating at temperature of 105+5 oC . Table 2

Nominal size of material

mm

Minimum mass of test portion after rejection of oversize and

undersize particles kg

50 35 40 15 28 5 20 2 14 1 10 0.5



Procedure 1- Carry out a sieve analysis in accordance with 7.3 of BS 812-103.1:1989 using the

standard sieves. 2- Discard all aggregates retained on the 63.0 mm test sieve and aggregates passing the

6.3 mm test sieve. 3- Weigh each of the individual size-fractions retained on the sieves, and store them in

separate trays with their size marked on the tray. 4- From the sums of the masses of the fractions in the trays(M1), calculate the individual

percentage retained on each of the various sieves. Discard any fraction whose mass is 5% or less of mass M1.Record the mass remaining (M2).

5- Gauge each fraction by using the thickness gauge : select the thickness gauge appropriate to the size-fraction under testand gauge each particle of that size-fraction separately by hand.

6- Combine and weigh all the particles passing each of the gauges (M3) Calculation and expression of the results The value of the flakiness index is calculated from the expression: Flakiness index = M3/M2 x 100

Fig.10 Thickness gauge ( Dimensions are in millimeters )



Test No.9

Method of determination of particle shape "Elongation index" BS 812-105.2:1989

Scope: The test describes the method for determining the elongation index of coarse aggregate. Principle Aggregate particles are classified as elongated when they have a length (greatest dimension) of more than 1.8 of their mean sieve size. The flakiness index of an aggregate sample is found by separating the flaky particles and expressing their mass as a percentage of the mass tested. The test is not applicable to material passing a 6.30mm BS test sieve or retained on a 50.0 mm BS test sieve. . Apparatus

1- A sample divider 2- A ventilated oven. 3- A balance accurate to 0.1% of the mass of the test portion. 4- Test sieves. 5- A mechanical sieve shaker. 6- Trays of suitable size. 7- A metal length gauge ( see figure).

Preparation of test sample 1- Reduce the sample using sample splitter to produce a test portion that complies with

table 2 with due allowance for the later rejection of particles retained on a 50.0 mm test sieve and passing a 6.30 mm test sieve.

2- Dry the test portion by heating at temperature of 105+5 oC . Table 2

Nominal size of material

mm

Minimum mass of test portion after rejection of oversize and

undersize particles kg

40 15 28 5 20 2 14 1 10 0.5



Procedure 1- Carry out a sieve analysis in accordance with 7.3 of BS 812-103.1:1989 using the

standard sieves. 2- Discard all aggregates retained on the 50.0 mm test sieve and aggregates passing the

6.3 mm test sieve. 3- Weigh each of the individual size-fractions retained on the sieves, and store them in

separate trays with their size marked on the tray. 4- From the sums of the masses of the fractions in the trays(M1), calculate the individual

percentage retained on each of the various sieves. Discard any fraction whose mass is 5% or less of mass M1.Record the mass remaining (M2).

5- Gauge each fraction as follows. Select the length gauge appropriate to the size fraction under test (see Table 3) and gauge each particle separately by hand. Elongated particles are those whose greatest dimension prevents them from passing through the gauge, and these are placed to one side. 6- Combine and weigh all the elongated particles (M3)

Calculation and expression of the results The value of the Elongation index is calculated from the expression: Elongation index = M3/M2 x 100 where M2 is the sum of the masses of fractions that have a mass greater than 5 % of the total mass. M3 is the mass of all the elongated particles. Express the elongation index to the nearest whole number

Figure 11 — Metal length gauge



Test No.10

Method for determination of water-soluble chloride salts

BS 812-117:1988

1 Scope This Part of BS 812 describes the method for determination of the water-soluble chloride salt content of aggregate. Note: In appendix A, a qualitative test is described and appendix B describes a more rapid method of test than the test described in the main text. Appendix B Field tests for determination of chloride ions Apparatus and reagents 1 Plastics bucket, capacity 10 L. 2 Water, preferably free from chloride ions. If this is not available, it is necessary to measure the chloride content of the water ( use distilled water) 3 Beakers or plastics drinking cups, of any preferred volume. 100 mL to 250 mL is the recommended range. 4 Filter paper, medium grade( Whatman No. 40 has been found suitable). 5 Balance, capable of weighing up to 10 kg accurate to 50 g. 6 Chloride test kit or strips. Note: Two commercial materials which have been found to be suitable are: a) Quantab test strips. Type 1175. (Miles Laboratories, Stoke Poges, Bucks); or b) Hach tester, Chloride 7-P. (Camlab Ltd, Cambridge.) Procedure 1 Extraction of chloride Weigh 2 kg of fine aggregate or 4 kg of coarse or mixed aggregate directly into a clean pre-weighed bucket. Weigh 2 kg of water into the bucket. Stir the materials in the bucket intermittently for at least 15 min for fine aggregate or 10 h for coarse or mixed aggregate. Note 1 One hour extraction can be used for the coarse or mixed aggregate provided the relationship between chloride extracted at 1 h and 10 h is known and can be allowed for. Note 2 These shorter extraction times may result in lower chloride contents than the standard test. When the required extraction time is complete, allow the aggregate to settle and remove some of the supernatant extraction liquid into a beaker or cup.



2 Measurement of chloride in the extract ( Using the Quantab test strip). Fold a filter paper into a cone and place it apex down in the test liquid. Place a test strip in the clear filtered solution appearing in the bottom of the filter paper cone. Follow the manufacturer’s instructions at all times. When the operation of the strip is complete read off the scale the height of the white column. Refer this reading to the calibration chart supplied with the test strip, ensuring that the chart bears the same reference number as the bottle of the test strips, and record the concentration of chloride as mg Cl–/L.



Test No.11

Methods for determination of sulphate content

BS 812-118: 1988 Scope This Part of BS 812 describes two methods for determining the sulphate content of aggregates. The first method determines the water-soluble sulphate content of aggregates, which applies to natural and synthetic aggregates to be used as drainage materials or for fill or hard core, e.g. unbound road bases or sub-bases or foundations. The second method determines the total sulphate content of aggregates, which applies to aggregates used in concrete and cement bound materials. Note1 The second method for the determination of total sulphate by acid extraction is specified as it is impractical to produce a method for the determination of total water Soluble sulphate because of low water solubility of calcium sulphate. For practical purposes for aggregates in concrete the total sulphate content determined by this method is taken to be the same as the total water-soluble sulphate content. Note2 In Appendix A two procedures for a semi-quantitative test are described. It is strongly recommended that one of these is used as a preliminary check before resorting to the test described in the main text, which may be needed for compliance with specification. Appendix A Semi-quantitative test for the presence of sulphate ions 1 Apparatus and reagents a Plastics bucket, capacity 10 L. b Beaker or plastics drinking cup. c Reagent for method 1 d Sulphate test strips6). e Stop watch. 2 Procedure i- Place approximately 5 kg of coarse aggregate or 1 kg of sand in the bucket and add an equivalent mass of water of low sulphate content. Agitate the contents intermittently for 7 h and then pour some solution into a beaker or plastics drinking cup. ii- Carry out the following procedure . Allow any solids to settle and briefly dip the sulphate test strip into the clear supernatant liquid. After 2 min observe the coloration of the three test zones. If none of the test zones has changed from red to yellow the sulphate in the aggregate can be taken to be less than 0.02 %.



