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

骨料在混凝土和砂浆中占最大体积分数，其形状特性影响混凝土在新鲜状态和硬化状态下的性能。不同于标准的实验室程序，如片状度或形状指数的测定，计算机断层扫描能够测定集合样品中每个颗粒的广泛的三维形状参数。在之前的项目中，开发了一个程序来扫描聚合样品作为松散块，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触摸颗粒之间的边界识别。细或粗集料的代表性样品的颗粒形状的表征现在成为可能。在文献中，首次报道了三维颗粒形状参数对某些新鲜砂浆和硬化砂浆性能影响的实验结果。然而，对骨料分数内形状参数的最佳分布进行详细的分析，以精确地影响新鲜或硬化砂浆的性能，仍然缺乏。该项目下一步的主要重点是分析利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。研究了四种细料的形状表征与鲜砂浆的需水量、填充密度、流动性、微坍落度、动粘度、屈服以及硬化砂浆的抗弯强度、抗压强度和杨氏模量之间的关系。在砂浆试验中，骨料的剥落度、伸长率、角度或表面不规则度不同。在协方差分析的基础上，导出了形状参数在集料分数内的最优分布。第一个目的是根据理想的应用领域，根据最佳形状参数分布来配制砂浆的骨料掺量，并通过骨料形状来控制砂浆的新鲜和硬化性能。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.