Research Of Permeability And Carbonation Resistance On Service Concrete

Now many scholars have studied the durability of concrete, but most of the researches are in the stage of "pure material"(without loading).As know to all, durability of concrete is restricted by three factors:first, quality of materials; second, pore structure; third, corrosion agent. The tradition methods that research the durability of concrete quality of materials and corrosion agent are the same with actual situation, but the pore structure will be different. This is the reason that the result get from tradition methods will distortion.As we know, the concrete will plastic deformation after loading, so after loading-unloading cycle, most of the micro cracks and pore structure in the test block will retain, the test block after loading-unloading cycle nearly has retained the pore structure. This thesis based on the mechanical properties of concrete, using new method of "testing after loading", study the effect of the durability of permeability and carbonation resistance on service concrete that influence by stress level, strength grade and fly ash.Research draw the following conclusions:first, there is a big difference between the durability of permeability and carbonation resistance on service concrete and "pure material", it prove that the validity of the new way that simulating working stress of the service concrete. The result is closer to the actual situation after consider the loading. Second, the impermeability of service concrete is approximately60%of pure merterial. and carbonization resistance75%. Third, when stress level increased from0%～60%. the decreasing rate of the impermeability of the high strength concrete is1.4times as the low stength one. and carbonization resistance1.7times. the improvement of the impermeability contributed by fly ash is only65%of pure meterial concrete.