Compressible Stacking Model Based On Modified Aggregate Morphology Parameters And Its Application In Concrete Materials

The theory of particle packing is widely used in the field of medical pharmacy,ceramic technology,powder metallurgy and other materials applications for economic analysis and optimization.In recent years,it is also used in the optimization design of cement-based composites,especially the compressible packing model(CPM).However,the technology for application of the particle packing model is still in the experimental research stage,has not formed application theory of cement-based composites design.The application theory and design method of particular packing model of low cement content green ecological concrete will benefit its health and sustainable development in concrete engineering.The development of the existing particle packing model was reviewed.It was found that the theoretical derivation of these particle packing model did not directly consider the influence of particle morphology on the particle system.And this is one of the main reasons for the difference between the predicted value and the experimental value of the packing density of the mixed particle system by the particle packing model.Thus,so this paper focuses on the morphology characteristics of aggregate particles and optimizes the effect coefficients of CPM to further improve the accuracy of CPM model.Firstly,eight representative quantitative(flatness ratio,elongation,fractal dimension,convexity ratio,sphericity,angularity,shape factor,angularity and roundness)are selected and analyzed systematically.The image processing of the samples for the selected aggregate particles is carried out by the use of digital image processing technology(Digital)to extract parameters related to these 8 particle morphology.In the meantime,in order to verify the reasonable feasibility of these quantitative parameters,the correlation between these quantitative parameters and the compacting degree of mixed granular system is studied.The results show that the correlation between seven quantitative parameters and the packing density of particle system is higher than the shape factor.Secondly,based on the theoretical derivation and development of the compressible packing model and the morphological characteristics of aggregate particles,two parameters(sphericity and angularity)are selected as the best quantitative morphological parameters of the loosening effect and wall effect of CPM model,then two morphological functions of the effect coefficient are proposed.Finally,the ternary mixture particle system is studied by the use of the modified CPM,and the relative errors of model prediction and experimental value in three-element mixed particle packing density system between modified CPM model and CPM model are compared.Thus,the accuracy of modified CPM model predictive hybrid particle system is verified.And the feasibility and accuracy of modified CPM is further verified by the combination of prediction models for workability and mechanical performance.According to the applications of the modified CPM in concrete,the performance optimization design method of green concrete based on CPM is recommended,promoting the sustainable development of concrete economy with good comprehensive performance.