Effect of thermal curing on slurry stability and thermal conductivity coefficient of aerated concrete based on industrial solid wastes

Abstract

This paper explores the effect of curing temperature on the slurry stability and thermal conductivity coefficient (TCC) of aerated concrete based on industrial solid wastes, aiming to prepare a porous insulation material with such a concrete. Specifically, aerated concrete was prepared from the basic cementitious materials of steel slag (SS), blast furnace slag (BFS) and flue gas desulfurization (FGD) gypsum and the foaming agent of aluminum powder paste, and subjected to repeated tests and scanning electron microscopy. The results show that the slurry stability of the aerated concrete based on steel slag(SS)-blast furnace slag(BFS)-flue gas desulfurization (FGD)gypsum is jointed affected by fluid heat conduction and hydration rate of the cementitious material; the cementitious material with the specific surface area (SSA) of 350 m2/kg can achieve the best foaming effect under the curing temperature of 70 °C, with a volume expansion rate of 305 %, while that with the SSA of 500 m2/kg can achieve the best foaming effect under 45 °C, with a volume expansion rate of 295 %; the latter material will undergo bubble collapse under the combined effects of temperature and pressure if cured under 70 °C. Under the optimal foaming temperatures, the TCCs of the two groups of cementitious materials are respectively 0.086 W/(m K) and 0.071 W/(m K). In this case, both materials have good thermal insulation effect and can be used for exterior wall insulation.