Preparation of eco-friendly functional lightweight gypsum: Effect of three different lightweight aggregates

Phosphogypsum (PG) is the main solid waste produced in the phosphorous chemical industry, and its resource utilization has become an international problem. Simultaneously, the research and development of lightweight building materials are the key means to achieving building energy conservation and reducing energy consumption. This paper uses hemihydrate phosphogypsum-based cementitious material as the matrix material, and porous structure lightweight aggregate (LWA) as the lightweight component to prepare lightweight gypsum. The properties of the composites were carefully investigated by the examination of mechanical strength, bulk density, drying shrinkage, thermal conductivity, sound absorption coefficient, pore structure, and microstructure. The results show that it can be achieved to obtain lightweight gypsum with a bulk density ranging from 300 kg/m3 to 1500 kg/m3. In terms of thermal behaviour and sound absorption, the lightweight gypsum with pottery sand has the smallest reduction in thermal conductivity, and EPS particles have the largest reduction. Through the introduction of a cavity resonance structure, expanded perlite significantly improved the sound-absorbing performance of the composites, while pottery sand had the least favorable effects. Pottery sand reduces the number of open pores, while expanded perlite increases the number of open pores in the composites. However, the addition of EPS particles can greatly increase the number of closed pores in the composites. This research offers a useful method for the preparation of eco-friendly and functional integrated lightweight gypsum.