Test No.12

Standard Test Method for

Organic Impurities in Fine Aggregates for Concrete ASTM C 40 – 99

Scope This test method covers two procedures for an approximate determination of the presence of injurious organic impurities in fine aggregates that are to be used in hydraulic cement mortar or concrete. One procedure uses a standard color solution and the other uses a glass color standard. Apparatus 1- Glass Bottles—Colorless glass graduated bottles, approximately 350 to 470-mL nominal capacity. The graduations on the bottles shall be in millimeters 2- Balance. Reagent and Standard Color Solution 1 Reagent Sodium Hydroxide Solution (3 %)—Dissolve 3 parts by mass of reagent grade sodium hydroxide (NaOH) in 97 parts of water. 2 Standard Color Solution—Dissolve reagent grade potassium dichromate (K2Cr2O7) in concentrated sulfuric acid (sp gr 1.84) at the rate of 0.250 g/100 mL of acid. The solution must be freshly made for the color comparison using gentle heat if necessary to effect solution. Test Sample The test sample shall have a mass of about approximately 450 g (1 lb) and be taken from the larger sample in accordance with Practice C 702. Procedure 1- Fill a glass bottle to the approximately 130-mL (41⁄2- fluid oz) level with the sample of the fine aggregate to be tested. 2- Add the sodium hydroxide solution until the volume of the fine aggregate and liquid, indicated after shaking, is approximately 200 mL (7 fluid oz). 3- Stopper the bottle, shake vigorously, and then allow to stand for 24 h. Determination of Color Value 1 Standard Color Solution Procedure—At the end of the 24-h standing period, fill a glass bottle to the approximately 75-mL (21⁄2-fluid oz) level with the fresh standard color solution, prepared not longer than 2 h previously, as prescribed above. Hold the bottle with the test sample and the bottle with the standard color solution side-by-side, and compare the color of light transmitted through the supernatant liquid above the sample with the color of light transmitted through the standard color solution. Record whether the color of the supernatant liquid is lighter, darker, or equal to the color of the standard color solution.



Test No.13

Standard Test Method for Soundness of Aggregates by Use of Sodium Sulfate or

Magnesium Sulfate

ASTM C 88 – 99a Scope This test method covers the testing of aggregates to estimate their soundness when subjected to weathering action in concrete or other applications. This is accomplished by repeated immersion in saturated solutions of sodium or magnesium sulfate followed by oven drying to partially or completely dehydrate the salt precipitated in permeable pore spaces. The internal expansive force, derived from the rehydration of the salt upon re-immersion, simulates the expansion of water on freezing. This test method furnishes information helpful in judging the soundness of aggregates when adequate information is not available from service records of the material exposed to actual weathering conditions. Apparatus 1- Sieves—With square openings of the following sizes conforming to Specifications E11 or E 323, for sieving the samples in accordance with Sections 6, 7, and 9: 150 μm (No. 100) 8.0 mm (5⁄16 in.) 9.5 mm (3⁄8 in.) 300 μm (No. 50) 12.5 mm (1⁄2 in.) 16.0 mm (5⁄8 in.) 600 μm (No. 30) 19.0 mm (3⁄4 in.) 25.0 mm (1 in.) 1.18 mm (No. 16) 31.5 mm (11⁄4 in.) 2.36 mm (No. 8) 37.5 mm (11⁄2 in.) 50 mm (2 in.) 4.00 mm (No. 5) 63 mm (21⁄2 in.) larger sizes by 4.75 mm (No. 4) 12.5-mm (1⁄2-in.) spread 2- Containers—Containers for immersing the samples of aggregate in the solution, in accordance with the procedure described in this test method, shall be perforated in such a manner as to permit free access of the solution to the sample and drainage of the solution from the sample without loss of aggregate. 3- Temperature Regulation—Suitable means for regulating the temperature of the samples during immersion in the sodium sulfate or magnesium sulfate solution shall be provided. 4- Balances—For fine aggregate, a balance or scale accurate within 0.1 g over the range required for this test; for coarse aggregate, a balance or scale accurate within 0.1 % or 1g, whichever is greater, over the range required for this test. 5- Drying Oven—The oven shall be capable of being heated continuously at 230 6 9°F (110 6 5°C) and the rate of evaporation, at this range of temperature, shall be at least 25g/h for 4 h, during which period the doors of the oven shall be kept closed. This rate shall be determined



by the loss of water from 1-L Griffin low-form beakers, each initially containing 500 g of water at a temperature of 70 + 3°F (21 + 2°C), placed at each corner and the center of each shelf of the oven. The evaporation requirement is to apply to all test locations when the oven is empty except for the beakers of water. 6- Specific Gravity Measurement—Hydrometers conforming to the requirements of Specification E 100, or a suitable combination of graduated glassware and balance, capable of measuring the solution specific gravity within +0.001. Special Solutions Required 1- Prepare the solution for immersion of test samples from either sodium or magnesium sulfate. 1.1 Sodium Sulfate Solution—Prepare a saturated solution of sodium sulfate by dissolving a USP or equal grade of the salt in water at a temperature of 77 to 86°F (25 to 30°C). Add sufficient salt (Note 4), of either the anhydrous (Na2SO4) or the crystalline (Na2SO4·10H2O) form,6 to ensure not only saturation but also the presence of excess crystals when the solution is ready for use in the tests. Thoroughly stir the mixture during the addition of the salt and stir the solution at frequent intervals until used. To reduce evaporation and prevent contamination, keep the solution covered at all times when access is not needed. Allow the solution to cool to 70 + 2°F (21 + 1°C). Again stir, and allow the solution to remain at the designated temperature for at least 48 h before use. Prior to each use, break up the salt cake, if any, in the container, stir the solution thoroughly, and determine the specific gravity of the solution. When used, the solution shall have a specific gravity not less than 1.151 nor more than 1.174. Discard a discolored solution, or filter it and check for specific gravity. 1.2 Barium Chloride Solution—Prepare 100 mL of 5 % barium chloride solution by dissolving 5 g of BaCl2 in 100 mL of distilled water. Samples 1- The sample shall be obtained in general accordance with Practice D 75 and reduced to test portion size in accordance with Practice C 702. 2- Fine Aggregate—Fine aggregate for the test shall be passed through a 9.5-mm (3⁄8-in.) sieve. The sample shall be of such size that it will yield not less than 100 g of each of the following sizes, which shall be available in amounts of 5 % or more, expressed in terms of the following sieves: Passing Sieve Retained on Sieve 600 μm (No. 30) 300 μm (No. 50) 1.18 mm (No. 16) 600 μm (No. 30) 2.36 mm (No. 8) 1.18 mm (No. 16) 4.75 mm (No. 4) 2.36 mm (No. 8) 9.5 mm (3⁄8 in.) 4.75 mm (No. 4) 3- Coarse Aggregate—Coarse aggregate for the test shall consist of material from which the sizes finer than the No. 4 sieve have been removed. The sample shall be of such a size that it will yield the following amounts of the indicated sizes that are available in amounts of 5 % or more: Size (Square-Opening Sieves) Mass, g 9.5 mm (3⁄8 in.) to 4.75 mm (No. 4) 300 + 5 19.0 mm (3⁄4 in.) to 9.5 mm (3⁄8 in.) 1000 + 10 Consisting of: 12.5-mm (1⁄2-in.) to 9.5-mm (3⁄8-in.) material 330 + 5



