Experimental Study on Portland Pozzolana Cement-Superplasticiser Compatibility in Mortar

Chemical admixtures like Superplasticisers (SPs) have become a necessary component of high performance concrete in the present era. The selection of an appropriate type of admixture at an optimum dosage is very important. Most users apply a trial-and-error approach with these chemicals. This often results in an adverse experience and low cost-effectiveness, many times producing a bias against admixtures in general. The compatibility between the cement and admixture, which is influenced by the characteristics of cement paste and mortar, their type and dosage of admixtures, needs to be understood. The objective of this study is to understand the effect of SPs on the flowability of Portland Pozzolana cement mortar, with the aim of optimising the dosage through simple test methods. In order to evaluate the influence of SPs and cement characteristics, studies were conducted with different families of SPs and commercially available Portland Pozzolana Cement (PPC) on the aspects of fluidity and loss of fluidity. In construction industry, PPC is preferred to Ordinary Portland Cement (OPC) since it is more eco-friendly and durable. The standard mortar workability tests like marsh cone, flow table have been used to evaluate the flow behaviour of cement mortar. Based on the test results combined with the cost evaluation, compatible combinations of cement and SPs are recommended.