Experimental Investigation on Microstructure-Based Quality Assessment of TMT Reinforcing Bars

It has been several decades since mild steel and cold twisted deformed bars got replaced by Thermo Mechanically Treated (TMT) bars or otherwise called Quenched and Self Tempered (QST) bars. Though TMT bars are manufactured with the supreme technologies of tempcore, thermex, etc., researchers have indicated a lack of quality in rebars. The present study is conducted on 12 mm TMT steel rebars. The rebars of different chemical compositions were collected from construction sites for assessing the quality of the rebars based on their microstructure. The present state of affair at the construction site on quality checks on rebars are very much lacking. The study also emphasizes the need for better and expanded checks on quality standards for steel rebars used in concrete structures before embedment. An optical microscope-based characterization of rebar microstructure is conducted. A chemical test, the nital TM ring test is done to estimate the microstructure phase distribution in the collected rebars. The specimens collected were from different sites in the state of Kerala. The use of TMT rebars in the construction sector has undoubtedly enhanced construction quality in many ways. Proper quality checks play a pivotal role in further quality enhancement of reinforced concrete.