International Research Journal of Engineering and Technology (IRJET)
e-ISSN: 2395-0056
Volume: 10 Issue: 05 | May 2023
p-ISSN: 2395-0072
www.irjet.net
EFFECTS OF FLY ASH ON THE PROPERTIES OF COCONUT FIBRE REINFORCED CONCRETE 1S. I. Anowai, 2T. S. Ketkukah, 3M. Pam, 4M.E. Gukas, 5J.B. Rwang and 6C.D. Gyang 1 Senior Lecturer, Department of Building, University of Jos, Nigeria
2 Reader, Department of Civil Engineering, University of Jos, Nigeria 3Lecturer, Department of Quantity Surveying, University of Jos, Nigeria 4 Lecturers, Department of Building, University of Jos, Nigeria
5 Lecturer, Department of Quantity Surveying, University of Jos, Nigeria 6 Student, Department of Building, University of Jos, Nigeria
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Abstract - This study investigates the effects of partially replacing Ordinary Portland Cement (OPC) with fly ash on properties of
coconut fibre reinforced concrete. OPC was partially replaced with fly ash at 0%, 10%, 20% and 30% in coconut fibre reinforced concrete. The coconut fibres were extracted from coconut seeds and shredded into 60mm lengths. All the concrete specimens were reinforced with coconut fibre weighing 0.5% of the weight of fine the aggregates. Mix ratio of 1:2:4 and water/cement ratio 0.58 were adopted in this study. The slump, compaction factor, compressive strength, splitting tensile strength, flexural strength, alkalinity and water absorption of the concrete specimens were tested and analysed after curing periods of 7, 28 and 56 days respectively. Fly ash improved the workability, water absorption and reduced the alkalinity level of the matrix as percentage replacement of OPC with fly ash increases. The results also showed that specimens containing 10% partial replacement of cement with fly ash achieved highest compressive strength, flexural strength and splitting tensile strengths at all ages of curing. It can be concluded that 10% replacement of cement with fly ash replacement gave the best results for compressive strength, flexural strength and split tensile strength and reduced alkalinity and water absorption of coconut fibre reinforced concrete. It is thus recommended that OPC should be partially replaced with fly ash to improve the mechanical and durability properties of coconut fibre reinforced concrete.
Key Words: Coconut fibre, fly ash, workability, alkalinity, water absorption, mechanical properties. 1. INTRODUCTION Plain concrete possesses a high compressive strength but low tensile strength. Cracks develop in plain concretes even before loading due to drying shrinkage and when load is eventually applied the internal cracks propagate and open up due to stress and additional cracks are formed [1]. The propagation of these cracks can be arrested by the introduction of randomly distributed small pieces of reinforcing materials known as fibres. The introduction of fibres in concrete help to transfer loads at the internal micro cracks [2]. The fibres could be synthetic or cellulose (plant) fibres. The development of steel reinforcement has overcome the problem of poor tensile strength but it does not completely solve the problem of micro cracks due to drying and plastic shrinkage owing to weathering conditions and it is also expensive. The presence of micro cracks in the mortaraggregate interface is responsible for the inherent weakness of plain concrete. The weakness can be removed by inclusion of fibres in the mixture. Fibres cannot be used as conventional reinforcement but it can lower down the requirements of steel reinforcements [3]. Fibres are broadly classified into man-made and natural fibres. Man-made fibres are made from synthetic materials (such as petrochemicals) and metals while natural fibres originate from vegetable, animal and mineral sources. Natural fibre such as coconut fibre has certain physical and mechanical characteristics that can be utilized effectively in the development of reinforced concrete material [4].. Use of coconut fibre can lead to improvement in properties of cement concrete in addition to providing a proper solution for disposal of this natural waste. In most cases, these coconut fibres are dumped as agricultural waste, so can be easily available in large quantity hence making them cheap [5]. Coconut fibre has been described as the most ductile fibre amongst all natural fibres being that they are capable of taking strain 4-6 times more than other fibres [6]. Coconut fibre is extracted from the outer shell of a coconut. Its scientific name and the plant family of the coconut fibre is “Cocos Nucifera” and “Arecaceae (Palm)” respectively, while it is commonly referred to as “Coir” [7]. Large quantities of coconut fruit are produced in the rainforest zones of South-West and South-South regions of Nigeria with minor productions in other geo-political zones [8]. Coconut fibre is obtained from the husk of the coconut palm. The fruits are dehusked with a spike and after retting, the fibres are subtracted from the husk with beating and washing.
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