19.0-mm (3⁄4-in.) to 12.5-mm (1⁄2-in.) material 670 + 10 37.5-mm (11⁄2-in.) to 19.0-mm (3⁄4 in.) 1500 + 50 Consisting of: 25.0-mm (1-in.) to 19.0-mm (3⁄4-in.) material 500 + 30 37.5-mm (11⁄2-in.) to 25.0-mm (1-in.) material 1000 + 50 63-mm (21⁄2 in.) to 37.5-mm (11⁄2 in.) 5000 + 300 Consisting of: 50-mm (2 in.) to 37.5-mm (11⁄2-in.) material 2000 + 200 63-mm (21⁄2-in.) to 50-mm (2-in.) material 3000 + 300 Larger sizes by 25-mm (1-in.) spread in sieve size, each fraction 7000 + 1000 4- When an aggregate to be tested contains appreciable amounts of both fine and coarse material, having a grading with more than 10 weight % coarser than the 9.5-mm (3⁄8-in.) sieve and, also, more than 10 weight % finer than the 4.75-mm (No. 4) sieve, test separate samples of the minus No. 4 fraction and the plus No. 4 fraction in accordance with the procedures for fine aggregate and coarse aggregate, respectively. Report the results separately for the fine-aggregate fraction and the coarse-aggregate fraction, giving the percentages of the coarse and fine-size fractions in the initial grading. Preparation of Test Sample 1. Fine Aggregate—Thoroughly wash the sample of fine aggregate on a 300-μm (No. 50) sieve, dry to constant weight at 230 + 9°F (110 + 5°C), and separate into the different sizes by sieving, as follows: Make a rough separation of the graded sample by means of a nest of the standard sieves specified above. From the fractions obtained in this manner, select samples of sufficient size to yield 100 g after sieving to refusal. (In general, a 110g sample will be sufficient.) Do not use fine aggregate sticking in the meshes of the sieves in preparing the samples. Weigh samples consisting of 100 + 0.1 g out of each of the separated fractions after final sieving and place in separate containers for the test. 2. Coarse Aggregate—Thoroughly wash and dry the sample of coarse aggregate to constant weight at 230 + 6 9°F (110 + 5°C) and separate it into the different sizes shown in (3) above by sieving to refusal. Weigh out quantities of the different sizes within the tolerances of (3) and, where the test portion consists of two sizes, combine them to the designated total weight. Record the weights of the test samples and their fractional components. In the case of sizes larger than 19.0 mm (3⁄4in.), record the number of particles in the test samples. Procedure 1- Storage of Samples in Solution—Immerse the samples in the prepared solution of sodium sulfate or magnesium sulfate for not less than 16 h nor more than 18 h in such a manner that the solution covers them to a depth of at least 1⁄2 in. (Note ). Cover the containers to reduce evaporation and prevent the accidental addition of extraneous substances. Maintain the samples immersed in the solution at a temperature of 70 + 2°F (21 + 1°C) for the immersion period.



2- Drying Samples After Immersion—After the immersion period, remove the aggregate sample from the solution, permit it to drain for 15 + 5 min, and place in the drying oven. The temperature of the oven shall have been brought previously to 230 +9°F (110+5°C). Dry the samples at the specified temperature until constant weight has been achieved. Establish the time required to attain constant weight as follows: with the oven containing the maximum sample load expected, check the weight losses of test samples by removing and weighing them, without cooling, at intervals of 2 to 4 h; make enough checks to establish required drying time for the least favorable oven location. Constant weight will be considered to have been achieved when weight loss is less than 0.1 % of sample weight in 4 h of drying. After constant weight has been achieved, allow the samples to cool to room temperature, when they shall again be immersed in the prepared solution as described above. 3- Number of Cycles—Repeat the process of alternate immersion and drying until the required number of cycles is obtained. 4- After the completion of the final cycle and after the sample has cooled, wash the sample free from the sodium sulfate or magnesium sulfate as determined by the reaction of the wash water with barium chloride (BaCl2). Wash by circulating water at 230 + 9°F (110 + 5°C).through the samples in their containers. This may be done by placing them in a tank into which the hot water can be introduced near the bottom and allowed to overflow. In the washing operation, the samples shall not be subjected to impact or abrasion that may tend to break up particles. Quantitative Examination 1- Make the quantitative examination as follows: 1.1- After the sodium sulfate or magnesium sulfate has been removed, dry each fraction of the sample to constant weight at 230 + 9°F (110 + 5°C). Sieve the fine aggregate over the same sieve on which it was retained before the test, and sieve the coarse aggregate over the sieve shown below for the appropriate size of particle. For fine aggregate, the method and duration of sieving shall be the same as were used in preparing the test samples. For coarse aggregate, sieving shall be by hand, with agitation sufficient only to assure that all undersize material passes the designated sieve. No extra manipulation shall be employed to break up particles or cause them to pass the sieves. Weigh the material retained on each sieve and record each amount. The difference between each of these amounts and the initial weight of the fraction of the sample tested is the loss in the test and is to be expressed as a percentage of the initial weight for use in Table 1. Size of Aggregate Sieve used to determine loss 63 mm (21⁄2 in.) to 37.5 mm (11⁄2 in.) 31.5 mm (11⁄4 in.) 37.5 mm (11⁄2 in.) to 19.0 mm (3⁄4 in.) 16.0 mm (5⁄8 in.) 19 mm (3⁄4 in.) to 9.5 mm (3⁄8 in.) 8.0 mm (5⁄16 in.) 9.5 mm (3⁄8 in.) to 4.75 mm (No. 4) 4.0 mm (No. 5) Qualitative Examination 1 Make a qualitative examination of test samples coarser than 19.0 mm (3⁄4 in.) as follows (Note 9): 1.1 Separate the particles of each test sample into groups according to the action produced by the test (Note 9). 1.2 Record the number of particles showing each type of distress.



Report 1 Report the following data : 1.1 Weight of each fraction of each sample before test, 1.2 Material from each fraction of the sample finer than the sieve designated for sieving after test, expressed as a percentage of the original weight of the fraction, 1.3 Weighted average calculated in accordance with Test Method C 136 from the percentage of loss for each fraction, based on the grading of the sample as received for examination or, preferably, on the average grading of the material from that portion of the supply of which the sample is representative except that: 1.3.1 For fine aggregates (with less than 10 % coarser than the 9.5-mm (3⁄8-in.) sieve), assume sizes finer than the 300-μm (No. 50) sieve to have 0 % loss and sizes coarser than the 9.5-mm (3⁄8-in.) sieve to have the same loss as the next smaller size for which test data are available. 1.3.2 For coarse aggregate (with less than 10 % finer than the 4.75-mm (No. 4) sieve), assume sizes finer than the 4.75-mm (No. 4) sieve to have the same loss as the next larger size for which test data are available. 1.3.3 For an aggregate containing appreciable amounts of both fine and coarse material tested as two separate samples as required in 6.4, compute the weighted average losses separately for the minus No. 4 and plus No. 4 fractions based on recomputed grading considering the fine fraction as 100 % and the coarse fraction as 100 %. Report the results separately giving the percentage of the minus No. 4 and plus No.4 material in the initial grading. 1.3.4 For the purpose of calculating the weighted average, consider any sizes in 6.2 or 6.3 that contain less than 5 % of the sample to have the same loss as the average of the next smaller and the next larger size, or if one of these sizes is absent, to have the same loss as the next larger or next smaller size, whichever is present. 1.4 Report the weighted percentage loss to the nearest whole number, 1.5 In the case of particles coarser than 19.0 mm (3⁄4 in.) before test: (1) The number of particles in each fraction before test, and (2) the number of particles affected, classified as to number disintegrating, splitting, crumbling, cracking, flaking, etc., as shown in Table 2, and 1.6 Kind of solution (sodium or magnesium sulfate) and whether the solution was freshly prepared or previously used.



