EXPERIMENTAL INVESTIGATION OF MECHANICAL PROPERTIES OF RC SHORT COLUMNS EXPOSED TO SODIUM CHLORID AND REPAIRED WITH GFRP

Abstract

This paper carries out the effects of sodium chloride on the strength of RC short columns, and evaluates the role of glass fiber-reinforced polymer (GFRP) in enhancing the strength of the column when it is exposed to the penetration of chloride ions. The short columns were prepared with a single concrete mixture of European Standard Cement (EN 197-01:2011, CEM I 42.5 N) having a water-cement ratio of 0.65 and a density of 2356.68 kg/m³. The columns were constructed with main reinforcements of 3 rods having 10 mm diameter, closed stirrups of 3 mm diameter, and 58 reinforced concrete cylinders cured in varying chloride levels (0%,5%,10%,15%) . While testing, a strict procedure of keeping one group of columns directly in the solution and exposing the other group to wet and dry cycle in difference concentrations of NaCl (5%,10%,15%) with curing time of 28 and 56 days has been followed. The cylinders were repaired and strengthened externally with epoxy bonding by laminating GFRP to the concrete surface. The compressive test was conducted on two groups with duration of 28 and 56 days, in addition to a group that was repaired after 28 days, and later returned to the cured environments and tested them at 56 days. The results showed that the use of GFRP sheets for strengthening reinforced concrete columns, exposed to chloride ions penetrations, is an efficient technique to maintain structural integrity.

In addition, the experimental results of the study have been compared to the numerical results obtained using current constitutive relationships found in the technical literature. In conclusion, it can be stated that the proposed model performs of FRP-confined concrete predicting the ultimate conditions of GFRP-confined samples.