Research On Mechanical Properties And Freeze-proof Durability Of Concrete After Fire

This Paper researchs residual strength and durability of concrete after hightemperature and freeze-thaw injury, by high temperature, freeze-thaw and mechanicaltest. The research results can provide technical parameter and theoretical guidance fordamage assessment and maintenance reinforcement of the structures after fire, it hasalso theoretical significance and application prospect. This article mainly researchs thefollowing content through experimental investigation and numerical simulation: Thequality and mechanical properties changes of concrete, after different temperature,different thermostatic time and different cooling way; Under natural cooling, the quality,permeability, compressive strength and freeze-thaw durability changes of concrete, afterdifferent temperature, thermostatic time and freeze-thaw cycle times; Simulating thetemperature field distribution of concrete coupon by using ABAQUS, and discussinghow to select the thermostatic time.The specific work shows as:1. Under the same thermostatic time and different temperature, test studying: thequality, compressive strength and constitutive relation of concrete under differentcooling ways, the result is that different cooling ways have great influence on them, andcoming up with the calculation formula of compressive strength under different coolingways; After natural cooling and different freeze-thaw cycle, the quality and compressivestrength of the same temperature type concrete are reducing with freeze-thaw cycletimes increasing, and the higher the temperature, the greater the magnitude of reduction, and coming up with the calculation formula of compressive strength under sametemperature and different freeze-thaw cycle times.2. Under the same temperature and natural cooling, Test studying: the quality andcompressive strength of concrete under different thermostatic time, the result shows thatit has certain effect on both of them in three hours, and the influence can be ignored, ifit exceeds three hours; The quality and compressive strength of concrete are reducingwith thermostatic time increasing, after same freeze-thaw cycle times and differentthermostatic time.3. Simulating the temperature field distribution of concrete coupon by usingABAQUS, getting the temperature field distribution rule of concrete after differenttemperature and thermostatic time. The results have verifyed the rationality ofthermostatic time adoptted in experiment, and suggest that how much thermostatic timethis types experiment should choose.