Influence of Magnesium Sulphate on the Compressive Strength of Internal Cured (IC) Rice Husk Ash based High Performance Concrete

Abstract

The incorporation of superabsorbent polymers (SAP) and pre-saturated lightweight aggregate (LWA) as internal curing agents (IC) have been proven to be more effective and acceptable in autogenous shrinkage and self-desiccation mitigation. However, the incorporation of the internal water reservoirs (SAP & LWA) increases the porosity of the concrete matrix which can injure the strength and durability properties of the HPC. This paper explores the use of the two IC agents as internal curing agents and the comparative study was investigated on their influence on compressive strength of RHA-based high-performance concrete in an aggressive MgSO4 environment. HPC mixtures of designed C55/67 target minimum cube strength at 28-day were studied. Concrete cubes of 100 mm were cast and cured in both water and MgSO4 solution for a 28-day hydration period. The result reveals that the mix with LWA (PHPC1) is better with the highest residual compressive strength compared to the SAP mixes in terms of MgSO4 resistance but another way round in terms of the compressive strength of specimens cured in water.