Wang Xiaolong, Shang Huaishuai, Zhou Junhao, Gu Lilong, Xiao Zhenhao, Wang Xiaoqin, Wang Ruiping
School of Civil Engineering, Qingdao University of Technology, Qingdao 266033, China.
Zhongqing Jianan Group, Qingdao 266011, China.
Materials (Basel). 2024 Jul 18;17(14):3548. doi: 10.3390/ma17143548.
This study investigates the enhancement of hydraulic lime mortar (HLM) using varying contents of metakaolin (MK) to improve its application in the restoration of historic buildings. Samples from historic structures were analyzed, and the effects of different MK contents on the physical and mechanical properties of HLM were examined. The reaction mechanism and microstructural changes were evaluated using XRD and SEM analysis. The results indicated that increasing MK levels in HLM led to a decrease in fluidity, with fluidity reducing by 4.8% at 12% MK. The addition of MK increased water consumption for standard consistency by 5.4% and shortened the final setting time by 10.2%. MK consumption promoted secondary hydration, enhancing compressive strength by up to 98.1% and flexural strength by up to 55.1%, and increasing bonding strength by 26.9%. The density of HLM improved with MK addition, slightly reducing moisture content by 4.5% and water absorption by 4.6%, while the water vapor transmission properties decreased by 50.9%, indicating reduced porosity. The elastic modulus of the mortar increased significantly from 2.19 GPa to 7.88 GPa with the addition of MK, enhancing rigidity and crack resistance. The optimal blend for restoration materials was found to be 9.0% MK and 25.0% heavy calcium carbonate and was characterized by moderate mechanical strength, enhanced early strength, commendable permeability, minimal risk of cracking, and ease of application. This blend is highly suitable for the rehabilitation of historic structures.
本研究调查了使用不同含量偏高岭土（MK）增强水硬石灰砂浆（HLM），以改善其在历史建筑修复中的应用。对历史建筑结构的样本进行了分析，并研究了不同MK含量对HLM物理和力学性能的影响。使用X射线衍射（XRD）和扫描电子显微镜（SEM）分析评估了反应机理和微观结构变化。结果表明，HLM中MK含量增加导致流动性降低，在MK含量为12%时流动性降低了4.8%。MK的添加使标准稠度用水量增加了5.4%，并使终凝时间缩短了10.2%。MK的消耗促进了二次水化，抗压强度提高了98.1%，抗折强度提高了55.1%，粘结强度提高了26.9%。添加MK后HLM的密度提高，含水量略有降低4.5%，吸水率降低4.6%，而水蒸气透过性能降低了50.9%，表明孔隙率降低。随着MK的添加，砂浆的弹性模量从2.19吉帕显著增加到7.88吉帕，提高了刚性和抗裂性。发现修复材料的最佳配方为9.0%的MK和25.0%的重质碳酸钙，其特点是机械强度适中、早期强度增强、渗透性良好、开裂风险最小且易于施工。这种配方非常适合历史建筑结构的修复。
