Triaxial tests on high ductile concrete under different environmental conditions

Triaxial compression tests were conducted on high ductile concrete (HDC) under three curing conditions to study its triaxial mechanical properties under different curing environments. The three different curing conditions are as follows: standard curing (temperature 20 +/- 2 degrees C, humidity >= 95%), water curing (temperature 15 +/- 2 degrees C, humidity >= 95%), and -20 degrees C (-20 +/- 2 degrees C, humidity >= 85%). The variation laws of stress-strain response, peak stress, peak strain, and volume strain were analyzed for HDC under different environmental conditions. The mechanism of the effect of HDC mesostructure on strength under different curing conditions was revealed using ultrasonic and nuclear magnetic resonance detection technology. The relationship between HDC uniaxial compressive strength and ultrasonic speed was obtained by fitting the test data, and the relationship between the shear strength and temperature was provided. Results show that the peak stress of HDC under the same confining pressure increases with the rise in the curing temperature. The peak strain also decreases, and the HDC exhibits better ductility under -20 degrees C curing. The peak stress and peak strain of HDC under the same curing conditions increase with the rise in confining pressure. HDC specimen fracture is in the composite failure mode of shear and splitting, and it cracks but does not disintegrate. The pore size is larger and the strength is lower when the pores are more harmful.