Sintering effect on cement bonded sewage sludge ash

Through foaming reaction, hydration reaction and pozzolanic effect, sewage sludge ash (SSA) was used as main material to produce a sewage sludge ash foamed lightweight material (SSAFLM). Firing tests were conducted at different temperatures. This was to study how the use of sewage sludge ash (SSA) improved the thermal properties and sintering effects of cement-base materials, and to evaluate the feasibility of using SSA to improve the soundness of cement-base materials under high temperature. The experimental results revealed that when the sintering temperature was lower than 600 °C, the engineering properties and microstructure of SSAFLM were mainly affected by dewatering and hydrates decomposition. However, when the temperature was over 600 °C, the results were chiefly affected by sintering effects. At high temperatures, the more SSA was used, less crack formation resulted. Moreover, after fired at 1093 °C for 4 h, the compressive strength was improved by 44%, and the total pore volume decreased by 30% in average.