Experimental Study On Frost Resistance Properties Of Pumice Mixed Aggregate Concrete

Mixed aggregate concrete is a transitional concrete based on ordinary concrete and light weight aggregate concrete , which using part of light weight aggregate instead of normal coarse aggregate. It is helpful to improve compressive strength, specific strength and elastic modulus of the light weight aggregate concrete,also it is helpful to reduce the volume density of common concrete and improve the frost-resistance. Mixed aggregate concrete which compounded of light weight aggregate and coarse aggregate with different proportions can meet the demands of different engineering and economize cost, energy and resources.In this paper, different amount of pumice are used to replace gravel to make mixed aggregate concrete, the cubic compressive strength and the frost-resistance of mixed aggregate concrete are studied.And by adding polypropylene fiber into the concrete to study the influence of polypropylene fiber to the compressive strength and the frost resistance of the concrete. The cube compressive strength test results show that the cube compressive strength and apparent density of the mixed aggregate concrete decrease linearly with the increase of pumice replacement rate.The changes of specific strength are also affected by the influence of polypropylene fiber.For the mixed aggregate concrete without polypropylene fibers, the specific strength decreases with the increase of pumice replacement rate,and for the mixed aggregate concrete with a proportion of 0.9kg/m3 polypropylene fibers , the specific strength increases a little at first then decreases with the increase of pumice replacement rate. The cube compressive strength and the specific strength of the mixed aggregate concrete declined due to the mixing of polypropylene fiber ,but the apparent density changed a little. Frost resistance test results show that the mass loss and strength loss rate gradually decreases and the relative dynamic elastic modulus gradually increases with the increase of pumice rate.Polypropylene fibers can reduce the strength loss rate strength,improve the relative dynamic elastic modulus, but has little effect to improve the mass loss.Through the frost resistance,we get a conclusion that the frost resistance of concrete improved with the increase of pumice content, at the same time, polypropylene fiber also can improve the frost resistance of concrete.