关键词: 盐渍土, 混凝土, 抗冻性能, 损伤机理, 工程措施, 南疆地区

Abstract: Field investigation reveals surface erosion, cracks and loosening, exposure of coarse aggregate in large area, as well as separation of salt crystal from concrete caused by salt corrosion and freezing-thawing damage in many concrete structures in south Xinjiang autonomous region. Three main reasons, which give rise to the salt corrosion and the freezing-thawing damage in this region, are concluded: 1) tensile stress generated by the freeze of pore water in concrete; 2) tensile stress produced by salt crystallization permeated in concrete; 3) tensile stress generated by the chemical reaction of sulfate and hydration products of the cement. The synthetic actions of these factors give rise to the concrete damage, break and destroy from the outside to the inside. By adjusting water-bonder ratio, optimizing air content value and stir time of concrete as well as aggregates gradation, using anti-sulfate cement, and increasing the thickness of anti-corrosion coating of asphalt grout on the concrete surface, the capacity of concrete structure in resisting salt corrosion and frost damage can be improved.

Key words: saline soil, concrete structure, frost resistance, damage mechanism, engineering measures, south Xinjiang