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The pervious study on rice husk ash suggests that optimum level of replacement of rice husk ash in concrete is 10% of total weight of cement. This paper aims for maximum optimum value within 10% of replacement for better compressive strength and durability. RHA exhibits high pozzolanic characteristics and shows good pozzolanic behavior due to its high silica content. Rice husk ash (RHA) essentially consists of amorphous silica (90% SiO2), 5% carbon, and 2% K2O. Rice husk ash has been partially replaced at different percentages (0%, 5%, 6%, 7%, 8%, 9% and 10%) by weight of cement for mixand cured for different curing periods (28 days, 60days, 90 days). This study suggests that at 6% replacement of OPC with RHA Exhibits good compressive strength, because of its high pozzolanic activity. Effect of Sulphuric acid (H2SO4) on properties of replaced RHA concrete and compressive strength of cement concrete is taken as study area. The study reviles that the rate of development of compressive strength decreased with increase in concentration of H2SO4 at 28days, 60days and 90days.but at 6% replaced RHA shows good resistance to sulphuric acid attack.

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Optical properties of transparent alumina prepared through gel process at room temperature and coloured with dopants have been studied. The absorption bands, molar absorptivity, effect of concentration and the dependence of oxidation state of copper on the copper content and water content are similar to the random network glasses. The ultraviolet absorption edge at lower energies confirm the disordered nature of the transition phase aluminas 7 and 6. The absorption bands in the visible suggest the octahedral symmetry of oxygen around aluminum.