The Effect of Recycled Concrete Aggregates and Metakaolin on the Mechanical Properties of Self-Compacting Concrete Containing Nanoparticles

Nowadays, finding appropriate solutions for reducing the environmental pollutions as a consequence of buildings is important. Using recycled concrete from demolished buildings as an aggregate in new concrete preparation can have a significant role in the sustainable development of the concrete industry; therefore, in this research work, the effect of employing different percentages (i.e., 20, 40, 60, 80 and 100%) of recycled concrete aggregates and the impact of using metakaolin as pozzolan in self-compacting concrete containing SiO2 nanoparticles were investigated. Hence, some properties of hardened self-compacting concrete such as compressive strength, tensile strength, modulus of elasticity, water absorption, density and apparent porosity of the samples were studied. The results demonstrate that construction of self-compacting concrete with complete replacement of recycled aggregates is possible. Although the strength of recycled self-compacting concretes is almost 11% less than the control samples, the use of metakaolin with optimum percentage as additives of cement leads to improvement in the recycled concretes properties.