Microscopic Test Research Of Sulfate Attack Concrete In A Complex Environment

Sulfate attack of concrete deterioration caused degradation failure of concrete isconsidered to be one of the four main factors. At the same time, concrete sulfate attackis one of the most complex and most harmfulness environmental water erosion. Coldregion in north China of hydraulic and marine engineering concrete structure often beardouble factors that the role of the freeze-thaw cycle and salt corrosion and due to thechanging of the tides, makes some concrete building under dry-wet circulation for along time, and again there is a sulfate in water or saline soil, the freeze-thaw and thedry-wet circulation failures of concrete are common in engineering examples. Thematerial chemical composition and microstructure of concrete and the internal structuredetermine its macroscopic mechanical properties, and microstructure of sulfate attackconcrete study provides the basis for further studied the performance degradation ofconcrete sulfate attack and so on.This paper carried out sulfate attack concrete corrosion test under the condition offreezing and thawing by freezing method consider the impact of erosion solutioncationic species, and carrying out sulfate erosion test under the condition of dry-wetcirculation, considering the solution concentration, water-binder ratio, cationic species.Using X-ray diffraction (XRD), scanning electron microscope (SEM) and thermalanalysis TG-DSC these microcosmic test methods, sulfate erosion corrosion productswithin concrete was studied of qualitative and quantitative analysis under the conditionof freeze-thaw and the dry-wet circulation.Through the test and analysis, sulfate attack concrete corrosion products are mainlyettringite or gypsum under the condition of the freeze-thaw and dry-wet circles. As the growth of the age, it begins to have a gypsum product generation until the sulfuric acidroot ion accumulation to a certain concentration; the greater the water-binder ratio, thehigher the corrosion solution concentration, the more beneficial to the formation ofcorrosion products under the condition of dry-wet circles. Given the erosion corrosionproducts content change rule at the same depth and ettringite and gypsum contentchange in the different layers.