Thermohydraulic spalling mechanisms in concretes with different binders without and with PP fibers exposed to fire: An experimental and numerical analysis

含有不同粘合剂、不含和含有 PP 纤维的混凝土中的热水力剥落机制：实验和数值分析

• 批准号: 491928256
• 负责人: Professor Dr. Günther Meschke
• 金额: --
• 依托单位: Lehrstuhl für Statik und Dynamik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/491928256?language=en
• 关键词: Thermohydraulic; spalling; mechanisms; concretes; different

Current investigations show that the type of binder system has a major influence on the fire-induced spalling behavior of concrete. For example, investigations show that concretes with Portland blastfurnace cements tend to spall more strongly as compared to concretes with Portland and Portland limestone cements. Due to the targeted reduction of CO2 emissions in the construction industry and the associated increased use of Portland composite cements with inert and reactive cement constituents, the question of the role played by thermohydraulic processes raises in this context. The aim of the research project is therefore to gain insights into the interaction of binder-specific dehydration mechanisms of the hardened cement paste, the microcrack network that forms and its changes during thermal exposure of the concrete, and the resulting thermohydraulic transport processes. The spectrum of laboratory tests planned for this purpose ranges from fire tests on small-format components to in-depth analysis of the drying behavior and the crack formation processes in the different types of concrete without and with PP fibers. The numerical simulations pursue the goal of describing the thermally induced microcrack formation, taking into account the initial crack formation and the interacting transport processes. For this purpose, a combination of multiphysical models for predicting the hydro-thermo-mechanical behavior of the investigated concretes with submodels for characterizing the damage and transport processes on several spatial scales is envisaged. Based on the experimental results and the validated models, the spalling behavior of concretes with blast-furnace and selected Portland-composite cements is evaluated and predicted with special reference to the thermohydraulic mechanisms. For the spalling-prone concretes, the crack-inducing effect and the effectiveness of adding PP-fibers to reduce the spalling tendency are additionally evaluated as a function of the cement type used.

目前的研究表明，粘结剂系统的类型对火灾引起的混凝土剥落行为有很大的影响。例如，研究表明，与使用波特兰和波特兰石灰石水泥的混凝土相比，使用波特兰高炉水泥的混凝土倾向于更强烈地剥落。由于有针对性地减少建筑行业的二氧化碳排放量，以及与此相关的增加使用含有惰性和活性水泥成分的波特兰复合水泥，在这种情况下，提出了热工水力过程所起作用的问题。因此，该研究项目的目的是深入了解硬化水泥浆体的粘合剂特定脱水机制的相互作用，在混凝土的热暴露过程中形成的微裂纹网络及其变化，以及由此产生的热工水力运输过程。为此目的计划的实验室测试范围从小型组件的防火测试到深入分析不同类型的无PP纤维和有PP纤维混凝土的干燥行为和裂缝形成过程。数值模拟追求的目标是描述热致微裂纹的形成，考虑到初始裂纹的形成和相互作用的运输过程。为此，设想了一种多物理模型的组合，用于预测所研究的混凝土的水热力学行为，并具有用于表征在几个空间尺度上的损伤和运输过程的子模型。基于实验结果和验证模型，剥落行为的混凝土高炉和选择波特兰复合水泥进行评估和预测，特别是参考热工水力机制。对于易剥落的混凝土，裂纹诱导效应和有效性的PP纤维，以减少剥落的倾向，另外评估作为一个功能的水泥类型使用。