Effects of acid and sulphate attack on concrete containing recycled plastic waste fine aggregate

The use of plastic waste in concrete not only makes it more cost-effective but also reduces the difficulties associated with its disposal and the degradation of the environment. Literature reviews have shown that the use of plastic waste reduces the strength of concrete due to poor adhesion between the plastic waste and cementitious matrices. In this research, an attempt was made to utilize Recycled Plastic Waste (RPW) obtained by recycling plastic carry bag waste as a partial replacement by volume for conventional fine aggregate. The effect of chemical treatment on RPW fine aggregate was also investigated to improve the bond between the RPW fine aggregate and cementitious matrices. The methodology involved determining the effect of using different percentages (0%, 5%, 10%, 15%, and 20%) of treated and untreated RPW fine aggregate on the mass loss and strength reduction of concrete subjected to sodium sulphate and hydrochloric acid solutions. The concrete properties were evaluated after exposure to sulphate and acid for 28, 56, 90, 120, 150, and 180 days. Microstructural properties of the concrete specimens were also examined using Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD). Test results showed that exposure to hydrochloric acid adversely affected the strength of concrete containing plastic aggregate. However, the strength loss was about 56% under sulphate attack. To mitigate the environmental impact of plastic waste and the depletion of non-renewable natural resources, the findings of this study can contribute to the development of more sustainable and eco-friendly concrete.