Research On Engineering Geological Characteristics And Suitability Of Aggregate Replacement Of Desert Sand In The Border Area Of Shaanxi,Inner Mongolia And Ningxia

The border area of Shaanxi,Inner Mongolia and Ningxia is an important energy and chemical construction base in the country at this stage.With the increase of engineering construction year by year,the amount of concrete materials and engineering sand has also increased sharply.However,the sand resources for construction and mining in this region are seriously scarce,exploring the desert sand in this area and preparing concrete as an aggregate has significant engineering application value for alleviating the shortage of sand in this area.The paper Based on the advantages of abundant desert sand resources in the junction area of Shaanxi,Inner Mongolia and Ningxia,this paper takes the desert sands of the Kubuqi Desert,the Mu Us Sandy Land and the Badain Jaran Desert as the research objects,through field sampling and a series of indoor tests,etc.and deeply studies the occurrence of three kinds of desert sands.Based on the conditions and its engineering geological characteristics,the engineering suitability of desert sand to replace fine aggregate in concrete is discussed,and the conclusion is drawn that desert sand can replace fine aggregate to prepare mortar.The main research results are as follows::(1)The grain size distribution of Kubuqi and Mu Us sand is similar,and the proportion of fine sand and medium sand is the largest,while the Badain Jaran Desert sand is composed of extremely fine sand and fine sand.Sand and Kubuqi sand are relatively small;the chemical elements of the three desert sands are similar,mainly SiO2,Al2O3,CaO,Fe2O3,and element enrichment and depletion have occurred to different degrees,indicating that the three desert sands have undergone a long-term After weathering and transport redeposition,most of the weathering leaching and enrichment occurred;(2)The apparent density and bulk density of desert sand and river sand are basically the same,the mud content is much lower than that required for construction sand,the particle size is smaller and basically concentrated between 0.1～1 mm,and the overall shape is round or nearly round,and the content of SiO2,Al2O3 and CaO in desert sand accounts for more than 80%of the overall content,which has the potential hydration activity capacity and is conducive to the hydration reaction of cement at a later stage.(3)Desert sand could replace fine aggregate in the preparation of mortar,the replacement rate of desert sand should not exceed 40%,the early strength characteristics are obvious,with the increase in the replacement rate of desert sand,the strength shows a trend of first increasing and then decreasing,the mechanical properties and work performance of mortar at 30%replacement rate is the best.(4)With Wuhua Expressway’s Masongliang Tunnel as the test section,the desert sand shotcrete fully meets the design requirements and even has a high strength surplus,the tunnel support effect is better and and has remarkable economicbenefits.This research can provide a basic research basis for the preparation of concrete from desert sand as aggregate.It is of great practical significance and practical value to applying it in practical projects has great practical significance for promoting the global energy transformation and the basic engineering construction of countries in the desert areas along the "Belt and Road".