Download or read book Stiffness Response of Chemically Stabilized Sulfate Rich Soil Via Resonant Column Testing written by Miftah Semane and published by . This book was released on 2014 with total page 87 pages. Available in PDF, EPUB and Kindle. Book excerpt: Stabilization of expansive soils using lime and cement additives have been used by practitioners over the last few years. However, recent heaving and premature pavement failures in lime and cement-treated subgrades containing sulfates led to questioning the validity of calcium based stabilization. When expansive soils containing sulfates are treated with calcium-based stabilizers, the calcium from the stabilizer reacts with soil sulfates and alumina to form the expansive mineral Ettringite. A series of resonant column (RC) tests (ASTM D 4015-92) was conducted on several chemically stabilized specimens of high-plasticity, sulfate-rich expansive clay from Sherman, Texas. Test results were used to assess the influence of mellowing period on the stiffness properties of stabilized soil. Specimens were tested for different stabilizer, mellowing periods, curing times, and confining pressures, and elapsed times under constant confinement. Two stabilizers, 6% lime and 4% lime + 8% fly ash, were used. Soil stiffness parameters investigated include small-strain shear modulus (G) and small-strain material damping ratio (D). Tests were also conducted at mid- to high-strain levels to study stiffness degradation effects of torsional shearing. 4% lime + 8% fly ash treatment method shows the best results.

Download or read book Performance of Lime and Cement Based Treatments of Sulfate rich Soil Via RC Testing written by Azadeh Asghariastaneh and published by . This book was released on 2017 with total page 83 pages. Available in PDF, EPUB and Kindle. Book excerpt: Chemical treatment of expansive sulfate-rich soils, particularly lime- and cement-based methods, had been rather popular due to their relatively low cost and ready availability. However, over the last few decades, extensively documented pavement failures, mainly caused by excessive heaving and/or shrinkage of lime- and cement-treated subgrades with moderate-to-high sulfate content, have led to thorough investigations to assess the actual feasibility and effectiveness of calcium based stabilizers in sulfate-rich soils. Studies have concluded, with solid experimental evidence, that the calcium present in the chemical stabilizers react with the sulfate and alumina of the treated soil to form Ettringite, an expansive mineral that has detrimental effects on the overall performance of the treated soil. Most of these studies have mainly focused on detrimental effects of lime- and cement-based treatment methods in terms of Atterberg limits, swell-shrink potential, and unconfined compressive strength. The present study is aimed at gaining valuable insight into the effects of lime- and cement-based treatment methods on stiffness of sulfate-rich soils, namely, shear modulus and damping, which are fundamental properties in the analysis and design of pavement infrastructure. To achieve this goal, a thorough series of resonant column (RC) tests was conducted on several chemically stabilized specimens of high-plasticity, sulfate-rich expansive clay from Sherman, Texas. Test results were analyzed to assess the influence of lime- and cement-based stabilizer dosage, curing time, and confining pressure on the shear modulus and damping of the treated soil, including 8%lime + 2% fly ash, 6% lime + 4% fly ash, and 3% cement + 2% fly ash. In general, results show a detrimental effect of all treatment methods on soil stiffness, only rendering 6% lime + 4% fly ash as a potentially viable treatment method with curing time longer than 14 days.

