Study On Long-term Performance Ofair-bubble Mixed Light Soil

As a new type of filling material,air bubble mixed lightweight soil has been used more and more widely on roads in cold areas in recent years.However,due to the harsh climatic environment in these areas,under the action of loads and various environmental factors,the structural function may be affected due to insufficient long-term performance.Therefore,it is necessary to have a full understanding and understanding of the long-term performance of air-bubble mixed lightweight soil in order to effectively eliminate hidden dangers in construction projects.At present,there are relatively few studies on the long-term performance of air-bubble mixed light soil at home and abroad,so it is necessary to study the long-term performance.In this paper,the physical and mechanical properties of air-bubble mixed lightweight soil are studied by the method of indoor test,and frost resistance and drying shrinkage tests are carried out.The density grade,initial moisture content and the frost resistance of the air-bubble mixed light soil are discussed.The law of influence and improvement mechanism.Mainly get the following conclusions :1.Study the change law and correlation between density,foam content,age and compressive strength.The study found that the wet density and dry density of the air-blown mixed lightweight soil are basically linearly negatively correlated with the foam content.With the increase of the foam content,the volumetric water absorption rate of the air-blown mixed lightweight soil increases,and the compressive strength decreases.The strength of the first 3 days has the fastest growth,followed by 3-7 days,and the slowest growth in 7-28 days.On the 7th day,the air-blended mixed light soil of each bulk density can almost reach about 75% of the 28-day strength.2.For air bubble mixed light soils of different bulk density grades,the higher the density grade,the smaller the strength loss and the better the frost resistance.Because the test block participating in the freeze-thaw cycle initially contains water,and the surface of the test block does not peel off and corners,the mass loss rate cannot truly reflect the mass loss.3.The effect of initial moisture content on the frost resistance of air-bubble mixed light soil was studied.Studies have shown that under the same density level,the direct freezing and thawing of the air-bubble mixed light soil test block with unsaturated water after reaching the curing age is smaller than that of freezing and thawing after 3days of saturation.It shows that the higher the initial moisture content of the air bubble mixed light soil,the worse the frost resistance.4.The air-bubble mixed lightweight soil is sealed with different waterproof materials for freeze-thaw cycle tests.Studies have shown that plastic film sealed test blocks have the best frost resistance,and the frost resistance of emulsified asphalt and water glass waterproofing materials is better than that of cement paste,indicating that in terms of the effect of improving the frost resistance of air bubble mixed light soil,flexibility The frost resistance of waterproof materials is better than rigid waterproof materials.5.Study the relationship between age,shrinkage and moisture content.Studies have shown that under the same density level,the longer the age,the greater the drying shrinkage value of the air-blended mixed lightweight soil,and the lower the moisture content.The higher the density level,the lower the moisture content,the smaller the drying shrinkage value,and the longer it takes for the drying shrinkage value to stabilize.The drying shrinkage value of the air-bubble mixed lightweight soil shows a stepwise change with the extension of the drying time: in the first stage,the moisture content of the specimen is higher,and the moisture loss will come from relatively large pores,which will not cause the specimen to be noticeable.In the second stage,when the moisture content of the test piece is lower than 25%,the dry shrinkage of the test piece begins to increase rapidly;in the third stage,the dry shrinkage value of the test piece increases slowly and tends to stabilize after the setting period is reached.