The macro-performance variation in parameters,including mass,ultrasonic velocity,compressive strength and stress-strain curves,was compared through some experiments between the concrete with barium hydroxide reagent and without reagent under typical sulfate attack conditions.The microstructure and corrosion products component were studied using various microcosmic test methods such as scanning electron microscopy,energy dispersion spectrum analysis,X-ray diffraction and thermogravimetry-differential thermal analysis.The mechanism of barium hydroxide reagent on the sulfate corrosion process of concrete was researched.The research results show that:① The rate of erosion and degeneration of the concrete with barium hydroxide reagent extremely decrease by contrast.The change of mass and ultrasonic velocity decreases less.Compared with the strength before sulfate attack,at 300-day corrosion age the strength of concrete without and with barium hydroxide is decreased by 17％ and 3％,respectively.Barium hydroxide reduces the effect of sulfate attack.② Compared with the common concrete,at the same corrosion time the microstructure of concrete with barium hydroxide is denser and the contents of corrosion products such as ettringite and gypsum are lower with the production of barium sulfate.As corrosion time goes on,the corrosion products content of concrete with barium hydroxide decreases significantly compared with the common concrete.③ The barium sulfate and ettringite formation reactions exist simultaneously in the concrete with barium hydroxide and there is a competitive relationship between these two reactions.Sulfates reacts with barium hydroxide preferentially and comes out as barium sulfate sediment.The deposited barium sulfate blocks the formation pore space and reduces sulfate solution permeability,which delays the corrosion reaction.%通过试验比较不掺/掺加氢氧化钡混凝土在典型硫酸盐环境中质量、超声波传播速度、强度等宏观性能的变化,并采用扫描电镜、能谱分析、X射线衍射及热重-差热分析等微观试验手段观测腐蚀引起微结构和腐蚀产物组分的变化,探讨氢氧化钡对混凝土腐蚀劣化的影响机理.试验结果表明:①掺加氢氧化钡的混凝土腐蚀劣化速率减缓,腐蚀引起的质量和波速的变化幅度均降低,腐蚀300 d后不掺/掺加氢氧化钡混凝土强度较腐蚀前分别下降17％和3％,氢氧化钡的掺入削弱了硫酸盐腐蚀的破坏程度;②相比普通试件,同样腐蚀时间下,掺加氢氧化钡试件的内部结构更完整致密,钙矾石、石膏等腐蚀产物含量有所降低,伴有硫酸钡生成,且随着腐蚀时间延长,掺加氢氧化钡试件内腐蚀产物数量较普通试件显著降低;③掺入氢氧化钡的试件内部同时发生了硫酸钡和钙矾石的生成反应,2者存在竞争性,硫酸根优先与氢氧化钡反应生成硫酸钡沉淀,硫酸钡沉淀阻塞硫酸盐溶液入侵的孔隙通道,进一步延缓了腐蚀反应的进行.
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