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  3. The effect of stabilization with lime and steelmaking slag of Isfahan iron smelter (BOS) on the durability of clay soil and clay contaminated with chemical substances

The effect of stabilization with lime and steelmaking slag of Isfahan iron smelter (BOS) on the durability of clay soil and clay contaminated with chemical substances

Number of pages: 187 File Format: word File Code: 31459
Year: 2013 University Degree: Master's degree Category: Civil Engineering
Tags/Keywords: Clay contaminated with chemicals - Contaminated clay - Durability of clay soil - Fine-grained clay soils - Iron smelting steelmaking slag - Soil and foundation mechanics - Soil stabilization - Stabilization of clay with lime - Stabilization with lime - steel making
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  • Summary of The effect of stabilization with lime and steelmaking slag of Isfahan iron smelter (BOS) on the durability of clay soil and clay contaminated with chemical substances

    Dissertation for Master's Degree in Civil Engineering, Soil and Soil Mechanics

    Abstract:

    Clayey soils have always caused problems in construction projects. One of the ways to improve the properties of problematic clay soils is to use lime to stabilize the soil, if the soil contains sulfate ions or the stabilized soil is exposed to sulfated water. Therefore, the presence of lime not only reduces the swelling of the stabilized layer, but also causes the opposite result and increases the swelling. This phenomenon is due to the chemical reactions between clay, lime and sulfate minerals, which lead to the formation of ettringite and tamasite minerals, and these minerals swell greatly by absorbing water. Recently, new chemical compounds have been used to stabilize clay soils, among which the use of steelmaking slag (BOS) is considered a new method to increase the strength of clay. In cold regions, the depth of freezing may reach the soil of the road bed layer, which ultimately leads to a decrease in the strength and bearing capacity of the soil due to the increase in moisture caused by the melting of ice. and contaminated with chemicals (sodium sulfate) has been investigated using uniaxial tests. The soil used in this research is kaolinite clay mixed with different percentages of moisture and subjected to durability tests after a 28-day curing period at 35°C 400 uniaxial samples were made for durability tests. It should be noted that in the wet and dry tests, the samples were immersed in water together with the mold. Also, the results indicated a greater resistance drop in freezing and thawing cycles compared to wet and drying cycles. The results of the durability tests showed that, compared to the soil contaminated with magnesium sulfate and the uncontaminated soil, sodium sulfate caused a greater loss of resistance. In general, little research has been done on the use of BOS in the stabilization of clay soils, since slag is considered a waste material in nature, so the results of this research can be of particular importance in the use of these waste materials from the economic point of view and environmental aspects.

    Key words: Clay, stabilization, lime, slag, sodium and magnesium sulfate, freezing and thawing, wetting and drying

