In order to investigate the corrosion damage of bridge pile foundation under the action of freeze-thaw cycles in alpine salt swamp areas

laboratory model test was conducted to simulate the effect of pile foundation concrete mixture ratio and compound salt solution concentration on the corrosion resistance of pile foundation concrete under the conditions of curing freeze-thaw cycles. The corrosion damage mechanism of pile foundation was analyzed by measuring the appearance

quality

compressive strength

dynamic elastic modulus

and SEM of the concrete. Results show that concrete mixture ratio had significant impact on the corrosion resistance of pile foundation. When fly ash

silica fume

and expansive agent (proportion III) were added to concrete

the relative dynamic elastic modulus was reduced by less than 10%. The anti-erosion coefficient was more than 0.9

the mass loss was less than 5%

and there was only a slight shedding on the concrete surface

which could improve the anti-erosion performance of the pile foundation. The compound salt solutions with different concentrations were prepared. The pile foundation concrete showed different degrees of corrosion under the conditions of freeze-thaw cycles

the higher the concentration was

the more obvious the mutual inhibition of compound salt ions was

and the corrosion of concrete was weakened. When the concentration reached 15.4%

the mass loss showed a negative growth. According to the SEM test results

ettringite

wollastonite gypsum

and Friedel′s salt were the main products leading to the corrosion damage of pile foundation concrete structure. It is suggested that the reduction factor of the design life of pile foundation is 0.6

which can prevent the adverse effect of freeze-thaw cycle on the design life of pile foundation under the corrosion of reference concentration solution.