DOI: 10.14457/tu.the.2018.941
title: Repair and strengthening of reinforced concrete members

description: This thesis mainly divided into two parts. The first part is a strengthening part which aims to use natural fiber as replacement of carbon fiber reinforced polymer (CFRP) which consider having efficiency but also costly to help reinforce concrete deep beam. The natural fiber is local material which could help reduce the cost of strengthening material. The second part is a proposed method which could help increase the life span of the reinforced concrete beam by using cathodic protection system.The first part of this thesis mainly aims to investigate the strengthening of reinforced concrete (RC) members, mainly focus into a deep beam. Externally bonded natural fiber polymer (FRP) composite is used as strengthening the material, apply to the specimen by hand lay-up method. The behavior and failure mode of the specimen are also observed during the experimental program.There is a total of 14 deep beams using as sample specimens. Two types of natural fiber, which is unidirectional and multidirectional, has been applied in a different configuration. Configuration “A” and “B” is 2-side configuration and u-wrap configuration consecutively. Experimental program starting from a single layer of reinforcement, then add up more layer varies follow result for each test. Maximum of 4 layers is conducted within this experiment. For an extended test, 3 additional larger scaled deep beams are tested with reinforcing only along shear line.As add up more layer, thickness de-bonding problem was observed in some specimens. The fiber is not ruptured mean that the fiber did not reach their maximum potential yet, but it detaches from the beam. In order to solve this problem, additional anchoring method is introduced to provide stronger bonding power between natural fiber reinforced polymer composite and concrete beam. In this experiment, mechanical bolt is used as an anchoring system. The test result is provided in chapter 6 and the failure mode for each group of the beam can be found in the same chapter.From the experimental result, using natural fiber reinforce polymer composite as strengthening material show significant benefit increase ultimate load capability and ductility of the reinforced concrete deep beam. Using of the mechanical bolt also provides additional strength to the specimen. The result of the first part is considered to be very satisfactory.The second part which is considered as an additional part of this thesis, it is about another aspect which could help maintain the strength of the reinforced concrete member. One of the most common problems of reinforced concrete structure is the corrosion problem, which results in reducing strengthening or lifespan of the structure. Experimental on corrosion protection of the cathodic protection system using sacrificial anode has been conducted in this thesis.There are a total of 8 beam specimens. Two different types of anode, Zinc, Aluminum has been used as anodic material in this experimental program. A different amount of chloride content varies from 0%, 4% 10% has been used to stimulate the different level of chloride attack level. Beam with 10% chloride use to stimulate severe condition of chloride attack. Half-Cell measurement method has been used to determine the effectiveness of cathodic protection by the measure voltage difference between the close and open circuit of CP systems. There are two stages of measurement conducted which is first 3 months represent an early stage to test and long stage measurement which is a year after the first measurement.The result from measurements shows that the cathodic protection system able to work with a beam with low chloride content as increase chloride content, the efficiency of cathodic protection system decreases up until show no support in term of corrosion protection to the reinforced concrete beam.