Experimentell investigations and microstructure-based modeling of the elastic and visco-elastic behavior of PCC depending on temperature

PCC 弹性和粘弹性行为随温度变化的实验研究和基于微观结构的建模

• 批准号: 429470033
• 负责人: Professorin Dr.-Ing. Andrea Osburg
• 金额: --
• 依托单位: Lehrstuhl Bauchemie und Polymere Werkstoffe
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2019
• 资助国家: 德国
• 起止时间: 2018-12-31 至 2023-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/429470033?language=en
• 关键词: Experimentell; investigations; microstructure; based; modeling

Due to increasing economic and ecological requirements regarding engineering structures, there is a growing need to optimize the resistance of the building material concrete against a wide variety of loads. The modification of the binder with thermoplastic polymers has been an established method for improving the durability, chemical resistance, and adhesive properties of cementitious materials for many years. The fields of application for polymer-modified cement mortars and concretes (PCC) have therefore been steadily extended in recent years. In order to establish PCC also in construction, a comprehensive understanding of the effects of polymer modifications on the mechanical behavior is fundamental. Particularly with regard to the elastic and viscous deformations properties, the PCC differ significantly from conventional mortars and concretes. However, due to the pronounced temperature dependence of the polymers, it is necessary to describe the mechanical behavior of PCC as a function of the temperature. The objective of the proposed project is to characterize the temperature dependence of the elastic and viscoelastic properties of PCC. For this purpose, cross-scale experimental and analytical approaches that complement each other are used. The temperature-dependent influence of the polymers on the load-deformation behavior of cement pastes, mortars, and concretes is characterized both by standard measurements and by novel experimental campaigns. The latter include short-term creep tests according to which the sample is subjected to a compressive force once every hour for three minutes during the first week after production. This procedure enables the quasi-continuous determination of the elastic properties and the creep strains of the samples. The results are complemented by long-term creep tests so that the creep behavior of PCC can be comprehensively described. The respective investigations are carried out at different temperatures between -20 and +60 °C. Microstructural investigations before and after the temperature influence also provide information on changes in the morphology of single phases.The results of the study are bundled in a semi-analytical multiscale model based on the methods of continuum micromechanics. By means of a bottom-up approach, homogenized properties at the macroscale are determined using the specific microstructural behavior. The microstructure changing as a result of the temperature influence can thus be directly correlated with the macroscopic material behavior. After extending an existing multiscale model by considering principles of thermo-poro-elasticity, the temperature dependence of the mechanical properties of PCC will be predictable.

由于工程结构的经济和生态要求不断提高，越来越需要优化建筑材料混凝土对各种荷载的抵抗力，用热塑性聚合物对粘合剂进行改性已成为提高耐久性的既定方法。近年来，聚合物改性水泥砂浆和混凝土（PCC）的应用领域不断扩大，以建立对PCC在建筑领域的全面了解。聚合物改性的影响机械行为是根本性的，特别是在弹性和粘性变形特性方面，PCC 与传统砂浆和混凝土显着不同，但是，由于聚合物具有明显的温度依赖性，因此有必要将 PCC 的机械行为描述为该项目的目标是表征 PCC 的弹性和粘弹性特性的温度依赖性，为此，使用了相互补充的跨尺度实验和分析方法。聚合物对水泥浆、砂浆和混凝土的载荷变形行为的影响通过标准测量和新颖的实验活动来表征，后者包括短期蠕变测试，根据该测试，样品受到一次压缩力。在生产后的第一周内，每小时进行一次，持续三分钟。该程序可以准连续测定样品的弹性性能和蠕变应变，并通过长期蠕变测试来补充结果，以便可以确定 PCC 的蠕变行为。进行全面描述。各自的研究在 -20 至 +60 °C 之间的不同温度下进行。温度影响前后的微观结构研究也提供了单相形态变化的信息。研究结果集中在半分析中。基于连续微观力学方法的多尺度模型，通过自下而上的方法，使用特定的微观结构行为来确定宏观尺度的均匀特性，从而可以将因温度影响而发生的微观结构变化直接关联起来。宏观材料行为。通过考虑热孔隙弹性原理扩展现有的多尺度模型后，PCC 机械性能的温度依赖性将是可预测的。