Effect of design parameters on microstructure of steel-concrete interface in reinforced concrete

Porous band at the steel-concrete interface in reinforced concrete can significantly affect the corrosion-induced cracking process of concrete. The quantification of this porous band is of great significance for accurate prediction of service life of corrosion affected concrete structures. In this paper, the effects of concrete design parameters, namely water to cement ratio, aggregate size and concrete cover, on the thickness of porous band at the steel-concrete interface are quantitatively investigated using the technique of Backscattered electron imaging. The results show that the porous band is not uniformly distributed around the steel bar at the steel-concrete interface with the thickness ranging from few microns to a hundred microns. The results also show that the water to cement ratio and concrete cover affect the thickness of porous band proportionally. The significance of these findings is that they can provide guidance on the design of reinforced concrete with a view to alleviating porous band at the steel-concrete interface. © 2019 Elsevier Ltd