内掺型防水处理的PVA-SHCC高温后性能试验研究

发布时间：2018-04-29 05:41

  本文选题：PVA-SHCC + 温度作用　； 参考：《青岛理工大学》2013年硕士论文

【摘要】：火灾、地震、甚至环境潮湿等是加速钢筋混凝土结构劣化的主要因素，严重影响整体结构的耐久性和安全性，因此结构在使用寿命周期内需要进行维护、修复和加固。传统水泥基材料由于自身脆性、抗拉强度低、易开裂等缺点限制了其发展，而随着现代土木工程向大跨度、轻型、高耸结构和地下、海洋中的发展，工程结构对修复材料性能的要求也越来越高。聚乙烯醇纤维增强应变硬化水泥基复合材料（PVA-SHCC：PolyvinylAlcohol Fiber Reinforced Strain-Hardening Cementitious Composites）具有高韧性、应变硬化和多微裂缝破坏特征、高能量耗散性等特点，将其应用于我国的重大工程建设、结构耐久性防护或已有受损部位的修复加固，对提高结构的耐久性和抗震性具有重要意义。 本文通过抗折强度试验、抗压强度试验、三点弯曲试验、四点弯曲试验和毛细吸水试验研究了高温、内掺型防水处理与否对PVA-SHCC抗折强度、抗压强度、抗弯承载能力、变形能力、能量吸收能力、弯曲韧性和抗渗性能的影响，并与未掺加PVA纤维的基准试件进行了对比。力学性能试验结果表明，掺加PVA纤维能显著提高SHCC的抗折强度、抗弯能力、变形能力、能量吸收能力和弯曲韧性，一定程度提高SHCC的抗压强度；PVA纤维的引入改变了SHCC的弯曲破坏形态，与基准试件“一裂即断”的弯曲破坏形态不同，SHCC表现出明显的应变硬化和多微裂缝破坏特征；PVA纤维对SHCC的增强和增韧作用在100℃之前变化较小，200℃时大幅下降；PVA-SHCC在300℃时丧失韧性，表现出脆性破坏形态；内掺硅烷乳液防水处理对不同温度作用后SHCC的强度、变形能力、能量吸收能力、韧性等力学性能影响较小。毛细吸水试验结果表明，不同温度作用后SHCC的毛细吸水量和毛细吸收系数均高于基准试件，PVA纤维的引入降低了SHCC的抗渗性能；内掺硅烷乳液防水处理明显降低了SHCC的毛细吸水量和毛细吸收系数，有效改善了SHCC的抗渗性能；硅烷乳液防水剂发生分解的温度区间为200℃-300℃，300℃时，硅烷乳液防水剂未完全失效，仍能表现出良好的防水效果。
[Abstract]:Fire, earthquake and even humidity are the main factors to accelerate the deterioration of reinforced concrete structure, which seriously affect the durability and safety of the whole structure. Therefore, the structure needs to be maintained, repaired and strengthened during its life cycle. The development of traditional cement-based materials is limited by their own brittleness, low tensile strength and easy cracking. However, with the development of modern civil engineering to large span, light, towering structures and underground, ocean, etc. The requirements of engineering structures for the properties of repair materials are becoming higher and higher. PVA-SHCC: PolyvinylAlcohol Fiber Reinforced Strain-Hardening Cementitious composer (PVA-SHCC: PolyvinylAlcohol Fiber Reinforced Strain-Hardening Cementitious composer) has the characteristics of high toughness, strain hardening, multi-microcrack failure, high energy dissipation and so on. It is of great significance to improve the durability and seismic resistance of structures by durability protection or repair and reinforcement of existing damaged parts. In this paper, the flexural strength test, compressive strength test, three-point bending test, four-point bending test and capillary water absorption test are used to study the effects of high temperature, waterproof treatment with admixture type on the flexural strength, compressive strength, flexural bearing capacity and deformation ability of PVA-SHCC. The effects of energy absorption, flexural toughness and impermeability were compared with the reference specimen without PVA fiber. The results of mechanical properties test show that the addition of PVA fiber can significantly improve the flexural strength, bending ability, deformation ability, energy absorption ability and bending toughness of SHCC. Increasing the compressive strength of SHCC to some extent the introduction of PVA fiber changes the bending failure pattern of SHCC. Different from the flexural failure pattern of the reference specimen, SHCC shows obvious strain hardening and multi-crack failure characteristics. The reinforcing and toughening effect of PVA fiber on SHCC decreases significantly when the change is less than 200 鈩，

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