The construction industry is the world’s largest emitter of greenhouse gases. The CO₂ emission levels in the atmosphere are already reaching a tipping point and could cause severe climate change. An important element is the introduction of a technology that allows for the capture and sequencing of carbon dioxide levels, reducing both emissions and the carbon footprint from the production of Portland cement and cement-based building materials. The European Union has started work on the European Climate Law, establishing the European Green Deal program, which introduces the achievement of climate neutrality in the European Union countries. This includes a new policy of sustainable construction, the aim of which is to develop products with a closed life cycle through proper waste management. All efforts are being made to create generated waste and thus to support their production and/or use as substitutes for raw materials to produce biocomposites. This article reviews environmental issues and characterizes selected waste materials from the agri-food, mineral, and industrial sectors with specific properties that can be used as valuable secondary raw materials to produce traditional cements and biocomposite materials, while maintaining or improving their mechanical properties and applications.

Polyurethane foams constitute highly problematic waste due to their low density and consequently large volume. Among the most promising recycling approaches, the glycolysis of polyurethane waste stands out and was extensively discussed in this article. Existing literature reviews lack a detailed analysis of glycolysis processes and a clear presentation of the most important data. However, in this review, the scientific literature on glycolysis has been thoroughly examined and updated with the latest research in the field. The article provides an overview of glycolysis methods, categorized into rigid and flexible foams, along with a review of the catalysts and process conditions employed. Additionally, this study offers a comprehensive analysis of industrial methods protected by active patents, which has not been previously explored in the literature. This detailed examination of patent information adds significant value to the review and distinguishes it from others. Furthermore, this review also aims to introduce the main types of polyurethanes and their properties. It outlines the fundamentals of recycling strategies, thermomodernization trends, and environmental considerations, highlighting the critical role of recycling in the industry. The article serves as a complete foundation for exploring new alternative methods in this field.

The new climate law introduces a policy of sustainable construction, the assumption of which is the reduction of CO2 by the construction industry and the use of environmentally friendly materials, such as agricultural, mineral, and recycled waste, while limiting the consumption of natural resources. The article is a literature review that analyzes selected waste materials from various sectors of the economy that can be used as additives or partial substitutes for natural resources in the production of cement and in and cement building materials, the production of which reduces CO2 emissions, producing materials with high mechanical strength and environmentally friendly.

Biochar (BC), derived from wood biomass through pyrolysis, exhibits properties that make it a promising additive in mortars for sustainable construction. This study investigated the influence of biochar produced at three pyrolysis temperatures (450 °C, 550 °C, and 700 °C) on the performance of cementitious adhesive mortars. The evaluation encompassed physicochemical characterization, mechanical and adhesive strength, volatile organic compound (VOC) emissions, leachability of contaminants, and a life-cycle assessment (LCA). The results demonstrate that biochar obtained at 700 °C has the highest carbon content, an alkaline pH, and increased porosity. In contrast, biochar produced at 450 °C exhibits better sorption capacity and a higher concentration of functional groups. Incorporating 1–5% BC (produced at any temperature) improves mortar performance; however, higher doses negatively affect adhesion to expanded polystyrene board (EPS) and concrete. Emissions of VOCs and leachable metals largely remained within environmental threshold values, with only isolated instances of exceedance. The LCA revealed that substituting mineral fillers with biochar could reduce the carbon footprint by up to 35% compared to the reference formulation. These findings confirm biochar’s potential as a safe and environmentally beneficial component in low-emission construction materials, aligning with the principles of the circular economy and climate-neutral goals.

Combustion and hydrolysis of lignocellulosic biomass generate renewable energy and biofuels, but also yield by-products, such as biomass combustion ash (BCA) and waste lignin (WL). This study investigates the reuse of these by-products in cement mortars, promoting circular economy principles and sustainable construction practices. The addition of BCA at 1–10% improved mortar consistency, homogeneity, and adhesion—most notably, formulations with 5–10% BCA increased adhesion to EPS by up to 4.3%, and compressive strength remained above the 20 MPa threshold. WL additions of 0.5–1% enhanced viscosity and adhesion to both mineral and EPS substrates, with a 0.2% WL dosage improving adhesion to EPS by 9.4% compared to the control sample. Life Cycle Assessment (LCA) confirmed a reduction in the carbon footprint by up to 14% (from 1509.5 to 1297.5 Mg CO₂/year), while VOC emissions remained within acceptable limits. Leachability tests confirmed safe environmental performance. The results validate BCA and WL as functional and eco-efficient additives in cementitious composites suitable for thermal retrofitting.