Download or read book Stabilization of High Sulfate Soils written by Nagasreenivasu Talluri and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Stabilization of expansive soils using lime and cement additives have been used by practitioners over the years. However, recent heaving and premature pavement failures in lime and cement-treated subgrades containing sulfates led to questioning the validity of calciumbased stabilization. When expansive soils containing sulfates are treated with calcium-based stabilizers, the calcium from the stabilizer reacts with soil sulfates and alumina to form the expansive mineral Ettringite. Formation and growth of the mineral Ettringite has been reported as the cause of severe heaving in several pavement failures. Under favorable environmental conditions, Ettringite transforms itself into another expansive mineral, Thaumasite. This heaving is termed as 'sulfate-induced heave' in literature. Several theories have been proposed to understand the heaving mechanisms in sulfate bearing soils. Based on the theoretical background, researchers and practitioners have proposed various methods to treat sulfate soils. Applicability of these methods is mostly limited to soils containing sulfate content less than 8,000 ppm. Soils with sulfate content above 8,000 ppm are termed as 'high sulfate' soils, and chemical treatment of such soils is currently not considered. Hence there exists a research need to create better understanding of the heaving phenomenon in soils with higher sulfate contents and develop practical techniques for stabilizing such soils. This research is designed to aid in understanding the heaving phenomenon in soils with sulfate contents above 8,000 ppm and to develop practical techniques to stabilize such soils. Six soils: four high plasticity clays, one low-plasticity clay soil and one high-plasticity silt, with sulfate contents varying from 200 ppm - 44,000 ppm, were considered for this research. Chemical and mineralogical tests were performed on the untreated soils to establish the clay mineral distribution and composition of the soils. Additional Gypsum was added to the soils with sulfate contents below 8,000 ppm so they could be considered as 'high sulfate'. These soils were treated with lime and mellowed for periods of zero, three and seven days. Following the mellowing, the samples were remixed, compacted and subjected to various engineering, mineralogical and chemical tests. The present high-sulfate soils were treated lime stabilization with varying mellowing periods and treated soils after treatment were subjected to the engineering and chemical tests. Tests results were analyzed to understand the effectiveness of mellowing period on the heaving phenomenon of 'high sulfate' soils. Both Ettringite formation and crystal growth have contributed significantly to the overall swell of the treated soils. Swell trends observed in the treated soils at respective mellowing periods were attributed to the variability in sulfate levels and reactive alumina and silica contents. Treated soils at higher mellowing periods showed lesser sulfate induced heaving when sulfate levels are lesser than 30,000 ppm. At higher sulfate levels, the mellowing did not result in effective treatment of soils. It was also observed that compaction void ratios and soil clay mineralogy have a significant impact on the swell behavior of chemically treated high-sulfate soils at different mellowing periods. Hence, mellowing effectiveness is explained using free energy and massvolume approaches. Threshold void ratio framework comprising of natural soil void ratio and sulfate content was developed to predict Ettringite-induced heaving in chemically treated high sulfate soils at different mellowing periods. Another treatment method using lime-fly ash treatment is also studied on two soils and the test results showed that the combined treatment has resulted in lesser soil heaving in these soils. The improvements here are mainly attributed to low amounts of calcium in the combined chemical additive used here. In the final study, the rate of Ettringite formation and growth in the treated soils was indirectly assessed by measuring stiffness properties using the Bender Element tests. Bender Element tests revealed material softening and subsequent stiffness degradation in chemicallytreated high-sulfate soils, and threshold stiffness loss values were established for the treated soils. This non-destructive study assessment can be used to evaluate the Ettringite induced soil heaving in sulfate soils under various chemical treatments.

Download or read book Expansive Soils written by Amer Ali Al-Rawas and published by Taylor & Francis. This book was released on 2006-06-08 with total page 540 pages. Available in PDF, EPUB and Kindle. Book excerpt: Expansive Soils provides the reader with easy and specific access to problems associated with expansive soils, characterisitics and treatment, and evaluation and remediation. Set up with contributions from worlwide expert, this main reference guide is intended for engineers, researchers and senior students working on soil

