Performance Enhancement of TMT Rebar in Accelerated Corrosion

Akshatha Shetty,Katta Venkataramana,Praveen B B,Indrani Gogoi

doi:10.5923/j.jce.20120201.03

Abstract

Thermo-Mechanically-Treated (TMT) bars have recently been used as advancement over the conventional mild steel bars in reinforced concrete structures in order to enhance the durability in corrosive environment. Corrosion of steel reinforcement leads to cracking of reinforced concrete sections and thus may further reduce the load carrying capacity and serviceability of the structural members. Corrosion of rebars may cause reduction in yield strength of steel, affect the bond strength due to delamination of rust formed on the rebar surface. In this paper, the results of an experimental investi- gation on effects of corrosion on the mechanical strength of TMT steel rebars are presented. Corrosion is induced on the bars by impressed current method. The rebars are subjected to varying levels of corrosion and their stress strain characteris- tics are studied. The stress strain characteristics indicate a decrease in the area under stress strain curve with increasing level of corrosion. Further, it is observed that the yield strength of steel bars is not affected at a lower percentage of corro- sion, but for higher percentage of corrosion there is a considerable reduction in yield strength, percentage of elongation. It was also observed that at a higher percentage of corrosion the failure pattern of bars had changed from ductile mode to brit- tle mode.

Highlights

Reinforced concrete structures exposed to marine environment are subjected to simultaneous action of number of physical chemical and electro chemical deterioration process
In the view of immense cost involved in initial construction and in repair and rehabilitation, it is quite important that these structures should able to resist the ravages of time and deleterious effects of harsh environmental condition with minimum maintenance cost and reinforcement corrosion has been identified as the predominant deterioration mechanism for reinforced concrete structures, which seriously affects the serviceability and the safety of the structures
It has long been recognized that carbon steel reinforcing bars have a low resistance to corrosion in chloride-bearing environments, resulting in many and marine structures having been severely damaged by corrosion of the reinforcement

Summary

Introduction

Reinforced concrete structures exposed to marine environment are subjected to simultaneous action of number of physical chemical and electro chemical deterioration process. Technological advances during the last few years in the field of deformed bar production steel manufacturing industry has successfully developed a corrosion-resistant variety of rebar for the construction industry. This type of steel, called thermo-mechanically treated (TMT), which imparts the better corrosion resistance against severe environment conditions. The thermal gradient existing across the rebar section emerges from the quenching zone causes heat to flow from the hot austenitic core toward the rebar surface This results in the tempering of the surface martensite, and an equalization of the surface and core temperatures takes place. After knowing degree of corrosion the rebars were tested in tension to evaluate their mechanical properties

Effect of Corrosion on Mechanical Properties of Steel

Experimental Program

Results and Discussion

Conclusions