Effect of Delaying Addition of Heat Stimulated Superplasticizer on Fresh Properties of Mortar

Abstract

To assure the quality and required workability of mortar or concrete, various types of superplasticizers are used. There are many factors affecting the performance of superplasticizers explicitly, type and dosage of the superplasticizers, type of cement, temperature and mixing procedure, as well as the addition times of the superplasticizers. Some researchers investigated the effect of delaying the addition time of superplasticizer to mortar or concrete, but there is not enough data about the effect of external temperature on performance of superplasticizers and consequent influences on fresh properties of mortar or concrete. In this research the effect of delaying the addition time of superplasticizers and influence of external temperature, namely, heat stimulation of superplasticizers, on fluidity, fresh density and air content of fresh cement mortar was investigated. Two types of Precast and Ready-Mix of Polycarboxylic acid-based ether superplasticizers with Ordinary Portland Cement was used. Delaying the addition time of superplasticizers enhanced the fluidity, slightly decreased the fresh density and increased the air content of mortar in comparison with simultaneous addition time with both heated and non-heated Superplasticizers.