Utilization of recycled concrete aggregates in LDPE-bonded cementless paver blocks

Abstract

This study investigates the utilization of recycled concrete aggregates (RCA) in waste low-density polyethylene (LDPE)-bonded, non-traffic cementless paver blocks. RCA is incorporated at varying percentages (0%, 25%, 50%, 75%, and 100%) to replace virgin coarse aggregates. Differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA), and melt flow index (MFI) were performed to characterize the thermal and physical properties of LDPE. RCA was treated using a 2-phase treatment technique to incorporate its efficient utilization. Four types of LDPE-to-aggregate mixes, namely, A (1:2.5), B (1:3), C (1:3.5), and D (1:4), were prepared to determine the optimal ratio and the quality control parameters through trial mixes. Paver blocks were evaluated based on their compressive strength, density, water absorption, and thermal strength stability. The results indicate that performing a double-treatment on RCA, optimized mix ratios, and identifying quality control parameters enhances the overall performance of paver blocks. A 35 MPa strength is achieved with 75% replacement, 1:3.5 LDPE-to-aggregate ratio, 30:70 coarse to fine aggregate ratio, and 50 mm depth, with a melt mixing temperature of 180–210°C. Microstructure analysis reveals a strong inter-transition zone (ITZ) for 75% replacement. The ANOVA, followed by a post-hoc analysis, was performed to validate the significance of these results.