PSI - Issue 68

Zoi S. Metaxa et al. / Procedia Structural Integrity 68 (2025) 184–189 Z.S. Metaxa et al. / Structural Integrity Procedia 00 (2025) 000–000

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1. Introduction The construction sector is under increasing pressure to adopt sustainable practices due to its high levels of resource consumption and waste generation (Coppola et al., 2018). A large portion of this waste includes non-biodegradable materials such as Extruded Polystyrene (XPS), which accumulate in landfills, contributing to environmental degradation. The need for sustainable construction materials that mitigate environmental impacts has led to research on the repurposing of waste materials for structural applications (Hossain et al., 2019; Nguyen et al., 2021; Del Rio Merino et al., 2022; Shabbar et al., 2024). In this context, XPS waste presents an opportunity for the development of lightweight, energy-efficient building materials (Petrella et al., 2020; Bergmann Becker et al., 2022; Bideci et al., 2023). By incorporating XPS into cement based composites, it is possible to reduce waste, decrease the environmental footprint, and finally produce materials with enhanced thermal insulation properties. Most of the research studies have explored the incorporation of synthetic polymers, such as Expanded Polystyrene (EPS), into concrete and mortar mixtures, demonstrating benefits such as reduced weight and improved thermal insulation (Dixit et al., 2019; Koksal et al., 2020; Horna et al., 2022). Nevertheless, the exploitation of EPS often results in a decrease in mechanical strength, limiting its application in structural applications. On the other hand, XPS offers several advantages over EPS, including higher mechanical strength and lower water absorption, making it more suitable for structural applications where both mechanical strength and thermal insulation are needed (Yoshihara et al., 2022). Despite these promising characteristics, the use of XPS in cement-based composites has not been widely investigated (San Antonio Gonzalez et al., 2022), as the majority of the research is focusing on EPS. This gap presents a unique opportunity to explore the potential of XPS waste in developing new, sustainable building materials. This investigation focuses on the mechanical and thermal performance of XPS-modified mortars, assessing their suitability for structural applications while simultaneously improving energy efficiency. The research investigates how the inclusion of mechanically shredded XPS waste as a sand replacement in mortar mixtures affects the load carrying capacity, density and thermal conductivity of the composite materials. This article aims to provide a sustainable and high-performance alternative for construction, contributing to both waste reduction and the development of energy This experimental investigation aimed to evaluate the mechanical and thermal behavior of XPS-modified mortars by replacing standard sand with mechanically shredded XPS waste at varying proportions. The mortar mixtures were prepared using Portland cement (CEM II/B-M (P-W-L) 42.5 N), CEN standard sand, water, and XPS particles. The particle sizes of the XPS ranged from 0.16 mm to 2.0 mm to closely replicate the granulometry of the standard sand used in the reference mix. A consistent water-to-cement ratio of 0.5 was maintained across all mixtures to standardize the hydration process and ensure reliable comparisons between different XPS content levels. Mortar specimens with XPS replacement levels ranging from 0 % to 100 % by volume were prepared, with prismatic specimens (40 mm × 40 mm × 160 mm) tested for mechanical loading values and cuboid specimens (205 mm × 205 mm × 50 mm) were used for thermal conductivity measurements. 2.1. Mechanical testing Three-point bending (flexure) tests were conducted on the prismatic specimens at 3, 7, and 28 days to assess their flexural strength values. A 25 kN servo-hydraulic testing machine operating under displacement control (0.1 mm/min) was used. The experimental set up and loading rate was according to EN196-1. The objective was to observe the load deformation behavior and determine the impact of XPS content on the flexural strength of the mortars. efficient building technologies. 2. Experimental procedure