PUBLIC WORKS DEPARTMENT SANTKABIRNAGAR

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CONTENT

PWD OVERVIEW INTRODUCTION ROAD AND PAVEMENT TYPES OF PAVEMENT TYPES OF CONCRETE PAVEMENT USED MATERIAL CEMENT SAND AGGREGATE CONCRETE PROPORTIONING TEST PROCEDURE OF CONSTRUCT THE PAVEMENT

PREPARATION OF BASE FORM WORKING PREPARATION OF SUBGRADE WATERING OF BASE JOINTS MATERIAL MIX & PLACING COMPACTION FINISHING

FLOATING BELTING BROOMING

CURING JOINT FILLING EDGING OPEN TO TRAFFIC

ROAD VERGE COST ANALYSIS OF RIGID PAVEMENT CONCLUSION

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A

SUMMER TRAINING REPORT

ON

CONSTRUCTION OF CEMENT CONCRETE ROAD

AT

U.P.P.W.D. SANTKABIR NAGAR

SUBMITTED FOR PARTIAL FULFILLMENT OF

BACHELOR OF TECHNOLOGY

CIVIL ENGINEERING

SUBMITTED TO:- SUBMITTED BY:-Mr. V.K.SRIVASTAVA Vikas Kumar Mishra (HOD of Civil Engg. Department.) B.Tech - 4th yr (Civil Engg) Mr. PUNEET SHUKLA (Faculty of Civil Engg. Department) Guided By:- Er. V.P. Singh Executive Engineer (PUBLIC WORKS DEPARTMENT)

INSTITUTE OF TECHNOLOGY AND MANAGEMENT3

AL-1 Sector-7, GIDA , GorakhpurBatch:- 2016-2017

Name of Work :-- Construction of CC RoadAgreement no. :-- 04/CR/CE-III/2016-2017Name of Contractor :-- Roshan real estate pvt ltd.Plot size :-- 59845 Sqm Area

Estimated Cost :-- civil work 60147287 Elec.Work 2475332 Total Cost 62622609

Tendered cost :-- Civil work 65788182 Elec. Work 2869490

Date of Start :-- May 29, 2016Stipulated date of completion :-- May 26, 2017Actual Date of Completion :-- work is under processTime Allowed :-- 365 days

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Acknowledgement

It is indeed a great pleasure and privilege to present this report on training at PUBLIC WORKS DEPARTMENT.

I am extremely grateful to my training and placement officer for issuing a training letter, which made my training possible at PUBLIC WORKS DEPARTMENT Gorakhpur.

I would like to express my gratitude to Er. V.P.SINGH for his invaluable suggestions, motivation, guidance and support throughout the training. His methodology to start from simple ant then deepen through made me to bring out this project report without anxiety.

Thanks to all other PUBLIC WORKS DEPARTMENT officials, operators and all other members of PUBLIC WORKS DEPARTMENT, yet uncounted for their help in completing the project and see the light of success.

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I am very thankful to my friend, collegues and all other persons who rendred their assistance directly or indirectly to complete this project work successfully..

Dated :- July 8,2016

PUBLIC WORKS DEPARTMENT : AN OVERVIEW

PUBLIC WORKS DEPARTMENT under the ministry of PUBLIC WORKS DEPARTMENT is the pioneer in construction arena of UTTAR P RADESH. Over about four centuries, PUBLIC WORKS DEPARTMENT could successfully set the trend and standard the state’s infrastructure development. It plays a pivotal role in the implementation of govt. construction project. It also undertakes project for autonomous bodies as deposit works. PUBLIC WORKS DEPARTMENT has highly qualified and experienced professionals forming a multi-disciplinary team of civil, electrical and mechanical engineers who work alongside architects from the Department of Architecture. With its base of standards

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and professionals developed over the years. PUBLIC WORKS DEPARTMENT is the repository of expertise and hence the first choices among discerning clients for any type of construction project in Uttar Pradesh. Besides being the construction agency of the govt. it performs regulatory function in setting the pace and managing project for the country’s construction industry under the close supervision of the ministry of housing and public works..

Planning of PUBLIC WORKS DEPARTMENT project mainly includes:---

Pre requisites for execution of works Deposite of works Preparation of estimates Execution of original works Expeniture on survey, exhibition Register of buildings Green building norms

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Preparation and accounting of standard measurement book

Preparation and passing bills for payment Documentation of accounts General departmental charges Contracts and forms Preparation of tender documents Publicity of tenders Sale of documents Earnest of money Issue of material to contractors Issue of tool and plant Payment to contractors Insurance Losses and damages Budgeting Quality assurance and technical audit wing Inspection and audit by chief controller Public accounts committee..

