A study on compatibility of superplasticizers with high strength blended cement paste

Abstract

Adoption of High-Performance Concrete (HPC) made with low water to binder ratios in practical applications are being encouraged widely for enhanced development of high early strength and durability. The type of superplasticizers incorporated, highly influences the development of HPC. At low water-cement ratio, HPC is made workable by the incorporation of superplasticizers. The wrong proportion of cement and admixture in a mix causes low fluidity, rapid/delayed setting, segregation, bleeding etc. Therefore, it is important to underline the interaction mechanism between cement and superplasticizer for the better utilization of concrete. As more blended cements are used now a day, it is imperative to investigate the compatibility of superplasticizers in such paste systems. In this study, the saturation dosages and compatibility of sulphonated naphthalene formaldehyde (SNF) and poly carboxylate ether (PCE) superplasticizers with cement paste prepared from Ordinary Portland Cement (OPC) 53 grade, Portland Pozzolana Cement (PPC) and Slag cement (PSC) for different water-binder (w/b) ratios are analysed using the marsh cone test and mini slump test. As per the result obtained, PSC was found to have higher saturation dosages than OPC and PPC. The optimum dosages for PCE admixture are lower than that for SNF as their mechanism of action are different.