Use of recycled concrete and rice husk ash for concrete: A review

The rapid development of populations and the demand in the consumption of concrete is generating the need to produce larger quantities of cement, which brings with it negative effects for the environment. Approximately 0.87 kg of CO2 is produced by the manufacture of cement; In addition, the use of aggregates is generating great concern in the construction industry, due to the costs and the restriction of these. Similarly, the accumulation of construction and demolition waste (RCA) and rice husk ash (RHA) contribute to pollution. Therefore, the objective of this manuscript is to review the literature on the use of RCA and RHA for the elaboration of concrete. For this, indexed articles were used, between the years 2017-2021. The results showed that when 8% RHA is added, the concrete reaches a compressive strength of 70 MPa; as well as, the flexural strength of concrete by adding 50% RCA + 1.50% basalt microfibers was increased by 29.44%. On the other hand, when RHA is added by 15% it reaches a compressive strength of 48.8 MPa; in turn, the mechanical performance at bending with 10% seashell by fine aggregate and 20% RHA by cement, reached a resistance of 65 MPa. Concluding, that the behavior of concrete undoubtedly depends on the proportions of either RCA or RHA; however, the percentages must be no more than 8% and 15% respectively.