Study On Basic Mechanical Properties Of PVA-ECC Prepared By Desert Sand

In recent years,as China's environmental problems have become more and more serious,all walks of life have advocated sustainable development.The direction of the development of engineered cementitious composites(ECC)must be environmental protection,energy conservation,and high mechanical performance.In this context,more and more scholars have begun to study the energy saving and high performance of ECC.In the northwest of China,there are rich resources of desert sand.The total area of the desert is about 18%of the country's land area.Although China advocates sustainable development,new deserts are gradually developing every year.Especially in the northwestern region where sandification has become more and more serious.Natural fines are relatively scarce,but they are rich in fine desert sand.For a long time,the ultra-fine sand resources have not been used rationally and actively.The search for new materials to replace the growing lack of natural river sand to formulate concrete that can be applied to the field of construction engineering is the most important thing at present.According to the characteristics of local resources,ECC(PVA-DSECC)is prepared by sand part of desert sand instead of common river sand,and high performance fiber reinforced cement based composite is prepared with PVA fiber as reinforced material.It can not only take local material,but also reduce the damage to the ecological environment.It can also reduce the cause of natural river sand.Therefore,the main contents of this paper are as follows:(1)Through the influence of water-binder ratio,fly ash content,desert sand replacement and content of PVA fiber on compressive strength,flexural strength,splitting tensile strength and consistency of PVA-DSECC by the comprehensive balance method,5-factor and 4-level of orthogonal test was designed,there is a blank factor,using the Sans universal testing machine,mortar consistency tester and flexural testing machine to obtain test data,by analyzing the test data,the following test conclusions are drawn:?The influence of desert sand on PVA-DSECC strength is small.In the case of meeting the PVA-DSECC strength requirement,a higher desert sand content should be used.?Fly ash content is the most important factor affecting PVA-DSECC strength.With the increase of fly ash content,the PVA-DSECC strength first increases and then decreases.When the fly ash content is 40%,The PVA-DSECC strength reaches its maximum value.?The content of PVA fiber has a great influence on the splitting tensile strength and flexural strength of the specimens,but the impact on the compressive strength of the specimens is relatively small.With the increase of PVA fiber content,the resistance of PVA-DSECC increases.Splitting tensile strength and flexural strength are also enhanced.The PVA fiber prevents splitting of the specimens,which is beneficial to enhance the toughness of the test specimens.(2)Through single factor analysis,the experiment was conducted to study the effect of desert sand replacement on the compressive strength,flexural strength and splitting tensile strength of PVA-DSECC,and the replacement of desert sand was determined.The data obtained from the test finally confirmed the optimum mixture ratio of PVA-DSECC in this test,namely:water-binder ratio:0.29;fly ash content:0.4;desert sand content:40%;sand-binder ratio:0.36;PVA fiber content:1.75%.(3)Compressive strength and flexural strength of multiple specimens were tested under the optimal mixture ratio of PVA-DSECC.Through data analysis,the relationship between compressive strength and flexural strength of PVA-DSECC was obtained.