持续荷载下混凝土的硫酸盐腐蚀研究(英文)

Damage of concrete attacked by sulfate and sustained loading

研究了普通混凝土和高强混凝土在2．5％，5．0％和10％Na2SO4溶液（质量分数），以及承受不同应力比（0.25％和50％）弯曲荷载作用下的损伤失效规律、特点．结果表明：混凝土在硫酸盐溶液中腐蚀，其损伤劣化包括初始劣化段、性能改善段和性能劣化段．腐蚀溶液中Na2SO4浓度从2．5％增加到5．0％，混凝土失效时间缩短了25％左右；Na2SO4浓度增加到10％，失效时间缩短了40％．弯曲荷载在腐蚀后期加速混凝土的损伤劣化速度，应力比由0增加到25％，混凝土破坏时间降低15％；应力比增加到50％，其破坏时间降低25％～35％．此外，用SEM、能谱和XRD分析了混凝土在硫酸盐腐蚀作用下的腐蚀产物．

The damage processes of ordinary concrete and high strength concrete, attacked by solutions of 2. 5%, 5. 0% and 10% Na2SO4（mass fraction）are studied. And the effects of flexural loads with stress ratios of 25% and 50% of the initial flexural strength on the damage process of concrete are also investigated. The results show that the damage process of concrete attacked by sulfate salt exhibits an initial damaged stage, a performance improving stage and a performance worsening stage. When the concentration of Na2SO4 in a solution increases from 2. 5% to 5.0%, the service time of the concrete decreases approximately 25%. Furthermore, it decreases to even 40% with an increase in a Na2SO4 concentration up to 10%. And the flexural load accelerates the deterioration rate of the concrete in the latter period. The stress ratio increases from 0 to 25%, the failure time of the concrete decreases 15% ; and the failure time decreases between 25% and 35% when the stress ratio increases from 25% to 50%. In addition, sulfate corrosion products of concrete are studied by SEM （scanning electron microscopy）, EDS （energy disperse spectroscopy） and XRD（X-ray diffraction）.