Polyvinyl chloride (PVC) waste in pressed geopolymer concrete: Analyzing properties and feasibility application considerations

The problem of waste plastic labels, commonly from polyvinyl chloride (PVC), in the environment, has frequently been disregarded. This study proposed the use of polyvinyl chloride plastic waste (PW) aggregate as a partial substitution for limestone dust aggregate in pressed geopolymer concrete (PG). The PW replacement contents ranged from 0 % to 30 % by volume, and ratios of fly ash-to-aggregate ratio (FA/A) of 0.14, 0.17, and 0.20 by weight were used. PG properties including compressive strength, density, water absorption, porosity, thermal conductivity, ultrasonic pulse velocity, and sound absorption were tested and compared with those of pressed ordinary Portland cement concrete (PC). The results showed that the incorporation of PW led to reduced performances on several concrete properties including reduced compressive strength, and ultrasonic pulse velocity, but other properties including reduced weight, better sound absorption, and lower thermal conductivity were obtained. Such effects were greater in PC than in PG, as demonstrated by a significant reduction in compressive strength of up to 95.5 % in PC, accompanied by considerably higher water absorption and porosity than those of PG. This suggests that geopolymer paste was more compatible with plastic aggregates. Additionally, the production of hollow non-load-bearing geopolymer concrete blocks using PG and PC mixtures was tried. The mix with 20 % PW substitution and 0.20 FA/A ratio met the requirements as per the standard for hollow non-load-bearing concrete masonry units (TIS 58–2017). In addition, an increase in the FA/A ratio tended to improve the properties of the blocks. This study thus provides useful information for producing geopolymer concrete blocks incorporating plastic waste as well as opening up opportunities for further research in this field.