Synergistic Effects of GGBS and Recycled Aggregates on the Tribological, Mechanical, and Fracture Behavior of Polymer Concretes.

While the individual effects of sustainable fillers on cementitious systems are widely known, their combined tribological and fracture behaviors within a polymer concrete matrix remain largely unexplored. Addressing this gap, this study experimentally investigates the physical, mechanical, and tribological characteristics of polyester-based polymer concrete (PC). In addition to reference specimens produced with polyester resin and silica sand, modified mixtures were developed by replacing the silica sand with ground granulated blast-furnace slag (GGBS) and recycled waste concrete aggregate (WC) at various substitution ratios (0%, 5%, 10%, 15%, 20%, and 25%). To evaluate the performance of the developed PCs, parameters including unit weight, water absorption capacity, flexural and compressive strengths, Shore D hardness, surface roughness, acid resistance, Bohme abrasion resistance, and fracture energy were analyzed. Furthermore, temperature variations on the friction surfaces were monitored in real time using a thermal camera during the Bohme abrasion tests. To elucidate the fracture mechanisms, the fractured surfaces were examined via digital microscopy. The quantitative findings indicate that a 25% GGBS replacement optimizes mechanical performance, increasing the compressive and flexural strengths by 21.2% (108.30 MPa) and 30.6% (35.29 MPa), respectively, alongside a 27% improvement in Bohme abrasion resistance. However, this modification significantly increases material brittleness, reducing the fracture energy by 53.3% compared to the reference. Conversely, although incorporating WC offers sustainability advantages, it limits mechanical performance, leading to decreases of up to 9.9% (80.46 MPa) in compressive strength and 15% (22.97 MPa) in flexural strength at a 20% substitution rate. Regarding fracture energy, while the W20 series absorbed more energy than the B25 series, it still remained 47.8% lower than the reference. Additionally, the GGBS-incorporated series demonstrated higher susceptibility to sulfuric acid attack compared to the WC-incorporated series.