Pavement Quality Concrete with Treated Recycled Concrete Aggregate: Combined Experimental and Predictive Analysis via Machine Learning

The scarcity of natural stone resources for the construction industry has led to increased costs and shortages of coarse aggregates. The use of recycled concrete aggregates (RCAs) has caught the attention of many researchers for promoting sustainability in construction. Its use in pavement-quality concrete (PQC) has been minimal because of its higher water absorption value. However, with a proper beneficiation method the deficient properties of RCA can be improved. In this study, a new and novel treatment method involving mechanical mixing and soaking in an aqueous solution of sodium silicate and cement was developed. Up to 100% treated RCA (TRCA) was used, replacing natural coarse aggregates (NCAs) for M40- and M50-grade PQC mixes. The results showed that the compressive strength of PQC mixes of M40 and M50 grades increased by 6.3% and 4%, respectively, using 100% TRCA (at 90 days of curing). An increase in flexural strength also was observed, by 33.3% and 30% for M40- and M50-grade PQC mixes, respectively, at 90 days of curing. A typical example of a concrete pavement was considered for thickness design purpose as per the latest relevant guideline of the Indian Roads Congress, and it was observed that the design thickness of the slab decreased for the concrete pavement made with PQC with 100% NCA replacement by the developed TRCA. This ultimately reduces the overall cost of construction of concrete pavement by 24%–28%. This research is significant for sustainable construction, because it offers a viable solution to the scarcity of natural resources and the rising costs in the construction industry. Additionally, a machine learning (ML) model for compressive strength prediction was developed to validate the experimental results obtained in this study.