Partial Replacement of Plastic Waste and Coconut Fibre in Concrete

Abstract: The increasing demand for concrete in the construction industry, coupled with the overuse of natural resources and rising environmentalconcerns, has necessitated the development of sustainable alternatives. This research project focuses on the partial replacement of cement with coconut fiber powder and fine aggregate withHDPE plastic waste (10 mm flakes) in M25 grade concrete. The primary aim is to reduce the environmental burden associated with cement production and plastic pollution while maintaining the required mechanical properties of concrete. The experimental program involved preparing concrete mixes with varying proportions ofcoconutfiberpowder (0%,0.5%,0.8%,1.0%, and 1.5%) and HDPE plastic waste (0%, 5%, 10%, and 15%). A total of 36 cube specimens were cast and tested for compressive strength at 7, 14, and 28 days of curing. The optimal results were observed for the mix containing 1% coconut fiber and 10% plastic waste, which achieved a compressive strength of 26.8 N/mm² at 28 days—exceeding the minimum requirement for M25 concrete. Additionally, the use of a superplasticizer of Polycarboxylate ether further enhanced the strength to 28.5 N/mm². The findings confirm that coconut fiber and plastic waste can be effectively used as partial replacements for cement and sand without compromising the strength or performance of concrete. This study demonstrates the potential of converting agricultural and industrial waste into valuable resources for eco-friendly, cost-effective, and sustainable construction.