The compressive strength of recycled concrete is acknowledged to be largely conditioned
by the incorporation ratio of Recycled Concrete Aggregate (RCA), although that ratio needs to be
carefully assessed to optimize the design of structural applications. In this study, Self-Compacting
Concrete (SCC) mixes containing 100% coarse RCA and variable amounts, between 0% and 100%,
of fine RCA were manufactured and their compressive strengths were tested in the laboratory for a
statistical analysis of their strength variations, which exhibited robustness and normality according
to the common statistical procedures. The results of the confidence intervals, the one-factor ANalysis
Of VAriance (ANOVA), and the Kruskal–Wallis test showed that an increase in fine RCA content
did not necessarily result in a significant decrease in strength, although the addition of fine RCA
delayed the development of the final strength. The statistical models presented in this research can
be used to define the optimum incorporation ratio that would produce the highest compressive
strength. Furthermore, the multiple regression models offered accurate estimations of compressive
strength, considering the interaction between the incorporation ratio of fine RCA and the curing age
of concrete that the two-factor ANOVA revealed. Lastly, the probability distribution predictions,
obtained through a log-likelihood analysis, fitted the results better than the predictions based on
current standards, which clearly underestimated the compressive strength of SCC manufactured with
fine RCA and require adjustment to take full advantage of these recycled materials. This analysis
could be carried out on any type of waste and concrete, which would allow one to evaluate the same
aspects as in this research and ensure that the use of recycled concrete maximizes both sustainability
and strength.
