Strengthening effect of natural fiber reinforced polymer composites (NFRP) on concrete

Abstract

To date a large number of studies have been carried out on the use of different materials such as concrete, steel, fiber reinforced polymer (FRP) composites, to enhance the strength and ductility of the reinforced concrete (RC) members. Among these materials, concrete and steel are heavy weight, whereas FRP are expensive along with skin problems during handling and installations. In this paper, the efficiency of natural sisal fiber reinforced polymer composites is evaluated on strength and ductility of RC members. The salient features of natural sisal FRPs are low density, higher toughness, acceptable strength properties, reduced irritation to the skin and respiratory system, biodegradable and sustainable since they are natural products. The objectives of this research were twofold. The first was to evaluate the compressive and flexural behavior of small-sized concrete specimens (cylinders and beams) strengthened with natural sisal FRPs, considering different resin matrices, FRP thickness and concrete strengths. Whereas, the second objective was to investigate the strengthening effect of natural sisal FRP strengthening on the flexural response of RC beams. Test results showed that externally bonded natural sisal FRPs are significantly effective to increase the strength and ductility of the concrete members. In general, the experimental results demonstrated a higher increase in the load carrying capacity when the thickness of the sisal FRPs was increased. However, RC beams strengthened by natural sisal FRP, may fail by de-bonding of FRP from the concrete surface. To avoid this failure, a new anchoring system has been proposed and tested to evaluate their performance in preventing the de-bonding of FRP from concrete surface. Based on experimental results, proposed anchoring system was found to be effective to prevent the delamination of natural sisal FRPs from concrete surface.