Leaching and efflorescence effects in geopolymer concrete

The leaching behaviour and efflorescence effects were minimal for geopolymer concrete synthesised from fly ash of three different origins have been evaluated. The specimens used in the studies were geopolymer concrete synthesized at ambient temperature with alkali activators of different concentrations. During these studies, extraction and leaching of various heavy metals and trace elements like Zn, Ni, Cu, Fe, Pb, Mn, Mg, and Cd were carried out by applying batch leach test and toxicity characteristic leaching procedure (TCLP) to check the possibility of ground water contamination. The effect of efflorescence was examined visually and by determining the residual compressive strength up to 180 days after 28 days maturity of concrete specimens. The bulk of the pores lie in the 0.01–1.5μm range. The number of pores below pore size of 0.01 μm and above pore size of 1.5 μm is less. 6MFA3GC was better resistant as compared to 6MFA1GC and 6MFA2GC for leaching and efflorescence effect. The strength comparison of geopolymer concrete specimens in laboratory conditions and on exposure to weathering conditions are within 10%.