Engineering Properties and Impact Resistance of Kenaf and Rice Straw Fibres Reinforced Concrete

Natural fibre reinforced concrete (NFRC) has been a subject of interest for research in the past few decades due to the many advantages of natural fibres such as abundantly available, lightweight, cheap, diverse and as reinforcement in composite, provide great energy absorption and good impact resistance to the composite. The purpose of this paper is to study the engineering properties (workability, compressive, flexural and split tensile strengths, and impact resistance of NFRC, particularly kenaf (K) and rice straw (RS) fibres. Both fibres are investigated to determine feasibility of using abundant waste (RS) instead of kenaf (planted) as natural fibre reinforcement in concrete for impact resistance application such as roof tiles. Samples consist of untreated kenaf and rice straw fibres, with different percentages by volume of cement (0, 1, 1.5, 2, 3, 4 and 5%), as concrete reinforcement. The slump, compressive, flexural, split tensile strengths, and impact resistance are determined in accordance to BS, ASTM and ACI codes of practice. Results show that, due to high rate of water absorption of rice straw fibre, reduction in workability and compressive strength of RSFRC can be observed compared to KFRC. Increasing the volume of RS fibre leads to high volumes of entrapped air after curing process, resulting in decrease of concrete strength. However, addition of both fibres as reinforcement, enhanced the flexural, split tensile and impact resistance of concrete at up to a certain volume fraction of fibres. The energy absorption of RAFRC at 2% is superior compared to other fibres, except only coir and exhibit better performance in resisting impact even though kenaf has superior properties compared to RA due to its higher ductility compared to kenaf.