Why is the effect of recycled concrete aggregate on the compressive strength of self-compacting concrete not homogeneous? A bibliographic review

This literature review deepens in how the properties of Recycled Concrete Aggregate (RCA) affect the strength behavior of Self-Compacting Concrete (SCC) and how the expected effect of RCA can be modified by changes in its composition. It is demonstrated that, if the flowability of the SCC remains constant, the compressive strength decreases linearly with the RCA content, although this decrease is lower if the RCA is obtained from the crushing of a concrete with higher strength. The decrease of the water-to-cement ratio allows compensating this loss of strength, although its value should also allow keeping a suitable flowability. The water absorption of RCA and its interaction with other components of the mix increase the variability of the effect of RCA. Therefore, due to the large number of factors involved in this behavior, it is recommended to experimentally study the RCA and the SCC produced with it before its use.

Automated summary

This literature review explores how the properties of Recycled Concrete Aggregate (RCA) affect the strength behavior of Self-Compacting Concrete (SCC) and how changes in RCA composition can modify its expected effect. It is found that, when the flowability of SCC remains constant, the compressive strength decreases linearly with increasing RCA content, albeit to a lesser extent if the RCA is obtained from higher strength concrete. Reducing the water-to-cement ratio can compensate for this loss of strength, while maintaining suitable flowability. The water absorption of RCA and its interaction with other mix components increase the variability of RCA's effect. Therefore, it is recommended to experimentally study the RCA and SCC produced with it before use.