Mechanical and physical properties of concrete containing FGD waste

The work reported here forms part of a wide-ranging research project on the optimum use of waste from dry and semi-dry flue gas desulfurisation (FGD) processes in concrete. This study examined the influence of a typical simulated desulfurised waste (SDW) on the physical and mechanical and physical properties of concrete. SDW was chosen due to the wide variability in the composition of actual FGD waste. Two binder systems were investigated: cement and SDW (C-SDW) and cement, slag and SDW (C-S-SDW). The SDW content ranged from 0 to 70% and the slag from 0 to 90% as partial cement replacements. The properties examined included compressive and flexural strengths, water absorption, shrinkage and expansion. The results showed that replacing cement with SDW beyond 20% systematically reduces strength. An increase in SDW content reduces shrinkage. The presence of small amounts of slag allows the use of high proportions of SDW. The use of desulfurised waste in concrete applications is possible as adequate strength can be achieved.