TABLE 1 Suggested Form for Recording Test Data (with Illustrative Test Values)

Original sample Fractions % passing % loss % Before Test, g Designated sieve After test _____________________________________________________________________________________________________________

Soundness Test of Fine Aggregate Minus 150 μm (No. 100) 6 ... ... ... 300 μm (No. 50) to No. 100 11 ... ... ... 600 μm (No. 30) to No. 50 26 100 4.2 1.1 1.18 mm (No. 16) to No. 30 25 100 4.8 1.2 2.36 mm (No. 8) to No. 16 17 100 8.0 1.4 4.75 mm (No. 4) to No. 8 11 100 11.2 1.2 9.5 mm (3⁄8 in.) to No. 4 4 ... 11.2a 0.4 Totals 100.0 ... ... 5

Soundness Test of Coarse Aggregate 63 mm (21⁄2 in.) to 50 mm (2 in.) 2825 g 50 mm (2 in.) to 37.5 mm (11⁄2 in.) 1958 g 20 4783 4.8 1.0 37.5 mm (11⁄2 in.) to 25.0 mm (1 in.) 1012 g 25 mm (1 in.) to 19.0 mm (3⁄4 in.) 513 g 45 1525 8.0 3.6 19.0 mm (3⁄4 in.) to 12.5 mm (1⁄2 in.) 675 g 12.5 mm (in.) to 9.5 mm (in.) 333 g 23 1008 9.6 2.2 9.5 mm (3⁄8 in.) to 4.75 mm (No. 4) 298 g 12 298 11.2 1.3

Totals 100.0 ... ... 8 A The percentage loss (11.2 %) of the next smaller size is used as the percentage loss for this size, since this size contains less than 5 % of the original sample as received.



Cement Tests

Test No. 14

“Fineness of Hydraulic Cement by No.100 or No. 200 Sieve”

(ASTM C 184-83)

Scope: This test method covers determination of the finesses of hydraulic cement by means of the 150 µm (No.100) and 75µm (No.200) sieves.

Apparatus:- 1. Sieve:- Standard 150 µm (No.100) or 75µm (No.200) sieves. 2. Balance and weights. 3. Brush: a bristle brush will be required for use in cleaning the 150 µm or 75µm sieve. 4. A pan and a cover for the sieve.

Procedure: 1. Place 50-gm sample of the cement on the clean, dry (No.100) or (No.200) sieve with the pan attached. 2. While holding the sieve and uncovered pan in both hands, sieve with a gentle wrist motion until most of the fine material has passed through and the residue looks fairly clean (3 or 4 minutes). 3. Place the cover on the sieve and remove the pan. 4.With the sieve and cover held firmly in one hand, gently tap the side of the sieve with the handle of the brush used for cleaning the sieve. 5.Empty the pan and wipe it out with a cloth, replace the sieve in the pan and carefully remove the cover . 6. Continue sieving without the cover for 5 to 10 min or until not more than (0.05gm) of the material passes through in 1 minutes of continuous sieving. 7.Carefully open the set and transfer the residue on the sieve to a white clean paper, and record the weight. 8. Calculate the percentage residue as:

% residue = wt. of residue x 100 50

9. Specifications requires that %retained on sieve (No.200) Shall not exceed 22%. and on sieve (No.100) not more than 10%.



Test No.15

“Normal Consistency of Hydraulic Cement”

ASTM ( C 187-86)

Scope: This test method cover the determination of the normal consistency of hydraulic cement. That is by determining the amount of water required to prepare cement pastes for Initial and final time of setting test.

Apparatus: 1.Weight and weighing devices. 2. Glass graduates (200 or 250) ml capacity. 3. Vicat apparatus with the plunger end, 10 mm in diameter. 4.Electrical mixer , trowel and containers. 5. Mixing glass plate 30cm x 30cm.

Procedure:

1- Weigh 400 g of cement and prepare the weight of water to be between 24% to 30% of the cement, then place the dry paddle and the dry bowl in the mixing position in the mixer.

2- Place all the mixing water in the bowl.

3- Add the cement to the water and allow 30 s for a absorption of the water.

4- Start the mixer at low speed for 30 s

5- Stop for (15 s) and make sure no materials have collected on the sides of the bowel.

6- Start mixing at medium speed for (1 min).

7- Quickly form the cement paste into the approximate shape of a ball with gloved hands

8- Putting hand at (15cm) distance, throw the cement paste ball from hand to hand six times.

9- Press the ball into the larger end of the conical ring, completely fill the ring with paste.

10- Remove the excess at the larger end by a single movement of the palm of the hand. Place the ring on its larger end on the base of the plate of Vicat apparatus.



11- Slice off the excess paste at the smaller end at the top of the ring by a single sharp- ended trowel and smooth the top. (Take care not to compress the paste).

12- Center the paste under the plunger end which shall be brought in contact with the surface of the paste, and tighten the set-screw.

13- Set the movable indicator to the upper zero mark of the scale or take an initial reading, and release the rod immediately. This must not exceed 30 seconds after completion of mixing.

14- The paste shall be of normal consistency when the rod settles to a point 10±1mm below the original surface in 30 seconds after being released.

15- . Make trial paste with varying percentages of water until the normal consistency is obtained. Make each trial with fresh cement.

16- . Prepare a table in the form:

Penetration (mm) Water Volume (ml)

Weight of cement (gm)

W/c

24% 26% 28% 30%

17. Draw the penetration — w/c curve.

pent.(mm)

w/c

18. From the curve state the w/c% which will give (10mm) that is the percentage for Normal Consistency.



Fig.(12) The Vicat Apparatus.



Test No.16

“Initial and Final Time of Setting of Cement”

(ASTM C191-82)

Scope: This test covers determination of the time of Setting of cement by means of the Vicat needle.

Apparatus: 1. Vicat Apparatus with the needle end, 1mm in diameter. 2. Weights and weighing Device. 3. Glass Graduates (200 or 250) ml capacity. 4. A trowel and containers.

Procedure: 1. Weigh (400) gm cement. 2. Prepare amount of water as to that calculated in normal consistency test. 3. Prepare a cement paste following same steps mentioned in the previous test (test No. 9). Place in Vicat conical ring like test No. 9. Don't forget to record the time since the cement is added to the water. 4. Allow the time of setting specimen to remain in the moist cabinet for 30 minutes after molding without being disturbed. Determine the Penetration of the 1mm needle at this time and every (15) minutes until a penetration of 25mm or less is obtained 5. To read the penetration, lower the needle of Vicat Apparatus until it touches the surface of the cement paste. Tighten the screw and take an initial reading. Release the set screw and allow the needle to settle for 30 seconds, and then take the reading to determine the penetration. 6. Note that no penetration shall be made closer than (6mm) from any previous penetration and no penetration shall be made closer than (9.5mm) from the inside of the mold. Record the results of all penetration, then by drawing a curve determine the time when a penetration of 25 mm is obtained. This is the initial setting time 7. The final setting time is when the needle dose not sinks visible into the paste. 8. Draw a graph for (penetration — time). Show the time which gives penetration of (25 mm) this will be the initial setting time.

Note:

According to ASTM C150

Initial time of setting, not less than 45 min.

Final time of setting, not more than 375 min



Test No.17

“Density and Specific Gravity of cement”

(ASTM C188-87)

Scope: This test covers determination of the density of cement and its specific gravity. The density of cement is defined as the mass of a unit volume of the solids.

Apparatus: 1- Le chatelire flask: the standard flask which is circular in cross section with special shape and dimensions 2- Kerosene, free of water. 3- Balance. 4- Holder. 5- Water bath.

