Effect of natural pozzolan content on the properties of engineered cementitious composites as repair material

In order to determine the effect of Natural Pozzolan (NP) content on the mechanical properties and durability characteristics on Engineered Cementitious Composites (ECC) as repair material. This study focused on the evaluation of the most factors influencing compatibility between the repair material and the base concrete including mechanicals properties such as, compressive and flexural strengths, elastic modulus, capillary absorption and drying shrinkage. The experimental results showed that natural pozzolan reduces the compressive strength and the flexural strength of ECC at all ages. The elastic modulus of ECC was remarkably lower than that of normal-strength concrete. This lower Young’s modulus is desirable for repair concrete, because it prevents the stresses induced by restrained shrinkage. In addition, the incorporation of high-volume natural pozzolan decreases significantly the coefficient of capillary absorption at long term and increases the drying shrinkage. Generally, based on the results obtained in the present experimental investigation, ECC can be used effectively as an overlay material over existing parent concrete.