| FCB has the properties of light weight,adjustable strength and thermal insulation,and has been widely promoted and applied in recent years.In particular,it has made considerable progress in the treatment of highway subgrade.In this paper,the strength and durability of Bulle mixed lightweight soils in subgrade treatment were studied through laboratory tests.The following conclusions were obtained:1.The variation regularity and the mechanism of physical properties such as density,water absorption,electrical resistivity and thermal condu ctivity of bubble-mixed lightweight soil were studied.(1)The density of bubble-mixed lightweight soil is affected by the stirring time,stirring speed,and bubble content.In the mixing process of air Foamed cement banking,the mixing time should not be too long,too long will produce defoaming phenomenon and bubble burst;stirring speed should not be too large,the speed is too large to make the foam directly rupture.Bubble content is the main factor influencing the density of light soil.The more the bubble content is,the smaller the density is.(2)Soaking time and bubble content have influence on the water abs orption performance of light soil.The longer the soaking time is,the long er the soaking time is,the greater the density is,and the more the water is absorbed,the more water-absorbing performance of bubble-mixed light s oil becomes larger with the increase of the amount of bubbles.(3)The bubble content and slag content will affect the resistivity and thermal conductivity of light soil.With the increase of slag content,the r esistivity of light soil shows an increasing trend,and it has a certain linear correlation;with the increase of air bubble content,the resistivity of light soil increases gradually;with the increase of air bubble content,the light ness increases.The thermal conductivity of soil shows a rapid decline,bu t with the increase of slag content,the thermal conductivity has a tendenc y to increase,but the change is small.2.The influencing factors of the unconfined compressive strength of air-bubble blended lightweight soil were studied and analyzed,and the mathematical relationship between compressive strength and its basic physical properties was established.(1)The bubble content,curing conditions,slag content,and fiber len gth and dosage all affect the compressive strength of lightweight soil.The strength of air-Foamed cement banking decreases with the increase of th e incorporation rate of air bubbles;the strength of light soils maintained i n water is higher than that of light soils under standard conservation envir onment;in the same conservation environment,the amount of slag Incorp oration can increase the strength of light soil.The unconfined compressiv e strength of light soil increases with the increase of basalt fiber content.The longer the fiber length,the higher the strength of light soil and the gr eater the increase rate.(2)Dry density is the main factor affecting the strength.It meets a ce rtain functional relationship with the strength.As the dry density increase s,the unconfined compressive strength of light soil increases gradually;T he unconfined compressive strength and the resistivity of the unconfined compressive stress are generally nonlinearly decreasing,and the strength of the light soil decreases with the increase of the resistivity,while the unconfined compressive strength and thermal conductivity of the light soil b ased on the bubble content are reduced.The coefficients generally assum e a nonlinear increasing relationship,and the light soil strength increases with the increase of resistivity.3.The strength durability of air-Foamed cement bankings in different salt solutions was studied,and the durability mechanism was revealed by XRD analysis.(1)When the light soil is cured in the sodium salt solution,sulfate io ns enter the pores to generate intumescent substances such as gypsum and ettringite.The existence of bubbles makes it possible to release part of th e expansion force by squeezing holes.It has played a role in delaying dest ruction and thus reducing damage.(2)Light soil in the maintenance of sodium chloride solution will pr oduce hydration calcium chloroaluminate,hydration calcium chloroalumi nate has a certain degree of expansion,played a role in filling the pores,i mprove the strength of the matrix,thereby enhancing the light Soil strengt h.(3)In the maintenance of compound salt solution,the strength of lig ht soil will be improved.This is because when two kinds of ions coexist,chloride ions can diffuse into the matrix through rapid diffusion and react with calcium hydroxide to generate hydrated chloroaluminate.Calcium a nd Friedel salt,etc.,make it possible to generate a proper amount of ettrin gite to play a co MPact role and increase strength. |
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