INTRODUCTION

Point of view geographic and population of the state is the nation’s largest state. State industrial , economic and social development of the state and the population of each village is absolutely necessary to reconnect to the main roads. In addition to state important national roads, state roads and district roads and their proper broad be made to improve the quality of traffic point of view is of particular importance. PUBLIC WORKS DEPARTMENT to

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build roads and improve connectivity in rural zones, other district roads and state broad and improvement of rural roads and main routes narrow construction of zones and depleted bridges reconstruction of the bases and transacted on a priority basis. Also under Pradhan mantri Gram Sadak Yojna and pre fabricated construction of rural roads linking the work of other district roads broad Suddikrn the scale bases are edited.

Successful operation of various schemes for the PUBLIC WORKS DEPARTMENT engineers and supervisory boards in different districts of the engineer’s office has been settled. Activities by planning, execution and quality control etc. remove impediments find joy in relation to the supervision over the activities and focused. Various schemes operated by the department of the office of the regional chief engineers and chief engineers’ office..

Road The Organization for Economic Co-operation and Development (OECD) defines a road as "a line of

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communication (travelled way) using a stabilized base other than rails or air strips open to public traffic, primarily for the use of road motor vehicles running on their own wheels," which includes "bridges, tunnels, supporting structures, junctions, crossings, interchanges, and toll roads, but not cycle paths. Construction

Road surface   or   pavement is the durable surface material laid down on an area intended to sustain vehicular or foot traffic, such as aroad or walkway. In the past, gravel road surfaces, cobblestone and granite setts were extensively used, but these surfaces have mostly been replaced by asphalt or concrete laid on a compacted base course. Road surfaces are frequently marked to guide traffic. Today,permeable paving methods are beginning to be used for low-impact roadways and walkways.

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Types of Pavements :--There are various type of pavements depending upon the materials used. A briefs description of all types is given here.  Flexible Pavements

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a)Bitumen has been widely used in the construction of flexible pavements for a long time. This is the most convenient and simple type of construction. The cost of construction of single lane bituminous pavement varies from 20 to 30 lakhs per km in plain areas. In summer season, due to high temperature, the bitumen becomes soft resulting in bleeding, rutting and segregation finally leading to failure of pavement.

b)In Winter season, due to low temperature, the bitumen becomes brittle resulting in cracking, raveling and unevenness which makes the pavement unsuitable for use.

c) In rainy season, water enters the pavement resulting into pot holes and sometimes total removal of bituminous layer.

d)In hilly areas, due to sub zero temperature, the freeze thaw and heave cycle takes place. Due to freezing and melting of ice in bituminous voids, volume expansion and contraction occur. This leads to pavements failure.

e)The cost of bitumen has been rising continuously. In near future, there will be scarcity of bitumen and it will be impossible to procure bitumen at very high costs.

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Semi Rigid Pavements

The pavements constructed using the waste materials, which are more strong the traditional aggregates may be treated as Semi-Rigid Pavement.  

Rigid Pavements

i. Rigid pavements, though costly in initial investment, are cheap in long run because of low maintenance costs. There are various merits in the use of Rigid pavements (Concrete pavements) are summarized below:

ii. Bitumen is derived from petroleum crude, which is in short supply globally and the price of which has been rising steeply. India imports nearly 70% of the petroleum crude. The demand for bitumen in the coming years is likely to grow steeply, far outstripping the availability. Hence it will be in India's interest to explore alternative binders. Cement is available in sufficient quantity in India, and its availability in the future is also assured. Thus cement concrete roads should be the obvious choice in future road programmes.

iii. Besides the easy available of cement, concrete roads have a long life and are practically maintenance-free.

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iv. Another major advantage of concrete roads is the savings in fuel by commercial vehicles to an extent of 14-20%. The fuel savings themselves can support a large programme of concreting.

v. Cement concrete roads save a substantial quantity of stone aggregates and this factor must be considered when a choice pavements is made,

vi. Concrete roads can withstand extreme weather conditions – wide ranging temperatures, heavy rainfall and water logging.

vii. Though cement concrete roads may cost slightly more than a flexible pavement initially, they are economical when whole-life-costing is considered.

viii. Reduction in the cost of concrete pavements can be brought about by developing semi-self-compacting concrete techniques and the use of closely spaced thin joints. R&D efforts should be initiated in this area.

WaterWater used for mixing of the cement concrete, and also that used for curing of the cement concrete road construction shall be clean and portable. The water should be free from salt, acid, oil and other organic matter.

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Admixture in   Cement Concrete Road ConstructionCommonly used chemical admixture in the cement concrete road construction are:i. To improve the workability of the concrete; a suitable

air entraining agent may be used.

ii. To provide an adequate extension of setting time of the concrete mix without adversely affecting the other desirable properties of the concrete; super-plasticizers which retard the setting time may be used. The total quality of chemical admixture used is limited to a maximum of 2.0 %by weight of the cement or used.

