Experimental Study And Theoretical Analysis For The Freeze Proof Durebility Of Concrete Filled Steel Tube

The freeze proof durability of concrete is one of the important field of durability of concrete research and also one of significant indexes in engineering design, especially in severe cold regions. Internal composition of concrete affects the freeze proof durability of concrete. So, the studies having been done contain adding water reducing agent to reduce water cement ration and adding air entraining agent to produce small and well-proportioned pore which can relief the pressure of concrete in freeze process.In this paper, in order to change frost heaving pressure of concrete, we use steel tube to wrap up concrete. On one hand, steel tube can isolate the concrete and keep concrete from the external environment, on the other hand, at freeze model, steel tube can make hoop action to concrete which can reduce expansion crack stress by frost heaving. In the experiment, mass loss, the relative dynamic elasticity modulus and the strength of concrete after freeze-thaw end are analyzed. The results show that, the freeze proof durability of concrete filled steel tube is better than ordinary concrete. The paper based on the damage mechanics, fracture mechanics, elasticity theory and experimental date. According to the concrete damage constitutive equations and fracture model, the relationship between frost heave stress and hoop stress is derived.