Utilization of phosphogypsum for the preparation of non-autoclaved aerated concrete

Phosphogypsum (PG) was used as raw material for the preparation of non-autoclaved aerated concrete, a series of technological parameters, such as water to solid ratio (W/S), quick lime content, steam temperature, and chemical activators, were investigated based on the density and compressive strength of specimens in this paper and the performances of products were also tested. The optimal mix proportion for preparing PG non-autoclaved aerated concrete (about 700 kg/m3) is as follows: cement 15%, Ground Granulated Blast Furnace Slag (GGBFS) 30%, PG 55%, quick lime 7%, Na2SO4 1.6%, aluminum powder 0.074%, W/S 0.45. The best steam temperature used for curing the specimens is 90 °C. The compressive strength, frost-resistance and thermal conductivity of products meet the requirements of Chinese autoclaved aerated concrete blocks standard, however, the shrinking of non-autoclaved aerated concrete is still a challenge and the durability also must be observed in the next work. The results also show that phosphogypsum not only plays the role of filler but also plays the role of activator.