Effect Of Sand Particle Size On Concrete Performance And Microstructure Analysis

At the present stage,with the rapid development of infrastructure construction,the consumption of natural river sand is in great demand,and the reserves and sources of natural sand are rapidly decreasing,especially in dashishan area where there are more stones and less sand,the river sand resources are very scarce,and the contradiction between supply and demand of sand is becoming increasingly prominent.According to the current limitations of natural resources,machine-made sand emerges as the times require.At present,using machine-made sand instead of natural sand as the raw material of concrete has become a common phenomenon in the concrete industry,showing more prominent economic and social benefits,representing the scientific development direction of the industry.In summary,based on the production process of a pebble machine-made sand in Baise,Guangxi,this study analyzes the specific physical properties of pebble machine-made sand combined with relevant indicators,and uses pebble machine-made sand as fine aggregate.The mix proportion of pebble machine-made sand concrete is calculated and adjusted to explore the mechanical properties of machine-made sand concrete with different particle sizes.Through comparative study and other scientific research methods,starting from the grain shape characteristics,the relationship between the pebble machine-made sand and the performance of concrete is studied and analyzed,and the influence mechanism of the pebble machine-made sand on its performance in the concrete preparation process is discussed and analyzed with the grain shape,stone powder content,MB value and other research indexes.The conclusions are as follows:1.Based on the indexes such as particle size distribution,fineness modulus,apparent density,clay content and MB value,the similarities and differences of physical properties between manufactured sand and natural sand are compared and analyzed.It is confirmed that there is no significant difference in the degree of similarity between the two indexes.2.Taking pebble manufactured sand as fine aggregate,five kinds of concrete made of pebble manufactured sand and natural sand with fine to coarse grain gradation were designed,and the mechanical properties of concrete with each grain gradation were compared and analyzed.3.The gradation of pebble machine-made sand has an effect on the workability of concrete,but its multi angular characteristics are conducive to improving the strength and volume stability of concrete.The workability of concrete with manufactured pebble sand can be improved by appropriately increasing the content of part of the particle size of manufactured pebble sand,that is,the percentage of small particle size grade.4.The content of stone powder and mud powder in pebble manufactured sand particles has more significant influence on the performance of concrete.In addition,appropriate stone powder content is beneficial to reduce the porosity formed by free water and improve the compactness and strength of concrete,while relatively high stone powder content will also have adverse effects on the preparation of concrete.Specifically,part of stone powder will exist in the interface transition zone or cement stone in the form of free state,which has adverse effects on the bond between cement stone and aggregate In addition,excessive mud powder will limit and restrict the hydration of cement,and cause adverse effects on the strength of concrete.5.Through the study of pebble machine-made sand and comparative analysis of related structures,it is concluded that the performance of pebble machine-made sand concrete is not much different from that of other machine-made sand and river sand concrete,and pebble machine-made sand can be used as one of the concrete sand.