Dynamic vapour sorption (DVS) balance to evaluate the microstructure of porous building materials

所有影响混凝土结构的劣化机制都涉及气体或液体的传输过程。胶凝材料的传输特性和孔结构随着龄期和暴露条件的变化而变化。有必要对这些变化进行具体描述和量化，以便更全面地了解退化机理(S)，并预测混凝土随时间的性能。吸附/解吸等温线是分析孔特征和传输特性的有力工具。与其他测量蒸汽等温线数据的方法相比，动态蒸汽吸附(DVS)平衡法的三个关键优点是：快速(试验持续时间1-5天)，使用DVS设备进行的实验是申请人研究计划的一个组成部分，以实现以下研究目标：量化和解耦水分粘结剂和离子粘结剂对传输特性的影响，以建立经验关联；并区分化学水化和化学结合对材料微观结构和运输性能的影响。DVS实验结果将用于开发新的分析混凝土耐久性模型，以反映物理和化学过程。据估计，在获得DVS平衡的前5年内，约有10名学生(3名博士、3名硕士和4名本科生)将使用该设备并对数据进行分析。这项研究预计将产生新的贡献，并通过更好地了解混凝土降解机理和开发分析耐久性模型来影响混凝土技术的进步。它们捕捉物理和化学过程。研究成果将通过期刊出版物、会议和研讨会广泛传播。

All deterioration mechanisms that affect concrete structures involve either gaseous or liquid transport processes.  The transport properties and pore structure of cementitious materials change with age, and exposure conditions.  Specific descriptions and quantification of these changes is warranted to more completely understand the mechanism(s) of degradation and also to predict the performance of concrete over time.  Adsorption/desorption isotherms are a powerful tool to analyze the pore characteristics, and transport properties.  In comparison to alternative methods to measure vapour isotherm data, three key advantages of the Dynamic Vapour Sorption (DVS) balance approach are that it is: rapid (1- 5 days test duration), precise (continuous measurements with high precision balance), and it prevents carbonation of the cementitious samples.  Experiments conducting using the DVS equipment is an integral part of the applicant's research program to achieve the following research objectives: to quantify and decouple the moisture-binder and ion-binder effects on transport properties to establish empirical correlations; and to discriminate between the effects of chemical hydration and chemical binding on the material's microstructure and transport properties.  The DVS experimental outcomes will be used to develop  new analytical concrete durability models to reflect both physical and chemical processes.  It is estimated that approximately 10 students (3 Ph.D., 3 M.A.Sc., and 4 undergraduate), within the first 5 years of acquiring the DVS balance will use the equipment and conduct analysis of the data.  The research is anticipated to yield novel contributions and impact the advancement of concrete technology through an improved understanding of concrete degradation mechanisms and the development of analytical durability models, which capture physical and chemical processes. Research findings will be widely disseminated through journal publications, conferences and workshops.