Experimental characterization of repaired cracked RC beams which strengthened with different healing methods subjected to torsion load

Abstract

Crack on concrete structures and its expansion leads to the destruction of concrete elements. There are some measures that can be taken to repair the cracks and extend the life cycle of the structures. These methods are considered to prevent extensive human and financial losses. Some of them such as FRP (Fiber Reinforced Polymer) and NSM (Near Surface Mounted), are used for most concrete elements, but others, such as bacterial injections, using some special mortars, or other self-healing ways are more applicable to special buildings such as oil platforms. All sorts of loads including bending, shear, torsion, and axial force can contribute to creating cracks. This research pays particular attention to the torsional load; how it can create, and what kind of repairing material can be used. For this purpose, twenty reinforced concrete beams were constructed and the effect of methods such as FRP (Fiber Reinforced Polymer), NSM (Near Surface Mount), epoxy injection, Bactria injection, self-healing concrete by using encapsulated polyurethane (with the length of 100 and 10 cm), mineral material injection and grout injection was experimentally evaluated. The results of displacements, torsion load, torsion moment, and angle of twist proved that the use of FRP and grout had the most and the least effect on repairing. In addition, by considering criterion FRP's impact in the restoration of a cracked concrete beam under torsional load based on the ACI (318-08), some coefficients were calculated to present the contribution of each method in the healing process.