| The damage to natural environment and infraction of ambient medium toengineering construction are increasingly obvious with the rapid development ofindustrialization and fundamental construction. Economic losses caused by corrosion canreach 2-4% of gross domestic production. Corrosion was deemed to be the first factor thataffects the durability of the structure. The corrosion of the building foundation tends to beosmotic. If it once be found, the treatment will be more complicated than thesuperstructure and the consequence of corrosion often is destructive. However, theimportance of some geotechnical environment problem has not been regarded, forexample, the corrosion of ground water and soil. There are many aspects problems duringthe researching. For instance, 《Code for investigation of Geotechnical engineering》(GB50021-2001) and 《 Code for anticorrosion design of industrial construction 》(GB50046-95) only consider the evaluation of single factor. Factors considered areinadequate and the limits of corrosion evaluation are unreasonable. Then, how to treat anddeal with the dynamic of composition of water and soil? How to treat the corrosionmechanisms and evaluation of multi-factor? Emphasis was put on groundwater and thesoil in situ was ignored in evaluation of corrosivity. How to treat the unicity of corrosiontesting and evaluation indicators? This thesis aimed to solve these problems. Concrete was a complex material which is heterogeneous,multivariant,multiapertureand polyphase. The concrete corrosion includes the decompose , crystal andcrystal-decompose compound in series. Corrosion of decomposition includes hydratedecomposition as a result of decreasing alkalinity with neutralization between acid andalkalinity, solution loss as a result of calcium salt creation between acid group andcalcium in concrete, substitution of Ca2+ as a result of hydrate interaction between Mg2+and Ca(OH)2 or others, solution loss as a result of Ca(HCO3)2 creation with interactionbetween carbonic acid and Ca2+. Corrosion of crystallization is due to cubical dilatationwith interaction just like SO42-and Ca(OH)2. MgSO4 are of capability of crystallizationand decomposition corrosion. The steel corrosion had two series mechanics that includesthe galvano-chemistry corrosion leaded by charry-acting and the chemistry corrosionleaded by Cl salt & galvano-chemistry synthesis action. The characters of steel & concreteand the mediator condition make defferent effect on the corrosion of reinforced concrete.The nature mediator was complex multicomponent. So generally speaking the corrosionof concrete was complexed, therefore it was one-sided according a hand of density changerate to judgment weather or not effect the concrete corrodibility. The norm assesscorrodiblity sensor-single factor and the limit of the corrosion had irrational. because thecharacter of concrete had not considered. there are many method of concrete antiseptictreatment for example: increase concrete solidity,impermeability;surfacecti proteon;adding germicidal agent;change soil layer and ground base separate and so on. the sameas bar it have select the corrosion-resistant material or non-metal material for replace;setting surfacecti anticorrosive coating;adding inhibitor;cathodic protection;increasingthe surfacecti proteon and so on.In order to assess the item of corrosion evaluation in code, evaluate the corrosivity ofsoil in sity and meet command for study. Handan city was chosed to be example to becarried out the study of corrosivity evaluation which also has typical corrosionenvironment in the thesis. Some new understandings were got and shortage was found incode from the studying.In studying of chemical constitution distribution about groundwater and soil in situ,many materials of ground-water quality was collected in study area. The extract of soilsamples was made an chemical analysis which was get from in situ. Contour chart andstereo-lattice map of component distribution of groundwater and soil in situ & zoningmap of ion conponent and corrosivity were drawn by means of Able Software R2V,MapInfo Professional 7.0SCP,Golden Software Surfer 7.0 and Origin5. Regularities ofdistribution and influencing factor were analyzed about groundwater and soil in situ.Results show that the chemical component distribution of groundwater and soil in situwas very inhomogeneousn which apparently suffered severely artifical pollution.groundwater has many ionics mainly including HCO3-,SO42-,Cl-& Ca2+,Na+,Mg2+,in which the SO42-and Cl-were main corrosive factor, and they were controlled bydistribution of pollutant source and landform & topographical feature. The corrodibility ofCO2 was one of the main factor in groundwater, which distribution depends on interactionof organic and microbe. Study shows that if the low limit of corrosion was put down alittle the effect of evaluation is great to SO42-and Cl-in ground-water. The SO42-and Cl-was the main factors of corrodibility to steel and concrete. The SO42-distribution wascontrolled by pollutant source, landform & relief and soil type. The effect of the soil typewas that soil sample with high content of SO42-was almost silty clay. This paper gives arational explanation. The Cl-distribution coupled with groundwater and surface watermore intimately compared with SO42-, because of the small radii of Cl-and its highpermeability. pH value was the main factor to corrode concrete in the layer with highpermeability. In the longitudinal direction, the max content of SO42-,Cl-and the minvalue of pH have the high frequency in the depth of 1.0 meter which infer that thecorrosive component was typically vertical influent through atmospheric precipitation.The factors that affect the