    Chapter One

    Introduction

    1-1- General

    Clay soils are always in the group of problematic soils in terms of bearing capacity and settlement, and usually the structures that are built on this type Soils are built, special arrangements should be considered for them. In general, various methods have been proposed to improve the properties of these soils, one of these methods to improve these soils, in order to increase their bearing capacity and reduce their swelling, is the stabilization method. Considering the extent of fine-grained soils and the necessity of implementing many projects on such soils, the importance of stabilizing fine-grained soils, especially clay soils, becomes clear. Soil stabilization is used to improve the engineering properties of poor soils in the construction of civil engineering structures such as roads, airports, embankments, dams, and shallow foundations. Since the rapid growth of the industry has led to the production of large amounts of waste materials, most of these materials have no important use and cause environmental problems. In some cases, these waste materials have a high potential and can be useful as a raw material in cement manufacturing or other industries. Using waste materials not only reduces environmental problems; It also helps to preserve natural resources such as lime and aggregate. Steelmaking slag has favorable mechanical properties as a granular material, including good erosion resistance and good load-bearing capacity. Slag is used as granular materials in embankments, dirt shoulders of highways, asphalt pavements, highways and hydraulic structures. Swelling of clay soils is one of the important topics that is of interest to many researchers.Swelling in clay can occur for various reasons, one of which is the damaging effect of sulfate in lime-stabilized soil. Replacing lime with slag reduces the amount of free lime and decreases the pH value. Therefore, by increasing the ratio of slag to lime, even in high concentrations of sulfate, the swelling decreases. In cold areas, soils are exposed to freezing and thawing cycles. This cycle of freezing and thawing creates important changes on geotechnical properties. Fine-grained soils undergo changes in volume, strength and compressibility, density, amount of unfrozen water and bearing capacity in the microstructure under the influence of freezing and thawing cycle. Damage caused by freezing and thawing is one of the basic problems for fine-grained soils. Strength and durability are reduced by freeze-thaw cycles. Cracks and fissures are the most common damage caused by freezing and thawing. Therefore, the swelling caused by frost and the swelling caused by the presence of sulfate in fine-grained soils stabilized with lime is considered an important issue in construction projects, and the need for more research in this field is felt in construction projects. Problematic is the use of lime to stabilize the soil, if the soil contains sulfate ions or the stabilized soil is exposed to sulfated water, the presence of lime not only reduces the swelling of the stabilized layer, but also gives the opposite result and causes the swelling to increase. This phenomenon is due to chemical reactions between clay, lime and sulfate minerals, which lead to the formation of ettringite and tamasite minerals, and these minerals swell greatly by absorbing water. Recently, new chemical compounds have been used to stabilize clay soils, among which the use of steelmaking slag (BOS [1]) is considered a new method to increase the strength of clay, since soils are composed of grains and clay minerals, they have problems with the phenomenon of freezing and thawing and consecutive wetting and drying, and in cold regions, the depth of freezing may reach the soil layer of the roads, which eventually It leads to a decrease in the strength and bearing capacity of the soil due to the increase in moisture caused by the melting of ice. In this research, the effect of Isfahan iron smelting steel slag on the durability of clay, in two cases without contamination and contaminated with chemical substances (sodium and magnesium sulfate), has been investigated with the help of a uniaxial test. (in improving soil properties) can be of particular importance from the point of view of economics and environmental aspects. This dissertation is a continuation of the previous dissertations of the Faculty of Engineering of Bualesina by Akrami (1385), Naderi (1388), Nejati (1389) and Safa (1392). Dissertation

    The chapters in this thesis are as follows:

    Chapter One: Introduction

    Chapter Two: Stabilization of clay with lime and steelmaking slag and the effect of sulfate on clay stabilized with lime

    In this chapter, after the general introduction of clay, the effect of lime and slag on soil stabilization is investigated. Then, the effect of sulfate on the strength and durability of clay has been investigated. .

    Chapter three: Durability of soil against freezing and thawing and wetting and drying

    In this chapter, the effect of cycles of freezing and thawing and wetting and drying on the strength and durability of soil is investigated.

    Chapter four: Materials and test methods

    In this chapter of the thesis, the stages and process of sampling and related tests are described.

    Chapter five: Results Experiments and analysis of results

    In this chapter, the graphs obtained from the results of the experiments are first presented, then the results are analyzed.

    Sixth chapter: conclusions and suggestions

    In the sixth chapter, the general results are summarized and also the necessary suggestions to continue the path of this research and work in the following fields are given.

    List of references

    At the end, the list of references used in this thesis. has been provided.

  • Contents & References of The effect of stabilization with lime and steelmaking slag of Isfahan iron smelter (BOS) on the durability of clay soil and clay contaminated with chemical substances

    List:

    Chapter One: Introduction

    3.. 1-1- Generalities

    5.. 1-2- Objectives of the thesis

    6. 1-3- Introduction of thesis chapters

    Chapter two: stabilization of clay with lime and steelmaking slag and the effect of sulfate on clay stabilized with lime

    9.. 2-1- Introduction

    11.. 2-2- Clay minerals

    11. 2-2-1- The composition and structure of clay minerals

    13.. 2-2-2-Kaolinite

    14.. 2-2-3- Illite

    15. 2-2-4- Montmorillonite

    16. 2-3- Characteristics of clay minerals

    16. CEC2-3-1- Cation exchange capacity (

    16.. 2-4- Soil stabilization

    17.. 2-5- Stabilization objectives

    18. 2-6- Soil stabilization with lime

    23. 2-6-1- Soils suitable for stabilization with lime

    24. 2-6-2- Characteristics of soil stabilized with lime Lime compared to unstabilized soil

