Compressive Stress–Strain Relationship and Its Variability of Self-Compacting Concrete Incorporating Recycled Aggregate

The addition of recycled aggregate (RA) in self-compacting concrete (SCC) offers compelling opportunities for green and high-end applications of concrete. However, research on the constitutive relationship of the resulting concrete (termed RASCC herein) is sparse. This motivates the current study to look at the compressive stress-strain behavior of RASCC and its variability. A total of 120 cylinders were prepared with waste concrete from different sources. It was found that the workability of the concrete did decrease with the use of RA, especially when recycled fine aggregate was incorporated. The addition of RA had a less pronounced impact on the ascending branch of the averaged stress-strain curve, but increased the steepness of the descending branch markedly. It was also observed that the RA incorporation reduced the modulus of elasticity, peak stress, strain at peak stress, and toughness of the finished concrete. Most notably and importantly, the variability of those four properties was much more sensitive to the incorporation of recycled fine aggregate than to recycled coarse aggregate. Nevertheless, controlling the replacement ratio and using high-strength RA can allow the products to achieve compressive behavior comparable to that of conventional self-compacting concrete. A stochastic stress-strain model for RASCC is developed and experimentally validated.