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Determining the Ultrasonic Pulse Velocity (UPV) of Cement Mortar with Partial Replacement of OPC with CKD and SF

A significant number of researches pointed to the serious environmental and health effects of the Ordinary Portland Cement (OPC), including the harmful emissions and alkaline wastewaters. Therefore, the development of eco-friendly alternatives for the OPC is one of the priorities of nowadays studies. However, the suggested eco-friendly alternatives to the OPC might possess negative influences on the properties of the concrete. This research aims at investigating the applicability of by-product materials, such as cement kiln dust (CKD) and silica fume (SF), as an alternative to OPC in the cement mortars. The mortar specimens were mixed with 0 to70% CKD with SF (equal values) as a partial replacement for cement. The hardening samples have been tested by the UPV test at ages 1 week to 4 weeks. The results indicated that high ratios of CKD and SF replacements result in a slight decrease in the pulse velocity of specimens, while small replacement ratios show improvement in these properties. Time of curing is very important in improving the properties of the hardening mortars. Using a small amount of CKD and SF (20-30%) could improve the durability of cement mortars and it seems to be reasonable value in mixers.