SteelSteel dowel bars with yield strength 2400 kg/sq. cm or 240 Mpa is used for the load transfer across in the expansion joints and construction joints of cement concrete roads. Plan or twisted steel bars are used as tie bars at longitudinal joints. All steel rods shall be coated with epoxy paint for protection against corrosion.

Concrete

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Concrete is a composite material composed of coarse aggregate bonded together with a fluid cement which hardens over time. Most concretes used are lime-based concretes such as Portland cement concrete or concretes made with other hydraulic cements, such asciment fondu. However, asphalt concrete which is very frequently used for road surfaces is also a type of concrete, where the cement material is bitumen, and polymer concretes are sometimes used where the cementing material is a polymer.In Portland cement concrete (and other hydraulic cement concretes), when the aggregate is mixed together with the dry cement and water, they form a fluid mass that is easily molded into shape. The cement reacts chemically with the water and other ingredients to form a hard matrix which binds all the materials together into a durable stone-like material that has many uses.[2] Often, additives (such as pozzolans orsuperplasticizers) are included in the mixture to improve the physical properties of the wet mix or the finished material. Most concrete is poured with reinforcing materials (such as rebar) embedded to provide tensile strength, yielding reinforced concrete. Composition of concrete

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There are many types of concrete available, created by varying the proportions of the main ingredients below. In this way or by substitution for the cementitious and aggregate phases, the finished product can be tailored to its application with varying strength, density, or chemical and thermal resistance properties.Aggregate consists of large chunks of material in a concrete mix, generally a coarse gravel or crushed rocks such as limestone, or granite, along with finer materials such as sand.Cement, most commonly Portland cement, is associated with the general term "concrete." A range of materials can be used as the cement in concrete. One of the most familiar of these alternative cements is asphalt concrete. Other cementitious materials such as fly ash and slag cement, are sometimes added as mineral admixtures (see below) - either pre-blended with the cement or directly as a concrete component - and become a part of the binder for the aggregate.To produce concrete from most cements (excluding asphalt), water is mixed with the dry powder and aggregate, which produces a semi-liquid that workers can shape, typically by pouring it into a form. The concrete solidifies and hardens through a chemical process called hydration. The water reacts with the cement, which bonds the other components together, creating a robust stone-like material.

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Chemical admixtures are added to achieve varied properties. These ingredients may accelerate or slow down the rate at which the concrete hardens, and impart many other useful properties including increased tensile strength, entrainment of air, and/or water resistance.Reinforcement is often included in concrete. Concrete can be formulated with high compressive strength, but always has lower tensile strength. For this reason it is usually reinforced with materials that are strong in tension, often steel.Mineral admixtures are becoming more popular in recent decades. The use of recycled materials as concrete ingredients has been gaining popularity because of increasingly stringent environmental legislation, and the discovery that such materials often have complementary and valuable properties. The most conspicuous of these are fly ash, a by-product of coal-fired power plants, ground granulated blast furnace slag, and silica fume, a byproduct of industrial electric arc furnaces. The use of these materials in concrete reduces the amount of resources required, as the mineral admixtures act as a partial cement replacement. This displaces some cement production, an energetically expensive and environmentally problematic process, while reducing the amount of industrial waste that must be disposed of. Mineral admixtures can be pre-blended with the cement during its production for sale and use as a blended cement, or mixed directly with other components when the concrete is produced.

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CementPortland cement is the most common type of cement in general usage. It is a basic ingredient of concrete, mortar and many plasters. English masonry worker Joseph Aspdin patented Portland cement in 1824. It was named because of the similarity of its color to Portland limestone, quarried from the English Isle of Portland and used extensively in London architecture. It consists of a mixture of calcium silicates (alite, belite), aluminates and ferrites - compounds which combine calcium, silicon, aluminium and iron in forms which will react with water. Portland cement and similar materials are made by heating limestone (a source of calcium) with clay and/or shale (a source of silicon, aluminium and iron) and grinding this product (called clinker) with a source of sulfate (most commonly gypsum).

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In modern cement kilns many advanced features are used to lower the fuel consumption per ton of clinker produced. Cement kilns are extremely large, complex, and inherently dusty industrial installations, and have emissions which must be controlled. Even complex and efficient kilns require 3.3 to 3.6 gigajoules of energy to produce a ton of clinker and then grind it into cement. Many kilns can be fueled with difficult-to-dispose-of wastes, the most common being used tires. The extremely high temperatures and long periods of time at those temperatures allows cement kilns to efficiently and completely burn even difficult-to-use fuels.

