Study On Frost Resistance Experiment Of Concrete In Alpine Region

This paper is based upon the traffic subject-------key technological research to improve the durability of bridge structure concrete .The climate in Tibet is dry, year-round snow, big temperature difference between day and night as well as seasons. And it's necessary to improve the frost resistance, because concrete structural object is located in salinized area, what's more the part attached with water will be freezing and thawing more seriously. This paper mainly researches engineering concerning with concrete (C30, C40, C50) meeting the requirements of high frost resistance. The main works as follow:①After analyzing amount of documentation, and through adding mineral admixture, Water-reducing agent, Air-entraining make concrete (C30,C40, C50). To research how do the different admixture and dosage influence mechanical properties of concrete C30, C40, C50. After getting preferred proper dosage research the influence of different double doping methods and air content to concrete'frost resistance and permeability resistance of chloride ion to decide proper air content of different grade of frost resistance concrete. Integrated mechanical properties and resistance permeability of chloride ion to bring up a concrete formulation which can performance well in paramos.②To research the mechanical properties of concrete C30, C40, C50, finding out different strength grade need different dosage. To C30, a better dosage of admixture should be: Siliceous dust 6%, slag 10%, fly ash 10%. To C40: Siliceous dust 6%, slag 20%, fly ash 10%. To C50: Siliceous dust 6%, slag 20%, fly ash 20%.③Experiment the concrete ability of air-entraining with different strength grade to get this result that is air content will influence concrete'mechanical greatly. If the air content ranges between 3.5% to 5%, and that is said the strength of concrete will be reduced by 3% to 4% as 1% of air content is entrained. After 1% of air content is entrained, the strength of concrete will be reduced by 7% to 8% when the air content exceeds 5%.④A great quantity of experiments show as air content increasing the frost resistance of concrete will enhance firstly then reduce, and when the air content is close, double doping is better than single doping.⑤Through researching the influence of air content to permeability resistance of chloride ion, finding that as the increasing of air content, chloride ion'Permeability of every strength grade concrete will enhance firstly then it will reduce. And the double doping concrete can improve the permeability resistance of chloride ion obviously.⑥All the freeze-thaw cycle of different strength grade concrete can reach 300 times after double doping 6% Siliceous dust, 10% slag and proper air-entraining. There's a proposal that in paramos to C30 the air content should be better controlled between 3.5% to 5%, and to C40 about 5%, to C50 5% to 7%. Coefficient of durability and intensity decline rate will reach 0.9.