Study On The Sulfate Corrosion Of Concrete Under Different Conditions And Inhibition Mechanism Of Chloride

In the western and eastern coastal saline and other regions, sulfate and other corrosive substances widespread exist in Soil and rivers. Sulfate corrosion Corrosion is an important element of the durability of concrete, and is the most complex factors、the greatest danger of an environmental erosion. How to prevent sulfate corrosion of concrete structures has become a major problem todayThrough different soaking method, the full immersion zone and half soaking,of different concentrations of sodium sulfate solution,getting corrosion mechanism and development model of corrosion layer thickness in different ways to soak concrete. By chemical titration methods, getting the content of soluble sulfate ions at different depths within the concrete content,and geting the limit concentration of sulfate ion at the beginning of concrete corrosion damage. When the sulfate ion content in concrete is less than the threshold, corrosion only play the advantageous role of filling, no corrosion damage.But when the sulfate ion content in concrete is moer than the threshold, corrosive effect on concrete began to damage concrete.Through analysised of different periods of concrete compressive strength, ultrasonic measurement of the speed of sound research and microscopic scan of SEM, the content of chemical titration, Combined with chloride corrosion mechanism of concrete,we can get that chloride solution environment almost unaffect the properties of concrete. Penetration thickness of chloride is much greater than the thickness of the sulfate ion penetration. Chloride and Ca(OH) 2 can form the stable Friedel’s salt. It inhibites the corrosion of sulfate to concrete.It is found that different types of bending stress has different effects to concrete slab. Bending tensile stress accelerate the sulfate corrosion,and bending stress inhibite the sulfate corrosion. By studying the magnitude of the stress load on different areas,getting load influence coefficient of different tensile stress about sulfate corrosion to concrete. In the stress ratio referred to herein,the greater bending stress,the more obvious of suppressing effect. The greater bending tensile stress, the more obvious of promoting effect.By wet- dry cycles of water and 10% concentration of sulfate solution, finding strength in both wet concrete has a significant decline. Due to the of dissolution of concrete and Ca(OH) 2,that leads to The decline of strength of concrete under wet- dry cycles of water. By the chemical titration of sulfate ion content, the sulfate ion content increase rapidly with the increase of cyclic coefficient. Wet-dry cycles accelerates sulfate ions into the concrete.