WaterCombining water with a cementitious material forms a cement paste by the process of hydration. The cement paste glues the aggregate together, fills voids within it, and makes it flow more freely.[24]

A lower water-to-cement ratio yields a stronger, more durable concrete, whereas more water gives a freer-flowing concrete with a higher slump.[25] Impure water used to make concrete can cause problems when setting or in causing premature failure of the structure.[26]

Hydration involves many different reactions, often occurring at the same time. As the reactions proceed, the products of the cement hydration process gradually bond together the individual sand and gravel particles and other components of the concrete to form a solid mass.[27]

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Reaction: Cement chemist notation: C3S + H → C-S-H + CHStandard notation: Ca3SiO5 + H2O → (CaO)·(SiO2)·(H2O)(gel) + Ca(OH)2

Balanced: 2Ca3SiO5 + 7H2O → 3(CaO)·2(SiO2)·4(H2O)(gel) + 3Ca(OH)2 (approximately; the exact ratios of the CaO, SiO2 and H2O in C-S-H can vary)ReinforcementConcrete is strong in compression, as the aggregate efficiently carries the compression load. However, it is weak in tension as the cement holding the aggregate in place can crack, allowing the structure to fail. Reinforced concrete adds either steel reinforcing bars, steel fibers, to carry tensile loadFly ash : A by-product of coal-fired electric generating plants, it is used to partially replace Portland cement (by up to 60% by mass). The properties of fly ash depend on the type of coal burnt. In general, siliceous fly ash is pozzolanic, while calcareous fly ash has latent hydraulic properties. Ground granulated blast furnace slag (GGBFS or GGBS): A by-product of steel production is used to partially replace Portland cement (by up to 80% by mass). It has latent hydraulic properties.[

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Silica fume : A byproduct of the production of silicon and ferrosilicon alloys. Silica fume is similar to fly ash, but has a particle size 100 times smaller. This results in a higher surface-to-volume ratio and a much faster pozzolanic reaction. Silica fume is used to increase strength and durability of concrete, but generally requires the use of super plasticizers for workability. High reactivity   Met kaolin   (HRM): Met kaolin produces concrete with strength and durability similar to concrete made with silica fume. While silica fume is usually dark gray or black in color, high-reactivity met kaolin is usually bright white in color, making it the preferred choice for architectural concrete where appearance is important.Carbon nanofibres can be added to concrete to enhance compressive strength and higher Young’s modulus, and also to improve the electrical properties required for strain monitoring, damage evaluation and self-health monitoring of concrete. has many advantages in terms of mechanical and electrical properties (e.g. higher strength ) and self-monitoring behavior due to the high tensile strength and high conductivity.

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Workability

Workability is the ability of a fresh (plastic) concrete mix to fill the form/mold properly with the desired work (vibration) and without reducing the concrete's quality. Workability depends on water content, aggregate (shape and size distribution), cementitious content and age (level of hydration) and can be modified by adding chemical admixtures, like superplasticizer. Raising the water content or adding chemical admixtures increases concrete workability. Excessive water leads to increased bleeding and/or segregation of aggregates (when the cement and aggregates start to separate), with the resulting concrete having reduced quality. The use of an aggregate with an undesirable gradation[clarification needed] can result in a very harsh mix design with a very low slump, which cannot readily be made more workable by addition of reasonable amounts of water. Workability can be measured by the concrete slump test, a simplistic measure of the plasticity of a fresh batch of concrete following theASTM C 143 or EN 12350-2 test standards. Slump is normally measured by filling an "Abrams cone" with a sample from a fresh batch of concrete. The cone is placed with the wide end down onto a level, non-absorptive surface. It is then filled in three layers of equal volume, with each layer being tamped with a steel rod to consolidate the layer. When the cone is

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carefully lifted off, the enclosed material slumps a certain amount, owing to gravity. A relatively dry sample slumps very little, having a slump value of one or two inches (25 or 50 mm) out of one foot (305 mm). A relatively wet concrete sample may slump as much as eight inches. Workability can also be measured by the flow table test.

