The Research Of Frost-resisting Durability Of Concrete

Freeze-thaw resistance is used as a key to measure the durability of concrete. Presently, most experimental and theoretical studies are focused on the relative dynamic modulus of elasticity, weight loss. Practically, with the increasing of freeze-thaw cycles, the strength of concrete was decreased. Combined with the stress state of concrete structure under different freeze-thaw cycles,The article added another index about the cubic concrete compressive.Inner Mongolia lies in the Northwest China, and has heavily undergoing freeze, but the data of concrete antifreeze was deficiency. In order to guide the construction mixture ratio of antifreeze concrete, the article experimented on 5 water cement ration. They were w/c=0.60,w/c =0.55,w/c =0.50,w/c =0.45 and w/c =0.40. tested on plain concrete and air-entrained concrete (blending air-entraining agent concrete) to each water-cement, and then measured dynamic elastic modulus,quality and cubic stress of concrete after different freeze-thaw cycles. Main contents in this paper were listed as follows:(1) the surface of air-entrained concrete and plain concrete specimens have been observed after different cycles of freeze-thaw, and the dynamic elastic modulus,quality and cubic stress have been measured.(2) To plain concrete specimens: the cycles have been judged when they were frost damaged, the relationship between water cement ratio and frost-thaw cycle times has been found, by analyzing, the conclusion that they followed exponential relationship was found when water cement ratio was at the range of 0.40～0.60.(3) To air-entrained concrete specimens: the cycles have been judged when freeze-thaw cycle was terminated. By analyzing, the relationship between water cement ratio and frost-thaw cycle times has been found when concrete's air-containing was at the range of 4.0% to 4.5%, these specimens which water cement ration were lower than 0.50 could endure 300 freeze-thaw cycle times; those specimens'water cement ratio and freeze-thaw cycle times followed exponential relationship when water cement ratio were at ranged from 0.50 to 0.60.(4) To different water cement specimens: the discrepancy between plain concrete and air-entrained concrete in anti-freeze has been analyzed, and relationship between freezing-thawing durability of concrete and frost-thaw cycle times has been established.