Influence of the microstructure of TMT reinforcing bars on their corrosion behavior in concrete with chlorides

Abstract

Thermomechanically treated (TMT) carbon steel bars, often known as "TempCore" bars, are commonly used as reinforcements in concrete structures. TMT causes the formation of a martensite case in the outer surface of the bars, increasing their hardness, while the remaining ferritic-perlitic core maintains the typical ductility of hot rolled bars. In this work, the effect of this TMT induced microstructure on the development of pitting attacks in chloride media has been analyzed in depth. Electrochemical impedance spectroscopy (EIS) measurements and polarization curves have been carried out in simulated pore solutions to understand the effect of the presence of different phases in the microstructure and to quantify the strength of the galvanic couple that the outer martensite can form with the inner core. Moreover, accelerated corrosion tests in chloride contaminated concrete slabs have also been performed. Bars from six different slabs where corrosive attack has been forced for different times have been studied. The shape of the main pits in the bars corroded in concrete has been analyzed through optoelectronic microscopy and the results obtained prove that the depth of the attack is related to the microstructure of the TMT bars.

Effect of Calcium Stearate in the Mechanical and Physical Properties of Concrete with PCC and Fly Ash as Binders

“…The chemical and physical content of PCC and fly ash are shown in Table 2. The physical characteristics Materials 2020, 13,1394 3 of 16 of the PCC used are presented in Table 3. The physical properties of the sand and crushed stone are shown in Table 4.…”

“…Besides that, the appearance of fly ash in concrete also raises the alkalinity of concrete [11]. The higher the alkalinity of concrete, the greater the passive layer protected steel bar in concrete is from corrosion attack.Not only additives such as fly ash, slag, and silica fumes, but superplasticizers such as water reducers [12] in concrete also can reduce the capillaries and pores [13] in concrete. Although the water/cement ratio used in concrete is very small, the workability of fresh concrete remains good, and this is easily maintained by adding a superplasticizer to the concrete [14].…”

“…Not only additives such as fly ash, slag, and silica fumes, but superplasticizers such as water reducers [12] in concrete also can reduce the capillaries and pores [13] in concrete. Although the water/cement ratio used in concrete is very small, the workability of fresh concrete remains good, and this is easily maintained by adding a superplasticizer to the concrete [14].…”

Post-2000 Building Industry in Kabul City from Sustainability Perspective

“…This is a form of mud plaster, an admixture of straw and mud with a specific percentage of each ingredient. Straw increases the adhesiveness of mud and the length of each straw should not be less than 10 cm [20]. Kahgel is the material used as a finishing layer on the roof of residential buildings.…”

Effect of Formwork Removal Time Reduction on Construction Productivity Improvement by Mix Design of Early Strength Concrete

“…The formwork removal time was shortened as the temperature increased, and 330HFS_ePC and 330EP exhibited almost similar formwork removal times. Further, future studies should be conducted on securing the demolding time of the formwork using environmentally friendly materials [37,38] and the corrosion resistance according to the SO3 content [39].…”