Procedure: 1- Fill the flask with Kerosene to a point on the stem between 0 and 1ml mark. 2- Put the flask in the water bath at a constant temperature for a sufficient period of time in order to avoid flask temperature variations greater than 0.2 °C between the initial and final readings. 3- Record the final reading on the flask. 4- Prepare (64) gm of cement weighed to the nearest (0.05) gm and place it in the flask in small increments. Take care to avoid splashing and see that the cement dose not adheres to the inside of the flask above the liquid. 5- After all the cement has been introduced, place the stopper in the flask and roll the flask in an inclined position so as to free the cement from air until no further air bubbles rise to the surface of the liquid. 6- Put the flask in the water bath as in step (2). 7- Take the final reading.

Calculations: 1- The difference between the first and the final readings represents the volume of liquid displaced by the mass of cement used in the test. 2- Calculate the cement density ρ as:

Mass of cement cement = ρ Volume

Specific Gravity = ρ cement / ρ water



Fig.(13) Le Chatelire flask.



Test No. 18

“Compressive Strength of Hydraulic Cement Mortars''

''Using 50 mm Cube Specimens”

( ASTM C109-88 )

Scope This test method covers determination of the compressive strength of cement mortars, using 2 in ( 50 mm ) cube specimens.

Apparatus 1- Weights and weighing device. 2- Glass Graduate . 3- Specimens molds: three cubes of (50mm) side. 4- Mixer ( electrically driven mechanical mixer of the type equipped with paddle and mixing bowl). 5- Testing machine. 6- Tamper and trowel.

Materials:

Graded standard sand should be used (C778) . with cement in the proportion 1 Cement : 2.75 Sand by weight. Use water – cement ratio of 0.485 for all Portland cements and 0.460 for all air- entraining Portland cements.

Note: For other than Portland and air- entraining Portland cements, do flow table test , to determine the amount of mixing water.

Procedure:

A. Preparation of Mortar :-

1. Weigh (300)gm of cement and Prepare the corresponding weights of standard sand and water.

2. Place the dry paddle and the dry bowl in the mixing position in the mixer . Then introduce the materials for a batch into the bowl and mix in the following manner: i- Place all the mixing water in the bowl. ii-Add the cement to the water, then start the mixer and mix at the low speed (140± 5 r/ min) for (30 s).



iii-Add the entire quantity of sand slowly over a (30 s) period , while mixing at slow speed.

.s30 and mix for ) min/r10 +285 (e to medium speed chang, Stop the mixer-iv v-Stop the mixer and let the mortar stand for 1.5 min . During the first (15 s) of this interval, quickly scrape down into the batch any mortar that may have collected on the side of the bowl. vi-Finish by mixing for (1min) at medium speed.

B-Molding test specimens: i-Thinly cover the interior faces of the specimen molds with oil. ii-Start molding the specimens within a total time of not more than 2.5 min after completion of mixing . iii-Place a layer of mortar a bout 25 mm (half the depth of the mold ) in all the cube specimens . iv- Tamp the mortar in each cube 32 times (4x8) , about 4 rounds , each round to be at right angles to the other.

The tamping pressure shall be just sufficient to insure uniform filling of the molds. v- The 4 rounds of taming shall be completed in one cube before going to the next . vi-When the tamping of the first layer in all cubes is completed , fill the molds with

the remaining mortar and tamp as specified for the first layer . vii- Cut off the mortar to a plane surface with a straight edge. viii- Keep the molds in a moist room for 20-24 hours then open them and keep the specimens in a water basin for a week.

C-Testing specimens:

dry them with a, take the specimens out of the basin, ) hours3 +(days 7 After -1 clean cloth , put them, one after the other, in the testing machine. 2- The cubes must be put on one side , using extra steel plates up and down the specimen .

) in a minute 3- Start loading in a speed of 1.4 kN /sec or (350 kg /cm2

4- When failure, record load and the compressive strength.

:Calculations 1-Table the results:

Compressive strength( MPa) Load(kN) Cube No.

17

8

34

526

45

67

8

32

1



2- Compare with [ ASTM C150-89]: σc ≥ 19.3 MPa [ For type I cement ] age 7 days (Fig. 14 )The mixer to be used to mix the mortar (Fig.15) The specimens molds



Test No. 19

Tensile Strength of Cement Mortar

(ASTM C 190-85)

: Scope This test method covers the determination of the tensile strength of cement mortars employing the Briquet specimens.

: Apparatus 1- Weights and weighing device. 2- Tools and containers for mixing. 3- Briquet molds. 4- Water basin. 5- Testing Machine.

-:Procedure

1- The proportions of materials for the standard mortar shall be 1 part of cement to 3 parts standard sand by weight .For making 3 briquets, prepare 300 gm of cement with 3x300 = 900 gm of standard sand. The percentage of water used in the standard mortar shall depend upon the percentage of water required to produce a neat cement paste of normal consistency from the same sample of cement as in table (1).

Table 1- Percentage of water for standard Mortars

Water for Mortar of 1part Cement to 3 parts standard Sand

%

Water for neat cement paste of Normal Consistency %

9 15 9.2 16 9.3 17 9.5 18 9.7 19 9.8 20 10 21

10.2 22 10.3 23 10.5 24 10.7 25 10.8 26 11 27

11.2 28 11.3 29 11.5 30



:Note

The values being in percentage of the combined dry weights of the cement and standard sand.

2-Mix dry cement with dry sand and make a crater in the middle, then pour water in the crater, and turn the material on the outer edge into the crater within 30 seconds by the aid of

a trowel. 3- After an additional interval of 30 seconds for the absorption of the water, mix

thoroughly for 1.5 minutes. 4- Prepare Briquet molds, clean and thinly covered with a film of mineral oil. 5- Fill the molds heaping full without compacting, then press the mortar in, firmly with the thumbs, applying the force 12 times to each Briquet at points to include the entire surface. 6- Heap the mortar above the mold and smooth it off with a trowel. 7- Cover the mold with a plane glass and turn over the mold and plates. Remove the

top plate and repeat the operation of heaping, thumbing and smoothing off. 8- Keep all test specimens in moist room for 24 hours. 9-Open molds and immerse the specimens in water in the storage tank. Keep them in water for a week. 10- Take specimens out of water, dry with clean cloth then fix them in the testing machine (one after the other). 11-Record the load causing failure and the cross-sectional area at the fracture point.

-:Calculation

Load causing failure (P) Tensile strength σt = -------------------------------------------------

Area at the fracture (A)

:Note According to [ ASTM C 150-58] σt ≥ 1896 kPa [ For type 1cement → 1days in moist air +6 days in water ]



(Fig.16) The testing machine for cement mortar specimens in tension.

(Fig.17) The briqute molds.



