Concrete is one of the most important and most widely used materials for construction activities around the world. However, it has inherent deficiencies, e.g., brittleness, low impact resistance, low tensile strength, low fire resistance, low durability, and lower resistance to crack formation. Fibers and waste materials of different types are added as partial replacement of cement and aggregates in concrete to improve performance properties and reduce environmental pollution. In the present study, a thorough review of the use of various types of fibers with high and low elastic moduli in concrete to improve mechanical performance and reduce environmental pollution issues has been conducted. This review paper also provides comprehensive information on the different types of waste materials, e.g., biodegradable and non-biodegradable, which are used in concrete. The use of waste materials in concrete reduces the amount of waste sent to landfill and, in addition, improves some mechanical properties of concrete. This review is aimed at evaluating and understanding the strengths and weaknesses of fiber-reinforced concrete by using SWOT (Strengths, Weaknesses, Opportunities, Threats) analysis. Moreover, this study also concluded that carbon fiber-reinforced concrete proves to be stronger and more durable but more expensive than other fibers. An ideal percentage of natural origin fibers used in concrete can greatly improve the mechanical performance. This study also discussed that waste from polymeric materials can be used in concrete as a partial replacement of cement and other components, e.g., coarse aggregates. It can be inferred that the optimum content of fibers that gives effective results is about 1%, and the reinforcement of concrete with different varieties of wastes as a replacement for fine aggregates should not be more than 2%. Parametric optimization of fiber content will be necessary for the best possible combination of performance properties.

Recycled materials are employed in several areas to reduce the environmental burden. Therefore, recycling textiles is a vast domain being investigated by several researchers. Functionalization of textiles using active nanomaterials is a growing area of interest nowadays. However, functionalized textiles with antibacterial properties still do not employ the incorporation of recycled materials. The huge consumer need for different types of functional textiles necessitates a focus on recycled textiles in this area. Hence, this research focuses on the development of metal oxide nanoparticle-functionalized antibacterial textiles using recycled cotton and polyester yarns. Two different finishes have been used with a 50:50 ratio. Using a two-fold approach, antibacterial finishes were applied during both the yarn and fabric stages to analyze the differences in performance. Agar plate qualitative antibacterial analysis revealed efficient antibacterial function both before and after commercial laundering. However, thermo-physiological comfort properties were found to be variable for recycled yarn types and finishing stages. The air permeability of fabric-finished specimens was found to be about 47% lower than yarn-finished specimens owing to reduced porosities. However, the overall moisture management capability (OMMC) index was found to be 21% higher than that of yarn-finished specimens. Among serviceability parameters, bursting strength was found to decrease with increasing concentration, as the finishing treatments made the yarns crispier which eventually compromised yarn strength.

This article examines the reuse of waste polyurethane foam (PUF) as a material in line with circular economy principles. The main objective was to evaluate how crushed polyurethane filler of different bulk densities—35 kg·m⁻³ (PUF35), 60 kg·m⁻³ (PUF60), and their blends at 1–5 wt%—affects the mechanical behaviour and structural integrity of hybrid composite systems and bonded laminated joints. An epoxy resin matrix was combined with 3D-printed polylactide (PLA) honeycomb structures, with rectangular and hexagonal core geometries. Static tensile tests showed that the blended filler (PUF35/60) preserves tensile strength and increases the modulus of elasticity for both core geometries, reaching maximum values at 4 wt% (3.8 GPa for rectangular, 3.6 GPa for hexagonal cores). In bonded lap joints, 1 wt% PUF35 resulted in the highest tensile adhesive bond strength (13.3 MPa). SEM confirmed a high-quality phase interface and continuous adhesive contact between the epoxy matrix and the 3D-printed PLA surface, with dominant cohesive failure and effective mechanical anchoring of foam particles, even near local printing defects. The results confirm mechanically recycled PUF as a promising filler for advanced sandwich structures and adhesive systems.