Phosphogypsum resource utilization in road engineering (II): The cement-modified PG with gravel filler

Phosphogypsum (PG) is the major industrial waste emitted in the phosphate industry, which may lead to water and air pollution. To exploit a large-scale consumption method for the solid waste, a filler material was proposed, and engineering testing was carried out. Research and practice have shown that: (1) the strength of the cement-modified PG increased slowly, a 28d of curing is necessary for the cement-modified PG filler. (2) PG was generated by fine particles, and it is hard to compact. Adding 35%~60% gravel (particle size 9.5~19.0 mm) to the PG filler makes the cement-modified PG with gravel filler have good compressibility. (3) Compared with the cement-stabilized gravel, the PG filler has a lower cost (saving about 30%).