Reinforced Concrete Slabs Containing Recycled Concrete as Coarse Aggregate

Abstract

This research presents an experimental study on the performance of reinforced recycled aggregate concrete (RAC) that contains one of two types of recycled coarse aggregate, one from normal concrete and another from self – compacting concrete (SCC). The replacement percentages (by weight) of natural coarse aggregate with the recycled coarse aggregate are (0, 33.3, 66.7 & 100) % by weight. Moreover, Silica Fume was used as an admixture for all (RAC) mixtures. Concrete compressive strength, split tensile strength, and flexural strengths were studied for all of the reference and (RAC) mixtures at (28) days age, by testing concrete cubes, cylinders and reinforced concrete slabs specimens respectively. The results showed that the using of recycled waste concrete as concrete as aggregate will largely decreasing the slabs flexure strength while using of recycled (SCC) mixtures have relatively small effect in reducing the slabs flexure strength. The adding of silica fume to the concrete mix will increasing the slabs flexural strength and that increase is larger for recycled (SCC) aggregate mixtures than the recycled concrete aggregate mixtures. The results also indicate that the compressive strength and tensile strength are decreased by different ratio when using of recycled waste concrete as aggregate, while using of recycled (SCC) aggregate will also reduce the tensile strength and the modulus of rupture while the compressive strength increased when using this type of recycled aggregate. On the other hand, the mixtures with the Silica Fume showed a significant enhancement in the mechanical properties compared to those without the Silica Fume.