The characterization of the rheological properties of suspension, mortar and concrete under the influence of hydration, temperature, pressure and vibration

表征悬浮液、砂浆和混凝土在水化、温度、压力和振动影响下的流变特性

• 批准号: 387065685
• 负责人: Professor Dr.-Ing. Harald Garrecht
• 金额: --
• 依托单位: Institut für Werkstoffe im Bauwesen
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2017
• 资助国家: 德国
• 起止时间: 2016-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/387065685?language=en
• 关键词: characterization; rheological; properties; suspension; mortar

Maintaining the homogeneity of the mixture is a prerequisite for carrying out rheological measurements. With new measurement techniques, the homogeneity during rheological measurements is to be recorded in two rheometers (MODUL II). In the known rheometers, a shear-induced segregation takes place in the pre-shear phase. In the following measuring phase, a material which is not homogeneous is thus measured. Inhomogeneities, which are based on sedimentation processes, cannot be recognized either. The IWB has a unique machine (KNIELE KKM-RT 22.5/15) that can be used as a mixer and as a rheometer and avoid inhomogeneities of the material during preshear.This research project involves the production and (repeated) determination of the rheological parameters in a single device with preshear on the level of mixing! The intensive-mixer allows the range of mixing techniques and sizes to be mapped by adapting the mixing intensity.In addition, the machine can actively homogenize the mixture in the pre-shear phase and counteract sedimentation. The structure caused by thixotropy is degraded without reducing the mixing quality.According to MODUL II, the rheological properties of granular suspensions are to be determined by two known rheometers. Particular attention is paid to the inhomogeneities caused by shear and sedimentation. Inhomogeneities in the vessels of the ICAR and the KNIELE are detected locally by means of four miniature moisture probes, via changes in the measured values for moisture and the radar-based conductivity. A mixer camera in the KNIELE makes it possible to identify the actual sheared area (shear-radius) and to take it into account during the calculation. Only with the ability to correctly measure it is possible to quantify the rheological properties of fresh concrete and to understand the correlation between the proportions of the components in the fresh state.The probes also measure the ionic conductivity of the suspension via the so-called radar-based conductivity. It is to be investigated whether changes in the fresh concrete properties can be explained by changes in the ionic conductivity over time. The connection to MODUL I is thus achieved and a further parameter for the characterization of the fresh mortar or concrete properties would thus be found.Further connections to the MODULE I and III will be carried out by the rheology-based mixture development. For packing-density optimized mix designs the demand for water and concrete additives is determined by the analysis of the mixer raw data (MODUL III). The mixing probes also supply the necessary measured values for the evaluation by the radar-measured conductivity (MODUL I). In order to be able to carry out the rheological measurements with active homogenization in the pre-shear phase under other boundary conditions, the KNIELE is also expanded. To a pressure cell, a temperature control unit, a vibration unit for vibrating concrete and a calorimeter.

保持混合物的均匀性是进行流变测量的先决条件。采用新的测量技术，流变测量过程中的均匀性将在两台流变仪（MODUL II）中记录。在已知的流变仪中，在预剪切阶段发生剪切诱导的分离。在接下来的测量阶段中，测量不均匀的材料。基于沉积过程的不均匀性也无法识别。IWB有一台独特的机器（Kniele KKM-RT 22.5/15），可以用作混合机和流变仪，避免在预剪切过程中材料的不均匀性。该研究项目涉及在混合水平上进行预剪切的单个设备中生产和（重复）测定流变参数！通过调整混合强度，强力混合机可实现混合技术和尺寸范围的映射。此外，该机器可在预剪切阶段主动均化混合物并抵消沉淀。由触变性引起的结构退化而不降低混合质量。根据MODUL II，颗粒悬浮液的流变特性将由两种已知的流变仪测定。特别注意的是由剪切和沉降引起的不均匀性。ICAR和KNIELE容器中的不均匀性通过四个微型水分探头进行局部检测，通过水分和基于雷达的电导率测量值的变化。Kniele中的混合器摄像头可以识别实际剪切面积（剪切半径），并在计算过程中将其考虑在内。只有具备正确测量的能力，才能量化新拌混凝土的流变特性，并了解新拌状态下各组分比例之间的相关性。探头还通过所谓的雷达电导率测量悬浮液的离子电导率。这是要调查是否可以解释在新拌混凝土性能的变化，随着时间的推移在离子电导率的变化。这样就实现了与MODUL I的连接，从而找到了表征新拌砂浆或混凝土性能的另一个参数。通过基于流变学的混合物开发，将实现与MODUL I和III的进一步连接。对于填充密度优化的配合比设计，对水和混凝土添加剂的需求是通过对搅拌机原始数据的分析来确定的（模块III）。混合探头还提供必要的测量值，用于通过雷达测量的电导率（MODUL I）进行评估。为了能够在其他边界条件下在预剪切阶段进行主动均质化的流变测量，KNIELE也进行了扩展。涉及压力单元、温度控制单元、用于振动混凝土的振动单元和热量计。