Study On Alkaline Environment Under Freeze-thaw And Dry-wet Cycling Of Concrete

In our country, the regions of Saline-alkali and Salt Lake are broadness, but the environment is very serious, so the durability of concrete is a particularly serious problem. Especially, in saline areas in northern China, concrete is often subjected to destruction of many factors. However, few articles which the durability of concrete is subjected to many factors were studied. Especially, the study of under double salts'solution freeze-thaw and wet-dry cycles is less. Therefore, in-depth study of freeze-thaw and wet-dry cycles of concrete under saline environment, for saline areas in northern durability of concrete structures to provide theoretical support, has far-reaching significance.In this article, using freeze-thaw and wet-dry cycles of method study the concrete in complex salts and the influence of the aqueous solution, and to explore the damage process of law and its significance.Studies have shown that concentration on the impact of freeze-thaw cycles damage to the critical value of C=4.7%, when the sodium sulafte solution's concentration C>4.7 %, the concentration has little effect on the freeze-thaw damage,and concentration of C<4.7%, with the increased concentration of severely damaged.Complex salts freeze-thaw and wet-dry cycles, with the complex salt concentration to improve the quality loss and the loss of relative dynamic elastic modulus were increased; when the sulAFte concentration is low, mainly chloride damage, loss of priority to destroy the quality indicators; the other hand, the relative loss of dynamic elastic modulus first to destroy the target. Other things being equal, the freeze-thaw and wet-dry cycles destroy>freeze-thaw cycles damage>destruction of wet-dry cycles, wet and dry cycles to promote increased freeze-thaw damage. Mixed with fly ash concrete frost resistance and improve corrosion resistance.Re-establishment of concrete in complex salts freeze-thaw and wet-dry cycles under damage equation, correlation coefficient R2 in equations between 0.96 to 0.99; In addition, for many factors working together, raised a number of factors, the definition of D-type damage and effect factor, and explain its physical meaning. Sodium chloride is positive effects of concrete in sodium solution freeze-thaw and wet-dry cycles.