Contesting crack modes modeling of reinforced concrete structure threatened by the progressive rust expansion in rebars in the presence of external load

Abstract

Disastrous concrete cracks as initiated by rebars pit corrosion and the resulted rust expansion have continually threatened the vitality of the reinforced concrete structures. In investigating the effects attributed to the rust expansion, existing scholastic works have, however, either focused only on examining one type of major crack or disregarded the influence of the external loading. Therefore, various contesting crack modes of the reinforced concrete structure due to rust progressive expansion from the rebars pit corrosion under external load are analytically modeled in this paper. To begin, such a multi-factors incident has been formulated under the premise of a thick cylindrical section with plane strain conditions and the new consideration of external loading. Considered major contesting crack modes include those of vertical, diagonal, and horizontal. Furthermore, a novel experimentally complying expansion ratio relating the rust expansion with the corrosion penetration depth is introduced into the model. Concrete cover thicknesses are categorized via the fracture mechanics process zone length, LFPZ, in determining the crack mode. In conclusion, thin covers are dominated by the vertical crack whereas thicker covers may crack diagonally or horizontally, depending on LFPZ and the crack tip deformation state. The rust expansion reduces both the moment capacity and the critical crack time to reach the concrete cover surface. tcr, while the critical corrosion penetration depth increases with the concrete cover thickness. However, the horizontal crack when dominating can offset this concrete cover effect by significantly reducing tcr. Additionally, the rust expansion affects the concrete cracking more than the external load.