Abstract:
This research work investigated strength development, setting and metal leaching from thesolidified wastes. Reactive rice husk ash (rRHA) was used as partial substitution for ordinaryportland cement (OPC) to solidify the electroplating sludge from a zinc-cyanide process. The rRHAwas prepared by burning the rice husk at 650 ๐C for 1 hour. The Silicon dioxide content of rRHAwas 95.58 % and it mostly amorphous with solubility of silicon dioxide solution in sodiumhydroxide solution was 595.96 mg.Si/g. wt. of rRHA. The rRHA was then used to substitute forOPC at 0, 10, 20 and 30 wt.% to solidify the electroplating sludge at loading of 0, 10, 20 and 30wt.%, respectively. Results showed that the strength of cement containing 10 wt.% replacementwith rRHA gained higher strength than the control cement paste after 7 days of curing. Strength ofsolidified wasted with 10 and 20 wt.% electroplating sludge was higher than the minimumrequirement of landfilling at every curing duration observed, except for those with 30 wt%. It isnoticed that rRHA interfered with normal setting of OPC by decreasing initial and final setting time.However, the interference from rRHA was not so strong as that observed from the electroplatingsludge. The concentration of Zn, Fe and Cr in TCLP leachates were not exceeded the values .