Utilizing recycled PET blends with demolition wastes as construction materials

Abstract

The rapid growth in plastic and demolition wastes generation by municipal and commercial industries is a significant challenge to developed and developing countries. The substitution of traditional construction materials with recycled materials is a sustainable solution which mitigates landfilling concerns and reduces the need for virgin quarry materials. In this research, an evaluation of the geotechnical and geo-environmental properties of Polyethylene terephthalate (PET) plastic waste and its blends, with two major constituents of construction and demolition (C&D) waste materials was undertaken. Recycled concrete aggregate (RCA) and crushed brick (CB) were blended with 3% and 5% of PET, and the geotechnical properties of six PET blends were evaluated in the laboratory. The experimental programme included particle size distribution, particle density, sieve analysis, flakiness index, Los Angeles abrasion, water absorption, modified Proctor compaction, hydraulic conductivity, and California bearing ratio (CBR) tests. In addition, the response of the PET blends under repeated dynamic loading conditions was investigated using repeated load triaxial (RLT) tests. CBR results of all six PET blends were higher than the minimum CBR requirements for usage as a subbase material. The RLT testing results indicated that PET blends with RCA and CB performed satisfactorily at 98% maximum dry density and at their optimum moisture contents under modified Proctor compaction effort. Furthermore, a geo-environmental evaluation of the PET blends was undertaken which consisted of determination of organic matter content, pH value, total/leachate concentration of the recycled materials for a range of contaminant constituents and the results were compared with requirements specified by environmental authorities. Control samples, 3% and 5% PET blends with RCA and CB satisfied the CBR requirements. Similarly, control samples, 3% and 5% PET blends with RCA were found to be satisfactory for RLT requirements for subbase applications.