Effect of Microwave Energy on Compressive Strength and Durability of Cement Paste Containing Rice Husk Ash and Fly Ash

Abstract

This research is to study the compressive strength and durability of cement paste mixed with therice husk ash (RHA) and fly ash (FA) under sodium sulfate (Na2SO4) and magnesium sulfate (MgSO4)attacks with the concentration of 5% by weight. The basic properties of cement paste containing RHA andFA were tested that included strength index at the ages of 1, 3 and 5 days, setting time and sulfate resistanceproperties such as expansion in terms of length change and weight loss. The percentage replacements ofRHA and FA by weight of Portland cement type I were 0 and 20 and ratios and water-to-binder ratios were0.32 , 0.33 and 0.34.

From the tested results, it was found that the optimum condition for microwave curing cementpaste was 100 watts of microwave power, 15 minutes for curing time and final setting time for delay time.Additionally, the cement paste curing microwave had higher strength than cement paste containing RHAand cement paste containing FA .The compressive strength of microwave curing cement paste was higherthan water curing cement paste. For the durability for sulfate attack, it was found that the expansion (lengthchange) of specimens in sodium sulfate solution was more than those in magnesium sulfate solution bothmicrowave and water curing. At the percentage replacements of RHA in Portland cement type I equal to20 by weight for microwave curing, it was found that the weight loss and the expansion (length change)were lower than other specimens.

Keywords : Microwave Energy / Cement Paste / Compressive Strength / Durability /Rice Husk Ash / Fly Ash