Thermal treatment and utilization of flue gas desulphurization gypsum as an admixture in cement and concrete

In this paper, the possibility of flue gas desulphurization (FGD) gypsum as an admixture in cement and concrete was explored. The gypsum was baked at the proper temperature of 200 °C for 60 min and then mixed into slag powder forming Compound-slag in which SO3 content was controlled at the optimum ratio of 3.5%. Performances of Portland cement with Compound-slag were further explored. The results show that addition of the gypsum prolongs setting time and increases strength of cement. In addition, adaptability of Portland cement with Compound-slag to concrete plasticizers was also investigated. It is well adapted to melamine and naphthalene super-plasticizers but not to lignosulphonate.