Study On The Strength Of Wet-screened Mass Concrete Under Multiaxial Stress States After Freeze-thaw Cycles

Freeze-thaw resistance is used as a key to measure the durability of concrete. Presently, most experimental and theoretical studies are focused on normal mass concrete. The experiments about mass concrete after freeze-thaw cycles are fewer at home and abroad. So, based on the project of National Nature Science Foundation named " multiaxial strength and failure criterion of concrete in freeze-thaw environments "(50479059), the experimental researches and theory studies on weight loss, the splitting-tensile, uniaxial compression and biaxial compression strength of wet-screened mass concrete after different freeze-thaw cycles are carried out. Main research contents in this paper are listed as follows:1. Freeze-thaw cycling experiments of wet-screened mass concrete (100mm×100mm×100mm) specimens have been carried out. The freeze-thaw cycles include 50,100,150,200,250,300. After different freeze-thaw cycles, the surface forms of wet-screened three-graded mass concrete are compared and analyzed. The weight loss is measured on each frost-resistance grades.2. The splitting-tensile experiments have been carried out on the wet-screened mass concrete specimens under normal environment and after different freeze-thaw cycles. The failure patterns of concrete are described. Relationship between the decreasing percents of strength of concrete and the freeze-thaw cycles is analyzed. Simultaneously, a formula to describe the relationship between the strength of concrete and freeze-thaw cycles is given.3. Uniaxial loading experiments of wet-screened mass concrete specimens under normal environment and after freeze-thaw cycles have been carried out with triaxial test system. The failure patterns of concrete are described. Relationship between the decreasing percents of strength and the freeze-thaw cycles is analyzed.4. The experimental study on strength of wet-screened mass concrete under biaxial compression after different cycles of freeze-thaw was performed. The failure modes and the direction of surface cracking were observed. The influences of freeze-thaw cycles and stress ratio on the ultimate compressive and tensilestrength were analyzed. In addition, the failure criterion of wet-screened mass concrete under biaxial compression with consideration of the influence of freeze-thaw cycles and stress ratio was proposed.