Influence of Water Binder Ratio and Chemical Admixture on the Properties of Self- Compacting Concrete with composite Cement- Fly Ash binder

Abstract

This paper describes an experimental investigation to study the combined effect of water binder ratio and chemical admixture on mechanical properties of self- compacting concrete (SCC) prepared using composite fly ash–cement binder. For this purpose, the mixture proportioning for SCC was based upon creating a high-degree of flowability by using High-Range Water-Reducing Admixtures (HRWRA) combined with Viscosity Modifying Admixture (VMA) to ensure homogeneity of the mixture. The flowability test results showed that the spread for all mixes was within the specified range recommended by EFNARC 2005 and EN 206. The J Ring height for all SCC mixes was observed to be between 17-20 mm, which was within the specified limits of EFNARC 2005. A visual stability index has been provided to all SCC mixes for qualitative assessment of the flowability indexes. The cementing efficiency factor of fly ash, adopted in the presented work, restores the cementitious content in the mix. At 0.36 w/b ratio, the cube compressive strength at 28 days was almost 51MPa when 2.2% HRWRA with VMA was added to the mix. Through the different flowability test results, an effort has been made to develop a correlation between different flowability parameters using regression analysis in MINITAB software. An empirical formula in the form of basic equations suggested by CEB-FIP and ACI 363R -92 to express the relationship between split tensile strength and compressive strength of SCC has also been proposed.