Abstract
The existence of chloride ions, sulfate ions, and vehicle dynamic loads may lead to a shortened service life and premature failure of the road and bridge structures in northwestern China. Immersed in a dual-salt solution while simultaneously applying cyclic flexural loads, the free chloride ion concentration and erosion depth in concrete specimens were measured. The influence of the sulfate concentration on the apparent surface chloride concentration (Cs) and apparent diffusion coefficient (Dapp) was studied. An exponential model was used to fit the Cs, and the influence of sulfate concentration on the Cs was analyzed. The result showed that cyclic loading and solution concentration were two primary factors affecting chloride diffusion. Meanwhile, compared with the emersion conditions, dynamic loading would induce significantly accelerated chloride ion penetration. Under the coupling effect of sulfate and dynamic loading, as the sulfate concentration increased, the chloride ion concentration and erosion depth were both decreased. The existence of sulfate ions improved the chloride ion penetration resistance of concrete. The results provide insight in designing concrete in regions where multiple salt ingression (sulfate and chloride) is a major durability issue of the structures.
Highlights
The existence of chloride ions and sulfate ions in salt lakes and saline soils in northwestern China leads to the corrosion and deterioration of road and bridge structures
The chloride ion concentration at different depths under cyclic loading increased significantly compared with the immersion test
A testing scheme was designed and customized to test concrete samples under a cyclic load simultaneously coupled with a dual-salt ingress
Summary
The existence of chloride ions and sulfate ions in salt lakes and saline soils in northwestern China leads to the corrosion and deterioration of road and bridge structures. Different stress levels have different influences on the chloride ion permeability of cyclic, compressively loaded concrete [4]. The chloride ion erosion of concrete under the dynamic flexural cyclic load was more serious than that under the static load and increases sharply with the increase of the dynamic bending stress level [15,16]. Qi et al obtained that the generation and propagation of microcracks under the bending load led to the increase of chloride content in recycled aggregate concrete [20] As it is there are a few studies that applied cyclic loading coupled with multiple salt ingress. The influences of the bending cyclic load and sulfate on chloride ion transport behavior was studied by analyzing chloride ion distribution, erosion depth, apparent surface chloride ion concentration, and apparent diffusion coefficient. The results will provide insight in designing concrete in regions where multiple salt ingression (sulfate and chloride) is a major durability issue of the structures
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