Strength and ductility of concrete confined with natural fiber reinforced polymers (NFRP)

The research work presents an experimental investigation on the confinement strength of concrete column using Natural fiber (Sisal fiber) Reinforced Polymer. In the deep detail is divided into 3 part: plain circular and square concrete column strengthened with NFRP, plain and RC rectangular concrete column strengthened with NFRP, and RC circular and square concrete column strengthened with NFRP. All of column were externally applied using NFRP and impregnate by epoxy resin. All the column specimens were loaded to failure under the uniaxial compression so as to evaluate the effect of confinement on the axial load carrying capacity and evaluate the performance of existing model that develop from another researcher. The results reveal that externally bonded NFRP composites are very effective to enhance strength and ductility. The strength and ductility were increased significantly with enhance the number of confinement thickness. But the efficiency of the confinement decreased when the strength of the concrete has high strength. And rupture strain of the confinement jacket at corner lower than rupture strain at middle of column for all of non-circular column. However, the investigation existing model is unsuitable for predicting the ultimate strength after column confined NFRP. So the new strength model was developed from hydrostatic pressure equation. New strength models are proposed based on the obtained experimental data which can use to prediction models in term of strength when NFRP-confined column.