Blenging Fly Ash Compound Cement Soil Mechanical Properties And Durability Research

In this paper, we do experimental research and theory analysis using the InnerMongolia Hetao area silty clay as raw material. This paper concretes new type materials,in order to applied in engineering practice，which has properties of strength and durability,using cement stabilized soil technology principle, through adding different capacity ofdifferent material.The main research work are as follows:In the first place, the paper studies the properties of raw material and solidificationprinciple of cement-soil, through changing proportions of compounding soil-cement andchanging experiment conditions, for studing effect the factors and transformation rules ofunconfined compressive strength of cement-treated soil.In the second place, on the basis of the composition and change rules of unconfinedcompressive strength of cement-treated soil, this paper designs experiment plan toimprove soil properties. Based on ordinary cement-soil, this paper studies how toimprove the fly ash cement and compound cement-soil compressive strength anddurability. Adding agent all the soil weight analysis and error analysis of experiment, thispaper studies influence composition and experimental error of fly ash cement-soil andcomposite cement-soil. According to weight analysis results，this paper tests andoptimizes mix proportion.In the third place, Through different kinds of cement-soil curing differents age, thispaper tests the nature of the infiltration, freeze-thaw cycle and scour, and get the changedrules of test. Combining with the form of the appearance of the earth observation andmicro electron micrograph analysis, the paper researchs the nature of degradationmechanism of cement-soil after freezing and thawing destruction. Due to cement-soilbelong to glue and brittle material, so the permeability and the durability of cement-soiltest has vital significance.In the fourth place，combined water soil curing mechanism，this paper does adetailed observation of characteristic of the cement-soil on macro level，and analyses thedifferent products composition, quantity, form and structure of cement-soil usingscanning electron microscopy (sem). So that we find out the internal cause of the changeof the unconfined compressive strength.In the fifth place, This paper analysis the composite cement-soil improvementeffect from mechanics mechanism, and resurchs the stress of the composite cement-soil strain changes, the change of elastic modulus, by repeatedly loading and unloadingexperiments. this paper establish unconfined compression state of composite cement-soilelastoplastic damage model by calculating injury factor and studing the degradation rule.According to indoor test and the test results in-depth research and analysis, theresults obtained are as follows:Firstly, on the basis of strong alkali excitation fly ash cement-soil, this paper do zheorthogonal test, getting the optimal mixture ratio is: Soil，water，cement，fly ash, calciumhydroxide, sodium hydroxide, surfactant=60.7%：12.3%：10%：7.50%：9%:0.40%:0.10%, getting the unconfined compressive strength of28d is11.04(MPa). The weight ofoptimal mixture ratio’s factor is: the sodium hydroxide, fly ash, calcium hydroxide，surfactant, error was2.62to2.64to2.62to1.27to0.57. Test result of unconfinedcompressive strength is ideal using in practical engineering.Secondly, by adding alkali lime, the unconfined compressive strength of fly ashcement-soil can be greatly improved. As adding15%fly ash for an example, adding limecomposite cement-soil permeability coefficient is1.87×10-8cm/s, is33%permeabilitycoefficient of not adding lime composite cement-soil. This test gets a goodanti-permeability matching: water, cement, fly ash, lime, powder clay=12%：10%：15%：3.75%：59.3%. Because of the fly ash, lime is a common engineering materials, thissolution can be used in engineering. Contrasted with lime fly-ash cement-soil, thepermeability coefficient of composite cement-soil of scheme8increased by45%.Thirdly, this paper gets the conclusion that composite cement-soil is affectted todamage by freeze-thaw cycle test. It is studied that more than30%compressive strengthof composite cement-soil damaged after12times of freeze-thaw cycle; compositecement-soil completely destroyed after20times of freeze-thaw cycle. This paper analysischaracteristics of the composite cement-soil freeze-thaw damaged from the point ofmacroscopic and microscopic.Fourthly, using scanning electron microscope and chemical composition of spectralanalysis, this paper describes the microstructure characteristics of composite cement-soiland fly ash cement-soil and analysis categories and forms of composite cement-soil’smaterial products, on the basis of this, and analysis curing mechanism of compositecement-soil and fly ash cement-soil, and find immanent cause why compressive strengthand seepage resistance performance of composite cement-soil is superior to ordinarycement-soil.Fifth, through the repeated loading unloading test and collection the test data ofunconfined compressive strength, this paper analysis mesoscopic damage mechanism and damage evolution rule and get injury tolerance of composite cement-soil, and establishthe elastoplastic damage model under the condition of uniaxial compression.