Study On Mesostructure And Freeze-thaw Resistance About Concrete Material

In cold areas, the insufficience of concrete anti-freezing is the major reason whichcreates the durability destroy, especially under the environment of water-contacted andfreezing,the concrete is required to have a highed anti-frozon-dissolved.to research theconcrete material's freeze-thaw resistance is an important aspect which solves the question ofthe durability of concrete,In the aspect of concrete's anti-frozon-dissolved, many of thedomestic and foreign scholars achieve a lot of results from macroscopic to microscopic,butthe relations between pore structure of microstructure and anti-frozon-sissolved ofmacroscopic are less researched.through the freeze-thaw test to different added matetion(complex minerals additive,air entraining agent,both mineral admixture and air entraining)and to different strengthen level concrete material (C20,C30,C40,C50), the project testedthe module of elasticity and the weight loss factor at the corresponding frozon-resolved cycletimes, judging it's anti-frozon-dissloved, and using mercury intrusion method to measure theparameter of limestone porestructure system, including total porosity, most probable porediameter, mean radius, and so on, analyzing the influencing of different admixture materialand different water/binder ratio to concrete pore structure and freeze-thaw resistance,discussing the relationship between pore structure and concrete. Achieving some conclusionas follows:For the concrete which is not added air entraining agent, it's freeze-thaw resistance willbecome stronger along with the decreasing of the material's porosity, the increasing of thespecific surface area and the minish of the average pore size, besides the percent'saugmentation of internal small pore whose size is less than 5Onto and the percent's fall ofpores whose size is more than 100nm, The anti-ffozon-dissolved index of standard concrete islinear function about the paste matrix's total porosity and is exponential functions about thepaste matrix's most probable pore diameter, The anti-ffozon-dissolved index of addingmineral admixture's concrete is logarithmic function about the paste matrix's total porosityand is exponential functions about the paste matrix's most probable pore diameter;For theconcrete which is added air entraining agent,in the scope of designed air content in the paper'st,the freeze-thaw resistance enhances with the increament of the material porosity and thepore ratio surface area and with the decresment of average pore size,and become strangerwith the increasement of the internal small pores whose size is less than 50nm. For theconcrete which is doped mineral admixture,air entraining and both of them.it's freeze-thawresistance all can be improved,especially when both of them are added the effect is distinet, and the effect is better when only air entraining is added, the effect isn't better thanother things although can improve the concrete's freeze-thaw resistance when only mineraladmixture is added.