The Research On High-grade Concrete With Machine-made Sand Prepared By High-frequency Vibration And Stirring

In the Twelfth Five-Year Plan,China's infrastructure construction,transportation and other engineering industries have rapidly developed.Currently,concrete is the most widely used building materials.However,due to the reasons like sustainable development strategies and environmental protection,it is limited to exploit natural sand resources by destroying the river ecosystem,and thus natural sand resources are gradually exhausted,followed by the prices increasingly rising.Although natural sands are the most optimum fine aggregates for concrete preparation,with the development of society and engineering industries,machine-made sands can replace natural sands to prepare concrete,which is in line with the demands of sustainable and conservation-oriented society development.Therefore,researches on machine-made sand concrete is of great significance.Through the preliminary investigation and data collection,it's concluded that the Guizhou Province is lack of natural sand resources,which thus is the first province to study the preparation of middle-and-low concrete by machine-made sands instead of natural sands in China,and promulgates relatively perfect local technical regulations.Based on the background of Pingtang-Luodian section of Yuqing-Anlong Expressway in Guizhou Province,this paper experimentally studies the high-grade concrete with C50 machine-made sand.In the experimental study,the main raw materials such as cement,machine-made sands,gravels and polycarboxylate superplasticizers were selected and their performance indexes were tested,so as to optimize the raw materials.The optimum mix proportion of the high-grade concrete with C50 machine-made sand was determined,and its workability and compressive strength were studied through tests.On this basis,the factors influencing the performance of the concrete were analyzed and studied.Afterwards,high-frequency vibration and stirring mechanism was used to improve the performance of the concrete.Besides,contrast tests were carried out on several kinds of high-grade concrete with C50 machine-made sand prepared by different stirring methods to study their workability,compressive strength and frost resistance.The industrial CT scanning was used to observe the internal microstructure of the high-grade concrete with C50 machine-made sand prepared by high-frequency vibration and stirring.Through the experimental study,the paper illustrates the use of machine-made sands as fine aggregates for high-grade concrete preparation and the use of high-frequency vibration and stirring to improve its performance,which provides a technical basis for machine-made sands to be widely used in high-grade,high-performance concrete preparation in the future.