خواص وفحوصات مواد الخرسانة لجزء النظري ا

المفردات . مقدمة وتعريف-1 .Aggregateالرآام -2 .المصدر والوزن, ملمس السطح , المقاس , الشكل : تصنيفه حسب -ا :. خواص الرآام -ب

. الخوص المطلوبة للمطابقة مع المواصفات-1 . المواصفات المطلوبة لحسابات تصميم خلطة خرسانية-2 .رطوبة في الرآام حاالت ال-ج . المواد الضارة في الرآام-د .Cement االسمنت -3 ).نبذة مختصرة( صناعة االسمنت -ا .النديت خواص االسمنت البور-ب .Hydration عملية االماهة -ج . اآتساب المقاومة-د .النديت أنواع السمنت البور-ـه . الخواص الفيزيائية لالسمنت- و : الماء-4 . ماء الخلط- ا . ماء المعالجة- ب



مقدمة وتعاريف oncrete Cالخرسانة

أي إن المكونات ,تضم داخلها حبيبات الرآام) االسمنت والماء(هي مادة مرآبة تتكون بشكل رئيسي من مادة الصقة :األساسية للخرسانة هي

االسمنت -1 الرآام-2 الماء-3 المضافات-4

:االسمنت .مادة مكونة من خليط من مواد غير عضوية تتماسك وتكتسب المقاومة بواسطة تفاعل آيميائي مع الماء

:الرآام

الماء لتشكيل وتستخدم مع االسمنت , الحجارة المكسرة أو خبث أفران الحديد، الحصى ،مثل الرمل مادة حبيبية .والتقلصد التمدد ضغير المكلف اقتصاديا ويوفر ثبات حجمي للخرسانة يمثل الرآام الجزء المالئ .الخرسانة او المونة

:الماء

والدمكيل تجعلها قابلة للوضع غهذا العنصر المهم للحصول على التفاعل مع االسمنت وآذلك إلعطاء الخلطة قابلية للتش .في القالب

:المضافات

الخلط لتحسين صفات الخرسانة الطازجة أو الخرسانة حديثة مواد آيميائية يمكن إضافتها للخرسانة قبل أو خالل عملية .الصب أو الخرسانة المتصلدة من ناحية اقتصادية أو فيزيائية

Aggregateالرآام ل و يمث ى 70ه ل % 75 إل بة ألج ات المناس شكل وبالكمي اره بال ام باختي ب االهتم ذا يج انة ،ل ي للخرس م الكل ن الحج م

.سيطرة النوعية على المنشآت الخرسانية الناتجةال :تصنيف الرآام

:باإلمكان تصنيف الرآام حسب اآلتي : الحجم-1 .ويسمى الرمل ) ملم 5 ملم او 4.75( قطر منوهو الرآام ذو الحبيبات اصغر : الرآام الصغير- ا .) ملم5 او ملم 4.75( قطرمنوهو الرآام ذو الحبيبات اآبر : الرآام الكبير-ب : المصدر-2ار وممكن أن يكون رمل أو حصى أو : الرآام الطبيعي - ا وهو الرآام الناتج عن عوامل التعرية الجوية او جريان األنه

.حجارة آبيرة طبيعية يتم تكسيرها إلى مقاسات مناسبة ل الحصول ع : الرآام الصناعي -ب وزن أو وهو الرآام الذي يتم إنتاجه ألغراض خاصة مث ام خفيف ال ى رآ ممكن أن ل

.يكون ناتج جانبي إلحدى الصناعات



:وحدة الوزن -3 .3م/ آغم1800 - 1500تكون وحدة الوزن له بين : الرآام ذو الوزن العادي- ار الحجم ) Pumic(مثل وهو قد يكون طبيعي : الرآام خفيف الوزن - ب ة ،او صناعي صغير او آبي وهي حجارة برآاني

.3م/ آغم1000وحدة الوزن له اقل من . الحاجة ويصنع عادة للحصول على خرسانة خفيفة الوزنحسبيستخدم عند الرغبة في الحصول على خرسانة عالية الكثافة في مالجئ اإلشعاعات واألغراض : الرآام ثقيل الوزن - ج

المصدراو صناعي) Barytes( المصدريوقد يكون طبيع . 3م/ آغم1800تكون وحدة الوزن له اآبر من . العسكرية ) Lead shots. ( : شكل الحبيبات-4

يل الخرسانة ، فالمستديرة تقلل االحتكاك بين الحبيبات والمساحة السطحية التي يجب غيؤثر شكل الحبيبات على قابلية تشاال ان . ذات الزوايا او غير المنتظمة ان تغلفها مونة االسمنت تكون اقل وبذلك تعطي قابلية للتشغيل افضل من الحبيبات

:ويمكن تصنيف االشكال آالتالي . الحبيبات ذات الزوايا توفر مقاومة افضل للخرسانة . المستديرة-1 . غير المنتظمة-2 . الزاوًية-3 . المفلطحة-4 . المستطالة-5

.ام في الخرسانةالمستديرة وغير المنتظمة والزاوًية هي األشكال األنسب لالستخد : ملمس السطح-5

الحبيبات الناعمة الملمس تعطي خرسانة ذات قابلية تشغيل أفضل إال أن المقاومة تكون اآبر عند استخدام حبيبات خشنة .الملمس بسبب زيادة الربط الناتج

:خواص الرآام

:. الخواص المطلوبة للمقارنة مع المواصفات-ا . التدرج الحبيبي-1 . مقاومة التهشم بفعل الخدش-2 . مايكرون75 الناعمة اصغر من قياس وجود المواد-3 . وجود آتل طينية-4 ) .soundness( الثبات -5 . نسبة وجود ايونات الكلور او الكبريتات-6 . نسبة التفلطح او االستطالة في الحبيبات-7 . وجود مواد عضوية في الرمل -8 :مطلوبة لتصميم الخلطات الخواص ال-ب

. الوزن النوعي االمتصاصي-1 . محتوى الرطوبة-2 . وحدة الوزن المدموك -3 . المقاس االقصى ومعامل النعومة-4

.وسنتكلم ببعض التفصيل عن آل هذه الخواص المذآورة أعاله : الخواص المطلوبة للمقارنة مع المواصفات-ا : التدرج الحبيبي-1

دام حبيبات ذات مقاسات مختلفة تتدرج في المقاس من اآبر مقاس الى اصغر مقاس بالرمل لتمكن الرآام يفضل استخمن التداخل مع بعضه للحصول على اقل ما يمكن من الفراغات التي يتطلب ملؤها بالمونة االسمنتية وآذلك لتقليل

.فرصة انعزال الخرسانة خالل النقل والصب :عل الخدش مقاومة التهشم بف-2

.هذه الخاصية مهمة بشكل خاص عند استخدام الخرسانة لتعبيد الطرق او لألسطح المعرضة للتعرية



: وجود مواد ناعمة أو آتل طينية في الرآام -4 ، 3

ة اإلسمنتية ام والمون ين الرآ ربط ب واد الطي . قد تغلف المواد الطينية حبيبات الرآام وذلك سيقلل ال ة وسواء أآانت الم نيا فهي سبب صغر حجمه ك ب تشكل غالف على الحبيبات او موجودة مع الرآام فان وجودها يغير بالخلطة الخرسانية وذل

. تؤثر على خواص الخرسانة الناتجةوتزيد المساحة السطحية للرآام وبذلك تحتاج إلى آمية اآبر من المونة اإلسمنتية :soundness الثبات -5

لحبيبات للمحافظة على سالمتها وعدم حصول تغيرات فيزيائية اوميكانيكية اوآيميائية فيها لدرجة ويعرف بانه قابلية ا .تؤثر فيها على خواص الخرسانة الناتجة في الناحية الهندسية او الجمالية

ت من اسباب عدم ثبات الحبيبات هو ما تتعرض له الخرسانة من تغيرات حجمية بفعل االنجماد والذوبان ،التغيرا .الحرارية ، البلل والجفاف

: وجود ايونات الكلور او الكبريتات -6 دية وتسبب الكبريتات فقد تخفض المقاومة الحوجود ايونات الكلور ممكن ان يسبب صدأ حديد التسليح ،اما ايونات