    2-6-3- Determination of suitable lime

    2-6-3-Use of test

    2-6-3- Use of unconfined compressive strength 28.. pH2-3-5 method. 2-6-4- chemical reactions between soil and lime. 2-6-4- ion exchange. 2-6-4- reaction Carbonation

    32. Effect of lime on soil characteristics

    34. Effect of lime on electrical conductivity

    35. Effect of lime on soil permeability

    2-6-5-4- The effect of lime on Etterberg limits

    36. 2-6-5-5- The effect of lime on dry weight

    37. 2-6-5-6- The effect of lime on soil resistance

    38. 2-7- An overview of the conducted research

    43. 2-8- The effect of sulfate on the reactions of soil and lime

    43.. 2-8-1- Introduction

    53. 2-8-2- The effect of sulfate on Etterberg limits 55. 2-8-3- The effect of sulfate on compression characteristics 57. 2-8-4- Examining the effect of sulfates on stabilized soils

    60. 2-9- Swelling caused by sulfate

    62.. 2-10- Etteringite

    63. 2-10-1- Swelling mechanism caused by ettringite

    64. 2-11- Methods of reducing the adverse effects of sulfates

    65. 2-11-1- The two-step method of mixing soil and lime

    67. 2-11-2- Implementation method

    67. 2-11-3- Use of stabilizers without calcium

    68. 2-11-4- Using geotextile - geogrid

    68. 2-11-5- Replacement with iron smelting furnace slag

    71. 2-12- Summary and conclusion

    Chapter three: Durability of soil against freezing and thawing and wetness and drying

    75. 3-1- Swelling due to frost

    76. 2-3- The negative effects of frost on road paving

    76. 3-3- Basic factors for swelling of the pavement due to frost

    76. 3-4- Solutions to prevent frost

    77. 5-3- Sensitive soils against freezing

    80. 3-6- Review of past studies

    96. 3-8- Summary and conclusion

    Chapter four: materials and test methods

    99.. 4-1- Introduction

    100. 4-2- Materials used in research

    100. 4-3- Granulation test

    101. 4-3-1- Granulation of kaolinite

    101. 4-4- Experiment to determine soil moisture percentage

    101. (Gs) 4-5- Density determination test

    102. 4-6- mental and dough limit test

    102. 4-7- Unconfined compressive strength test (uniaxial)

    104.. 4-7-1- Sample dimensions

    104. 4-7-2- Preparing and making samples

    104. 4-7-2-1- Preparation of soil contaminated with chemicals (sodium and magnesium sulfate)

    106. 4-7-2-2- Making samples for uniaxial testing

    108. 4-7-3- Samples used in unconfined compressive strength test

    109. 4-8- Freezing and thawing test

    111. 4-9- Wetting and drying test

    112. 4-10- Composition of tested samples

    114.. 4-11- Summary

    Chapter five: Test results and analysis of results

    117.. 5-1- Introduction

    118. 2-5- The results of preliminary clay tests

    118. 5-2-1- Granulation of kaolinite clay

    118. 5-2-2- Clay engineering properties

    119. 5-3- Mineralogy of consumables

    119. 5-3-1- kaolinite clay

    119.. 5-3-2- lime

    120.. 5-3-3- slag

    120.5-4- Combination of tested samples

    122. 5-5- Unconfined compressive strength test results

    122. 5-6- The results of the tests after applying freezing and thawing cycles

    122. 5-6-1- Soil without pollution

    127. 5-6-2- Soil contaminated with sodium sulfate

    130. 5-6-3- soil contaminated with magnesium sulfate

    133. 5-7- Unrestricted compressive strength after applying wet and dry cycles

    133. 5-7-1- Unpolluted soil

    136. 5-7-2- Soil contaminated with sodium sulfate

    140. 5-7-3- Soil contaminated with magnesium sulfate

    143. 8-5- Comparison of durability tests due to contamination with sodium and magnesium sulfate

    143. 5-8-1- Comparison of different states of freezing and thawing

    145. 5-8-2- Comparison of different states and drying

    147. (DI) 5-9- Durability parameter comparison

    152. 10-5- Comparison of the modulus of elasticity in contaminated soil and uncontaminated soil under the influence of durability tests 155. (SIR) 5-11- Comparison of soil resistance improvement ratio

    156. 5-12- Summary and conclusion

    Sixth chapter: conclusion and suggestions

    160. 6-1- Introduction

    160. 6-2- Results

    161. 6-3- Suggestions

    165. References

    Source:

    Scrochi, A. M. (1387), Soil Mechanics Laboratory, second edition, Academic Books Publishing.

