| In cold areas(taking Zhangjiakou as an example),the temperature difference is large.In recent years,vehicle overload has been increasing.The concrete bridge deck pavement is affected by the combination of ambient temperature and vehicle loads,and is prone to cracks,pits and other diseases.The addition of rubber to concrete can improve its toughness and resistance to deformation,and the addition of steel fibers can increase its tensile strength and crack resistance.In order to extend the service life of concrete bridges,the application performance of steel fiber-rubber concrete in cold areas is studied to provide a reference for the practical engineering application of steel fiber-rubber concrete.Through the freeze-thaw-mechanical coupling test on steel fiber-rubber concrete,analyze the freeze-thaw damage mechanism to study its frost resistance,and predict the life based on the damage model;study the compressive strength,resistance Tensile strength and impact resistance.The main conclusions are as follows:(1)Through the freeze-thaw cycle test of steel fiber-rubber concrete with different steel fiber content,the microstructure changes of concrete under freeze-thaw action were studied using an electron microscope.The results show that after freeze-thaw cycles,the rubber particles still have good adhesion with the cement matrix,and the interface damage is small.When the steel fiber content is 1.5% to 2.0%,the steel fiber and cement-based interface Affected by freeze-thaw damage.(2)Under the action of freeze-thaw cycles,the freeze-thaw damage of concrete is a fatigue damage failure process,which is mainly manifested by the gradual increase of the concrete mass loss rate and the relative dynamic elastic modulus of the concrete.Steel fiber-rubber concrete has less damage than ordinary concrete.When the number of freeze-thaw cycles reaches 200,the damage degree of the test piece with 1.0% steel fiber content is the smallest.According to the damage mechanics,the damage is predicted for the concrete,and its predicted life is Longest and best frost resistance.(3)The compressive strength of concrete gradually decreases with the increase of the number of freeze-thaw cycles.The addition of steel fibers and rubber can reduce the compressive strength loss rate of concrete under the freeze-thaw cycle to a certain extent.When the number of freeze-thaw cycles reaches 200 times When the steel fiber content is 1.0%,the compressive strength loss rate is the smallest.Moreover,the addition of steel fibers and rubber can significantly improve the tensile strength of concrete.The amount of steel fibers is an important factor affecting the tensile properties of concrete.The test piece with a steel fiber content of 1.5% has the highest tensile strength and tensile properties.Optimal.(4)The incorporation of steel fibers and rubber in concrete can improve the impact resistance of concrete under freeze-thaw cycles.As the number of freeze-thaw cycles increases,the impact resistance of concrete shows a downward trend,which is mainly manifested in the reduction of the number of impact damage resistance and the reduction of final energy consumption.Under the same freeze-thaw times,when the steel fiber content is 1.0%,the concrete has the best impact resistance.The two-parameter Weibull distribution theory can well describe the impact life of concrete under freeze-thaw damage.The impact life under different failure probability is approximately a quadratic curve relationship with the steel fiber content.(5)Analysis of the mechanical properties and economic benefits of steel fiber-rubber concrete has verified the feasibility of its application to bridge decks in cold areas.Among them,the steel fiber-rubber concrete with 1.0% steel fiber content has the best technical performance and economical and reasonable. |
