Multi-Response Optimization of Mechanically Processed Recycled Aggregate for Concrete

https://doi.org/10.46610/JOCCE.2026.v012i03.004

Abstract

The engineering performance of recycled aggregate concrete is strongly controlled by the quality of the recycled aggregate and, in particular, by the quantity and condition of adhered mortar. This study develops a multi-response interpretation of an experimental high-strength concrete dataset in which recycled coarse aggregate was mechanically processed for 0, 200, 500, and 700 Los Angeles abrasion-machine revolutions and incorporated at 0–100% replacement of virgin coarse aggregate. The analysis combines workability, density, 28-day compressive strength, flexural strength, split tensile strength, ultrasonic pulse velocity, and elastic modulus to identify a practical processing–replacement window. The source experimental programme used a high-strength concrete mix with a water-to-cement ratio of 0.26, silica fume, and polycarboxylate-ether superplasticizer. The results show that increasing replacement generally reduces hardened performance, whereas increasing processing intensity improves performance by reducing adhered mortar and improving the effective aggregate–paste interface. At 50% replacement, the reported 28-day compressive strength increased from 46.78 MPa for unprocessed aggregate to 73.23 MPa after 500 revolutions, while the corresponding value at 700 revolutions was 75.42 MPa. Thus, the incremental strength gain from 700 over 500 revolutions was only about 3%, indicating a diminishing-return region. Similar convergence was observed for UPV and elastic modulus. A 500-revolution treatment therefore emerges as a practical compromise between performance and processing demand, while replacement around 50% provides a useful balance between recycled-material utilization and structural performance. The paper presents the performance map based on replacement level and processing intensity and identifies the experimental variables.