.التفتت بسبب التمدد : االستطالة او التفلطح -7

عندما تكون النسبة بين المساحة . لتيها الطازجة او المتصلدة شكل الحبيبات يؤثر على خواص الخرسانة في حاالسطحية للحبيبات الى حجمها عالية فان ذلك يخفض قابلية تشغيل الخرسانة ،وهذا يتوفر في الحبيبات المفلطحة و

لخرسانة والحبيبات المفلطحة ايضا قد تحجز الماء او فراغات هوائية تحتها مما يؤثر على ديمومة ا. المستطالة)Durability.( : وجود شوائب عضوية في الرمل-8

الرآام الطبيعي عادة يكون بالمقاومة المطلوبة ومقاوم للتآآل لكنه يصبح غير مناسب للخرسانة اذا احتوى على شوائب .تها بالغسلويكون احتمال وجودها بالرمل اآثر من الرآام الكبير ويمكن ازال. عضوية النها تؤثر على عملية االماهة

: الخواص المطلوبة لتصميم خلطة خرسانية -ب : االمتصاص والوزن النوعي -1

هو الزيادة في وزن الرآام بسبب وجود الماء في الفراغات الموجودة داخل الحبيبات وال يشمل : االمتصاص - * نسب الخلط عند معرفة محتوى ويستخدم لتصحيح. ويعبر عنه آنسبة مئوية من الوزن الجاف . الرطوبة السطحية

.الرطوبة الماء المقطر عند درجة منحجم معين من مادة الى وزن نفس الحجم ) بالهواء( نسبة وزن : الوزن النوعي - *

.وهو مقدار بال وحدات . حرارة معينة الى وزن ) فذةت غير المنحجم بدون الفراغا(حجم معين من المادة ) بالهواء( نسبة وزن : الوزن النوعي الظاهري - *

. الماء المقطر في درجة حرارة معينة حجم مساوي له منيشمل الحجم حجم الفراغات المنفذة وغير (حجم معين من المادة ) بالهواء( نسبة وزن : الوزن النوعي الكلي - *

لحساب حجم الرآام في ويستخدم. الماء المقطر عند درجة حرارة معينة منإلى وزن حجم مساوي له ) ة المنفذ . المختلفة ولحساب نسبة الفراغات في تجربة وحدة الوزناتالخلط

يتضمن وزن الماء الموجود بالفراغات ( نسبة الوزن بالهواء لحجم في المادة ) : S S D( الوزن النوعي الكلي - *ويستخدم اذا . قطر بدرجة حرارة معينة الماء الممنالى وزن حجم مساوي له ) ساعة بالماء 24وذلك بغمر الحبيبات

.آان الرآام رطب : محتوى الرطوبة-2

عند عمل تصميم لخلطة خرسانية يجب معرفة محتوى الرطوبة لكل من الرمل والرآام الكبير وذلك لتصحيح نسب الخلط .مع معرفة نسبة االمتصاص لكل منها

: الكثافة الكلية للرآام -3 . 3م/ آغمـوتقاس بال. والحجم هنا يشمل حجم الرآام والفراغات البينية بين الحبيبات أيضا. ام آتلة حجم معين من الرآ

في حجم معين من الرآام هي المسافات البينية بين الحبيبات وال تشمل الفراغات داخل الحبيبات voidsالفراغات اما .رسانية بطريقة المعهد االمريكيوتستخدم الكثافة الكلية لحسابات تصميم الخلطات الخ .نفسها



: المقاس األقصى للرآام ومعامل المرونة-4 ويعرف بأنه اصغر مقاس منخل يمكن لمعظم حبيبات الرآام أن :Nominal Max Size المقاس االقصى الظاهري- *

وبذلك نحصل على مقاومة أفضل وبزيادة المقاس األقصى للرآام تقل الحاجة إلى المونة االسمنتية والماء. تمر من خالله .بنفس قابلية التشغيل إال أن هناك دائما حدود للمقاس األقصى اعتمادا على العمل نفسه والمواصفات

هو معامل يحسب بجمع نسبة المواد المتبقية على آل من المناخل : معامل النعومة - *150µm,300µm,600µm,1.8mm,2.36mm,4.75mm,9.5mm,19mm,37.5mm divided by(100)

:حاالت الرطوبة في الرآام المسامية والنفاذية واالمتصاص في الرآام يؤثر آل منها على الربط بين الرآام والمونة االسمنتية وعلى مقاومة

.الخرسانة لتأثير االنجماد والذوبان وآذلك على االستقرارية الكيميائية ومقاومة الخدش والوزن النوعي ).S.SD) . (مشبع جاف السطح(ل الفراغات مملؤة بالماء والسطح جاف تسمى حالةعندما تكون آ

لكن اذا جفف بالفرن للتخلص من آل ). air dry(وعندما تتبخر بعض الرطوبة في الفراغات يتحول الى جاف بالهواء ) .Oven dryجاف بالفرن (الرطوبة فيتحول بذلك الرآام الى

.عندما تكون آل الفراغات مشبعة وآذلك هناك رطوبة سطحية ايضا) moist or wet(ويكون الرآام رطب او مبلول

: وجودالمواد الضارة في الرآامالطين،الطمى،غبار الطباشير :مثل مع الرآام هناك بعض المواد تكون مضرة بالخرسانة في حالة وجودها بكميات آافية

.بعض تلك المواد يمكن ازالته بالغسل . وغيرها :اخذ النماذج واجراء الفحوصات

:عند إجراء أي فحص يجب تذآر اآلتي . يجب إجراء الفحص تماما بنفس الطريقة آل مرة-1 يجب اختيار النموذج المفحوص بعناية . النموذج المستخدم للفحص يجب ان يعبر بشكل حقيقي عن الكمية آلها-2

.وعمل تقسيم ربعي له

Cementاالسمنت مل والرآام يجري التفاعل بين االسمنت والماء مكونا نواتج تفاعل تقوم بربط الر, د خلط مواد الخرسانة مع بعض عن

.يل الخرسانةالكبير مع المونة لتشك وممكن أن تستمر هذه العملية لوقت طويل بشرط مالئمة درجة الحرارة hydrationعملية التفاعل هذه تسمى االماهة

.وهو تفاعل آيميائيوتوفر الرطوبة،

:صناعة االسمنت :باختصار الجل صناعة االسمنت يتم خلط حجارة آلسية مع حجارة رملية النتاج االسمنت وبالمراحل التالية

. مايكرومتر75 يا الى حوالالمواد الخام وتكسر ثم يًصغر حجمهتخلط : التكسير والتنعيم- :ضها مع بعاد هناك اسلوبين لخلط المو: الخلط -

الخلط الجاف تنقل الحبيبات في تيار عند استخدام في حين . آكتلة طينية غليظة القوامالخلط الرطب حيث تخلط المواد .تفضل الطريقة الجافة النها تستهلك طاقة اقل. هوائي الى الفرن

: التسخين-وقد تصل . فية لسحب اي ماء من الخليط يضخ الخليط الى فرن دوار مائل بمقدار بسيط وتكون الحرارة آا: 1المرحلة •

.م وتزداد درجة الحرارة تدريجيا مع طول الفرن7م طول وقطر 230ابعاد الفرن الى و يتحول الى الطباشير مع آربونات الكالسيوم م حيث يتحلل600Oترفع درجة حرارة الخليط الى حوالي : 2المرحلة •

) .Quick Lime ( حيجيرمن المواد تتحول إلى سائل وبعدها % 30-20م و 01500رة في هذه المرحلة تصل الى حوالي الحرا: 3المرحلة •

