Experimental study of dynamic biaxial compressive properties of full grade aggregate concrete after freeze thaw cycles

Most hydraulic concrete structures are in complex stress state, this study attempts to take some test of full grade aggregate concrete under biaxial compression after 0, 25, 50, 75, and 100 cycles of freeze-thaw. Five principle compression stress ratios of 1:0, 1:0.25, 1:0.5, 1:0.75 and 1:1 and four different strain rates of 10-5/s, 10-4/s, 10-3/s and 10-2/s were the main variables. The mass loss of concrete after freeze-thaw cycles has been studied. With the increase of freeze-thaw cycles, the quality loss is little. The failure pattern, ultimate strength, peak strain and stress-strain curve under different freeze-thaw cycles, stress ratios and strain rates were obtained. The dependence of ultimate strength on freeze-thaw cycles and ultimate strength, and the relationship between freeze-thaw cycles, stress ratio and strain rate were analyzed according to the testing data. The unified failure criterion of full grade aggregate concrete after freeze-thaw cycles under dynamic biaxial compressive stress state was established in principal stress space and octahedral stress space, respectively. The comparative analysis of experimental results of different types of concrete(large aggregate concrete, ordinary concrete, lightweight aggregate concrete, wet screened concrete) under biaxial compression after freeze-thaw cycles are made. With the increase of freeze-thaw cycles, the ultimate compressive strength of common concrete, wet screened con-crete, lightweight aggregate concrete and large aggregate concrete gradually decreases. The results may serve as an experimental and theoretical reference for the design and maintenance of hydraulic structures.