Experimental study and modeling of unidirectional jute FRP for concrete confinement

This study introduces a unidirectional jute fiber-reinforced polymer (UJFRP) composite to examine its application on concrete confinement. The study aims to explore the effect of UJFRP on the strength and ductility of concrete, and to propose a predictive model for the compressive behavior of UJFRP-confined concrete. Firstly, the tensile properties of UJFRP coupons were examined, followed by a series of compression tests conducted on UJFRP-confined concrete. The experimental program considered the effects of the compressive strength of concrete (low- and normal-strength concrete) and the number of UJFRP jackets (ranging from 1 to 4 layers). Experimental results indicated that UJFRP exhibited superior tensile performance compared to conventional bidirectional jute fiber-reinforced polymer. The ultimate compressive stress of UJFRP-confined concrete was significantly enhanced up to 5.0 times for low-strength concrete and 1.7 times for normal-strength concrete, due to the ascending behavior observed in UJFRP strengthening. Moreover, a simplified predictive model for the compressive behavior of UJFRP-confined concrete has been proposed. By substituting the concrete compressive strength and the tensile properties of UJFRP coupons into the simplified model, it is possible to estimate both the ultimate compressive strain and stress of UJFRP-confined concrete. The predictive values from the model showed good agreement with the experimental results. The findings in this study will facilitate the adoption of UJFRP as an eco-friendly alternative material for retrofitting and strengthening concrete structures.