Leaching Characteristics of Geopolymer Cement Concrete Containing Recycled Concrete Aggregates

Abstract

In this investigation, the effect of replacing some percentage of natural coarse aggregate with recycled concrete aggregate (RCA) in geopolymer concrete synthesis is studied. The study focuses on the compressive strength and release of elements from the geopolymer concrete samples. The toxicity characteristic leaching procedure (TCLP) was used to determine release of potentially hazardous heavy metals (PHHMs) and other constituents of potential concern (COPCs) from the geopolymer concrete and also to identify if the material should be categorized as either hazardous or nonhazardous. It was found that replacing virgin aggregates with RCA had a small impact on the compressive strength of the concrete, reducing it by a maximum of 34%. As measured by toxicity characteristics leaching procedure (TCLP), release of As was reduced by adding RCA. The leached concentrations of the elements, Ba, Cd, Cr, and Pb were found to be below TCLP regulatory limits.