Abstract This research was aimed to studying the effect of free lime (free CaO) content in fly ash on the expansion and weight loss of cement mortars, fly ash and limestone powder submerged in sulfate solutions. Free lime was added to the original fly ash in order to vary free lime content of fly ash. Test results revealed that the expansion of OPC type I mortar was higher than that of OPC type V mortar in sodium sulfate solution. It was also found that the expansion of mixture with 10% replacement of limestone powder was about the same as that of OPC type V mixture. The expansion of binary mixtures with fly ash and ternary mixtures with cement, fly ash and limestone powder depended very much on the content and type of fly ash such that mixtures with small replacement ratio of high CaO fly ash yielded high expansion. In magnesium sulfate solution, weight loss of OPC type I mortar was higher than those of OPC type V mortar and mortar with limestone powder. Weight loss of mortars with 20% and 40% fly ash were higher than those of OPC type I and OPC type V mortars. Ternary mixture incorporating cement, fly ash and limestone powder showed lower weight loss than OPC type I mixture and was similar to OPC type V mixture. Free lime (free CaO) content of fly ash had no effect on the expansion and weight loss of mortar in sulfate solutions.
Keywords: Information Free lime; Fly ash; Limestone powder; Sulfate; Durability
