基于三维扫描与数值技术的粗集料形状特征与级配研究

Research on the shape feature and gradation of coarse aggregate based on 3D scanning and numerical technology

粗集料体系作为混凝土主要组成部分,其颗粒构成对混凝土各项性能的改善起到了关键作用。为优化粗集料体系颗粒构成,以实现粗集料形状特征和级配精细化、数字化分析目标,采用激光三维扫描技术获取了粗集料的点云坐标,结合三维图像技术,进行粗集料的几何形状重构与三维形状参数准确测量,并提出球度、长短轴长比、粒径离散度和级配分形维数等指标。同时,基于粗集料的点云数值处理技术与分形理论,计算得到级配粒径和表面分形维数等指标,表征评价不同粒径粗集料形状特征及级配。研究结果表明:激光三维扫描和数值技术可快速重构出粗集料的真实形状,并能准确得到粗集料三维形状参数,提出的球度、长短轴长比和粒径离散度指标均能较好地对粗集料形状特征进行表征评价。其中,长短轴长比在表征粗集料球形度方面更具显著性与敏感性;采用三维图像数值技术与分形理论计算得到的粗集料级配分形与表面积分形维数,与粗集料粒径、表面粗糙度有密切联系,实现了粗集料几何特征的数值描述与评价;同时采用质量加权得到的粗集料级配分形维数,建立的粗集料颗粒级配计算函数计算结果与试验结果一致,研究结果可为粗集料级配的快速优化分析表征提供技术支持。

Coarse aggregate system is the main component of concrete, and its particle composition plays a key role in improving various properties of concrete. To optimize the particle composition of the coarse aggregate system to achieve the goal of fine-grained and digital analysis of the coarse aggregate shape and gradation, the laser three-dimensional scanning technology was used to obtain the point cloud coordinates of the coarse aggregate. The three-dimensional image technology was combined to carry out the rough collection. The geometric shape reconstruction of the material and the accurate measurement of the three-dimensional shape parameters, and the sphericity, the ratio of long and short axis length, the dispersion of particle size, and the fractal dimension of gradation were proposed. At the same time, based on the point cloud numerical processing technology and fractal theory of coarse aggregates, the gradation particle size and surface fractal dimension were calculated to characterize and evaluate the shape characteristics and gradation of coarse aggregates with different particle sizes. The results show that the laser three-dimensional scanning and numerical technology can quickly reconstruct the true shape of the coarse aggregate, and accurately obtain the three-dimensional shape parameters of the coarse aggregate. The proposed sphericity, the ratio of long and short axis length and the particle size dispersion index can all be better. Ground the characterization and evaluation of the coarse aggregate shape characteristics. Among them, the long-short axis length ratio is more significant and sensitive in characterizing the sphericity of coarse aggregates. The coarse aggregate gradation fractal and surface integral fractal dimensions calculated by using three-dimensional image numerical technology and fractal theory. The particle size and surface roughness are closely related to realize the numerical description and evaluation of the geometric characteristics of the coarse aggregate. At the same time, the coarse aggregate gradation fractal dimension obtained by mass weighting is used to establish the coarse aggregate particle gradation calculation function. The results are consistent with the experimental results. And the research results can provide technical support for the rapid optimization analysis and characterization of the coarse aggregate gradation.