Effects of Fine and Coarse Aggregates Recycled from Waste Concrete on the Properties of Self-Compacting Concrete

In this study, the possibility of using recycled aggregates, prepared from recycling plant of Kermanshah, in the production of self-compacting concrete is investigated. Recycled aggregates were randomly collected from the whole Kermanshah province resulted from destruction of buildings or natural disasters. Here, self-compacting concrete samples including different percentages of the recycled coarse and fine aggregates and a combination of both were prepared in the form of 16 different mix designs. Fresh concrete tests including slump flow, T50 and L-BOX, and hardened concrete tests including compressive, tensile and flexural strength tests, as well as modulus of elasticity and Poisson ratio tests were performed. In this study, fly ash was used to retrieve for the probable reduction in the concrete strength due to the use of randomly collected recycled aggregates instead of natural aggregates. The results showed that the mixtures prepared using recycled coarse aggregates had higher mechanical properties than mixtures prepared using recycled fine aggregates. In all hardened concrete tests, the performance of the mixtures prepared using the combination of recycled fine and coarse aggregates was significantly lower than the state of using the coarse or fine aggregates separately. Also, in the case of fresh phase concrete tests, it was observed that with increasing the amount of recycled fine and coarse aggregates, the rheological properties of self-compacting concrete decrease compared to the mixtures using natural aggregates. Therefore, the recycled fine aggregates have a greater effect on the reduction of the properties of fresh concrete compared to the recycled coarse aggregates.