corrosive component distribution of soil in situ are waste waterand air discharged from the industrial factory which also was the main factor, the type ofsoil in situ, relief condition, the radius,type,permeability of ionic and so on. Becausealternative condition was better in vertical direction than in horizon direction the contentof corrosive components is more below in soil than in groundwater in situ.Evaluation was put on corrosivity of groundwater and soil in situ, includingcorrosion of groundwater to concrete,steel, steel structure and corrosion of soil in situ toconcrete and steel, according to《Code for investigation fo Geotechnical engineering》 inthe paper. Results show that complicated characteristics of water and soil distributiondetermine the pattern of corrosive zone which are of many factors,many types and manygrades in coexistence. Corrosion of groundwater is of many types and grades whichdistribution is complicated. These are corrosion to concrete including crystal,decomposeand compound, but the weak crystal erosion is primary. And corrosion of decompose isgeneral in layer with high permeability. Corrosion in middle and weak degree is primaryto steel, and corrosion is in existence in whole range to steel structures, but the middlecorrosion is main. The corrosion of soil in situ to concrete includes weak crystal corrosionand acid decompose in layer with high permeability that changed in different depth.Corrosion of soil to steel is in middle and weak degree, but and the weak corrosion isprimary. Zoning of corrosion is greatly different between w<20% and w≥20% when thewater content is considered which show that the limit is unreasonable in code. Thecorrosion of soil in situ is weaker than that of groundwater in whole. The factors thatinfluenced the corrosion of soil depends not only on the distribution of pollutant ingroundwater, landform and terrain, the permeability of layer but also on the moisturecontent of soil, depth and kinds of ion etc.New understanding is get from by means of studying distribution of corrosivecomponent and evaluation of corrosivity. These include①the influencing pattern ofcorrosive component distribution is put forth in soil and groundwater in situ;②thecoefficient of corrosive capability is set forth;③the mechanism of silty clay with highcorrosivity is result of strong block action of clay and strong leaching of silt;④thedisplaced capability of Cl-is stronger than that of SO42-because the radius of Cl-is smaller;⑤the conclusion breaks the tradition conception that soil in situ without corrosion whichgets from the studying on evaluation of corrosion;⑥the reason why the content ofcorrosive components of soil in situ is lower than that of groundwater is that chemicalcomponent transfers more fastly in vertical direction than horizontal direction;⑦the limitof corrosion is unreasonable when the influence of moisture content is considered in code;⑧the influence to evaluate corrosivity is great if lower limit is adjusted a little in code.In order to consider the dynamic character of ground water and the soil, the systemof corrosive evaluation (ESWEC and ESSEC) is built based on code by means of GIStechnology which can give a dynamic analysis. It solved effectively the dynamic problemtaking into account corrosive component, and carried out chart and data together andlink .In order to solve the unicity problem of detection and evaluating indicator, analysesof mass metering, corrosive ingredient of liquor, X-Ray and sem analyses were adopted incorrosion test. The change rate of mass and component of corrosive solution were adoptedfirstly to evaluate quantitatively corrosivity. In order to improve evaluation method incode,The concept of potential coefficient of corrosion was set up. In order to solve theproblem of corrosion limit and inadequate factors in the code, single factors corrosion testconsidered multi-factor of concrete was carried out. Concrete block with six types ofmixture was created which suffered testing considered single factor in two stage based onfour types and six kinds of Density. We have X-ray with 14 blocks and sem analyses with12 blocks. It is reasonable to use αm andαc to evaluate corrosivity. The model ofrelationship was established between corrosive component and density. The character andmechanism of corrosion are discussed when concrete with different mixing proportion isin Cl-,SO42-,Mg2+ and acidic solution. Corrosion prediction mode was set up in 50years, the change in 50 years can be reckoned, and the factor of prediction is Ca2+ or OH-according to undeposit principle. The thickness of corrosion can be calculated based oncontent of Ca2+ in concrete and change of Ca2+in 50 years. According to protect thicknessof steel, single factor corrosion evaluation scheme was set forth based on six kinds ofmixing proportion, four corrosion factor and six types of density, the limit d50 5mm,10mm, 15mm, 20 mm is the corrosive lower limit of weak, middle, strong, very strongdegree. And comparison was made between that and code in use.In the analysis of the single-rate factors corrosion mechanisms based onconcentrations of corrosion liquid and its change rate, these were found :①the surface oftest block are loose through the corrosion of Cl-, SO42-and acid solution.②films, banhydrates are dissolved into borders out of order in the acid solution, acid solution makesneutralization-decomposition corrosion to concrete, and corrosion boosts up with therising of acidity. The relationship between change rates of component for a limitedpH=3.0 is secondary curve, and the limits may bear upon the impact of the pH value onSi(OH)4 cover-action.