Bond characteristics of quartz sand modified enamel coated steel bars with concrete

Abstract

Porcelain enamel, as a coating material, has a glassy and smooth surface that reduces the bond action with surrounding concrete when applied to steel rebar. In this work, quartz sand modified enamel (QSME) coatings are proposed for the first time to improve the bond action with concrete. The bond characteristics of QSME-coated steel bars in concrete are experimentally investigated by pull-out tests, and the effects of the size and content of quartz sand are considered. The microstructure of the steel bar/concrete interface is characterized by using a scanning electron microscope, and the surface profile is analyzed with a 3D scanner. Results show that QSME coating significantly increases the bond strength, bond stiffness, bond ductility, bond toughness, and residual bond strength of plain steel bars, which increase with an increase in the quartz sand content. The bond strength of QSME-coated deformed steel bars decreases compared with that of uncoated rebars due to the reduced rib height. However, QSME coating improves the bond stiffness, bond ductility, bond toughness, and residual bond strength of deformed steel bars. For QSME-coated steel bars, the bond strength linearly increases with an increase in the surface roughness.