Research On Freeze-thaw Resistance Of Service Concrete

For a long period, researches on freeze-thaw resistance of concrete are mostlybased on "pure material" form,without considering the impact of load. Concrete instructure is to withstand load (weight plus payload) which leads the internal porestructure of concrete changes. The results of testing freeze-thaw resistance of con-crete in a "pure material" form were often not consistent with actual situation. Cur-rent studies considering loads are often in the form of "multi-band clamp", whoseoperation is complex, difficult to get accurate results. This thesis used the " testingafter loading" method to study rules of stress levels, intensity and fly ash, fly ashcomplex-silica fume on freeze-thaw resistance of concrete in service.Research draw the following conclusions:1) There is a difference between service concrete(40%～60%stress level) and“pure material”(0%stress level) concrete on freeze-thaw resistance of concrete. themass loss rate and the dynamic modulus loss of "pure material" concrete is about1.5times the service concrete’s.2) Low-intensity concrete in service and high-strength concrete in servicehas nearly the same freeze-thaw resistance.3) Mass loss rate of fly ash concrete in service is about95%of normalconcrete (without admixture) in service. Mass loss rate of fly ash complex-silica fume concrete in service is about90%of normal concrete in service. Dynamic modulus loss of fly ash, fly ash complex-silica fume concrete in service is about90%of the normal concrete in service. Mineral admixtures improving the freeze-thaw resistance of concrete in service is not obvious.