防水剂对受荷开裂下PVA-SHCC渗透性能的影响

Influences by waterproofing agent on impermeability of strain hardening cement-based composite on the loading state

受荷载时产生的多重裂缝是SHCC的薄弱部位和外界介质侵入的通路,会加速了结构的耐久性劣化。而对SHCC进行防水处理是提高耐久性的有效措施,研究了防水剂对PVA-SHCC试件抗氯离子渗透性能和受荷开裂下的试件水毛细吸收系数的影响。试验结果表明:对PVA-SHCC进行防水处理可以显著降低试件中的氯离子扩散系数,外涂防水剂试件的氯离子扩散系数只是不掺防水剂的试样的8%到20%,内掺防水剂的试件的氯离子扩散系数只是不掺防水剂试件的60%左右。试件在受荷开裂下的抗渗性比未施加应力试件的抗渗性差,采取防水处理可以有效提高受荷试件的抗渗性能,外涂和内掺处理方式对提高抗渗的效果相差不大。SHCC渗透性能的研究可以为SHCC结构耐久性研究和服役寿命预测提供重要参考。

Cracks in strain hardening cement-based composite（SHCC）structures caused by mechanical load are the weakness under ser-vice condition,and they provide pathways for access of water and solution containing chloride into strain hardening cement-based com-posite. In the present paper,the influences by waterproofing agent to chloride resisting performances and capillary suction coefficient of specimen on the loading state are experimental studied.The experimental results indicate that water proof treatment can significantly reduce the chloride diffusion coefficient.The chloride diffusion coefficient of the specimen by external application of waterproofing agent is only between 8%and 20%of normal strain hardening cement-based composite specimen. And which of blended with waterproofing agent is ap-proximately 60%of normal strain hardening cement-based composite.Furthermore,the impermeability of strain hardening cement-based composite specimen under the loading state is much worse than that of unloaded strain hardening cement-based composite specimen.The water proofing treatments are capable to improve the and both external application of and blended with waterproofing agent have approxi-mate influences on impermeability.The experimental results will help to make proper durability assessment and service life prediction.