The Effects of Pretreated Coal Gasification Slag Aggregates on the Quality and Durability of Concrete

The integrated gasification combined cycle is a relatively new and eco-friendly power generation technology. However, this process produces coal gasification slag (CGS) as a by-product, which is usually landfilled or discarded. To enable efficient recycling of CGS, this study investigated the effects of using pretreated CGS as a fine aggregate on the quality and durability of concrete. A pretreatment system comprising sieve screening, size reduction, and wet flotation processes was devised. Experiments were conducted to evaluate the properties and durability of concrete prepared using mixtures of pretreated or non-pretreated CGS, ordinary Portland cement, crushed gravel, and crushed sand (CS). The results demonstrate that pretreated CGS (P_CGS) reduces the amounts of water-reducing and air-entraining agents required. In particular, it reduces the losses of air content induced when using CGS. P_CGS effectively increases the compressive strength of concrete; however, the strength decreases by 8–10% if the CGS content is >50%. P_CGS exhibits durability similar to that of commonly used CS, indicating its potential applicability as a valuable recycled construction material and safe aggregate for enhancing concrete durability.