Influence of self-ignition coal gangue on properties of foam concrete with steam curing

This paper aims to study the influence of coal gangue (CG) on compressive strength, drying shrinkage, air void structure, and microstructure of foam concrete with steam curing. Coal gangue foam concrete (CGFC) mixtures were prepared by introducing CG at levels of 10−50 % to replace ordinary Portland cement. Steam curing was applied to increase the early-age strength of CGFC. Experimental results showed that with the increase of CG dosage from 10 % to 50 %, the 1 d compressive strength of foam concrete was increased firstly and then decreased. With the same level of bulk density, the incorporation of 30 % CG reached the highest 1 d strength. The addition of 50 % CG decreased the drying shrinkage by 18.8 % for steam-cured samples. Air bubbles and porosity of foam concrete were coarsened by the steam curing but refined by the incorporation of CG. The mineral compositions results indicated that the steam-curing could accelerate the hydration of cement and the pozzolanic reaction of CG, being contribute to the improvement of early-age compressive strength. The scanning electron microscope images exhibited the formation of micro-cracks in steam-cured foam concrete samples which was alleviated by adding CG. Therefore, the utilization of coal gangue in foam concretes benefits both the environmental pollution control and the factory manufacture of lightweight wall panels for building structures.