Curing A common misconception is that concrete dries as it sets, but the opposite is true - damp concrete sets better than dry concrete. In other words, cement is "hydraulic": water allows it to gain strength. Too much water is counterproductive, but too little water is deleterious. Curing allows concrete to achieve optimal strength and hardness.[47] Curing is the hydration process that occurs after the concrete has been placed. In chemical terms, curing allows calcium-silicate hydrate (C-S-H) to form. To gain strength and harden fully, concrete curing requires time. In around 4 weeks, typically over 90% of the final strength is reached, although strengthening may continue for decades.[48]The conversion of calcium hydroxide in the concrete into calcium carbonate from absorption of CO2 over several decades further strengthens the concrete and makes it more resistant to damage. This carbonation reaction, however, lowers the pH of the cement pore solution and can corrode the reinforcement bars. Hydration and hardening of concrete during the first three days is critical. Abnormally fast drying and shrinkage due to factors such as evaporation from wind during placement may lead to increased tensile stresses

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at a time when it has not yet gained sufficient strength, resulting in greater shrinkage cracking. The early strength of the concrete can be increased if it is kept damp during the curing process. Minimizing stress prior to curing minimizes cracking. High-early-strength concrete is designed to hydrate faster, often by increased use of cement that increases shrinkage and cracking. The strength of concrete changes (increases) for up to three years. It depends on cross-section dimension of elements and conditions of structure exploitation.[49] Properly curing concrete leads to increased strength and lower permeability and avoids cracking where the surface dries out prematurely. Care must also be taken to avoid freezing or overheating due to the exothermic setting of cement. Improper curing can cause scaling, reduced strength, poor abrasion resistance and cracking.

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Surface finishesBlack basalt polished concrete floorRaw concrete surfaces tend to be porous, and have a relatively uninteresting appearance. Many different finishes can be applied to improve the appearance and preserve the surface against staining, water penetration, and freezing.The proper treatment of the surface of concrete, and therefore its characteristics, is an important stage in the construction and renovation of architectural structure

Concrete roads Concrete roads are more fuel efficient to drive on,[64] more reflective and last significantly longer than other paving surfaces, yet have a much smaller market share than other paving solutions. Modern paving methods and design practices have changed the economics of concrete paving, so that a well designed and placed concrete pavement will be less expensive on initial costs and significantly less expensive over the life cycle. Another major benefit is that pervious concrete can be used, which eliminates the need to place storm drainsnear the road, and reducing the need for slightly sloped roadway to help rainwater to run off. No longer requiring to discard the rainwater using drains also means that less electricity is needed (more pumping is otherwise needed in the water distribution system), and no rainwater gets polluted as it no longer mixes with polluted water; rather it is immediately absorbed by the ground.

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Fire safetyConcrete buildings are more resistant to fire than those constructed using steel frames, since concrete has lower heat conductivity than steel and can thus last longer under the same fire conditions. Concrete is sometimes used as a fire protection for steel frames, for the same effect as above. Concrete also provides good resistance against externally applied forces such as high winds, hurricanes, and tornadoes owing to its lateral stiffness, which results in minimal horizontal movement. Earthquake safetyAs discussed above, concrete is very strong in compression, but weak in tension. Larger earthquakes can generate very large shear loads on structures. These shear loads subject the structure to both tensile and compressional loads. Concrete structures without reinforcement, like other unreinforced masonry structures, can fail during severe earthquake shaking. Unreinforced masonry structures constitute one of the largest earthquake risks globally. These risks can be reduced through seismic retrofitting of at-risk buildings,

Concrete is used to create hard surfaces that contribute to surface runoff, which can cause heavy soil erosion, water pollution, and flooding, but conversely can be used to divert, dam, and control flooding.

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Concrete is a contributor to the urban heat island effect, though less so than asphalt. Workers who cut, grind or polish concrete are at risk of inhaling airborne silica, which can lead to silicosis.[82] Concrete dust released by building demolition and natural disasters can be a major source of dangerous air pollution.The presence of some substances in concrete, including useful and unwanted additives, can cause health concerns due to toxicity and radioactivity. Fresh concrete (before curing is complete) is highly alkaline and must be handled with proper protective equipment

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PROPORTIONINGCement, sand and coarse aggregates should be measure according to their fixed proportions.  Make a standard measuring box according to the volume of one cement bag. Volume of one cement bag is 1.25 cubic foot.Bulking of sand should be under consideration while measuring sand proportion. Consider dry sand while calculation of proportioning. Measure the moisture content in sand and add extra volume of sand. Continuously measure moisture content during construction work and add extra volume of sand according to the amount of moisture. Don’t compact coarse aggregates while proportioning.

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Particle Shape and Surface Texture   – the particle shape and surface texture of both coarse and fine aggregates have a significant influence on the properties of the plastic concrete. Rough textured, angular, or elongated particles require more water to produce workable concrete than smooth, rounded, compact aggregates, and as a result, these aggregates require more cementing materials to maintain the same water-cement ratio. Angular or poorly graded aggregates may result in the production of concrete that is more difficult to pump and also may be more difficult to finish. The hardened concrete strength will generally increase with increasing coarse aggregate angularity, and flat or elongated coarse aggregate particles should be avoided Rounded fine aggregate particles are more desirable because of their positive effect on plastic concrete workability.Durability   – resistance to freezing and thawing is necessary for concrete aggregates, and is related to the aggregate porosity, absorption, permeability, and pore structure.Deleterious Materials   – aggregates should be free of potentially deleterious materials such as clay lumps, shales, or other friable particles, and other materials that could affect its chemical stability, weathering resistance, or volumetric stability.

