Enhancing waterproof performance of phosphogypsum non-fired ceramics by coating silane-coupled unsaturated polyester resin

Phosphogypsum (PG) is a large amount of solid waste discharged from the phosphorus chemical industry and poses serious environmental pollution problems. The preparation of non-fired ceramics from PG is an effective method for substantially managing PG waste, but its actual production and utilization are difficult due to poor water resistance of PG. In this paper, a waterproof non-fired ceramic with a dense waterproof layer was prepared from PG by grafting silane coupling agent onto the PG non-fired ceramic and then coating it with unsaturated polyester resin. The bending strengths of waterproofed PG non-fired ceramics before and after soaking in water for 24 h were 20.5 and 15.2 MPa, respectively, and the corresponding softening coefficient was 0.74. Its water absorption rate was 1.12%, while contact angle was 81.6 degrees . The favorable qualities endow the waterproofed PG non-fired ceramics with broad application prospects in building materials. This technique has great potential to reduce the environmental pollution caused by PG with huge economic and social benefits. (C) 2019 Elsevier B.V. All rights reserved.