滨海混凝土化学自修复微胶囊制备及性能研究

摘要

制备了两种基于单氟磷酸钠微胶囊和亚硝酸微胶囊的化学自修复系统,微胶囊以乙基纤维素作为主要的囊壁成份,囊芯材料则分别是亚硝酸钠和单氟磷酸钠,微胶囊平均粒径分别为270和410 μm.两种微胶囊按水泥质量的5%含量掺入钢筋砂浆样品中,并采用恒温50 ℃干湿循环进行锈蚀加速过程,之后进行线性极化(LSV)测试和X射线层析成像(X-ray μCT)测试及图像分析.空白样在72 h干湿循环后出现点蚀,而加入亚硝酸钠微胶囊的样品在576 h干湿循环后钢筋依旧保持光滑的表面,而加入了单氟磷酸钠微胶囊的样品则在432 h后才出现点蚀现象.结果表明,两套化学修复系统的锈蚀过程滞后于不加胶囊的空白样,表现出缓蚀的效果,化学自修复微胶囊体系能够对混凝土内部钢筋起到显著的保护作用.%In this paper, a chemical self-healing system, including the sodium nitrite (NaNO2)/ethyl cellulose (EC) microcapsule system and the sodium monofluorophosphate (MFP)/ethyl cellulose (EC) microcapsule system, is designed and studied.First of all, microcapsules were fabricated via the extrusion spheronisation and spray drying method.Sodium nitrite/sodium monofluorophosphate is adopted as healing agent and ethyl cellulose (EC) serves as wall material.The average particle size of NaNO2/EC microcapsules is 270 μm, while MFP/EC microcapsule is 410 μm.Two kinds of capsules were respectively mixed into the mortar samples by 5% of the cement mass, and the corrosion acceleration process was carried out by using the wet-dry cycle test at 50 ℃.X-ray μCT (X-ray micro-tomography) testing technology and linear sweep voltammetry method were introduced to test the microcapsule inhibition efficiency.Pitting corrosion of the control sample took place after 72 h of wet-dry cycles, while the sample containing sodium nitrite microcapsules is smooth after 576 h.The sample with sodium monofluorophosphate microcapsules began to rust after 432 h.The results show that the chemical self-healing system has a very significant anti-corrosion performance.