Concrete Slump Test

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The concrete slump test is used for the measurement of a property of fresh concrete. The test is an empirical test that measures the workability of fresh concrete. More specifically, it measures consistency between batches. The test is popular due to the simplicity of apparatus used and simple procedure.PrincipleThe slump test result is a measure of the behavior of a compacted inverted cone of concrete under the action of gravity. It measures the consistency or the wetness of concrete.

Apparatusi. Slump coneii. Scale for measurementiii. Temping rod (steel)

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Procedure of Concrete Slump test:

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a)The mold for the slump test is a frustum of a cone, 300 mm (12 in) of height. The base is 200 mm (8in) in diameter and it has a smaller opening at the top of 100 mm (4 in).

b)The base is placed on a smooth surface and the container is filled with concrete in three layers, whose workability is to be tested .

c) Each layer is temped 25 times with a standard 16 mm (5/8 in) diameter steel rod, rounded at the end.

d)When the mold is completely filled with concrete, the top surface is struck off (leveled with mould top opening) by means of screening and rolling motion of the temping rod.

e)The mould must be firmly held against its base during the entire operation so that it could not move due to the pouring of concrete and this can be done by means of handles or foot - rests brazed to the mould.

f) Immediately after filling is completed and the concrete is leveled, the cone is slowly and carefully lifted vertically, an unsupported concrete will now slump.

g)The decrease in the height of the center of the slumped concrete is called slump.

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h)The slump is measured by placing the cone just besides the slump concrete and the temping rod is placed over the cone so that it should also come over the area of slumped concrete.

i) The decrease in height of concrete to that of mould is noted with scale. (usually measured to the nearest 5 mm (1/4 in).

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PrecautionsIn order to reduce the influence on slump of the variation in the surface friction, the inside of the mould and its base should be moistened at the beginning of every test, and prior to lifting of the mould the area immediately around the base of the cone should be cleaned from concrete which may have dropped accidentally.

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Types Of SlumpThe slumped concrete takes various shapes, and according to the profile of slumped concrete, the slump is termed as;

a)Collapse Slumb)Shear Slumpc) True Slump

Collapse SlumpIn a collapse slump the concrete collapses completely. A collapse slump will generally mean that the mix is too wet or that it is a high workability mix, for which slump test is not appropriate.

Shear SlumpIn a shear slump the top portion of the concrete shears off and slips sideways. ORIf one-half of the cone slides down an inclined plane, the slump is said to be a shear slump.If a shear or collapse slump is achieved, a fresh sample should be taken and the test is repeated.

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If the shear slump persists, as may the case with harsh mixes, this is an indication of lack of cohesion of the mix.

True SlumpIn a true slump the concrete simply subsides, keeping more or less to shapeThis is the only slump which is used in various tests.Mixes of stiff consistence have a Zero slump, so that in the rather dry range no variation can be detected between mixes of different workiability.However , in a lean mix with a tendency to harshness, a true slump can easily change to the shear slump type or even to collapse, and widely different values of slump can be obtained in different samples from the same mix; thus, the slump test is unreliable for lean mixes.

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SUBGRADESUsing information from a deliberate soil survey as outlined in Chapter 2 of FM 5-530, consider the following factors when determining the suitability of a subgrade:General characteristics of the subgrade soils.Depth to bedrock.Depth to the water table.Compaction that can be attained in the subgrade.CBR values of uncompacted and compacted subgrades.Presence of weak or soft layers or organics in the subsoil.Susceptibility to detrimental frost action or excessive swell.

COMPACTIONCompaction normally increases the strength of subgrade soils. A specification block should be used to determine limits for density and moisture content.

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Compaction is relatively simple in fill sections because all the layers are subjected to construction processes and can be compacted during construction. Compaction is more difficult in cut sections. Compaction must be obtained during construction to a depth at which the natural density of the material will resist further consolidation under traffic

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SELECTION OF BASE COURSESelection of the type of base-course construction depends on the materials and equipment available and the anticipated weather conditions during construction. A complete investigation should be made to determine the location and characteristics of all natural materials suitable for base-course construction. Base courses of untreated natural materials are less affected by adverse weather and normally require less technical control. Untreated bases are relatively easy and fast to build and are preferable to bituminous or cement-stabilized types. This is true even where suitable admixture materials for such construction are readily available, which is not true in many areas of the world.

