ALTERNATE AND LOW COST CONSTRUCTION MATERIALSRice Husk Ash

Ground Granulated Blast Furnace Slag

Rice Husk Ash (RHA)RHA is an available waste material in the developing countries from paddy mills .It is a by- product material obtained from rice husk which consist of non crystalline silicon dioxide with high specific surface area in high pozzolanic reactivity.

Introduction

Ground granulated blast furnace slag (GGBS) Ground Granulated blast furnace slag(GGBS) is a by- product from the blast furnaces used to make iron. GGBS can be used as direct replacement for ordinary cement. Replacement rates vary from 30% to up to 85% ,Generally used 50% in most of applications

Properties of Rice Husk AshRHA is a highly pozzolanic material, it contains non-crystalline silica and high specific surface area that are accountable for its high pozzolanic reactivity.The high silica content in the form of non crystalline or amorphous silica of RHA is dependent on burning temperatures 95% silica could be produced at 700 degree C for 6 hours. In order to ensure the quality of ash a suitable incinerator/furnace as well as grinding method is required for burning and grinding rice husk ash.Fineness of RHA is a valuable property for the strength of blended concrete, the ultra fine RHA mixed concrete produces greater strength than that of control concrete.At higher ages(90 days) RHA concrete has higher compressive strength than that of concrete without RHA due to filler effect of smaller particles of RHA

Properties

Properties of GGBSGGBS cement is routinely specified in concrete to provide protection against both sulphate attack and chloride attack. To protect against chloride attack, GGBS is used at a replacement level of 50% in concrete.In contrast to the stony grey colour of concrete made with Portland cement, the near-white color of GGBS cement permits architects to achieve a lighter color for exposed fair-faced concrete finishes, at no extra cost .GGBS cement also produces a smoother, more defect free surface, due to the fineness of the GGBS particles.Concrete made with GGBS continues to gain strength over time, and has been shown to double its 28-day strength over periods of 10 to 12 years.Concrete containing GGBS cement has a higher ultimate strength than concrete made with Portland cement. It has a higher proportion of the strength-enhancingcalcium silicate hydrates(CSH) than concrete made with Portland cement.

Use Of RHAThere are two areas for which RHA is used for the manufacture of low cost building blocks and in the production of high quality cement.Low cost building blocksOPC is expensive and unaffordable to a large portion of the worlds population since RHA offers improved concrete affordability ,particularly for low cost housing in developing countries.Enhanced properties of RHA cementPortland cement produces an excess of lime.Adding a pozzolan , such as RHA,this combine with lime in presence of water results in a stable and more amorphous hydrate(calcium silicate).This is stronger,less permeable and more resistant to chemical attack.The pozzolan is not just a filler,but a strength and performance enhancing additive.

Scope of ProjectThe experimental investigation is planned as follows:1)To obtain Mix proportions of Control concrete by IS method.2) To conduct Compression test on RHA and Control concrete on standard IS specimen size 150 x 150 x 150 mm.3) To conduct Flexural test on RHA and Control concrete on standard IS specimen size 100 x 100 x 500 mm.

Objective of ProjectThe aim of the present investigation is:a) To study different strength properties of Rice husk ash concrete with age in comparison to Control concrete.b) To study the relative strength development with age of Rice husk ash concretewith Control concrete of same grade.

Future Scope of RHA Other levels of replacements with rice husk ash can be researched.Some tests relating to durability aspects such as water permeability, resistance to penetration of chloride ions, corrosion of steel reinforcement, resistance to sulphate attack, durability in marine environment, etc with rice husk ash and GGBS needs investigation,For use of RHA concrete as a structural material, it is necessary to investigate the behaviour of reinforced RHA concrete under flexure, shear, torsion, and compression.

*