Effects of Expansive Additives on the Shrinkage Behavior of Coal Gangue Based Alkali Activated Materials

The suitability of applying shrinkage reducing additives in alkali activated coal gangue-slag composites is discussed this study. effect sulphoaluminate cement (SAC), high performance concrete expansion agent (HCSA) and U-type (UEA) on the reaction process, behavior, phase composition, microstructure mechanical properties are evaluated. results show that addition SAC slightly mitigates early stage while HCSA UEA can either accelerate or inhibit depending their dosage. presents an ideal balance between drying reduction strength increment. As for UEA, sensitive to replacement level; excessive dosage would result remarkable expansion. specific surface area average pore size hardened matrix found be closely related with behavior. introduces additional hydrotalcite phases within products, mainly formation CaCO3 Ca(OH)2. It concluded expansive effective approach mixtures, type must carefully handled.