Study On The Mechanics And Durability Of Desert Sand-Graphene Oxide Cementitious Composites

The contradiction between supply and demand of construction sand in Xinjiang is increasingly prominent,and the desert sand is abundant,so it is imperative to carry out the research on the desert sand cement-based materials in this area.With the development of nanotechnology,many scholars have found that nano materials nanometer scale can come from "the lack of product defects,but the application of nanometer materials to study in the desert sand is very few,this paper USES graphene oxide nanomaterials(GO)to improve the desert sand cement base material workability and mechanical properties,freezing-thawing resisting performance,sodium sulfate erosion resistance a systematic research in three aspects.At the same time,the mechanism was studied by means of microscopic observation technique and macroscopic detection method.The main research work is as follows:1.Workability and mechanical properties: through orthogonal test,the influence trend of GO,desert sand substitution rate,water-cement ratio and colloid-sand ratio on the compressive strength,flexural strength and consistency of desert sand-go cement matrix composites for 28 days was analyzed.On the basis of orthogonal test,the influence of desert sand substitution rate and GO content on the compressive strength and flexural strength of composite materials of 7d and 28 d was further revealed.The results show that the mechanical strength decreases with the increase of GO content;With the increase of desert sand replacement rate,the bending and compressive strength of go-desert sand mortar test block increased first and then decreased;However,when the replacement rate of desert sand is 100%,the strength of go-whole desert sand cement-based material with the content of 0.03% increases the most,and the compressive and flexural strength of 28 d can reach the strength of standard sand test block.In terms of working performance,when the GO content increased from 0.01wt% to 0.06wt%,the trend of cement slurry viscosity and thickening was obvious,the water demand increased,and the workability became worse.2.Research on freeze-thaw resistance: through mass loss rate and dynamic elastic modulus loss rate,the macroscopic performance of different GO contents in improving freeze-thaw resistance cycle test of desert sand cement based materials was analyzed and the products in each group were analyzed by SEM;The test block porosity was analyzed by mercury injection method;XRD was used to analyze the types of hydration products;TG curve was used to measure the content of hydration products.Adsorption test was conducted to illustrate the adsorption effect of GO on cement and desert sand particles;A selective solvent was used to verify whether the desert sand was reactive.The results show that when the cement content of GO is 0.04wt%-0.0.6wt%,it can improve the freeze-thaw resistance of desert sand cement based materials;Significantly increase the percentage of less harmful and harmless holes;Can promote the progress of hydration without affecting the type of hydration products;The content of hydration products is relatively high and the mechanical strength is large.The absorbency of cement is strong and that of desert sand is weak but stable;The difference in residual amounts indicates that desert sand is involved in the reaction.3.Research on sulfate resistance: the influence of different GO contents on the macroscopic properties of desert sand cement-based materials was determined by the expansion rate and corrosion resistance coefficient;The invasion depth and invasion amount of sulfate ions were determined by ultraviolet spectrophotometry;XRD and SEM were used to analyze the hydration products.The results showed that the GO006 group with GO content of 0.06wt% in cement had the best resistance to sulfate erosion;On the whole,the amount of sulfate ion invasion and curing was the least;The amount of ettringite and gypsum produced was also lower than that of samples without GO.GO improve desert sand mechanism of freezing-thawing resisting performance of cement base material is: GO adsorption desert sand and cement base material so as to optimize the interface strength,improve the whole block,the compressive strength,improve the porosity,on the other hand epitaxial layer GO across or out of the hydration area,closed pore space,increase the porosity of tortuosity,formationpermeability bottlenecks,reduce through the pore.Both of them work together to repair the original defect of poor freeze-thaw resistance of desert sand cement based materials.GO to improve the desert sand cement base material for the mechanism of sodium sulfate erosion resistance: GO besides can improve the hydration process,to reduce the harmful holes,porosity and change the pore morphology and connectivity,increase hole sinuosity and pore length also can form protective mechanism of large area,makes the sodium sulfate erosion path is blocked,formation of ettringite,gypsum rate greatly reduced.Moreover,when the material begins to expand due to erosion,GO can produce a tensile effect to hinder the extension and development of cracks.