The Use of Plastic Waste as Replacement of Coarse Aggregate in Concrete Industry

Abstract

Recycling solid waste is one of the most important ways to reduce carbon footprints and put sustainability into practice. This research aims to bridge the gap between the results of previous studies and the effectiveness and sustainability benefits of using plastic waste (PW) in concrete mixes by partially replacing coarse aggregate with PW. Furthermore, we examine the suitability of the concrete produced for use as a construction material. The research methodology is based on studying the physical and mechanical behavior of concrete produced by partially replacing coarse aggregate with 0%, 2.5%, 5%, 7.5%, 10%, and 12.5% PW. For the conventional concrete–CC mix of 0% PW, the design strength, fcu, was 35 MP, with a slump of 100 mm, using a water–cement ratio of 0.5, a M.A.S of coarse aggregate of 20 mm, and a sand F.M. of 2.2. According to British standards, BS, slump and density tests were carried out for concrete samples produced in their fresh state and strength tests, ultrasonic testing, etc. for concrete samples after hardening. The results indicated that there is no significant difference between the dry density and bulk density of concrete produced at all its age stages, regardless of the percentage of PW that replaces the aggregate. It also indicated that the compressive strength, the flexural strength, and the splitting tensile strength of the produced concrete decrease steadily and significantly when aggregates are replaced by PW by more than 2.5%. It was found that the decrease in compressive strength does not exceed 1% for concrete with 2.5% PW compared to the strength of CC, while the compressive strength of concrete with 5% PW decreases by 24%. The maximum reduction rate of the flexural strength and splitting tensile strength was 40% and 32%, respectively, for concrete at 12.5% PW compared to the strength of CC. Therefore, PW concrete can retain its strength when used in small quantities of up to 2.5% and can be applied in structural works.