Development of three-dimensional characteristic values for the classification of aggregates - Part 2: Correlation between three-dimensional particle shape and fresh and hardened mortar properties

集料是混凝土和砂浆中体积分数最大的部分，其形状特性影响着混凝土的新拌和硬化状态。与测定片状或形状指数等标准实验室程序不同，计算机断层扫描能够测定骨料样品中每个颗粒的广泛三维形状参数。在之前的项目中，开发了一个程序，用于扫描松散散装的骨料样品，并自动执行必要的图像处理步骤。这包括迄今为止手动执行的接触颗粒之间的边界识别。现在可以表征细骨料或粗骨料的代表性样品的颗粒形状。在文献中，第一个实验结果的三维颗粒形状参数对某些新鲜和硬化砂浆性能的影响。然而，详细分析的形状参数的最佳分布范围内的骨料分数，以精确地影响新鲜或硬化砂浆性能仍然是失踪。该项目后续课程的主要重点是分析使用计算机断层扫描确定的三维颗粒形状与新鲜和硬化砂浆性能之间的关系。研究了这四种细料的形状特征与新拌砂浆的需水量、堆积密度、流动性、微坍落度、动粘度和屈服强度以及硬化砂浆的抗折强度、抗压强度和杨氏模量之间的相关性。对于砂浆试验，使用具有不同片状度、伸长率、棱角度或表面不规则度值的骨料。基于协方差分析，得出骨料分数内的形状参数的最优分布。第一个目标是根据期望的应用领域，基于最佳形状参数分布来组成砂浆的骨料分数，并通过骨料形状来控制新鲜和硬化砂浆的性能。第二个目标是找到破碎骨料生产的优化方法。

Aggregates represent the largest volume fraction of concrete and mortar and their shape properties influence the properties in fresh as well as hardened state. Unlike standard laboratory procedures like the determination of flakiness or shape index computed tomography enables the determination of a wide range of three-dimensional shape parameters for every particle within an aggregate sample. Within the previous project a procedure was developed to scan aggregate samples as loose bulks and to automatically perform the necessary image processing steps. This includes the identification of bor-ders between touching particles which was performed manually so far. Characterization of particle shape of a representative sample of fine or coarse aggregates becomes now possible. In literature, first experimental results of the influence of three-dimensional particle shape parameters on certain fresh and hardened mortar properties are reported. However, detailed analysis of optimal distribution of shape parameters within the aggregate fraction to precisely influence fresh or hardened mortar properties is still missing. Main focus of the further course of the project is the analysis of the relation between three-dimensional particle shape determined using computed tomography and fresh and hardened mortar properties. Correlation between this shape characterization of four fine materials and the fresh mortar properties water demand, packing density, flowability, mini slump, dynamic viscosity and yield as well as the hardened mortar properties bending strength, compressive strength and Young’s modulus is investigated. For mortar tests aggregates with different values of flakiness, elongation, angularity or surface irregularity are used. Optimal distribution of shape parameters within the aggregate fraction is derived based on an analysis of covariance. First aim is to compose the aggregate fraction for mortar in dependence of the aspired field of application based on the optimal shape parameter distribution and to control fresh and hardened mortar properties by means of aggregate shape. Second aim is to find optimization approaches for crushed aggregate production.