Investigation on the effects of blended admixtures on workability of self compacting concrete

One of the most common problems in the ready mix concrete production industry is to determine the most appropriate proportion of concrete components for optimum performance. However, additives particularly admixtures introduced in the production of SCC to enhance some specific properties of fresh and hardened concrete may contribute to undesirable effects on the workability performance. In this study, superplasticizers blended with Accelerating and Air entraining admixtures were used in the mix and were tested for Slump Flow, V-Funnel, L-Box, U-Box, and Screen Stability tests to determine its influence on the rheological properties of SCC. Based on the results of the study, air entrainer provided microscopic bubbles acting as ball bearings between aggregates offering desirable effect in the workability of SCC. The highest dosage of 5.0% superplasticizers provided the best results in all the tests due to the dispersibility effect in the mixture causing a reduction in flow resistance. The accelerating admixture made SSC less susceptible to segregation, while the additive produced fresh concrete with lower flowability due to the rapid hydration and early strength development in the concrete. Among the two admixtures used, the air entrainer blended with 3.7% superplasticizer exhibited the best performance in all workability tests.