Modelling Water Absorption Index and Compressive Strength of Paving Stone Composites with Polyethylene Terephthalate (PET) as Total Binder Replacement

Abstract

Polyethylene terephthalate (PET) wastes were melted and mixed with river sand to produce paving stone composites (PSCs) of mix ratio 1:3, labelled (PET: 10, 20, 30, 40, and 50%); and sand-cement mix of 1:3 labelled PET 0% (control). In a mold measuring 50 × 100 × 200mm, three replicates of PSCs of each mix ratio and control, were produced and cured in water at a room temperature of (27 ± 2ºC) for 28 days. The PSCs showed a better water absorption property as it ranges from 6.98 % to 3.59 % as against 11.11 % for the control. Significant compressive strengths were shown by the PSCs; PET 30% had the highest mean value of 20.59 N/mm², while the control had the lowest mean value of 8.63 N/mm². Using Design Expert tool in analyzing the laboratory data obtained for both water absorption index and compressive strength, the results show that the developed quadratic model for water absorption index (WAI) has an adjusted and predicted coefficient of regressions of 0.9851 and 0.9821 respectively, with an average precision of 98.62% within the research work, allowing for simulation of WAI outcomes at different PET contents. Also, the compressive strength model is a quadratic, with adjusted and predicted coefficients of regressions of 0.9623 and 0.9526 respectively, and shows reduced variation between actual and predicted values, making it useful for design space navigation. The research suggests that utilizing PET waste as a complete binder replacement in paver production is a cost-effective method for managing waste