Study of the volume stability of slag cement mortar applied to desulfurization slag during high temperature operation

Abstract

In recent years, upon increasingly exploiting natural sandstone, the natural ecology has been damaged severely. To reduce the impact of market demand on natural resources, replacing natural resources with recycled materials, such as desulfurization slag and slag powder, is a very important topic at present. This study used desulfurization slag that had been passed through #4 sieves and slag at a fineness of approximately 4000cm2/g to replace fine aggregates (0, 10, 20 and 40%) and cement (0, 10, 20 and 40%), respectively, via a volumetric method to make cement mortar for testing its fresh properties. The hard properties and volume stability were tested at different ages in order to discuss the variance in the material volume stability under different mix proportions.The results show that the slump flow of the mix proportion with the slag powder is higher than the slump flow of the mix proportion without addition by 11.5–39%. The addition of desulfurization slag and slag powder increases the setting time. The compressive strength and the ultrasonic pulse velocity decrease as the replacement of desulfurization slag increases, and both increase with age. Under the influence of high temperature, a high compressive strength can be reached at an early age. When the addition level of desulfurization slag is the maximum, 40%, the weight loss is higher than observed at the other addition levels. The autoclave expansion increases as the desulfurization slag replacement increases and the amount of slag decreases. After high temperature catalysis, the expansion response increases as the curing time and desulfurization slag replacement increase and the slag powder decreases. The high temperature has an apparent effect on the volume stability of slag powder cement mortar with desulfurization slag, and the expansion response of all mix proportions is within safe specifications (0.06%).