Effect of metakaolin and silica fume on the mechanical property, shrinkage, and gas permeability of high performance concrete

Using mineral admixtures as substituting additives in concrete has a tendency to increase by the future in order to provide greater sustainability in construction industry. The issues regarding the cost, recycling the industrial wastes, rehabilitation in durability and mechanical performance of concrete will therefore put a pressure on utilization of such materials. This study investigates the effectiveness of metakaolin (MK) and silica fume (SF) in contribution to the mechanical, shrinkage, and gas permeability of high performance concretes. Replacement levels of 5 and 15% of MK or SF by the weight of cement were considered in this study. The other experimental parameter investigated in the study was water-to-cementitious material ratios (w/cm) which were 0.25 and 0.35. The performance characteristics of the plain and mineral admixture incorporated concretes were evaluated by measuring the compressive strength, splitting tensile strength, static modulus of elasticity, drying shrinkage, restrained shrinkage, water sorptivity, and gas permeability. Test results revealed that replacement level of MK and SF had significant effects on the mechanical and especially durability characteristics of high performance concretes.