AN OVERVIEW ON AUTOGENOUS AND DRYING SHRINKAGE OF ALKALI-ACTIVATED SLAG CEMENT

High shrinkage of concrete may result in cracking and decrease the durability of concrete. Alkali-activated binders have attracted worldwide attentions due to their advantages of simple production process, low energy consumptio, effective utilization of industrial by-products and reduction of greenhouse gas emission. This paper reviews the factor influencing autogenous and dryingshrinkage of alkali-activated slag cements. Depending on the nature of slag and activators used, the chemical/autogenous shrinkage of alkali-activated slag cements can be larger or less than that of PC. Higher contents of mesopores and silica-rich C-S-H gels in AASCs are the main reasons for their higher shrinkage than PC concrete. Incorporation of water saturated porous aggregate can effectively reduce the autogenous shrinkage, while the addition of shrinkage reducing admixtures is very effective for reducing drying shrinkage.