Research And Prediction Of Mix Proportion Design Method For Sand Concrete Based On Membrane Thickness Theory Mechanism

Currently,mechanized sand is widely used as a raw material for concrete in many engineering projects.On the one hand,this can reduce the collection of river sand and better protect China’s ecological environment.On the other hand,mechanized sand has adjustability during production and can produce different particle shapes of mechanized sand through adjustments to production machines,thereby targeting the specific sand and gravel types required for actual engineering.However,there is currently no accurate definition of the relationship between the characteristics of mechanized sand,such as particle shape and gradation,and the compactness of the pile and the working performance of the mortar.The prediction of concrete working performance still relies on traditional mixing methods,and the traditional dense packing theory and various empirical formulas no longer satisfy the method for designing the mix proportions of mechanized sand concrete.Therefore,it is crucial to predict the working performance of concrete reasonably and efficiently for the modern development of concrete.The thesis adopted the wet measurement method to measure the compactness of mortar made with mechanical sand with different particle shapes and different particle size distributions.Based on the consideration of the different compactness of mixture of mechanical sand and river sand,the compressible pile model(CPM model)was corrected by considering the characteristics of mechanical sand.The corrected model could consider the influence of particle shape and particle size distribution on compactness,and could overcome the drawback of the traditional CPM model that ignored the influence of sharp particle shape and edgelessness of mechanical sand,resulting in higher prediction values than measured values.The corrected compressible pile model could well fit the measured values.At the same time,through the study of film thickness theory,a corrected water film thickness model considering the characteristics of mechanical sand was established,and the relationship between the working performance of mortar and water film thickness was studied.The connection was established between the four aspects of mechanical sand characteristics,compactness,water film thickness,and mortar working performance,and a MATLAB calculation program was established to achieve the optimization process and results of concrete ratio design.Based on the film thickness theory and compressible packing model,this thesis has developed a successful program for predicting the working performance of mechanized sand mortar.The working performance of fine aggregate plays a decisive role in the working performance of concrete.Therefore,this thesis can provide new ideas for the mix proportion design of mechanized sand concrete in practical engineering.