Performance Enhancement of TMT Rebar in Accelerated Corrosion

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 investigation 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 characteristics 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 corrosion, 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 brittle mode.

Influence of plastic deformation of S235JR steel rods on their mechanical properties and corrosion behavior in NaCl solution

“…An important consequence of steel corrosion is the deterioration of its mechanical properties. Change in steel behavior can lead to unexpected problems and even to the undesired brittle failure due to a reduced cross section [2][3][4]. That is why it is of great importance to study the impact of corrosion on the mechanical properties in order to be able to make a correct assessment of the corroded steel structures.…”

Influence of the Loading Speed on the Ductility Properties of Corroded Reinforcing Bars in Concrete

“…If the corrosion had been uniform along the bar, the adjusting trend lines would have been horizontal. However, the lines decrease for all loading speeds [21]. This is because corrosion is not homogeneous in the bar surface, but occurs in a series of pitting spots typical for chloride corrosion of steel [46,47].…”

“…Regardless of the loading speed, the ratio has a small fluctuation near a fixed value while the corrosion ratio changed from zero to more than 4%. It is indicated that the ratio of R m /R e is irrelevant to the average corrosion ratio which shows that the decrease of yield strength is induced by the decrease of effective cross-section area of the steel bars [9,21].…”

“…With low levels of corrosion the loss of strength is also low: this means that the structural elements can still meet their resistance function, though the reduction of strain may not meet the minimum values required in Table 1 to ensure enough ductility. Previous studies [20,21] have shown that the ratio R m /R e remains constant with the increase of the corrosion level. This means that the steel may amply meet the R m /R e requirement but not the requirement of A gt .…”

Experimental study of zone of yield strength on corroded construction steel specimens for reuse

“…There are many ways and standards for obtaining accelerated corrosion, which by its very nature is artificially caused. We will use a galvanostatic method, as do other researchers [2][3][4][5][6][7]. The acceleration of the corrosion process is accomplished by using an external source of direct current and anodic dissolution of the steel.…”