Research On The Effect Of Fiber/Admixture On The Mechanical Properties Of Desert Aeolian Sand Cement-based Materials

Cement-based material is a widely used building material,but it also has shortcomings such as low flexural strength,high brittleness,and poor toughness.The addition of mineral admixtures and fibers to cement-based materials is an important means recognized in engineering applications to improve the above-mentioned shortcomings of cement-based materials.They can well improve the mechanical properties,durability and working performance of cement-based materials..The sand-retaining measures of concrete structures require a large amount of foreign sand and gravel building materials,and the transportation cost is high,which leads to the high cost of the concrete material structure,which is not conducive to popularization and use.Taking into account that there are abundant,cheap and easily accessible desert sand materials near Xinjiang and other western routes,if desert sand can be used as the main aggregate,instead of sand and stone aggregates in ordinary concrete,new sand-resisting,sand-fixing and anti-sanding materials can be prepared.Sand cement-based materials will have important practical engineering application value.Desert sand is silt fine sand.Therefore,to prepare new sand-fixing materials with it as the main building material,it is necessary to carry out the particle size analysis of desert sand,desert sand density,mud content,porosity and other basic properties of materials.Considering the need to use a large amount of desert sand,in order to improve its compressive strength and flexural strength,it is necessary to conduct theoretical and experimental research on mineral admixtures and fiber mechanical properties.Therefore,this article starts from the material’s flexural and compressive properties,and mainly focuses on fly ash,silica fume,desulfurized gypsum and fiber.The mechanical properties of the material are studied by changing the content of each mineral admixture,fiber content and fiber length.The main content and experimental conclusions are as follows:(1)Based on the orthogonal test method,the mix proportion of desert aeolian sand cement-based materials is optimized,and the influence of various factors on the mechanical properties of the materials is further studied by single factor test method.Taking the flexural strength of 28 days as the basis,the optimized mix proportion is as follows: fly ash content is 5%,silica fume content is 0%,desulfurization gypsum content is 5%,lime content is 3%,redispersible When the content of emulsion powder is 1% and the compressive strength of 28 d age is taken as the basis,the optimal mix proportion is as follows: the content of fly ash is 5%,the content of silica fume is 20%,the content of desulfurized gypsum is 0%,the content of lime is 3%,and the content of redispersible emulsion powder is 0%.The results of single factor test show that the content of fly ash in desert aeolian sand cement-based materials should not be more than12%,and the content of silica fume is 6% The results show that the mechanical properties of the material are the best,the optimal content of desulfurization gypsum is 2%,and the addition of silicon powder has the best effect on improving the mechanical properties of the material.(2)The effects of fiber content,fiber length and anti crack mortar powder content on the mechanical properties of desert aeolian sand cement-based materials were studied.The ratio of fiber in the material was determined by the index of flexural strength and compressive strength.When the fiber content was 0.5%,the fiber length was 19 mm and the anti crack mortar powder content was 0.3%,the flexural strength and compressive strength of the material were significantly improved compared with the reference group.(3)A single factor experiment was designed to study the effects of polypropylene fiber content and curing methods on the compressive strength and flexural strength of desert aeolian sand cement-based materials at the age of 28 d,45d,60 d and 90 d.The results show that the polypropylene fiber content has no good effect on the compressive strength of desert aeolian sand cement-based materials,but the curing methods have a great influence on the flexural and compressive properties.