Cl~-环境下冻融循环对混凝土材料性能的影响

发布时间：2018-05-27 17:10

本文选题：混凝土 + 超声波　；参考：《施工技术》2017年20期

【摘要】：对浸泡在质量分数为9.06%的饱和Na Cl溶液中的81个混凝土棱柱体试块和21个钢筋混凝土拔出试件先采用冻融循环后,进行棱柱体试件的抗压、抗折试验和钢筋黏结的拔出试验,探究了不同混凝土等级、不同浸泡龄期、不同冻融次数对材料物理性能的影响。结果表明:水胶比对冻融后混凝土的强度影响较大,添加高效减水剂有助于提高混凝土抵抗冻融破坏的能力;饱和Na Cl溶液浸泡素混凝土对其物理性质影响很小,可以忽略不计,但经过浸泡后产生裂缝,冻融循环对其影响很大;对钢筋拉拔试件来说,冻融到150次时,冻融循环对钢筋与混凝土黏结强度影响突然变大,在150次冻融循环后,由于机械摩擦力作用,冻融循环对其破坏速度趋于稳定。对棱柱体试件来说,冻融到300次循环时,棱柱体抗压、抗折损伤突然变大;另外通过SEM电镜扫描、超声波技术试验有效地解释了混凝土在冻融循环下强度降低的微观机理。
[Abstract]:81 concrete prisms and 21 reinforced concrete pull-out specimens immersed in saturated NaCl solution with 9.06% mass fraction were subjected to freeze-thaw cycle first, and then to the compression, flexural and bonding tests of the prisms. The effects of different concrete grade, different immersion age, different freezing and thawing times on the physical properties of the material were investigated. The results show that the strength of concrete after freeze-thawing is greatly influenced by water-binder ratio, the ability of resisting freeze-thaw failure is improved by adding high efficiency water-reducing agent, and the physical properties of concrete are little affected by saturated NaCl solution soaking plain concrete. It can be ignored, but after immersion cracks, freeze-thaw cycles have a great impact on them. For steel bar drawing specimens, when freeze-thaw cycles reach 150 times, the impact of freeze-thaw cycles on the bond strength between steel bars and concrete suddenly becomes greater, and after 150 freeze-thaw cycles, the impact of freeze-thaw cycles on the bond strength between steel bars and concrete suddenly becomes greater after 150 freeze-thaw cycles. Due to the mechanical friction, the freeze-thaw cycle tends to stabilize its failure speed. For the prism specimen, when freeze-thaw to 300 cycles, the prism is subjected to compression and the damage to bending suddenly increases. In addition, the microscopic mechanism of the strength reduction of concrete under freeze-thaw cycle is effectively explained by SEM scanning electron microscope and ultrasonic technique test.
【作者单位】：辽宁省交通高等专科学校;
【基金】：国家自然科学基金青年基金项目“考虑循环荷载作用历史的弯剪破坏RC柱抗震性能及地震损伤机理研究”(51508154)
【分类号】：TU528

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