Download or read book Effect of Fabric and Weathering Intensity on Dynamic Properties of Residual and Saprolitic Soils Via Resonant Column Testing written by Jorge A. Pineda and published by . This book was released on 2014 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt: Chemical weathering processes, such as decomposition and dissolution, are fairly well-understood phenomena as they relate to the formation of residual and saprolitic soils in the tropics. However, the effects that weathering intensity has on the physical characteristics and mechanical properties of weathered soil/rock materials, particularly their dynamic properties, are not yet fully understood. This paper presents the results of an experimental investigation conducted to assess the dynamic response of residual and saprolitic soils derived from a granodiorite rock in the central mountain range of Colombia and how this response relates to the soil microstructure and weathering intensity. Key dynamic properties, namely, shear modulus and material damping, were obtained via a fixed-free resonant column apparatus suitable for shear strain amplitudes ranging from 0.001 % to 0.1 %. Results from a short series of triaxial and oedometer tests substantiated the patterns of weathering intensity observed for each test soil. Soil fabric studies based on scanning electron microscopy observations, mercury intrusion porosimetry tests, and pore space distributions were also performed to identify the most relevant characteristics of the soil skeleton, as determined by the corresponding weathering intensity, that affect the dynamic response of each test soil. The residual soil, as the most altered/weathered material, was found to have a more rigid fabric, and thus greater stiffness, due to the presence of sesquioxides acting as cementing agents. In the saprolitic soil, a less weathered material, the soil fabric was dominated by distinct clay bridges formed between particle aggregations of partially decomposed primary minerals, resulting in less rigidity. The influence of confinement level on the shear modulus was found to be more pronounced in the saprolitic soil, which can be directly attributed to the changes in fabric of uncemented bonds during isotropic loading. Finally, and consistent with these general trends, the material damping of saprolitic soil was observed to be slightly less than that of residual soil, whereas the normalized shear moduli (G/Gmax) degradation curve was more pronounced in residual soil samples beyond a threshold value of shear strain amplitude.

Download or read book Effect of Loading Frequency on Dynamic Properties of Soils Using Resonant Column written by Soheil Moayerian and published by . This book was released on 2012 with total page 112 pages. Available in PDF, EPUB and Kindle. Book excerpt: Dynamic properties of soils (shear stiffness and damping ratio) are critical for the design of structures subjected to vibrations. The dynamic properties of a benchmark standardized laboratory sand (Ottawa silica sand) were evaluated with two different resonant column devices, utilising software with different analytical approaches for the evaluation of soil properties. The dynamic properties (shear modulus and damping ratio) are evaluated as a function of the shear strain level. The results are compared to evaluate the effect of the type of equipment and the form of the data analysis on the measured dynamic properties of the samples. The results are discussed in light of the applicability of the procedures in practice, the ease of the testing methods, and the errors they introduced into analysis and design. In general, the shear wave velocities obtained from the two different devices are in good agreement. However, the damping ratios they give show considerable differences as strains increase. Dynamic properties are typically measured by curve fitting of the transfer function between the excitation and the response using the resonant column device. However, the force function generated by sinusoidal sweep or random noise excitations induce different shear strain levels at different frequencies. Consequently, the shape of the measured transfer function is distorted and differs from the theoretical transfer function for an equivalent single-degree-of-freedom system. The difference between the measured and theoretical transfer functions as well as the bias in the computed dynamic properties becomes more pronounced with the increase in shear strain. This study presents a new methodology for the evaluation of dynamic properties from an equivalent constant-strain transfer function. The soil specimen is excited simultaneously using a sinusoidal excitation (carrier signal) at the required strain level and a small amplitude, narrow band random noise. The strain level induced by the fixed sine is shown to control the resonant frequency of the specimen; whereas the random noise introduces the required frequency bandwidth to determine the transfer function and hence the dynamic properties at a constant strain level. The new methodology also shows a good potential for the evaluation of frequency effects on the dynamic properties of soils in resonant column testing.

Download or read book Geo frontiers 2011 written by and published by . This book was released on 2011 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Dynamic Geotechnical Testing written by M. L. Silver and published by ASTM International. This book was released on 1978 with total page 416 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Deep Mixing Method written by Masaki Kitazume and published by CRC Press. This book was released on 2013-02-21 with total page 436 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Deep Mixing Method (DMM), a deep in-situ soil stabilization technique using cement and/or lime as a stabilizing agent, was developed in Japan and in the Nordic countries independently in the 1970s. Numerous research efforts have been made in these areas investigating properties of treated soil, behavior of DMM improved ground under static and d

Download or read book The Deep Mixing Method written by Coastal Development Institute Tokyo and published by CRC Press. This book was released on 2002-01-01 with total page 148 pages. Available in PDF, EPUB and Kindle. Book excerpt: A growing population and increasing urbanization over the past century have made it difficult to locate suitable ground for siting infrastructures in densely populated areas. The Deep Mixing Method (DMM) was developed and put into practice in Japan in 1975 to cope with the headaches of stability and/or excessive settlement in soft soil areas. This method involves using cement and/or lime as a soil stabilizer, added in-situ to deep soils, and has now been adopted not only in Japan but in the USA and other parts of the world as well. This book presents properties of this treated soil method, its various applications, its design and execution, and accumulated research results over the last twenty-five years.

