Evaluation of the Feasibility of Reutilizing Detoxic Incinerator Fly Ash as a Green Cement

摘要

Fly ash with the components of silica and aluminum oxides which enhanced compressive strength plays an important role in "high performance concrete." In type I Portland cement, ACI regulated that fly ashes of class C and F could be added at the ratio of 15-35% and 15-25%, respectively. In this paper, MSW incinerator fly ash was considered as a green cement for its application feasibility. Two incinerator fly ashes containing heavy metals were pretreated firstly to be non-hazardous fly ashes (NHFA). Therefore, 10%, 15%, 20%, 25%, 30%, and 35% of NHFA were mixed with type I Portland cement, respectively, at the ratio of water, ash-cement, and sand was 1:2:4, and produced test cylinders of green concrete. The physico-chemical properties of green concretes were then investigated and the results showed: (1) All TCLP tests of green concretes passed EPA criteria and total content (TC) of all metals were also reduced significantly. (2) Compressive strengths of cylinders decreased with the increase of NHFA and all compressive strengths were greater than 210 kg/cm{sup}2, indicating engineering feasibility of green concrete. (3) Compressive strength increasing with time was found, which hinted pozzolanic reactions of C-S-H and C-A-H had formed. In conclusion, all measurements providing detoxic MSW incinerator fly ash as a green cement was available.