Comparing Between the Effects of Limestone and Viscosity-Modifying Admixture on the Rheology of Self-Compacting Concrete Under Different Ambient Conditions

The effect of hot climate on the performance of fresh self-compacting concrete causes a number of problems including the reduced workability. This issue is due to the various demands of the fresh self-compacting concrete, much more complicated mix design and low yield stress of this type of concrete. Therefore, in design of the self-compacting concrete, in addition to the constituent elements the ambient conditions also are taken into consideration. In this research, the self-compacting concrete specimens with different amounts of limestone and viscosity-modifying admixture were made. Also the temperature of the concrete mixtures was selected with respect to the ambient conditions of different seasons. After the concrete specimen temperature reached the ambient temperature, the rheological properties of the fresh self-compacting concrete specimens containing limestone or viscosity-modifying admixture being a function of mixing time, and temperature with water to cement ratio of 0.42 were investigated. According to the obtained results the viscosity-modifying admixture has a better effect on the plastic viscosity with respect to limestone and reduces the slump loss by 50%. Thus in the hot climate where our goal is to maintain workability, the concretes with viscosity-modifying agents are the best options.