Design and Performance Evaluation of Plastic–Sand Interlocking Blocks Using Waste Polyethylene Terephthalate (PET) and Low-Density Polyethylene (LDPE) for Sustainable Construction

• Dauda ALI

  Author

• Auwal SHUAIBU

  Author

The increasing generation and improper disposal of plastic waste, coupled with the environmental impacts associated with conventional construction materials, have created a need for sustainable alternatives that can simultaneously address waste management and construction-material demands. This study investigated the production and comparative compressive performance of plastic–sand interlocking paving blocks manufactured using waste Polyethylene Terephthalate (PET) from discarded plastic bottles and Low-Density Polyethylene (LDPE) from pure-water sachets. The innovative procedure involved using waste PET and LDPE as complete polymeric binders, without cement or water, and combining each plastic type separately with sharp sand at a controlled 1:3 plastic-to-sand ratio. The plastics were sorted, cleaned, melted at controlled temperature ranges, mixed with sand, compacted in a 200 × 100 × 75 mm interlocking moulds, and allowed to cool before testing. Four specimens were produced for each plastic type and subjected to compressive-strength testing. PET specimens recorded an average weight of 2.81 kg, crushing load of 92.9 kN, and compressive strength of 4.65 N/mm², while LDPE specimens recorded 2.68 kg, 71.2 kN, and 3.56 N/mm², respectively. PET therefore demonstrated approximately 30.6% higher compressive strength and 30.5% higher crushing load than LDPE. The superior PET performance is attributed primarily to its greater rigidity, higher structural stability, and more effective load transfer within the plastic–sand composite, whereas the greater flexibility of LDPE may reduce resistance to compressive loading. The study contributes comparative experimental evidence on the performance of two commonly available plastic wastes under the same production conditions and provides a context-specific approach for converting locally available plastic waste into interlocking construction products. The findings indicate that PET-based blocks have greater potential for paving and other light-duty applications where higher compressive strength is required, while LDPE-based blocks are more appropriate for lightweight and non-load-bearing applications. The study provides a basis for further investigation of mix-ratio optimization, durability, abrasion resistance, water absorption, fire behaviour, and long-term environmental performance.

• 48_Ali and Shuaibu (2026)

Copyright (c) 2026 Dauda ALI, Auwal SHUAIBU (Author)

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