Study On The Effect Of Vibration Mixing On The Performance Of PVA Fiber Reinforced Cementitious Composites

With the rapid development of society,people have higher and higher requirements for the use of materials.In addition to optimizing the properties of materials,the application of new mixing equipment and process is also a way to improve.Some achievements have been made in the research of vibration mixing on concrete,but the influence of vibration mixing on fiber reinforced cementitious composites has not been systematically studied.In this paper,the effects of vibration mixing and ordinary mixing on the properties of PVA fiber reinforced cementitious composites(PVA-FRCC)are studied,including four aspects of working performance,mechanical performance,durability and micro performance,in order to provide more comprehensive suggestions for the application of vibration mixing in PVA fiber reinforced cementitious composites.The main research contents and conclusions are as follows:(1)The test of PVA fiber reinforced cementitious composites with different vibration intensities under vibration mixing is carried out,the results showing that compared with low vibration intensity of 30 Hz,the compressive and flexural strength of PVA fiber reinforced cementitious composites under high vibration intensity of 50Hz has a certain improvement.(2)Two kinds of mixing methods are used to analyze the working performance of PVA fiber reinforced cementitious composites with different fiber content and different water binder ratio.The experimental tests indicate that compared with ordinary mixing,the homogeneity of PVA fiber reinforced cementitious composites is better under low fiber content by vibration mixing.Vibration mixing can improve the working performance of the mixture to a certain extent,but the increase in its consistency is small.(3)The mechanical properties of PVA fiber reinforced cementitious composites are studied by different mixing methods,mainly containing compressive strength,flexural strength,splitting tensile strength and so on.The experimental tests indicate that the mechanical properties of PVA fiber reinforced cementitious composites can be improved to a certain extent by vibration mixing and adding appropriate amount of fiber.With different fiber content,vibration mixing has a certain difference in the increase in the strength of PVA fiber reinforced cementitious composites,and the increase range is mostly less than 10%.The flexural toughness and flexural strength of cementitious composites can be improved by adding appropriate amount of fiber under the two mixing methods.Compared with ordinary mixing,the flexural performance of PVA fiber reinforced cementitious composites can not be improved significantly by vibration mixing.(4)Through the freeze-thaw resistance test and chloride ion resistance test of PVA fiber reinforced cementitious composites,the effect of vibration mixing on its durability is studied.The experimental results show that the vibration mixing group has better frost resistance.Compared with ordinary stirring,the vibration stirring process has a certain improvement effect on the resistance to chloride ion penetration of PVAFRCC at a higher water-to-binder ratio.However,in the whole range of water binder ratio,the improvement effect is not obvious,the chloride ion mobility coefficient of the two mixing methods is almost the same.(5)Observing the scanning electron microscope image of the PVA fiber reinforced cementitious composites,it is concluded that the vibration mixing can make the internal structure of the composites more compact.The results of microstructure test show that vibration mixing can reduce the water absorption of PVA fiber reinforced cementitious composites.