Production of Sustainable Lightweight Sandcrete and Paving Blocks Using Waste Polyethylene Terephthalate and Periwinkle Shells: A Review

The construction industry increasingly seeks sustainable alternatives to traditional materials due to growing environmental concerns and material shortages. This review evaluates the potential of integrating waste polyethylene terephthalate (PET) and periwinkle shells (PWS) in the production of lightweight sandcrete and paving blocks. Emphasis is placed on mechanical, physical, and durability performance, as well as the environmental and economic implications. Results from existing studies indicate that PET can partially replace fine aggregates up to 5–10 % without significant loss of strength, while PWS can substitute coarse or fine aggregates up to 30 % to achieve lightweight units. However, excessive use of both materials leads to decreased compressive strength and increased water absorption. Combined application of PET and PWS remains underexplored, representing a promising avenue for sustainable construction research.