Volumetric Behavior and Soil Water Characteristic Curve of Untreated and Lime-Stabilized Reactive Clay (original) (raw)
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Water Retention and Compressibility of a Lime-Treated, High Plasticity Clay
Geotechnical and Geological Engineering, 2013
The paper presents a laboratory investigation, which quantified the beneficial effect of lime on the water retention, compressibility and overall volume changes of a high plasticity clay (London Clay). The study comprised oedometer testing (including suction controlled testing), shrinkage tests, and filter paper testing to determine the soil water retention curves of the drying soils. The latter tests showed that the shallowmixed lime-treated soils are likely to be partially saturated in situ depending on the environmental conditions; thus, unsaturated soil mechanics concepts are applicable for the description of their behaviour. The oedometer results quantified the marked decrease in the swelling and compressibility of the lime-treated soil compared to the untreated clay and the increase in the vertical effective yield stress (due to suction and cementation bonding). The lime enabled the soil to maintain a more open structure with respect to the untreated soil throughout the compression process, and appears to be the main factor influencing the compressibility of the unsaturated lime-treated soil (rather than suction) for the ranges of suction tested. Keywords Lime stabilisation Á London Clay Á Swelling Á Shrinkage Á Compressibility Á Moisture retention List of symbols e Void ratio G max Small-strain stiffness modulus G s Specific gravity m v Coefficient of volume compressibility m 1 s Coefficient of volume change of the soil skeleton with respect to net normal stress X. Zhang was formerly working at the Faculty of Engineering, Science and the Built Environment of London South Bank University, during the presented research.
Volumetric constitutive behaviour of an unsaturated basaltic expansive clay stabilised using lime
2018
The constitutive volumetric behaviour, in terms of a void ratio (e)-moisture ratio (ew)net stress () space, for a compacted untreated and lime-treated expansive clay was investigated. The studied expansive clay was a residual soil derived from a weathered Quaternary Basalt deposit located in the Victoria, Australia. Expansive soils, which are also referred to as unsaturated soils, moved from expansive clay to unsaturated soil display swelling or collapse behaviours relying on the state paths including loadingwetting-unloading. The Monash Peradeniya Kodikara (MPK) framework proposed by Kodikara (2012) describes the volumetric behaviour of unsaturated soil using void ratiomoisture ratio-net stress space. The virgin compression surface known as the Loading Wetting State Boundary Surface is established using traditional compaction curves. This framework suggests that moisture content is a practical approach in explaining most state paths relevant to practice, such as the deformation of clays under loading/unloading paths and wetting under constant stress. Therefore, this framework was adopted to describe the volumetric behaviour of an unsaturated compacted expansive clay, as well as an expansive clay stabilised with lime at the optimum lime content (OLC). The question raised in this research is whether collapse potential can be obtained in this condition, or whether the swelling potential will be close to zero if a soil is stabilised with lime at the OLC. A suite of tests was conducted to investigate the behaviour of stabilised basaltic expansive clays, which were collected from Braybrook and Whittlesea sites (western and northern suburbs of Melbourne, Australia) over the curing period, and to find the OLC. These tests included determining the pH concentration at various curing periods, Atterberg limit, linear shrinkage strain, swelling potential, and Unconfined Compressive Strength (UCS). Furthermore, X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) tests were conducted to investigate the mechanism of soil-lime reaction. These test results indicated that the longer the curing time, the larger the drop in pH concentration. As ASTM-D6276 (1999) recommends using the method by Eades and Grim (1966) that relies on measuring the pH 1 hr after stabilisation (the curing time is neglected), a new method to determine the OLC for basaltic expansive clays was USC Unconfined Compressive Strength XRD X-Ray Diffraction Chapter one Introduction 1 optimum lime content (i.e. specific gravity, organic content, grain size analysis, Atterberg limits, linear shrinkage, pH concentration, standard Proctor compaction, Unconfined Compressive Strength (UCS), swelling potential, X-Ray Diffraction (XRD), and Scanning Electron Microscopy (SEM)). To investigate the volume behaviour of unsaturated compacted expansive clay and stabilised expansive clay with lime, static compaction and different state path tests were conducted. To study the Soil Water Characteristic Curve (SWCC) for the untreated and treated clay, a tensiometer (Hyprop), filter paper and a chilled mirror hygrometer (WP4C) were used. To identify the climatic effect, cycles of swell-shrink tests were conducted. These test methodologies are explained in this chapter. Chapter Four investigates the effect of curing on determining the Optimum Lime Content (OLC) for the stabilised basaltic expansive clay (i.e. taking curing time and drop in pH content into account). A new method to measure the OLC for basaltic
Swelling Potential Behavior of Expansive Soils Treated with Hydrated Lime
Anais do XVIII Congresso Brasileiro de Mecânica dos Solos e Engenharia Geotécnica, 2015
This paper presents the results of an experimental program developed to investigate the effect of lime treatment on the reduction of swelling potential of an expansive soil. The swelling properties were determined using the new geotechnical centrifuge developed by The University of Texas at Austin. This new technology allows the infiltration water into the soil in shorter time than the conventional free-swell testing because of the high g-level acceleration applied in the specimens. The expansive clayey soil used in this study was Eagle Ford clay that was treated with different percentages of hydrated lime by weight of soil (between 0% and 4%). The compaction density of the specimens was varied between 94% and 100% of the maximum dry density, and the compaction moisture was varied between dry of optimum, optimum and wet of optimum moisture content. The centrifuge tests were carried out at three different g-levels acceleration in order to apply different vertical stresses during the swelling tests. The test results demonstrated that the effect of compaction density on the swelling potential is more significant when the specimens are compacted with low moisture content (dry of optimum) than specimens prepared at the optimum moisture content. However, most of the cases, higher potential swelling was observed in specimens prepared with densities near to the maximum than the specimens with lower density compaction. The results also allowed to conclude that the hydrate lime percentage required to avoid completely the swelling depends on the moisture condition and the effective stress. Samples compacted with wet of optimum moisture content required only 2% of lime to prevent the swelling behavior, whereas samples compacted at dry of optimum moisture content needed 4% of lime to avoid significant expansion at the same effective stress. The strong influence of the compaction moisture on swelling showed the same trend observed in untreated soils, where high potential swelling is produced when the specimens were compacted at dry of optimum moisture content than the compacted at optimum or wet of optimum moisture content. Higher compaction moisture than the optimum can be recommended for lime treated soils in order to allow the pozzolanic reactions taking place into the treated soil and to achieve the total elimination of swelling potential of expansive soils.
