Strength development and crack pattern of coconut fibre reinforced concrete (CFRC)
In tropical regions, natural fibres are abundantly available which when utilized as reinforcement will reduce thecost ofreinforced concrete.Hence, this paper investigated the use of coconut fibres as reinforcement in concrete. Coconut fibres were extracted from coconut pods and chopped into an average length of 40 mm. Concrete of mix ratio 1:2:4 was produced which contained coconut fibre of 1, 2, 3 and 4% by weight of cement. Compressive strength and modulus of rupture of CFRC specimens were determined following standard procedures at curing ages of 7, 21, 28 and 56 days. Crack pattern was also monitored. The results showed that the water-cement ratio for workable mix increased from 0.62 to 0.70 as coconut fibres (CF) increased from 0 to 4%, while the compressive strength only increased up to 2% CF inclusion but dropped afterwards when compared with normal concrete (NC). The 28-dayflexural strength of CFRC increased with increase in the coconut fibre in concrete. There was gradual tensile failure in CFRC with hair-like crack as compared to sudden failure with wide crack from tension zone to compression zone in normal concrete. The study concluded that up to 2% content of CFis recommended for concrete reinforcement in minor structural elements.