Fine GradingThe subgrade is fine graded to achieve the desired cross section established by final grade stakes. Before placing select material, subbase, and base course, the subgrade should be compacted to attain the required density, and ruts and other soft spots should be corrected. Hauling, Placing, and Spreading

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Placing and spreading material on the prepared subgrade may begin at the point nearest the borrow source or at the point farthest from the source. The advantage of working from the point nearest the source is that the haul vehicles can be routed over the spread material, which compacts the base and avoids damage to the subgrade. An advantage of working from the point farthest from the source is that hauling equipment will further compact the subgrade. Also, this practice will not overwork the base course, which can cause unwanted segregation. This method also reveals any weak spots in the subgrade so that they can be corrected prior to placement of the base courses, and interferes less with spreading and compaction equipment.The self-propelled aggregate spreader is the preferred piece of equipment for placing a base course. If a self-propelled spreader is not available, base-course material can be spread using towed spreaders, scrapers, or dump trucks. If equipment capable of spreading the aggregate in even lifts is not available, the material can be initially dumped in long windrows and subsequently spread with graders, dozers, or front-end loaders.Lift thickness should be based on the ability to compact the material to the required density. A good rule of thumb is to initially place the base course in 6-inch lifts. After testing the compacted density, increase or decrease the lift thickness as necessary to meet the project requirements.

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Blending and MixingMaterials to be blended and mixed should be spread on the road, runway, or taxiway in correct proportions, with the finer material on top. Fold the fine material into the coarser aggregate with the grader blade. If available, dry-mix the material using blades, disks, harrows, or rototillers, leaving the material in windrows. When a grader is used, thoroughly mix the materials by blading the windrows of materials from one side of the area to the other, with the blade of the grader set to give a rolling action to the material. The coarse and fine aggregates can also be mixed in mechanical plants (mobile or stationary) or on a paved area with graders and bucket loaders. Proportionally distribute the coarse and fine aggregates by weight or volume in quantities so that the specified gradation, LL, and PI requirements are attained after the base has been placed and compacted. Mixing operations should produce uniform blending.When mechanical mixing is used, place the coarse and fine aggregates in separate stockpiles or adjacent windrows to permit easy proportioning. When bucket loaders are used, place the fine-and coarse-aggregate portions in adjacent windrows on a paved area. Blade the windrows together to meet the requirements specified for the project.Watering Base Materials

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As in subgrade-compaction operations, obtaining the specified compacted density requires that the material be placed and compacted at a moisture content inside the specification block. The moisture content of the base material at the site can be obtained by a nuclear densometer, a speedy moisture tester, or by expedient methods. Given the on-site moisture content, the engineer in charge can calculate exactly how much water is to be added or if the base needs to be aerated to achieve the specified moisture content range.Controlled watering can be done with a truck-mounted water distributor. Asphalt distributors should not be used because the pump lubrication system is not designed for water. Any container capable of movement and gravity discharge of water may be used as an expedient water distributor.Compacting

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Base-course compacting must produce a uniformly dense layer that conforms to the specification block. Compact base-course material with vibratory or heavy, rubber-tired rollers. Maintain moisture content during the compaction procedure within the specified moisture-content range. Compact each layer through the full depth to the required density. Measure field densities on the total sample. Use a test strip to determine which rollers are most effective and how many roller passes are necessary to achieve the desired compaction. The care and judgment used when constructing the base course will directly reflect on the quality of the finished flexible pavement. Base-course layers that contain gravel and soil-binder material may be compacted initially with a sheepsfoot roller and rubber-tired rollers. Rubber-tired rollers are particularly effective in compacting base materials if a kneading motion is required to adjust and pack the particles. Base courses of crushed rock, lime rock, and shell are compacted with vibratory, steel-wheeled, or rubber-tired rollers. Select the equipment and methods on each job to suit the characteristics of the base material. When using rollers, begin compaction on the outside edges and work inward, overlapping passes by one-half of a roller width.

Finishing

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Finishing operations must closely follow compaction to furnish a crowned, light, water-shedding surface free of ruts and depressions that would inhibit runoff. Use the grader for finishing compacted aggregate bases. Blade the material from one side of the runway, taxiway, or road to the middle and back to the edge until the required lines and grades are obtained. Before final rolling, the bladed material must be within the specified moisture-content range so it will consolidate with the underlying material to form a dense, unyielding mass. If this is not done, thin layers of the material will not be bound to the base, and peeling and scabbing may result. Final rolling is done with rubber-tired and steel-wheeled rollers.Preparing SubgradeIf a macadam base course is constructed on a material with high plasticity, there may be base infiltration. This can be prevented with a blanket course of fine material such as crusher screenings or 3 to 4 inches of sand. The blanket course should be lightly moistened and rolled to a smooth surface before spreading the coarse macadam aggregate. A membrane or a geotextile fabric may be used in lieu of the blanket course.Spreading