.تنصهر مكونة آرات الكلنكر



.وهو ضروري لتجنب تلوث الهواء الجوي بغبار االسمنت : سحب الهواء - اء الداخل إلى الفرن ويكون يسقط الكلنكر في أحواض لتبريده وتستخدم الحرارة المنبعثة لرفع حرارة الهو: الكلنكر -

.ملم ) 25 -2(حجم حبيبات الكلنكر في هذه المرحلة ) 80-2(يتحول حجم الحبيبات الى . نكر مع الجبس ويسحقان مع بعض إلنتاج االسمنت يخلط الكل: سحق الكلنكر -

.وتتم إضافة الجبس لتجنب التصلب السريع لالسمنت بمجرد إضافة الماء. نمايكرو

:. االسمنت البورتالنديخواص :يتكون الكلنكر من أربع مرآبات أولية ،يلعب آل منها دورا خاصا في عملية االماهة، وهي

C4AF C3A C2S C3S Tetracalcium Alimino-

ferrite Tricalcium Aluminate

Dicalcium Silicate Tricalcium Silicate

.مرآبات وباختالفها يمكن الحصول على انواع مختلفة من االسمنت وتعتمد خواص االسمنت على نسب وجود هذه ال

:عملية االماهةعند خلط االسمنت مع الماء تبدأ سلسلة من التفاعالت الكيميائية تنتج عنها نواتج تفاعل تشكل فيما بعد مونة الخرسانة

).HCP(المتصلبة وذلك ( ويجب السيطرة عليه لتجنب التصلب السريع والماء وهو أسرع التفاعالتC3Aاول تفاعل يحصل هو بين

وبتكون نواتج التفاعل تبطأ عملية االماهة الن النواتج تحجز الماء عن حبيبات االسمنت وهذه الفترة ) بإضافة الجبس .مهمة ألنها تسمح بنقل الخرسانة إلى موقع صبها ودمكها تبدأ المرحلة الثانية من التفاعل حيث تبدأ قابلية التشغيل بعد فترة تتكسر تلك الحواجز الناتجة عن نواتج التفاعل

. باالنخفاض المصدر الرئيسي لمقاومة االسمنتC3S ،يعتبر C2S و C3S ـأهم تفاعل يؤدي إلى اآتساب المقاومة هو تفاعل ال

.تفاعله أبطأ لكنه يضيف للمقاومة بشكل مؤثر C2S في حين المبكرة .ومة الكثير لكنه مسؤول عن تحرر آمية من الحرارة في األيام األولى من التفاعل ال يضيف للمقاC3Aتفاعل .ويعتبر السبب األساسي للون االسمنت الرمادي. يضيف للمقاومة شي بسيطC4AFتفاعل

.ويوضح المخطط أدناه تأثير آل مرآب على المقاومة وآذلك االنبعاث الحراري



:أنواع االسمنت البورتالندي يتم صناع انواع عديدة من االسمنت البورتالندي حسب المواصفات

ASTMC150 , AASHTo M85 , ASTM C1157

)عادي:( Iنوع ات خاصة بنوع االسمنت مثل استخدامه لصناعة خرسانة للطرقات تكون هناك متطلب ويستخدم لالغراض العامة عندما ال

.، لألرضيات ، المنشات الخرسانية المسلحة ، الجسور ، الخزانات ، المستودعات ، األنابيب ، الكتل الخرسانية :IIنوع

.ويستخدم عند وجود أمالح الكبريتات بشكل متوسط مثل الخرسانة المعرضة للتربة او المياه الجوفية :IIIنوع

وفيه يتم سحق الحبيبات بدرجة أآثر نعومة ليعطي مقاومة أبكر وذلك عند الحاجة لرفع القوالب بوقت قصير أو عند .الحاجة إلى استخدام المنشأ بوقت قريب

:IVنوع عمل خرسانة ويستخدم ل. يستخدم عند الحاجة الن تكون الحرارة المنبعثة اقل ما يمكن ، ويتم اآتساب المقاومة ببطء

.آتلية مثل السدود :Vنوع

.Iويستخدم عندما تكون الخرسانة معرضة لكبريتات بنسبة عالية وتكتسب المقاومة ببطء مقارنة بالنوع : هناك انواع اخرى مثل *

داالسمنت البورتالندي ذو الهواء المقصو . وغيرهااالسمنت البورتالندي ابيض اللون

:منتالخواص الفيزيائية لالس، آلما زادت نعومة االسمنت زادت سرعة )االماهة( تؤثر النعومة على الحرارة الناتجة وعلى سرعة التفاعل : النعومة -

.التفاعل وبذلك تعجل اآتساب المقاومة .وتحسب نعومة االسمنت اما باستخدام فحص واآنر او باستخدام المناخل او باستخدام التحليل المنخلي باالشعة

والفحص المعني بها هو . نة االسمنتة المتصلبة للمحافظة على حجمها ي وهو يعني قابلية العج:بات الحجمي الث- BS حسب الـ soundnessفحص .ASTM حسب The autoclave-expansionفحص

صل بها اختراق هو مقياس لقدرة العجينة للجريان ، وتعتبر عجينة االسمنت ذات قوام قياسي اذا ح: القوام القياسي - . ASTM ملم باستخدام جهاز فايكت حسب المواصفات االمريكية 1±10بقدر

هذا الزمن من لحظة اضافة الماء الى االسمنت الى حين تحول العجينة الى لدنة ويعتبر هذا زمن : زمن التماسك - هذا زمن التماسك النهائي الجل التماسك االبتدائي و الزمن المطلوب للعجينة لتصل الى درجة تصلب معينة ويعتبر

.المقارنة مع المواصفات ملم من عجينة اسمنتية تعمل باستخدام رمل قياسي مع االسمنت 50ويتم قياسها بعمل مكعبات بضلع : مقاومة الضغط -

. وتفحص بعدها ASTMوالماء وذلك حسب المواصفات االمريكية . 3سم/وتقاس بالغرام) بدون الهواء بين الحبيبات(دة الحجم لحبيبات االسمنت وهي الكتلة لوح:الكثافة والوزن النوعي -

3.15بمعدل ) 3.25-3.1(بين وتتراوح لالسمنت البورتالندي



ماء الخلط في الخرسانة .باختصار أي ماء يصلح للشرب وخالي من الطعم والرائحة ،يمكن استخدامه لخلط الخرسانة

. تصلح للشرب ومع ذلك يمكن استخدامها لخلط الخرسانةهناك بعض انواع المياه ال التاآد من صالحية الماء لالستخدام بالخرسانة وذلك باجراء فحص مقاومة االنضغاط لمونة االسمنت واذا حصلنا ويتم

عن مقاومة انضغاط مكعبات اخرى من نفس االسمنت لكن باستخدام ماء مقطر او ماء % 90على مقاومة التقل عن .فان الماء يصلح لعمل الخرسانة . ح للشرب صال

.آذلك يجب التاآد من صالحية الماء من ناحية تاثيره على زمن التماسك االبتدائي والنهائي رغم ذلك فان الماء غير الصالح للشرب قد يؤدي استخدامه بالخرسانة الى حصول بقع على الخرسانة او صدا لحديد

).durability (يقلل الديمومةعدم ثبات حجمي وقد التسليح او

ماء معالجة الخرسانة .بشكل عام ،الماء المناسب لخلط الخرسانة يكون مناسب ايضا لمعالجة او رش الخرسانة

.يجي ان يخلو ماء المعالجة من الحديد او المواد العضوية او ثاني اآسيد الكربون الحر او هيدروآسيد الكالسيوم الذائب

properties and testing of concrete materials

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