Solidification and Leachability of Cr (VI)‎ in Rice Husk Ash-Blended Cement

Abstract EN

Investigations carried out to study the effect of Cr (VI) (1000–3000 mg/l) on solidification and hydration behavior of Ordinary Portland cement (OPC) and rice husk ash (RHA) blended (10%, 20%, and 30%) cement show that addition of RHA accelerates final setting as compared to control samples (OPC) and retardation in setting time has been observed on increase in rice husk ash concentration (10%–30%).

Solidification studies show that the compressive strength of controls and rice husk ash blended samples increases with increase in the curing period and maximum strength was observed with 20% RHA blended samples.

With the increase in Cr (VI) concentrations, the strength of OPC and RHA blended samples decreases as compared to controls (without chromium).

The results of Toxicity Characteristics Leaching Procedure (TCLP) test, (pH≅3), show that the retention capacity of OPC and RHA blended samples was in the range of 92% to 99% and the leached Cr (VI) concentration was under the allowable limit (5 mg/l) of U.S.

EPA.

The chemistry of influence of Cr (VI) on hydration of cement was examined by X-ray diffraction which shows the formation of various crystalline phases during solidification in rice hush ash blended cement.