    Ashroder, W. L. and Dickinson, S. E. (1381), Soils in Executive Plans, translated by Orumieh, A., first edition, Tarbiat Modares University Scientific Publication Office.

    Akarmi, A. (2007), study of clay stabilized with lime and furnace slag and the effect of sulfate on it, master's thesis, Bou Alisina University.

    Bakhtiari, A. (2017), The effect of silica fume on the durability of clay stabilized with lime in the vicinity of sulfate, Master's thesis, Bou Alisina University.

    Bahnia, K. and Tabatabai, A. M. (1384), Soil Mechanics, 11th edition, Publishing and Printing Institute of Tehran University, 457 p.

    Bandezadeh, A. (2017), Investigating the time factor and the percentage of lime and fly ash mixture on the physical and mechanical properties of fine-grained soil, Imran Modares scientific-research journal, 11th volume, number 3, p. 91-98.

    Transportation Research Institute (2008), guide for stabilization of embankment layers and road paving, Tehran, second edition, Ministry of Roads and Transport, 223 pages.

    Jasmani, M., Memarian, H. and Jamshidi, M. (2007), Investigating the geotechnical characteristics of Miqan desert soil in order to improve and stabilize it, Journal of Engineering Geology Society, Volume 1, Number 1, pp. 23-34.

    Jahanshahi, M. (1379), stabilization of chalky soils with lime and two-stage mixing method to prevent swelling of these soils, Master's thesis, Iran University of Science and Technology.

    Hami, A. (1382), building materials, 14th edition, Tehran University Press, 302 p.

    Das, B. M. (1373), Advanced Soil Mechanics, translated by Yazdchi, M., first edition, Mihan, 653 pp.

    Das, B. M. (1384), Principles of Soil Engineering, Volume I - Soil Mechanics, translated by Salehzadeh, H., 7th edition, Iran University of Science and Technology Publishing Center, 460 pages.

    Das, B. M. (1383), Principles of Geotechnical Engineering, Volume II - Foundation Engineering, translated by Tahoni, Sh., 8th edition, Pars Ain Publishing House, 992 pages.

    Dariae, M. and Kashfipour, S. M. (2009), investigation of changes in the axial strength of clay improved with lime by the addition of windy sand, the second seminar on geotechnical problems of drainage irrigation networks, May 2019, Technical and Engineering Research Institute of the Ministry of Agricultural Jihad, pp. 230-239.

    Technical Standards and Criteria Development Office (1382), Guidelines for Stabilization of Embankment Layers and Road Paving (Publication 268), Tehran, First Edition, Country Management and Planning Organization, Deputy for Support Affairs, Center for Scientific Documents and Publications, 92 p.

    Technical Standards and Standards Development Office (1382), Road Technical and General Specifications (Publication 101), First Revision, Edited Second, Tehran, Country Management and Planning Organization, Deputy for Support Affairs, Center for Scientific Documents and Publications, 754 p.

    Office for Compilation of Technical Standards and Criteria (1390), Regulations for Asphalt Paving of Iranian Roads, (Publication 234)., Tehran, First Revision, Country Management and Planning Organization, Deputy for Support Affairs, Center for Scientific Documents and Publications, 279 p.

    Roshanamid, H. (2006), The effect of silica fume on the soil stabilized with lime in the vicinity of sulfate, Master's thesis, Bou Alisina University.

    Salari, M.

The effect of stabilization with lime and steelmaking slag of Isfahan iron smelter (BOS) on the durability of clay soil and clay contaminated with chemical substances
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