EVA与硅烷乳液改善防水砂浆性能的微观机理
作者:
作者单位:

1.北京交通大学 土木建筑工程学院,北京 100044;2.清华大学 土木工程系,北京 100084

作者简介:

张艳荣(1985—),女,河北廊坊人,北京交通大学教授,博士生导师,博士.E-mail:yr.zhang@bjtu.edu.cn

通讯作者:

张艳荣(1985—),女,河北廊坊人,北京交通大学教授,博士生导师,博士.E-mail:yr.zhang@bjtu.edu.cn

中图分类号:

TU528

基金项目:

中央高校基本科研业务费专项资金资助项目(2023JBMC050)


Microstructural Mechanism of EVA and Silane Emulsion Improving Waterproof Mortar
Author:
Affiliation:

1.School of Civil Engineering, Beijing Jiaotong University, Beijing 100044, China;2.Department of Civil Engineering, Tsinghua University, Beijing 100084, China

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    摘要:

    通过四点弯曲强度、黏结强度、冻融循环及热重、压汞和扫描电镜等试验研究了乙烯-乙酸乙烯酯共聚乳液(EVA)和硅烷乳液对高韧性防水砂浆力学性能和抗冻性的影响规律及作用机理. 结果表明:EVA基本不影响砂浆后期弯曲性能,但显著提高其与基层的黏结强度;随EVA掺量增加,砂浆孔隙率先增大后减小,抗冻性先降低后提高;硅烷乳液的掺入显著降低了水化产物在聚乙烯醇(PVA)纤维表面的附着,导致砂浆弯曲性能下降;当硅烷乳液掺量较高时,PVA纤维与基体界面粗糙度明显增加,砂浆弯曲性能提高;内掺硅烷乳液增加了毛细孔含量,有助于缓解孔隙水结冰产生的膨胀应力,从而显著提高砂浆抗冻性.

    Abstract:

    Influence of ethylene-vinyl acetate copolymer(EVA) and silane emulsion on the mechanical properties and frost resistance of the high toughness waterproof mortar was investigated through four-point bending test, bonding test, freeze-thaw cycle test, thermogravimetric analysis, mercury intrusion test and scanning electron microscopy. The results show that EVA has little effect on the bending properties at late age, but significantly improves its bonding strength. With the increase of EVA content, the porosity of mortar initially increases and subsequently decreases, and the frost resistance decreases at first and then increases. The inclusion of silane emulsion significantly reduces the adhesion of hydration products on poly vinyl alcohol(PVA) fibers, resulting in the decreasing of bending properties of mortar. By contrast, at high dosages of silane emulsion, the interfacial roughness between fiber and matrix increases obviously, which is beneficial to increasing the bending properties. The incorporation of silane emulsion alleviates the expansion stress caused by water freezing due to the increasing capillary pores, which significately improves the frost resistance.

    表 1 P‧O 42.5水泥的物理性能Table 1 Physical properties of P‧O 42.5 cement
    图2 EVA乳液对高韧性防水砂浆的界面黏结强度和收缩的影响Fig.2 Effect of EVA emulsion on interface bonding strength and shrinkage of high toughness waterproof mortar
    图3 EVA乳液对高韧性防水砂浆抗冻性的影响Fig.3 Effect of EVA emulsion on the frost resistance of high toughness waterproof mortar
    图4 EVA乳液对硬化水泥浆的化学结合水和Ca(OH)2含量的影响Fig.4 Effect of EVA emulsion on chemical bound water and Ca(OH)2 in hardened cement pastes (28 d)
    图5 EVA乳液对高韧性防水砂浆孔结构的影响Fig.5 Effect of EVA emulsion on the pore structure of high toughness waterproof mortar (28 d)
    图6 EVA乳液对高韧性防水砂浆微观形貌的影响及作用机理示意图Fig.6 Effect of EVA emulsion on microstructure of high toughness waterproof mortar and its working mechanism(28 d)
    图7 硅烷乳液对高韧性防水砂浆弯曲性能的影响Fig.7 Effect of silane emulsion on bending properties of high toughness waterproof mortar
    图8 硅烷乳液对高韧性防水砂浆黏结强度和收缩的影响Fig.8 Effect of silane emulsion on bonding strength and shrinkage of high toughness waterproof mortar
    图9 硅烷乳液对高韧性防水砂浆抗冻性的影响与作用机理示意图Fig.9 Effect of silane emulsion on frost resistance of high toughness waterproof mortar and working mechanism
    图10 硅烷乳液对硬化水泥浆的化学结合水和Ca(OH)2含量的影响Fig.10 Effect of silane emulsion on chemical bound water and Ca(OH)2 in hardened cement pastes (28 d)
    图11 硅烷乳液对高韧性防水砂浆孔结构的影响Fig.11 Effect of silane emulsion on pore structure of high toughness waterproof mortar (28 d)
    图12 硅烷乳液对高韧性防水砂浆微观形貌的影响及机理图Fig.12 Effect of silane emulsion on microstructure of high toughness waterproof mortar (28 d)
    表 3 高韧性防水砂浆的弯曲性能参数Table 3 Parameters of bending properties of high toughness waterproof mortar
    表 2 PVA纤维的性能参数Table 2 Performance parameters of PVA fiber
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张艳荣,丁一,邹志龙,孔祥明,张雪松.EVA与硅烷乳液改善防水砂浆性能的微观机理[J].建筑材料学报,2024,27(11):1060-1070

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  • 收稿日期:2023-08-30
  • 最后修改日期:2024-01-27
  • 在线发布日期: 2024-12-10
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