Experimental Study On The Strength Of Concrete Under Uniaxial Tensile Load After Freeze-thaw Cycles

As the dominant structure in the infrastructure construction,concrete structures have been widely used in numerous fields,as a result is that the environment concrete structure was exposed to become more and more complicated.The influence caused by freezing and thawing damage,one of the main factors, performed increasingly prominent.At present,agreat deal of important results have been acquired about the experimental reach on the action of concrete under freeze-thaw cycles,but systemic study on the characteristic of prestressed concrete structure, in especial tensile strength, is so little, so it is significant for both theory and application to study on the tensile Strength of concrete after cyclic freezing and thawing.As a part of the project of Natural Science Foundation of China"reaserch about mechanical performance of reinforced concrete and pretsressed concrete structure under freeze-thaw cycles "(50978224),experiments on deformation and strength of normal concrete whose strength degree were geared to C20,C30,C40,C50 after different cycles of freeze-thaw cycling under uniaxial Load were made. Based on the comparison between experimental results of specimens after freeze-thaw cycling and that in normal environment, failure criterion of concrete after freeze-thaw cycling is established. Main researchful contents in this paper are as follows:1. Freeze-thaw cycling experiments of Concrete test specimens 150×150×150mm3 and heteromorphic concrete specimens 100×100×400 mm3 were made.Cycles of freeze-thaw cycling include 25,50,75,100 and 125. Weight loss and dynamic elastic moduli are measured.2. Experiments on uniaxial compression,splitting tensile,tensile of concrete specimens under normal environment and after freeze-thaw cycling were made using universal test system for concrete.3. Failure forms of common concrete under uniaxial compression,splitting tensile,tensile after freeze-thaw cycling are analyzed, and comparison of failure form with concrete in normal environment under same loading condition are made.4. Affection of freeze-thaw cycling,class on strength,strain of concrete are studied. Based on regression of experimental results, failure criterions of concrete under uniaxial compression,splitting tensile,tensile stress,initial modulus and elastic limit strain after freeze-thaw cycling are established. 5. Based on regression of comparison expression between dynamic elastic modulus and uniaxial compression,splitting tensile,tensile stress of concrete , failure criterions are studied.6.Curve equation of stress and strain rising step after freeze-thaw cycling are established.The studied result shows that the influence of reeze-thaw cycling and class on basic properties of concrete is obvious. With the increasing of the cyclic number,the capability of basic concrete declines obviously. Under the same number of freeze-thaw cycling, Increase of concrete level slows down the descent velocity...