Download or read book Principles and Practice of Ground Improvement written by Jie Han and published by John Wiley & Sons. This book was released on 2015-06-22 with total page 432 pages. Available in PDF, EPUB and Kindle. Book excerpt: Gain a stronger foundation with optimal ground improvement Before you break ground on a new structure, you need to analyze the structure of the ground. Expert analysis and optimization of the geo-materials on your site can mean the difference between a lasting structure and a school in a sinkhole. Sometimes problematic geology is expected because of the location, but other times it's only unearthed once construction has begun. You need to be able to quickly adapt your project plan to include an improvement to unfavorable ground before the project can safely continue. Principles and Practice of Ground Improvement is the only comprehensive, up-to-date compendium of solutions to this critical aspect of civil engineering. Dr. Jie Han, registered Professional Engineer and preeminent voice in geotechnical engineering, is the ultimate guide to the methods and best practices of ground improvement. Han walks you through various ground improvement solutions and provides theoretical and practical advice for determining which technique fits each situation. Follow examples to find solutions to complex problems Complete homework problems to tackle issues that present themselves in the field Study design procedures for each technique to simplify field implementation Brush up on modern ground improvement technologies to keep abreast of all available options Principles and Practice of Ground Improvement can be used as a textbook, and includes Powerpoint slides for instructors. It's also a handy field reference for contractors and installers who actually implement plans. There are many ground improvement solutions out there, but there is no single right answer to every situation. Principles and Practice of Ground Improvement will give you the information you need to analyze the problem, then design and implement the best possible solution.

Download or read book Evaluation of Soil and Rock Properties written by P. J. Sabatini and published by . This book was released on 2004-10-01 with total page 392 pages. Available in PDF, EPUB and Kindle. Book excerpt: This document presents state-of-the-practice information on the evaluation of soil and rock properties for geotechnical design applications. This document addresses the entire range of materials potentially encountered in highway engineering practice, from soft clay to intact rock and variations of materials that fall between these two extremes. Information is presented on parameters measured, evaluation of data quality, and interpretation of properties for conventional soil and rock laboratory testing, as well as in situ devices such as field vane testing, cone penetration testing, dilatometer, pressuremeter, and borehole jack. This document provides the design engineer with information that can be used to develop a rationale for accepting or rejecting data and for resolving inconsistencies between data provided by different laboratories and field tests. This document also includes information on: (1) the use of Geographical Information Systems (GIS) and Personal Data Assistance devices for the collection and interpretation of subsurface information; (2) quantitative measures for evaluating disturbance of laboratory soil samples; and (3) the use of measurements from geophysical testing techniques to obtain information on the modulus of soil. Also included are chapters on evaluating properties of special soil materials (e.g., loess, cemented sands, peats and organic soils, etc.) and the use of statistical information in evaluating anomalous data and obtaining design values for soil and rock properties. An appendix of three detailed soil and rock property selection examples is provided which illustrate the application of the methods described in the document.

Download or read book Guide to Full depth Reclamation FDR with Cement written by David Robert Luhr and published by . This book was released on 2005 with total page 15 pages. Available in PDF, EPUB and Kindle. Book excerpt: Full-depth reclamation (FDR) is a roadway rehabilitation process that recycles the materials from deteriorated asphalt pavement, and, with the addition of portland cement, creates a new stabilized base. This guide to FDR discusses its applications, benefits, design, construction, and testing.

