Experimental investigation of superplasticizer effect on mortar properties

Abstract

This paper investigates the influence of superplasticizers on the workability and mechanical properties of cement mortar at the ages of 2 and 7 days. The aim of the study was to examine how different dosages and timing of superplasticizer incorporation affect the properties of fresh and hardened mortar, with focus on compressive and flexural strength as well as workability. Superplasticizer was added in proportions of 0%, 0.5%, and 1% by cement mass, while the water-cement ratio was kept constant in all mixtures. The results show that mixtures containing superplasticizer achieved higher compressive and flexural strengths, as well as improved workability, compared to the reference mixture without admixture. It was particularly observed that the effectiveness of the admixture is significantly higher when added together with water during the initial mixing phase of the mortar components, while adding the admixture after initial mixing of the fresh mortar resulted in a smaller increase in strength. These findings highlight the importance not only of correct dosing but also of the timing of superplasticizer application. This indicates that the addition of superplasticizer has a positive impact on the workability and mechanical properties of mortar, where proper mix design and the choice of the optimal timing for admixture addition play the key role in achieving the desired properties.