Abstract: In this paper, the deep learning algorithm is used to segment the fine aggregate projection image, and the evaluation and analysis on the traditional threshold segmentation and three deep learning network model algorithms (PSPNet, DeepLab V3+ and U-Net) are conducted by comparing their segmentation results. At the same time, the results of grain size and gradation distribution of fine aggregate measured by two equivalent grain size calculation methods (single-sided projection method and double-sided projection method) were compared experimentally. The results show that the accuracy rate, recall rate, F-balance score and intersection ratio of U-Net network model in the deep learning model algorithm are 99.8%, 88.1%, 84.9% and 84.3%, respectively, which are superior to those of the control group model. For the single-grain segment fine aggregate with three different grain sizes, the deviation between the equivalent grain size $ D_{d} $ of fine aggregate calculated by double-sided projection method and the actual fine aggregate size is 1.40%, 2.10% and 3.12%, respectively. For the aggregate of mixed grain segment, the gradation distribution curve calculated by $ D_{d} $ is closer to the experimental results of screening method, which has universal applicability. The results provide a new idea for the study of grain size and grain type parameters of fine aggregate.
Keywords: fine aggregate; threshold segmentation; deep learning algorithm; equivalent grain size; fine aggregate grain type parameters