Physical and mechanical performance and influencing factors of high performance concrete under sulfate attack

In order to improve the ability of deep underground structure to resist erosion in underground complex environment,a accelerated corrosion test of high performance concrete(HPC) with water-binder ratio(w/b) of 0.35,0.32,0.30,0.28 and 0.26 was done in sodium sulfate solution.The cement was taken from Huaihai Cement Plant with the grade of 525 and the admixtures include silica powder and fly ash which was taken from Tongshan Plant.Physical and mechanical performance time-changing laws of HPC and the corresponding influencing factors,including corrosion solution concentration,w/b and stress state were studied.The test results show that the strength of HPC increases in early corrosion and then declines,while the quality decreases in preliminary stage and then increases.The higher corrosion solution concentration,the quicker compressive strength reduction,and the later the turning point time between declining and rising stage.The influence of corrosion on compressive strength of HPC with the w/b less than 0.28 is little,and with the increasing of w/b,the slopes in both the declining and rising phases add.The long-term strength change laws of HPC in four different kinds of stress state are consistent with the ones without stress.But they also have differences:sulfate corrosion has little impact on the strength and quality when stress ratio is less than 0.3,while the stress ratio reaches more than 0.5,the influence is bigger.