Effect Of W/Cm Ratio And Superplasticiser Dosages On Stablity And Flowablity Of Self-Compacting Concrete

Abstract

Self-compacting concrete (SCC) is a special concrete that does not require vibration for placing and compaction. It is able to flow under its own weight, completely filling formwork and achieving full compaction, even in the presence of congested reinforcement. The hardened concrete is dense, homogeneous and has the same engineering properties and durability as normal vibrated concrete.The use of self-compacting concrete (SCC) is increasing every day in concrete industry due to its improving production techniques. However, mix design methods and testing procedures are still developing. The water/cement ratio and superplasticiser dosages were being one of the main key parameters in proportioning of SCC mixtures. In this study three mixtures with different combinations of water/cement ratio and superplasticiser dosage levels are investigated. Slump flow test is carried out to determine the effect of w/cm and superplasticiser dosages on fresh and hardened properties of SCC that is bleeding, segregation, stability and compressive strength.The results show that when w/cm increased from 0.32 to 0.36, the flowability of SCC increased by 8.0% and 8.6% for superplasticiser dosages 1.8% and 2.2% respectively, and when w/cm increased from 0.36 to 0.4, the flowability of SCC increased to 4.5% and 5.3% for the same levels of superplasticiser dosages.Key words: Bleeding, Flowability, Segregations, Self-Compacting Concrete, Superplasticiser Dosage.