Abstract
ABSTRACT
This study summarizes an investigation into the performance of different ground granulated blast-furnace slag (GGBS)-based binders in toxic waste solidification/stabilization (S/S). The properties of two real industrial heavy metal wastes solidified/stabilized (S/S) with GGBS-based binders, including conventional ordinary Portland cement (OPC) + GGBS mixes and alkali-activated slag (AAS), were compared with those of wastes treated with conventional S/S systems involving OPC and 50% OPC + 50% pulverized fuel ash (PFA). The S/S wastes properties investigated were unconfined compressive strength (UCS), pore solution chemical composition, and leachability (using a modified version of the ANSI/ANS 16.1). This study showed that despite the higher strength of wastes treated with pure OPC, S/S wastes have variable leachability behavior primarily related to pore solution composition. In fact, leachates generated by ANSI/ANS 16.1 resembled diluted pore solution chemical compositions. The variation in concentrations of different elements in pore solution is attributed to the difference in pore solution characteristics of different binders. This leads to precipitation or dissolution of phases of different solubility and is reflected in lower Cr concentration and higher concentrations of Fe, Ni, and P in pore solutions of AAS compared with OPC-based binders.
Key words:
Waste solidification/stabilization; alkali-activated slag; pore solution; leachability
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