A conceptual approach of the mixture proportioning technique for producing self compacting concrete

Abstract

Self Compacting Concrete (SCC) refers to a highly flowable concrete composite, designed for sufficient viscosity and cohesion to avoid segregation of aggregates. A carefree concreting practice at construction site and reduction in construction time makes SCC the most popular material among civil engineers. However, the lack of good understanding of the material properties and a reliable mixture proportioning technique affected the development of SCC significantly. In order to simplify the mixture proportioning methodology of SCC, a conceptual approach was proposed in the present study. Initially, the optimum replacement of cement using flyash was obtained by the Pozzolanic Activity Index test and the optimum dosage of hyperplasticizers was obtained using Marsh cone studies. Further, the mixture proportioning for SCC was done based on the assumption that concrete was made up of two phase material (mortar and aggregate phase). The mortar phase was designed first to obtain the optimum fine aggregate content based on the maximum mortar spread. Finally, the different proportions of mortar phase and aggregate phase were arrived. The final mixture proportions were arrived based on the maximum concrete spread and stability and then validated using the standard characterization tests (J-ring, V-funnel, L-box and segregation resistance). The test results showed that, consistent flow properties was realized in the mixture which had 65% of mortar phase and 35% of aggregate phase. Also, a good stability and a uniform spread of concrete without segregation of aggregates or mortar were observed. Key words: Self compacting concrete, SCC, hyperplasticizers, flyash, marsh cone, characterization tests.