Lime treatment of an expansive soil for swelling potential reduction
2017
The effect of lime treatment on the reduction of swelling potential of an expansive soil was studied using the new geotechnical centrifuge developed by The University of Texas at Austin. The expansive soil Eagle Ford clay was treated with different percentages of lime. The compaction density was varied between 94% and 100% of the maximum dry density, and the compaction moisture was varied between dry of optimum, optimum and wet of optimum moisture content. The results demonstrated that higher potential swelling was observed in specimens prepared with densities near to the maximum than the specimens with lower density compaction. The strong influence of the compaction moisture on swelling showed the same trend observed in untreated soils. High potential swelling was produced in specimens compacted at dry of optimum moisture whereas specimens compacted at optimum or wet of optimum moisture content showed lower swelling potential. The lime percentage required to avoid the swelling depe...
The Impact of Moisture and Clay Content on the Unconfined Compressive Strength of Lime Treated Highly Reactive Clays, 2022
failure pattern was also studied to better understand the ultimate behaviour of lime stabilised clays. The results revealed that the strength of treated bentonite increased with the increase in the moisture content up to 30% above the corresponding optimum moisture content and with increasing the curing time and temperature. Nevertheless, substituting bentonite with sand on the specimen resulted in a significant reduction on the attained strength. Furthermore, the results of California Bearing Ratio and Resilient Modulus showed that values for both parameters are significantly enhanced with lime treatment. The microstructural analysis provided visual evidence to the improved strength in which the pozzolanic reaction was found to be significantly affected by the amount of moisture in the mixture. The results suggested that compacting lime treated expansive clays with moisture content moderately higher than the optimum moisture content would result in a significant enhancement to the attained strength over the period of curing.
E3S Web of Conferences, 2016
The paper presents some experimental results collected on samples recovered from an experimental embankment obtained by compacting a lime-treated clay. Samples were collected soon after the in situ compaction and they were cured in controlled environmental conditions for at least 18 months. Mercury intrusion porosimetry tests (MIP) were carried out on freeze-dried specimens to characterize the microstructure of the material. In order to assess the durability of the improved material, laboratory tests focused on the effects of cyclic variations of the degree of saturation on the water retention properties and the volumetric behaviour of the stabilized clay. Collected results show that the lime-treated clay undergoes an almost irreversible volumetric behaviour; this irreversible contraction is associated to severe drying processes, while wetting paths do not produce significant volumetric deformations.
Evaluating the Effect of Environment Acidity on Stabilized Expansive Clay
Studia Geotechnica et Mechanica, 2023
In this article, the effects of environmental acidity on the mechanical and volumetric properties of cement-stabilized clay soils have been investigated through various tests on experimental scale. In this study, a problematic clay was chemically stabilized by cement under three treatment conditions including short term, medium term, and long term with different conditions varying from acid to alkaline environments, which were tested by different methods to evaluate their mechanical and volumetric behavior and properties. Mechanical characteristics assessment tests in this study include compaction tests, and unconfined compressive strength, which was conducted on samples under different conditions in terms of acidity and treatment time. The results of the study indicated that soil improvement by cement increases the mechanical strength and decreases the rate of soil swelling over time and treatment duration. However, the degree of acidity of the environment affects the chemical reactions of soil and cement, especially cement hydration, which causes changes in soil strength and volume variation due to swelling.
Effect of Lime Filling on the Compactibility of Clay Soils
Civil and Environmental Engineering
Insufficient resilience of the natural environment is one of the many problems with the foundation of linear structures, and one of the ways to solve the foundation of a linear structure is the stabilization of soils. Fine-grained soils are problematic for traffic construction. The properties of clay soils change due to climatic conditions. They swell and become plastic in the presence of water, shrink in dry conditions, increase in volume, and freeze due to frost. Improving the properties of fine-grained soils with lime is a suitable solution to the problem in traffic construction. The purpose of soil improvement is to modify soil properties such as creating soil without cavities and gaps, increasing shear strength, reduce compressibility and permeability, the soil must be able to transfer the load without further settling (or unnatural compression). Soil improvement can be defined as an intervention in the natural geological environment or artificially built earth structures (emba...