Experimental Study on Effect of Plastic Waste as Coarse Aggregate on Concrete Properties
High demand for aggregate to meet day-to-day activities in construction industry has intensified mining of the natural aggregate resources, thereby resulting in depletion of the resources and which raised concerns on compromise of the future generation needs. Over time, the cost of construction kept increasing due to high cost of aggregates. Serious environmental concerns have been raised on the ineffective management of the plastic waste generated globally and which has caused environmental, ecological and economic sabotage. Interest in the environmentally friendly recycling of plastic waste as materials for concrete is being considered. This study investigates the performance of concrete with addition of plastic Poly ethylene terephthalate (PET) aggregate. The plastic PET aggregate was used as substitution for coarse aggregate at 10%, 20% and 30% replacement levels. Effects of the presence of plastic PET aggregate in concrete on workability, density, compressive strength, flexural strength and water absorption were determined. The results showed that the workability increases as the proportion of PET plastic waste increases in the concrete matrix. In comparison with the control concrete, the compressive and flexural strength of concrete reduces as the content of plastic PET aggregate increases. Compressive and flexural strength reduction trends of 25%, 47% and 53% and 38%, 43% and 51% for concrete containing 10%, 20% and 30% of plastic PET aggregate respectively. The loss of strength can be attributed to the ineffective bonding between plastic PET aggregate and mortar due to the smooth surface of the plastic PET aggregate. Also, plastic PET aggregate has relatively no water absorption and which makes excess water in the concrete. Upon hydration, the excess water gets evaporated and which creates voids in the concrete and weak region around the aggregates in the concrete. However, improvement in water absorption capacity were observed. As the content of plastic PET aggregate increases, the water absorption capacity reduces. However, significant reduction in strength properties was obtained for concrete with 20% and 30% of PET plastic waste. Meanwhile, the water absorption capacity of the concrete composite gets higher as the proportion of the PET plastic waste increases. From the study, it can be said that sand can be substituted with PET plastic waste up to 10% replacement levels in concrete matrix.
