Durability and microstructure of CSA cement-based materials from MSWI fly ash

Abstract

The decontamination and disposal of municipal solid waste incineration (MSWI) fly ash has great significance in the world. In this work, MSWI fly ash was successfully used as a raw material in sintering and preparing calcium sulphoaluminate (CSA) cement in the laboratory. Compressive strength, durability and microstructure of the prepared CSA cement-based materials were studied. The results show that compressive strength of the CSA cement has a developing trend similar to that of the Control Cement I which develops strength quickly at an early curing age, but after 7d, strength increases more slowly. The prepared CSA cement-based materials perform well with respect to resistance to drying shrinkage, carbonation, and water permeation. The CSA cement mortar immersed in sulfate solution has a more compact microstructure and has the potential to be used in engineering constructions which require high resistance to sulfate corrosion. Parts of the chloride ion from the MSWI fly ash could be sintered within the cement clinker and subsequently stabilized in hydration products. The leaching values of heavy metals from these systems are all within the current threshold limits.