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Macadam aggregate must be placed and spread carefully to ensure that hauling vehicles do not add objectionable material to the aggregate. Care is particularly necessary when placing the aggregate at the point nearest to the source and routing hauling vehicles over the spread material. If the compacted thickness of the lift is 4 inches or less, spread the loose macadam aggregate in a uniform layer of sufficient depth to meet requirements. For greater compacted thickness, apply the aggregate successively in two or more layers. Spreading should be from dump boards, towed aggregate spreaders, or moving vehicles that distribute the material in a uniform layer. When more than one layer is required, construction procedures are identical for all layers.

CompactingImmediately following spreading, compact the coarse aggregate the full width of the strip by rolling it with a steel-wheeled roller. Rolling should progress gradually from the sides to the middle of each strip in a crown section, and from the low side to the high side where there is a transverse slope across the road, runway, or taxiway. Continue rolling until the absence of creep or wave movement of the aggregate ahead of the roller indicates that the aggregate is stable. Do not attempt rolling when the subgrade is softened by rain.Finished Surfaces

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The base-course surface determines the smoothness of the finished pavement. If the finished base dots not conform to the specified grade when tested with a 12-foot straightedge, the finished pavement also will not conform. The base surface should be smooth and conform to specified design requirements.When tested with a 12-foot straightedge applied parallel and perpendicular to the centerline of the paved area, the surface of the base course should not show any deviation in excess of 3/4 inch for roads and airfields Correct any deviation in excess of these figures, and remove material to the total depth of the lift, replacing with new material and compacting as specified above.Applying WaterWet rolling does not require the large amount of water demanded for slush rolling, and the base course does not need to go through the curing period required by the slush-rolling method. Apply enough water to the base course to raise the moisture content of the upper 1 to 2 inches of the base course to approximately 2 percentage points above the minimum moisture content. The percent of moisture will vary with the type of material and is a matter of judgement by the project's quality control managerFinishing

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Finish the surface by having the grader blade lightly cut the final surface. The light blading will loosen the fines; the coarser particles of the base course will be carried along by the blade to form a windrow at the edge of the section being finished. This coarse aggregate can be evenly distributed over the area and incorporated into the surface of the base by a steel-wheeled roller closely following the grader. Additional water may be required, and rolling by the steel-wheeled and pneumatic-tired rollers must be continued until a smooth, dense surface is obtained. This method can also be used for correcting minor surface irregularities in the base coursen Soil StabilizationSoil Stabilization is the alteration of soils to enhance their physical properties. Stabilization can increase the shear strength of a soil and/or control the shrink-swell properties of a soil, thus improving the load bearing

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capacity of a subgrade to support pavements and

foundation.

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Edging and Kerbs

Kerbs (raise or flat edging) are typically used on the edge of roads and side-walks.  The profile (shape) and height of kerbs vary according to the application.Kerbing is a versatile product that provides both a neat finish as well as practical uses.  The most obvious function of kerbs is to guide storm water to catchment structures and precision measurements are required to ensure that no puddles are formed.Two construction methods are used for the installation of kerbs and edging; in-situ casting or packing pre-manufactured blocks (pre-cast).Using pre-cast kerbsFor pre-cast kerbs a foundation is dug, filled with a suitable stabilized mixture and then the kerbing blocks are positioned carefully according to horizontal and vertical measurements.  Every block is individually aligned and secured into position with the stabilized mixture before the openings between the blocks are filled with cement by experienced masons to create a neatly finished product.  This construction method is very labor-intensive creating jobs for a vast array of skilled, semi-skilled and unskilled laborers.Casting kerbs in-situ  

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In-situ kerbing is most cost-effective where long stretches of edging are required.  With in-situ (on site casting) the kerbing strip is cast with a “moving mould” (kerbing machine) in the correct position and finished by hand.  Although the concrete mixture for this process may vary according to application, every mixture requires specific ratios of the various materials (typically coarse gravel, river stone, sand, water and cement) to achieve the neat, yet strong final product..

Conclusions

Based on the above discussion, following conclusions are made:Concrete roads are good roads but not cheaper roads. These roads should be considered only if sufficient funds are available. The thickness of the pavement and the reinforcement should not be compromised.

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Semi Rigid pavements should be constructed in nearby areas of steel plants where these materials are available free of cost. In this regard, Government may pass an ordinance for compulsory use of these materials in such areas.Bitumen is going to more costly in future. So it should be used very judiciously. Modification like CR, EVA and SBS may be used to reduce the susceptibility of the bitumen. It will reduce the quantity of bitumen also.

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