EFFECT OF RE-VIBRATION TIME AND STEEL FIBER CONTENT ON THE PROPERTIES OF CRUSHED CEMENT-SAND MORTAR CONCRETE Dr.

AbstractThe investigation aims to study the effect of re-vibration time and amount of steelfiber on the properties of concrete made with crushed cement-sand mortar as coarseaggregate. Three mixes were prepared with 0.00, 50 and 100 percent replacement ofnatural gravel by crushed cement-sand mortar aggregates. Mix proportions of concretewere 1: 2: 3 by weight. The water cement ratio of 0.50 to 0.60 was used to obtain thesame workability for all mixes throughout the research. The specimens were cast toinvestigate compressive and splitting tensile strength of concrete.The results showed that concrete made of crushed cement-sand mortar as coarseaggregate had lower workability than concrete made with natural gravel aggregate forthe same water cement ratio. This reduction in workability is reduced for the richermixes and the influence of coarse aggregate on the workability decreases with anincrease in the amount of cement in the mixture. Concrete compressive and splittingtensile strength were improved due to re-vibration by about 19 percent at the peak value(about one hour after initial vibration) with volume fraction of steel fiber of about 0.5percent. The steel fibers improve the compressive strength of concrete by about 8-11percent and the splitting tensile strength by about 10.3 percent for the same period of revibration.