In this study, a novel superhydrophobic additive (MPSANS) was developed to enhance the freeze-thaw (F-T) resistance of mortar by modifying mica powder with stearic acid and hydrophobic nano-silica. Firstly, the effects of hydrophobic nano-silica content on the hydrophobic properties of MPSANS modified mortar were studied, and MPSA10NS5 exhibited the best hydrophobic property, the water absorption and water desorption of modified mortar decreased by 65.42 % and 35.84 %, respectively. On this basis, abundant tests were conducted to analyze the effects of MPSA10NS5 content on the F-T resistance of mortar. Analytical findings suggested that MPSA10NS5 noticeably reduced the loss of relative dynamic modulus of elasticity and compressive strength of mortar. Furthermore, the microstructure was determined by using the scanning electron microscopy and mercury intrusion porosimetry. According to the test results, MPSA10NS5 refined the pore structure inside mortar and inhibited the crack development. Meanwhile, MPSA10NS5 effectively reduced the most probable aperture of mortar, resulting in an increase of harmless pores and a decrease of harmful pores.

中文翻译：

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砂浆抗冻融性能实验研究：疏水性纳米二氧化硅改性疏水性材料的尝试


在这项研究中，通过用硬脂酸和疏水性纳米二氧化硅对云母粉进行改性，开发了一种新型超疏水添加剂（MPSANS）来增强砂浆的抗冻融性（FT）。首先研究了疏水性纳米二氧化硅含量对MPSANS改性砂浆疏水性能的影响，发现MPSA10NS5表现出最好的疏水性能，改性砂浆的吸水率和解吸率分别下降了65.42%和35.84%。在此基础上，通过大量试验分析了MPSA10NS5含量对砂浆抗FT性能的影响。分析结果表明，MPSA10NS5 显着降低了砂浆的相对动态弹性模量和抗压强度的损失。此外，使用扫描电子显微镜和压汞孔隙率测定法测定了微观结构。测试结果显示，MPSA10NS5细化了砂浆内部的孔隙结构，抑制了裂缝的发展。同时，MPSA10NS5有效降低了砂浆的最大可能孔径，导致无害孔隙增加，有害孔隙减少。