Manufacture of alkali-activated and geopolymer hybrid binder (AGHB) by municipal waste incineration fly ash incorporating aluminosilicate supplementary cementitious materials (ASCM).

Abstract

The treatment and disposal of municipal solid waste incineration fly ash (MSWI FA) faces many challenges, such as landfill space occupation, high costs and potential environmental threats. In this study, coal fly ash (CFA), metakaolin (MK) and silica fume (SF) were used as aluminosilicate supplementary cementitious materials (ASCM), and mixed with MSWI FA as precursors for the synthesis of alkali-activated and geopolymers hybrid binder (AGHB). The results show that this alkali-activated technology efficiently immobilized the heavy metals in MSWI FA, and the ASCM contributes to the compressive strength enhancement of the AGHB. The highest compressive strength of the synthesized products that mixed MSWI FA with CFA and MK as precursors, reached 5.34 and 9.06MPa, respectively. The compressive strength of the ASCM synthesized by mixing MSWI FA and SF in the mass ratio of 70:30 with the alkali activator modulus of 1.6M could reach 11.2MPa after 28d of curing, which met the quality standard of MU10 (NY/T 671-2003) for load-bearing brick.The leaching concentrations of Hg and Pb were reduced from 0.15 to 3.96mg/L to less than 0.003 and 0.107mg/L, which were below the limit established by the Chinese standard (GB 8978-1996). The research provides the technical parameters of the optimization conditions on the synthesis of MSWI FA-based AGHB, for the resource utilization of MSWI FA and reduction of the environmental risk.