Experimental Study on Freeze-Thaw Resistance of Concrete with Proto-machine-made Sand

Experiments were conducted to study the effects of source rock state and stone powder on freeze-thaw resistance of concrete with proto-machine-made sand, the strength grade of concrete was C50, the source rock states were gravel and crushed stone, the contents of stone powder in sand were 5%, 9% and 13% respectively. The values of relative dynamic elastic modulus and mass of concrete at different freeze-thaw cycle times were measured, the reduction of relative dynamic elastic modulus and mass loss were calculated to evaluate the freeze-thaw resistance of concrete. The results show that freeze-thaw resistances are controlled by the reduction of relative dynamic elastic modulus of concrete, which are good of concrete with proto-machine-made sand of gravel and crushed stone, and increases with the increasing content of stone powder in sand made of gravel. The reasons leading to difference of freeze-thaw resistance of concrete with sand made of gravel and crushed stone are discussed.