浸水环境下改性氯氧镁砂浆黏结强度变化规律

为了研究经青稞秸秆灰（HBSA）改性的氯氧镁水泥砂浆（MOCM）作为西部盐湖地区普通混凝土的外防护层，抵御盐湖区卤水侵蚀从而延长混凝土服役寿命的可行性，开展了浸水环境下掺入HBSA的MOCM的黏结强度等试验研究.采用普通混凝土作为黏结基层，以混凝土基层涂刷界面剂、MOCM中掺入HBSA以及砂浆层厚度等影响因素为变量，通过黏结拉拔试验分析各因素对MOCM黏结强度的影响规律，确定最优的设计参数，通过多项式模拟以及MATLAB中网格化处理等数值模拟方法，建立氯氧镁水泥黏结强度时变模型，进一步分析了浸水环境下改性MOCM黏结强度的损伤退化规律.采用微观测试技术分析了MOCM的物相组成、官能团结构、微观形貌、元素映射等特征，揭示了HBSA对MOCM黏结性能的影响机理.结果表明，HBSA中有较多的活性SiO2，能够与MOCM中的水化产物发生二次水化反应，生成水化硅酸镁（M―S―H）凝胶，填充MOCM内部孔隙，增强密实性，提高黏结性能.厚度为18 mm、掺入HBSA，且涂刷界面剂的MOCM黏结强度最高，其在浸水环境下的黏结强度退化速率最慢，基于三次多项式的数值模型能较好地反映其黏结强度的退化规律，最优组YY-18的相关性系数R2达到0.98.

Change Law of Bond Strength of Modified Magnesium Oxychloride Mortar under Water Immersion Environment

To study the feasibility of using magnesium oxychloride cement mortar （MOCM） modified by highland barley straw ash （HBSA） as an outer protective layer of ordinary concrete in the western salt lake area to resist brine erosion in the salt lake area and prolong the service life of the concrete， experimental research on the bonding strength of MOCM mixed with HBSA under water immersion environment was carried out. Ordinary concrete was used as the bonding base， and the influence factors such as the application of interface agent on the concrete base， the mixing of HBSA in MOCM， and the thickness of the mortar layer were used as variables. The bond pull-out tests were carried out to analyze the effect of each factor on MOCM bonding strength and to determine the optimal design parameters. Through numerical simulation methods such as polynomial simulation and grid processing in MATLAB， a time-varying model of magnesium oxychloride cement bond strength was established， and the damage degradation law of the bond strength of modified MOCM under water immersion environment was further analyzed. The phase composition， functional group structure， microscopic morphology， element mapping， and other characteristics of MOCM were analyzed by microscopic testing technology， and the mechanism of the influence of HBSA on the bonding performance of MOCM was revealed. The results show that there is more active SiO2 in HBSA， which can undergo a secondary hydration reaction with the hydration products in MOCM to form hydrated magnesium silicate （M―S―H） gel， which can fill the internal pores of MOCM， enhance the compactness， and improve the adhesive properties. The MOCM with a thickness of 18 mm， mixed with HBSA， and coated with interface agent has the highest bond strength， the bond strength degradation rate is the slowest in water immersion environment， and the numerical model based on the cubic polynomial can better reflect its bond strength. The degradation law of the optimal group YY-18 has a correlation coefficient R2 of 0.98.