③decomposition corrosion takes place due to creation of thedissolved CaCl2,MgCl2 with interaction between Cl-with Ca(OH)2, CaCO3 of concrete inCl-solution, and corrosion boosts up with the increasing concentrations of Cl-, thatconfirmed the viewpoint when solutions are significant concentrations of chlorine salt,Ca(OH)2 may be dissolved quickly……,creates a dissolve out corrosion.④undissolvedgypsum creates with interaction between SO42-with Ca(OH)2,CaCO3 of concrete inSO42-solution, the higher concentrations of SO42-is , the more powerful corrosion is,meanwhile gypsum crystallization objects are more, and the degree of crystallization ishigher. The minimum phenomenon ofαm may bear upon two corrosion phase of salt Eand salt G.⑤the undissolved Mg(OH)2,MgCO3 create with interaction between Mg2+with Ca(OH)2,CaCO3 of concrete in Mg2+ solution, corrosion boosts up with theincreasing concentrations of Mg2+, and the thickness of white powder Mg(OH)2 increaseson the surface of test block, so the extent of crystallization increase. A margin-facecontact Mg(OH)2 makes surface of the body porous and loose.αMg2+ and Mg2+concentration are associated with linear that show the scale of replacement on Mg2+ andCa2+ is identical, and for the 1:1 ratio.αm mostly is negative, that bear upon the porousloose Mg(OH)2 which adsorb combo-water.⑥Ordinary concrete corrosion increase withcorrosion element concentrations rise or intensity levels fall;Because of the very denseaction of spherical particles the Fly-ash advance concrete role in enhancing thepreservation of corrosion, in Cl-solution, the affection is not evidence quality, in Mg2+solution it weaken the preservation of corrosion, if mixed proper Fly-ash in it help toenhance their preservation of corrosion, but excessiveness will weaken its preservation.⑦The rate of increase to corrosive material changes with its initial concentration, whichis due to the enhanced effects of chemical concentration gradient.As a result of comparison between corrosive evaluation in the paper and evaluationmethods in《Code for investigation of geotechnical engineering》and 《Code foranticorrosion design of industrial construction》, these were found that:①Concrete in theinitial pH=2.0 acid liquid, only the corrosion of ordinary C20 concrete is in middle degree,the others is weak. When the initial pH≥3.0, there are no corrosion. But specification ofacid corrosion in code is conservative in this project.②For Cl-solution, all the test blockwith d50<5.0mm are free from corrosion.《Code for investigation of geotechnicalengineering》do not consider directly corrosion of Cl-, the 《Code for anticorrosion designof industrial construction》only consider the corrosivity with concentrations≤10000mg/Land evaluate the corrosivity of solution in middle or weak degree.③For SO42-solution,the ordinary concrete corrosion boost up with SO42-concentrations increasing or concretegrades falling. The preservation of corrosion to concrete with Fly-ash is weaker. Thespecification appraised to ordinary concrete corrode is conservative to the evaluation ofthe project, but is danger to concrete mixed with Fly-ash, thus it is necessary to decreasethe lower limit.④The corrosive effect of Mg2+ solution is very strong, except that theordinary C40 concrete in 2500mg/L solution is strong corrosion, the others are intensecorruption. The specification appraised to Mg2+ solution is all-out danger. It is suggestedto fall greatly the corrosion limits.To explore the corrosion problem of concrete in multi-component composite medium,the orthogonal tests of multi-factor corrosion were carried out based on three indicators,multi-level and three factors. In the orthogonal corrosion testing, the three indicators wereunified with integrated rating law. Through visual and finch analysis, these wereidentified about corrosion factors resulting sequence, the level portfolio of the strongestand weakest corruption factors and significant factors. It was found that there isinteraction in the two complex fluids, in which 'a' group had very strong interaction while'b' group is weaker due to the single factor Mg2+ through Finch analysis. Multi-factorcorrosive evaluation program were proposed based on corrosion thickness and theprinciples were set to corrosion prediction models.In analysis of the multi-factor corrosion mechanisms based on concentration andchange rate of corrosive fluid, we found that: 'a' group: Acid restrained corrosion of Gsalt while accelerated decomposition corrosion. The role of acid was weak with lowerSO42-concentrations, mainly the Cl-corrosive effect. With the lower [Cl-]/[SO42-], thecorrosivity of G salt was gradually increasing. There was strong corrosive interaction inthe complex fluids. 'b' group: corrosion was the role that Mg2+ and Ca(OH)2 and calciumsilicate hydrate and aluminum injection responded and generated Mg(OH)2 and separatedout Ca2+. Porous loose Mg(OH)2 adsorbed bound water and made the quality of the blockincreasing. When the concentration of Mg2+ was lower, Cl-responded to C3A firstlybecause of strong proliferation capacity and restrained the corrosion of Mg2+. Thecorrosion of Mg2+ was associated with its concentration. The cladding of Mg(OH)2restrained the penetration of Mg2+ and reduced the further division and corruption.In general, the thesis reached the anticipated goal. The contents and the results arepioneering in many aspects. Especially some new ideas are put forth on corrosion ofmulti-factor,limit of corrosion evaluation,dynamic evaluation,method and indexes ofevaluation which are valuable to recession of code and engineering practice. This thesis isimportant in effective solving many problems of corrosivity evaluation of ground waterand soil in situ.
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