Experimental tiles made from recycled plastics and local sisal fibres achieved 41.66 MPa compressive strength and 0.225% water absorption in laboratory testing.
Researchers at Rwanda Polytechnic-Ngoma College have developed experimental construction tiles using recycled plastic waste reinforced with locally sourced sisal fibres. The research combines several types of discarded plastics with natural fibre and mineral materials to create a potential construction application for hard-to-recycle plastic waste.
The study, published in Frontiers in Sustainability, investigated recycled HDPE, PET, PVC, polypropylene and polystyrene. The plastics were collected, sorted, washed and shredded before being processed with sand, marble chips, cement and sisal fibres under controlled heating and compression.
Researchers tested different levels of sisal reinforcement to determine how the fibre affected the mechanical performance of the tiles. The formulation containing 5% sisal by volume recorded the highest average compressive strength at 41.66 megapascals (MPa). This compared with 30.12 MPa for the formulation without sisal, representing an increase of about 38.3%.
The strongest formulation contained approximately 50.5% recycled plastic waste, 26.5% marble chips, 13% cement, 5% sisal fibres and 5% fine sand by volume. The researchers heated the plastic mixture to between 200°C and 300°C before combining it with the other materials, moulding the mixture and compressing it during cooling.
The experimental tiles also demonstrated low water absorption. Three tested samples recorded absorption rates of 0.223%, 0.216% and 0.238% after 24 hours of immersion, giving an average of 0.225%. The researchers attributed the result partly to the hydrophobic properties of the plastic matrix.
The researchers compared their results with conventional ceramic and Nyagatare granite tiles. The study reported compressive strengths of roughly 20–30 MPa for ceramic tiles and 60–80 MPa for Nyagatare granite, while the experimental recycled-plastic formulation reached 41.66 MPa. These comparisons are based on the study’s reported values and do not establish commercial performance equivalence.
The research addresses Rwanda’s continuing challenge of managing post-consumer rigid plastics. The study notes that existing collection and recycling capacity does not capture all rigid plastic waste, creating a need for additional applications that can turn discarded materials into useful products.
Sisal provides another locally available material in the composite. As a natural fibre, it can reinforce recycled-plastic materials while contributing to a composite that combines polymer waste with renewable agricultural material. The researchers specifically investigated sisal because of its availability and reinforcement potential in Rwanda.
The researchers also evaluated estimated production costs against ceramic and granite alternatives. Their calculations placed the experimental tiles at approximately 26,500–32,150 Rwandan francs per square metre, compared with reported estimates of 13,500–17,000 francs for ceramic and 36,000–45,400 francs for Nyagatare granite. These are study estimates rather than established commercial market prices.
However, the technology remains at the experimental laboratory stage. The researchers used a manual compression press and wooden moulds, and further work is required to assess large-scale manufacturing, quality consistency, long-term durability and performance under real-world conditions. The study also proposes future research into using artificial intelligence to predict cracking and fracture behaviour.
The development demonstrates one possible route for combining plastic waste recovery, natural-fibre reinforcement and construction-material production. If further testing confirms durability and manufacturing consistency, recycled plastic composites could potentially create additional outlets for waste materials while supplying alternative products for the construction sector.