Damage mechanism of pier concrete subjected to combined compressive stress, freeze-thaw, and salt attacks in saline soil

This study experimentally investigates the damage mechanism of pier concrete under the combined action of axial compressive stress (CS), freeze–thaw (FT) cycles, and salt attacks (SA). An indoor accelerated corrosion test of pier concrete under the combined action of CS, FT, and SA was conducted based on field investigations of concrete corrosion of piers in the saline soil of Xinjiang province in China. The experimental results of macro and micro analyses showed that the durability degradation of the pier concrete could be attributed to the damage to the cement slurry, aggregates, interface areas, and pore structure. A new delamination damage model was established to describe the mechanism of the combined damage, including the deterioration of the mortar layer, the generation of microcracks in the interface zone, the deposition of corrosion products, and crack development. The quantitative assessment of the durability degradation of the pier concrete was more accurate when the mass loss (ML) and relative dynamic elastic modulus (RDEM) were considered. These unique findings provide an important reference for the design and durability evaluation of pier concrete in saline soils.