Circular alternatives in the construction industry: An environmental performance assessment of sisal fiber-reinforced composites

In the development of new products, both the use of residues and the use of renewable materials are important strategies for a more circular production. However, it is not enough just to idealize a new product as environmentally sustainable, it is also necessary to prove the hypothesis through scientifically accepted methodologies, such as life cycle assessment (LCA). Thus, the objective of this study was to evaluate and compare, through LCA, the environmental performance of two composites reinforced with sisal fibers, one produced with a Portland cement matrix and the other with a geopolymer matrix based on a residue, in this case, the sludge from a water treatment plant. When comparing the environmental performance of composites using the impact assessment methods ReCiPe 2016 Midpoint/Endpoint and EN 15804, the results were convergent; the composite with the cement matrix has less environmental impact. The composite with the Portland cement matrix and 0.4% superplasticizer , for example, in the category Global warming, using the ReCiPe 2016 Midpoint method, was 42.48% less impactful than the geopolymeric composite without the avoided product. In the category Climate change, using the EN 15804 method, the composite with the Portland cement matrix and 0.4% superplasticizer was 42.05% less impactful than the geopolymeric composite without the avoided product. The sensitivity analysis showed that the critical environmental points in the two composites are the production of potassium hydroxide and transport in the case of the geopolymer composite , and the production of cement and transport for the Portland cement composite. This research contributes scientifically by presenting potential alternatives for the construction industry that have already been evaluated from an environmental perspective. It is important to environmentally assess new products still in the development stage, since stating that a building material has superior environmental performance just because it is produced from residues or from a renewable raw material may not be a true reflection of the facts. • A comparative cradle-to-gate LCA of two sisal fibers-reinforced composites was performed. • One of the composites was produced with a waste-based geopolymeric matrix, and the other with a Portland cement matrix. • The environmental performance of the composites was evaluated using the ReCiPe 2016 Midpoint and EN15804 methods. • The Portland cement matrix composite had better environmental performance in almost all the impact categories evaluated. • In the geopolymer composite the production of potassium hydroxide is the environmental tipping point.