Industrial resin waste as aggregate in concreteusage and sustainable concrete production and development

The increasing production and consumption of fiber-reinforced polymer (FRP) composites, widely used in advanced engineering applications, particularly in wind turbine blades, have led to the generation of substantial quantities of end-of-life composite waste, predominantly epoxy-based materials. The highly cross-linked thermoset structure of epoxy resins precludes their remelting or reshaping, a factor that significantly complicates recycling processes. Mechanical recycling is a low-energy and environmentally friendly method that enables the physical size reduction of the waste for subsequent reuse in cement-based composites, typically in powder or short-fiber form. This study investigated the potential of utilizing epoxy resin waste, generated during wind turbine blade manufacturing, as a fine aggregate replacement in cement mortars. Mechanically ground epoxy waste was subjected to silane-based surface modification to enhance its adhesion with the cement matrix and was used to replace fine aggregate by mass at ratios of 1%, 4%, 7%, and 10%. The produced mortars were experimentally evaluated for density, flow properties, flexural strength, compressive strength, water absorption behavior, ultrasonic pulse velocity (UPV), alkali-silica reaction (ASR) resistance, and performance characteristics under high temperatures. The experimental results indicate that increasing the substitution ratio of epoxy waste led to a decrease in the workability, unit weight, and mechanical strength of the mortars. Conversely, losses were found to be limited at low substitution ratios (%1–4). Furthermore, silane modification partially improved water absorption, high-temperature performance remained similar to that of the reference specimen, and the epoxy waste exhibited a suppressive effect on ASR expansions. Consequently, the utilization of epoxy resin waste as a fine aggregate replacement at a 1–4% ratio, when combined with mechanical recycling and surface modification, significantly enhances its potential for sustainable and technical incorporation into cementitious building materials.