Effect of reducing the amount of coarse aggregate on some properties of self-compacting concrete

Abstract

Abstract: In recent years, self compacting concrete (SCC) has become widely used especially in crowded reinforced concrete structures with difficult casting conditions. For such applications, fresh concrete must possess high fluidity and good cohesion. One of the most important projects in which this type of concrete was used is the foundation system for Khalifa tower  in Dubai, which is the most important high-rise building in the world. The content of coarse aggregate has a significant impact on the properties of the required concrete. Some studies have suggested that the total volume of coarse aggregate be within 50% of the solid concrete volume.

In this research, six mixtures were studied with different combinations of water-cement ratio and coarse aggregate quantity. Slump test (flow test) ,      (J-RING test) and concrete strength determination test were performed to determine the effect of reducing the amount of coarse aggregate in the mixture on some fresh and hardened properties of self compacting concrete (SCC).

The results showed that reducing the amount of coarse aggregate used in concrete requires increasing the amount of water required for mixing to achieve the required flow of self-tamping concrete, which leads to a decrease in the strength of concrete, and that the best ratio of coarse aggregate to the total aggregate is 65%, as it provides the highest resistance to concrete and achieves flow required, and using a percentage higher than that leads to not achieving the required flow and crossing completely.