Thermo-Mechanical Behavior of High-Strength Concrete with Nylon Granule Aggregates: Experimental Evaluation and Predictive Analysis

In recent years, incorporating polymer trash as a substitute for natural aggregates in cementitious material has emerged as a sustainable approach to minimize environmental impact. Despite growing interest, limited studies have addressed the mechanical and microstructural performance of high-strength concrete (HSC) incorporating polymer waste under elevated temperature conditions. This research investigates the residual stress-strain response of HSC incorporating nylon granules (NG) as a partial substitute for natural sand at proportions of ۰, ۱۰, and ۲۰%. Specimens were subjected to axial compressive loading after exposure to high temperatures of ۲۰, ۳۰۰, and ۶۰۰°C. The analysis covered several physical and mechanical characteristics such as loss of weight, compressive strength, splitting tensile strength, elastic modulus, strain at peak stress, ultimate strain, toughness, stress-strain model, visual changes, and microstructure. The experimental findings were benchmarked against established codes and standards, including ACI ۲۱۶, ASCE, EN ۱۹۹۴-۱-۲, EN ۱۹۹۲-۱-۲, and CEB-FIP. Results demonstrated that higher temperatures substantially impaired concrete performance, with compressive strength and modulus of elasticity declining by approximately ۵۹% and ۷۵%, respectively, at ۶۰۰°C. Furthermore, the inclusion of NG led to additional reductions in mechanical performance. Based on the experimental observations, predictive models were formulated for mechanical properties, and a stress-strain model for NG-modified concrete was developed, which correlated well with the experimental results.

کلیدواژه ها:

High-strength concrete ، Recycled nylon granules ، Elevated temperatures ، Mechanical properties ، Microstructure ، Compressive stress-strain behavior