Use of Coconut COIR in Fiber Reinforced Concrete, Soil and Lime

The use of lime as a binder and natural fibers as reinforcements have been in use since ancient human history. However, ordinary Portland cement and concrete have substituted these comparatively cheaper eco-friendlier materials due to their quick setting and strength parameters since the 19th century. However, their large-scale impact on the environment due to greenhouse gases emission has encouraged further research to develop novel composite materials comprising natural fibers like coconut coir and lime as partial cement substitute. In this review study, contemporary research studies conducted by different researchers were explored and has found this field quite encouraging and progressive for modern trends in construction materials. Coir is a material with great potential due to its high strength and ductility comparable to steel; the use of lime or saline treated coir in cement by 1% as optimum quantity and in some cases up to 2% quantity, enhanced the compressive, tensile and flexural strengths up to 5%-20%. Ductility and flexibility of concrete improved with more energy absorption capacity. However, more use of coir did not improve engineering properties of concrete rather deteriorated after 2% use by weight of cement. 1% to 2% coir use in expensive marine soil augmented by 5% use of lime revealed considerable increase in engineering properties of soil especially increase of compressive strength by 1.5 times, increase of compaction factor and plasticity and reduction in shrinkage and liquid limit thus supporting a fruitful use of coir and lime mixture in its properties enhancement. Coir being a natural fiber has a limitation of lesser degradation life so needs to be treated with some suitable natural coating material to enhance its life from 3 to 20 years and needs to be cleaned properly by soaking in lime or saline water to remove lignin, pith, cellulose and silicate crystals. The overall use of coir and lime as substituent of cement binders is highly recommended though further research is required to maximize usage for this economical and eco-friendly material.