Study On Prevention And Control Of Deicing Salt Harm To Bridge Concrete

The snow makes road pavement appeared snow icy phenomenon seriously in northern China,this makes driving dangerous.Deicing salt can clean the snow quickly and ensure that traffic flows freely,but at the same time,it causes corrosion damage to concrete buildings,especially for bridge concrete,so repair of reinforced concrete bridge structures has become a serious problem.We studied how to reduce the corrosive damage of deicing salt to concrete in bridge maintenance,treatment method of“Prevention and Control”are put forword,we also studied on the regularity of concrete corrosion damage and opening doors to reveal why composed admixture could improve corrosion resistance of concrete.The main contents and conclusions are as follows:An environmentally friendly deicing salt was researched and developed.Seven components with high snow melting rates were selected,they include calcium chloride,magnesium chloride,potassium acetate,sodium tungstate,potassium dihydrogen phosphate,sodium gluconate and zinc sulfate,they are the main raw materials.Ice block was adopted as sample for experimen,ice melting rate as an evaluation index,the composition of environmental deicing salt A was determined by orthogonal test,composition of deicing salts is m_CaCl2:m（MgCl2）:m（CH3COOK）:m（KH2PO4）=1:2.5:2.5:1;through testing other performance indicators of environmental deicing salt A and optimizing its composition,composition of environmental deicing salt B is m（CaCl2）:m（KHCO3）:m（CH3COOK）:m（KH2PO4）=1:2.5:2.5:1.The freeze-thaw and deicing salt damage of concrete caused by deicing salts and environmentally friendly deicing salts is studied comparatively,the result shows that all deicing salt has corrosive effect on concrete,arrangement of damage degree to concrete from large to small is:sodium chloride>environmental friendly deicing salt A>environmental friendly deicing salt B>sodium acetate.The optimum dosage and proportion of admixture for high performance concrete with"fly ash and slag"are determined.By testing the mechanical properties and chloride ion penetration resistance of high performance concrete,it is finally determined that 40%of the admixture is added when"fly ash and slag"is used.When FA:SLAG=1:3,the performance of concrete is the best.The mechanism of improving corrosion resistance of concrete with mineral admixtures was studied by means of microscopic method.Morphology of cement hydration products shows that the addition of admixture promotes the secondary hydration of cement,this is the reason why high performance concrete has higher salt and frost resistance.The corrosive damage law of environmental deicing salt to high performance concrete was studied by freeze-thaw and deicing salt damage of concrete.Compared with ordinary concrete（salt-frozen medium is sodium chloride solution）,measures of"Prevention and Control"for bridge concrete（use of environmental friendly deicing salt and high performance concrete）improved 8.4 times about the salt frost resistance of concrete.