基于拌合物信息的混凝土抗冻性表征技术研究

In order to solve the shortcomings of existing technology for evaluating the freezing-thawing resistance of concrete, such as long experiment period, high cost and hysteretic result et al., fresh concrete is set as the object of the study. Characterization technique for concrete freezing-thawing resistance based on the information of fresh concrete shall be researched. The significance of influence of fresh concrete characteristics on freezing-thawing resistance of hardened concrete shall be researched. The key parameters of fresh concrete to evaluate the freezing-thawing resistance of concrete including impermeability of fresh concrete, multi-scale pore structure and bubble film thickness will be proposed. The fresh concrete specimen for key parameters shall be prepared through frozen cryopreservation and heavy oil stabilizing bubble method. Different compositions (air content, water-binder ratio, mineral admixtures, and et al.) and different operations (vibration frequency and curing method) of fresh concrete will be researched through low temperature scanning electron microscope, air void analyzer, computed tomography and vacuum filtration method. The parameter characterization of fresh concrete shall be proposed. The multi-scale pore structure model of fresh concrete shall be established. The evolution rules with time of fresh and hardened concrete shall be contrasted. The correlation between key parameters of fresh concrete and frost resistance of hardened concrete shall be researched. The relationship of pore structure between fresh and hardened concrete shall be illustrated. The estimating index system of freezing-thawing resistance of concrete based on fresh concrete should be established.

为解决现有混凝土抗冻性评价方法试验周期长、费用高以及结果滞后等问题，拟选择新拌混凝土为研究对象，开展基于拌合物信息的混凝土抗冻性表征技术研究。系统研究混凝土拌合物特性对其硬化体抗冻性影响的显著性，提出评价混凝土抗冻性的拌合物关键信息参数；以新拌混凝土多尺度孔结构、渗透性以及气泡膜厚度等为关键信息参数，研究基于低温冷冻法以及重油稳定气泡法等新拌混凝土信息测试试件制备方法，采用低温扫描电镜、孔结构分析仪、断层扫描法、真空抽滤法等系统研究不同组成（含气量、水胶比、矿物掺合料等）以及不同制备过程（振捣频率、养护方式等）的混凝土拌合物信息特征，提出混凝土拌合物信息表征方法，建立多尺度混凝土拌合物孔结构模型；对比研究新拌混凝土与硬化混凝土孔结构经时演变规律，以及新拌混凝土关键信息参数与硬化混凝土抗冻性之间的相关性，阐明新拌混凝土与硬化混凝土孔结构的关系，建立基于拌合物信息的混凝土抗冻性评价指标体系。

为解决现有混凝土抗冻性评价方法试验周期长、费用高以及结果滞后的问题，研究提出了基于混凝土拌合物信息的混凝土抗冻性评价指标体系，实现了混凝土拌和后1h内获得硬化混凝土的抗冻性能，确保了混凝土结构的耐久性。研究确定了影响新拌混凝土气泡分析法测试的重要参数。以硬化混凝土耐久性指数为指标，揭示了新拌混凝土含气量、气泡间距系数、气泡比表面积与硬化混凝土耐久性指数的相关性，提出了基于耐久性指数的新拌混凝土气泡参数指标，即AVA仪测试混凝土的含气量以大于1.9%为宜，气泡间距系数宜小于360μm。掌握了主要原材料对有机硅防水涂料和聚合物水泥砂浆性能的影响规律，研制出适用于严寒地区冻融伤损高速铁路底座板的防护材料和修补材料。