Experimental study of corrosion inhibition of RCC element using glass FRP mats

Abstract

The corrosion of steel reinforced bars has been the main cause of affecting the strength of structural elements. An investigation on corrosion inducement at large scale on reinforced concrete beams by impressed current technique and their strengthening using Glass Fibre Reinforced polymer sheets. 5 Beams (1 uncovered + 4 covered with GFRP mats having different patterns) have been provided an accelerated environment to corrode, then tested to structural failure. The accelerated corrosion has been performed by dipping the beam into 5% NaCl solution upto half depth so as to target only the bottom rebar. The cathode has been fixed in the tub along with the beam as anode. An external power supply has been provided to supply a constant voltage of 15 V. One beam of each pattern and one controlled beam have been subjected to accelerated corrosion regime. After 150 hours of accelerated corrosion the beams have been subjected to Rebound hammer and Ultrasonic pulse velocity test i.e. non-destructive testing. After this beams have been subjected to Destructive testing like centre-point load flexure test. The decrease in area of steel reinforcement has been calculated using Faraday’s Law. Since the presence of Chloride ions in de-icing salts is the major cause the breakdown of the passive layer which is responsible to initiate corrosion. It only takes place if chlorides, oxygen and moisture are present in sufficient quantities at the level of reinforcing steel. Glass Fibre Reinforced polymer sheets have been sheathed around beams to protect and strengthen them from the loss of shear strength and confinement due to the corrosion of stirrups. Glass FRP’s are unaffected by electrochemical and electromechanical degradation. GFRP’s have corrosive inertia for aggressive corrosive effects of acids, alkalis, salts and similar aggregates under a wide range of temperatures. GFRP’s can be applied on the surface of concrete with the little apprehension of environmental degradation. Moreover, the FRP wraps provide a protective layer that may resist further corrosion of steel.