Experimental Investigation of Strength of Self Curing Concrete Incorporated with Light Weight Aggregate as Mineral Admixture

When the mineral admixtures react completely in a blended cement system, their demand for curing water (external or internal) can be much greater than that in a conventional ordinary Portland cement concrete. When this water is not readily available, due to depercolation of the capillary porosity significant autogenous deformation and (early-age) cracking may result. To overcome such conditions there is a need of water in concrete internally for complete hydration to achieve the expected strength. This is achieved by Internal curing using different agents which provides the water for hydration through capillary action even after evaporation of external curing water. The strength achieved by Internal curing (IC) could be more than that possible under saturated curing conditions. In present work the internal curing or self curing concept by addition of Light weight aggregate namely Light weight Expanded Clay Aggregate (LECA) as a mineral admixture in partial replacement of coarse aggregate is studied. For experimental investigation, seven mixes of M40 grade concrete with varied percentage of Light weight Expanded Clay Aggregate (LECA) i.e. 0%, 5%, 10%, 15%, 20% and 25% as a replacement of coarse aggregate were used. Among these, first and second mix (M1 & M2) were nominal mixes with 0% LECA. M1 was cured in a curing tank whereas M2 was cured under wet gunny bags. These specimens were then tested for Compressive strength, Split tensile strength, Flexural strength, ultrasonic pulse velocity and continuous immersion in salt water. Results shown that replacing coarse aggregate with LECA up to 10% will produce improvement in strengths in compression, tension and flexure also this mix has shown good resistance to chloride attack when tested in continuous immersion test with improvement of 10.74% in compressive strength. Whereas mix with 15% LECA has shown excellent quality of concrete in ultrasonic pulse velocity test and attained adequate strengths in compression and flexure. This leads to conclude that the optimum content of LECA in replacement of course aggregate in concrete should be 10% and it should not exceed 15% for attaining the required strength.