Properties of Supersulphated Phosphogysum-slag Cement (SSC) Concrete

Supersulphated phosphogysum-slag cement(SSC) is a newly developed non-burned cementitious material mainly composed of phosphogysum(PG) and ground granulated blast furnace slag(GGBFS), with small amount of steel slag(SS) and clinker(CL). SSC is a kind of environmentally-friendly cementitious material due to its energy-saving, low-carbon emission, and waste-utilization. We prepared concretes with supersulphated phosphogysum-slag cement, and studied the mechanical properties, microproperties and resistance to chloride penetration of concrete in comparison with those of portland slag cement(PSC) and ordinary portland cement(OPC) concrete. The test results show that the compressive strength of SSC concrete can reach 38.6 MPa after 28 d, close to PSC concrete and OPC concrete. Microanalyses indicate that large quantities of ettringite and C-S-H, and little amount of Ca(OH)2 are generated during the hydration of SSC. The dense cement paste structure of SSC is formed by ettringite and C-S-H, surrounded unreacted phosphogysum. The property of resistance to chloride penetration of SSC concrete is better than PSC and OPC concrete due to the fact that SSC can form much more ettringite to solidify more Cl-.