Download or read book Ground Improvement Third Edition written by Klaus Kirsch and published by CRC Press. This book was released on 2012-11-26 with total page 515 pages. Available in PDF, EPUB and Kindle. Book excerpt: When finding another location, redesigning a structure, or removing troublesome ground at a project site are not practical options, prevailing ground conditions must be addressed. Improving the ground—modifying its existing physical properties to enable effective, economic, and safe construction—to achieve appropriate engineering performance is an increasingly successful approach. This third edition of Ground Improvement provides a comprehensive overview of the major ground improvement techniques in use worldwide today. Written by recognized experts who bring a wealth of knowledge and experience to bear on their contributions, the chapters are fully updated with recent developments including advancements in equipment and methods since the last edition. The text provides an overview of the processes and the key geotechnical and design considerations as well as equipment needed for successful execution. The methods described are well illustrated with relevant case histories and include the following approaches: Densification using deep vibro techniques or dynamic compaction Consolidation employing deep fabricated drains and associated methods Injection techniques, such as permeation and jet grouting, soil fracture grouting, and compaction grouting New in-situ soil mixing processes, including trench-mixing TRD and panel-mixing CSM approaches The introductory chapter touches on the historical development, health and safety, greenhouse gas emissions, and two less common techniques: blasting and the only reversible process, ground freezing. This practical and established guide provides readers with a solid basis for understanding and further study of the most widely used processes for ground improvement. It is particularly relevant for civil and geotechnical engineers as well as contractors involved in piling and ground engineering of any kind. It would also be useful for advanced graduate and postgraduate civil engineering and geotechnical students.

Download or read book Unsaturated Soils Research Applications written by Nasser Khalili and published by CRC Press. This book was released on 2014-06-05 with total page 1872 pages. Available in PDF, EPUB and Kindle. Book excerpt: Unsaturated Soils: Research and Applications contains 247 papers presented at 6th International Conference on Unsaturated Soils (UNSAT2014, Sydney, Australia, 2-4 July 2014). The two volumes provide an overview of recent experimental and theoretical advances in a wide variety of topics related to unsaturated soil mechanics:- Unsaturated Soil Behavi

Download or read book Performance of Cement Based Materials in Aggressive Aqueous Environments written by Mark Alexander and published by Springer Science & Business Media. This book was released on 2012-12-18 with total page 471 pages. Available in PDF, EPUB and Kindle. Book excerpt: Concrete and cement-based materials must operate in increasingly aggressive aqueous environments, which may be either natural or industrial. These materials may suffer degradation in which ion addition and/or ion exchange reactions occur, leading to a breakdown of the matrix microstructure and consequent weakening. Sometimes this degradation can be extremely rapid and serious such as in acidic environments, while in other cases degradation occurs over long periods. Consequences of material failure are usually severe – adversely affecting the health and well-being of human communities and disturbing ecological balances. There are also large direct costs of maintaining and replacing deteriorated infrastructure and indirect costs from loss of production during maintenance work, which place a great burden on society. The focus of this book is on addressing issues concerning performance of cement-based materials in aggressive aqueous environments , by way of this State-of-the-Art Report. The book represents the work of many well-known and respected authors who contributed chapters or parts of chapters. Four main themes were addressed: I. Nature and kinetics of degradation and deterioration mechanisms of cement-based materials in aggressive aqueous environments, II. Modelling of deterioration in such environments, III. Test methods to assess performance of cement-based materials in such environments, and which can be used to characterise and rate relative performance and inform long term predictions, IV. Engineering implications and consequences of deterioration in aggressive aqueous environments, and engineering approaches to the problem.

Download or read book Soil Improvement and Ground Modification Methods written by Peter G. Nicholson and published by Butterworth-Heinemann. This book was released on 2014-08-29 with total page 472 pages. Available in PDF, EPUB and Kindle. Book excerpt: Written by an author with more than 25 years of field and academic experience, Soil Improvement and Ground Modification Methods explains ground improvement technologies for converting marginal soil into soil that will support all types of structures. Soil improvement is the alteration of any property of a soil to improve its engineering performance. Some sort of soil improvement must happen on every construction site. This combined with rapid urbanization and the industrial growth presents a huge dilemma to providing a solid structure at a competitive price. The perfect guide for new or practicing engineers, this reference covers projects involving soil stabilization and soil admixtures, including utilization of industrial waste and by-products, commercially available soil admixtures, conventional soil improvement techniques, and state-of-the-art testing methods. Conventional soil improvement techniques and state-of-the-art testing methods Methods for mitigating or removing the risk of liquefaction in the event of major vibrations Structural elements for stabilization of new or existing construction industrial waste/by-products, commercially available soil Innovative techniques for drainage, filtration, dewatering, stabilization of waste, and contaminant control and removal