氯盐侵蚀-冻融循环耦合作用下改性糯米灰浆耐久性能增强方法

Method for Enhancing Durability of Sticky Rice Mortar Under the Coupling Effect of Chloride Salt Erosion and Freeze-Thaw Cycle

为改善传统糯米灰浆应用在砖石古建筑修复与加固中的酥碱冻害,掺加质量分数为12.5%、25%和50%的偏高岭土与1%的麻纤维,获得了一种改性糯米灰浆复合材料。以力学强度、质量损失及相对动弹性模量为依据,详细研究了改性灰浆的应用性能。利用红外光衍射、X-ray粉末衍射和扫描电镜等微观分析方法,系统探究了改性灰浆在标准养护、冻融老化及氯盐侵蚀-冻融循环耦合作用下的性能演变机理。结果表明,混掺纤维和偏高岭土能显著改善灰浆的强度、抗冻性与耐盐性。偏高岭土生成的水化凝胶C-S-H与C-A-H可固化氯离子生成弗里德尔盐以抵抗孔隙破坏,增强了灰浆在氯盐环境下的抗冻性。氯盐侵蚀-冻融循环耦合作用下耐久性指标随麻纤维的掺加而小幅增大,随偏高岭土掺加而先提升后降低。其中以在糯米灰浆中混掺1%麻纤维与25%偏高岭土的增强方法最优。

For improving the frost damage caused by salt efflorescence of traditional sticky rice mortar applied in the restoration and reinforcement of ancient masonries,a kind of modified sticky rice mortar composite material was obtained by adding 12.5%,25%and 50%metakaolin and 1%flax fiber.Based on the mechanical strength,mass loss and relative dynamic elastic modulus of elasticity,the application performance of modified mortar was studied in detail.By means of infrared diffraction,X-ray powder diffraction and scanning electron microscopy,the perfor-mance evolution mechanism of modified mortar under normal curing,freeze-thaw aging and chloride corrosion freeze-thaw cycle coupling was studied.The results show that the strength,frost resistance and salt resistance of mortar can be significantly improved by mixing flax fiber and metakaolin.The hydrated gel C-S-H and C-A-H produced by metakaolin can solidify chloride ions to form Friedel salt to resist pore destruction and enhance the frost resistance of mortar in chloride environment.The durability index increases slightly with the addition of flax fiber,and increases first and then decreases with the addition of metakaolin.Among them,the reinforcement method of mixing sticky rice ash with 1%flax fiber and 25%metakaolin is the best.