Reuse of incinerated ash from industrial sludge-derived fuel

•Adding industrial sludge-derived fuel incinerated ash (FIA) can increase hydration heat and shorten setting time.•FIA is a very suitable mineral admixture for controlled low-strength materials (CLSMs).•Optimum proportion of FIA to cement paste is 10–20%.•Pore size of FIACPs mainly was >1μm. The demand for alternative fuel derived from industrial sludge has substantially increased. Therefore, sustainable methods for disposal of industrial sludge-derived fuel incinerated ash (FIA) are urgently needed. This study evaluates the feasibility of using FIA as an admixture for either pozzolanic material or concrete and proposes strategies for FIA reuse. Experiments showed that FIA cement paste (FIACP) was characterized by early setting and high hydration heat because of its high calcium chloride content and high alkalinity, which reduced the initial setting and final setting times by 60.47% and 45.42%, respectively. Therefore, FIA had the characteristics of a set-accelerating agent and is a very suitable mineral admixture for controlled low-strength materials (CLSMs). At mixing proportions of 10% and 20% FIA in Portland cement, minimum curing ages for FIACP were 28days and 60days, respectively, and the pozzolanic strength activity index (SAI) exceeded 75%. Thus, the optimum ratio of FIA to cement paste is 10–20%.