Use of Post-Consumer Plastics in the Production of Wood-Plastic Composites for Building Components: A Systematic Review

This systematic review study adopted the PRISMA methodology to investigate recent research on wood-plastic composites (WPC) utilizing post-consumer plastics in the construction industry. Initially, 3111 articles were selected from academic databases using keywords such as “wood and plastic composites”, “WPC”, “polymer”, “recycled”, “waste”, “construction”, and “sustainability.” After stringent exclusion criteria, 15 relevant studies on plastic waste composites were identified. These studies often employ post-consumer plastics like polypropylene and high-density polyethylene, along with plant-based fillers, aiming to enhance mechanical properties and reduce reliance on virgin materials. Analysis of these studies revealed that the optimal plastic composition in the composites ranged from 40% to 45% wood and from 50% to 60% plastic, with the extrusion process being the most employed for shaping. Specific factors, such as the use of compatibilizers and the particle size of raw materials, were identified as significant influencers on composite strength. These materials exhibited high thermal stability, rendering them suitable for construction applications exposed to high temperatures. The diversity of plastic waste explored in the studies underscores the potential to tailor thermal properties to specific application demands. These composites facilitate closed-loop plastic recycling, enabling their reintegration into the production chain and offering opportunities for lightweight, durable, and high-performance products in the construction industry. However, beyond the factors examined in the studies, a meticulous assessment of the fire resistance, weather resistance, ultraviolet resistance, moisture absorption, dimensional stability, degradation, long-term durability, impact strength, recyclability, and cost-effectiveness of the material is crucial. Thoughtful consideration of these factors is essential to achieving a comprehensive understanding of the potential and limitations of recycled plastic composites in promoting energy efficiency and sustainability in the construction industry

Multiple Dimensions of Energy Efficiency of Recycled Concrete: A Systematic Review

The focus on building energy efficiency using alternative materials in structures, especially concrete, and the main technical and environmental challenges therein, aligns with Sustainable Development Goals (SDG). This study proposes a review that analyzes structures made with recycled concrete, relating to the energy efficiency of buildings. A classification structure was proposed, addressing the following questions: (i) What are the various dimensions in which research into energy-efficient recycled concrete is concentrated? (ii) What are the themes and classes of research associated with these dimensions? (iii) What are the main shortcomings of current approaches, and what would be a good research agenda for the future development of energy-efficient recycled concrete? A bibliometric analysis was carried out, presenting geographical and cluster maps to understand different research trends and refine future research. This was followed by a bibliographic analysis, reviewing the most relevant studies from the last five years (2019–2024). The results showed some residual alternative materials (around 45 types from five different industries) used in the production of energy-efficient concrete. And, as a negative effect, as substitution rates increase, porosity is the property with the greatest impact on energy efficiency. The greater the number of pores and the greater their interconnection, the lower the material’s thermal insulation