Research On Appearance Geometric Characteristics Of Aggregate And Concrete Based On 3D Scanning Technology

3D scanning technology is a new technology,through scanning the surface of the object to collect the corresponding point cloud data,to achieve the reconstruction of the real 3D shape of the object.Based on the aggregate particles concrete appearance of geometric features accurate test characterization of demand,and combined with the current characteristics of the aggregate concrete appearance of geometric feature testing are mainly artificial measurement technology present situation,the thesis carried out numerical representation of aggregate particle properties and concrete appearance of geometric features based on 3D scanning technology and numerical calculation technology to provide technical support for more accurate and efficient grasp of aggregate particle characteristics,time-warp variation of concrete appearance size and geometric characteristics of appearance defects,and expand the application of advanced testing technology in concrete technology.The main achievements are as follows:(1)Point cloud coordinates of coarse aggregate with different particle sizes were obtained accurately based on 3D scanning technology,and geometric reconstruction of aggregate particles and accurate measurement of 3D shape parameters were realized.Therefore,sphericity,length ratio of long and short axes,particle size dispersion and fractal dimension of grading were proposed to more accurately describe the characteristics of aggregate particles.The fractal dimension of gradation,surface integral dimension and surface roughness index of coarse aggregate were obtained quickly by using numerical technique to process the 3D scanning results,which realized the numerical description and evaluation of geometric characteristics of coarse aggregate.The fractal dimension of coarse aggregate gradation and surface fractal dimension vary with particle size,and there is a close relationship between surface fractal dimension and surface roughness.(2)Based on the fractal dimension of coarse aggregate gradation obtained by mass weighting,the calculation function of coarse aggregate particle gradation passing rate was established.The calculation results were consistent with the experimental results,providing technical support for the digitization and high efficiency of coarse aggregate particle gradation analysis.At the same time,the real reconstruction models of aggregate with different particle sizes obtained by 3D scanning technology were imported into PFC 3D discrete element analysis software,and the voids of the system were simulated by referring to Fuller grading curve,so as to simulate and optimize aggregate grading.(3)Aiming at the characteristics of concrete shrinkage and deformation and the status quo of testing technology,we independently designed a concrete shrinkage and deformation testing device based on3 D scanning technology and numerical technical requirements.Through3 D scanning technology,we obtained point cloud data of geometric parameters on the surface of concrete specimens,and reconstructed the real 3D shape of the surface in real time.,the shrinkage deformation and surface quality of concrete are obtained from the time-dependent change of the apparent size in the test direction,and a new method for testing the shrinkage deformation of concrete specimens is creatively proposed.(4)Based on the 3D model of the surface of the specimen reconstructed by 3D scanning,the recognition algorithm of the surface depression was written through the computer-related numerical analysis software,and the characterization of the apparent morphology and geometric size of the concrete specimen based on the 3D point cloud data was creatively proposed.And visualization technology,the calculated results are in good agreement with the measured results.38 Figures,7 Tables,74 References...