Performance evaluation of concrete blended with industrial and agricultural wastes reinforced with hybrid fibres - a feasibility study

Engineering and research challenges include exhausting traditional construction resources and disposing of garbage. In order to solve these issues, industrial or agricultural waste is being extensively studied as a construction material alternative. Primary wastes in our country are Fly Ash (FA) and Coconut Shell (CS). They can cause major waste disposal concerns if mismanaged. This study is a feasibility study on employing FA (an industrial waste) as binder and coconut shell (an agricultural waste) as coarse aggregates. The composite obtained by incorporating waste materials is reinforced with hybrid fibres to enhance its mechanical performance. The work undertaken comprises four distinct phases, the first phase evaluates reference mix with conventional materials. FA is utilized as SCM in concrete in the second phase. In the third phase, Coconut Shell Aggregate (CSA) is used to partially replace Natural Coarse Aggregate (NCA). In the final phase, fibres in different proportions of polypropylene and steel fibres are included to Coconut Shell Aggregate Concrete (CSAC). The findings demonstrate that replacing up to 20% of cement with FA enhances compressive, split tensile and flexural strengths by 8.1%, 5.9%, and 7.8%, respectively. The use of CSA, while slightly reducing strength parameters compared to NCA. The incorporation of 1% steel fibers (SF) significantly enhanced the mechanical properties of CSA-based concrete, achieving increases of 11.9%, 33.0%, and 30.7% in compressive, split tensile, and flexural strengths, respectively. Adding 0.2% polypropylene fibers (PPF) to SF further amplified these strengths by 3.5%, 13.5%, and 15.6%, respectively and decrease the brittleness and improve the post-peak toughness. Advanced statistical method response surface method and artificial neural network (ANN) modeling using MATLAB proved highly effective for predicting compressive strength, with ANN showing superior accuracy compared to the response surface method. The results indicate that hybrid fibre reinforced coconut shell aggregate concrete (HFRCSAC) mixture has significant potential for use in civil engineering applications.