Study On Axial Compression Properties And Stress-strain Models Of Seawater And Sea-sand Cement-based Composites

Seawater sea sand fiber cement-based composites are one of the hot topics in the field of civil engineering materials.This article is to study the axial compression characteristics of seawater sea sand PVA fiber cement-based composites.Using undisturbed sea sand as fine aggregate,simulated seawater,considering strength grade,fiber content,seawater concentration and curing age,a total of 162 standard cylinder test specimens were designed and produced for axial compression tests.Through analysis and research,the following test results are obtained:(1)With the increase of the amount of PVA fiber,the surface of the test piece is destroyed,and diagonal cracks of low-strength materials appear,and the strength of the material increases from oblique cracks to vertical cracks;the bridging action of the fiber prevents the test piece from breaking off the surface;Under the combined effect of age and seawater concentration,the surface cracks of the specimen changed from oblique cracks to vertical cracks.The failure morphology of the specimen is related to the fiber content,seawater concentration,strength,age and their interactions.(2)When different ages and different seawater concentrations are constant,as the fiber content increases,the strength of the test piece decreases,and the strength level of the material increases,and the decrease is more obvious;the peak strain shows an upward trend.When the age and the amount of different fibers are constant,the seawater concentration increases.The strength of the C30 series specimens decreases,and the strength of the specimens with three times the seawater concentration decreases less.The peak strain of 1-time seawater concentration test specimens decreased,and the 3-fold seawater concentration increased;C50 series specimens reached 180 days of age,the strength showed a downward trend,and the peak strain showed an upward trend.(3)The change in seawater concentration will have a more obvious impact on the stress-strain curve of the C30 strength grade test specimens in the short-age period,and it will have a smaller effect on the high-strength grade and long-age specimens.slow.Increasing the concentration of seawater will increase the surface adhesion of the fibers and increase the peak stress and peak stress of the stress-strain curve of the specimen.(4)It has been verified that the stress-strain curves of seawater and sea-sandcement-based composites at different ages are in line with the Zhenhai model;an increase in seawater concentration will reduce the ductility coefficient of the specimen,and the incorporation of PVA fibers will increase the specimen’s ductility coefficient.The interaction has different degrees of influence on the ductility coefficient of the test piece.