One-dimensional Consolidation Tests Research Articles

Effects of hydrophilic and hydrophobic nanosilica on the hydromechanical behaviors of mudstone soil

In this study, the effects of hydrophilic (HPI) and hydrophobic (HPO) nanosilicas (NS) on the hydromechanical properties of mudstone soil were investigated in a laboratory. Mudstone soil samples treated with different contents (0.3%, 0.6%, 0.9%, and 1.2%) of both types of NS were prepared and rigorously examined through standard Proctor compaction, unconfined compression, three-dimensional volumetric shrinkage, and one-dimensional consolidation tests. In addition to the hydromechanical tests, nondestructive tests, including X-ray diffraction, X-ray fluorescence, and Fourier-transform infrared spectroscopy, were employed to inspect the geochemical and mineral composition of treated and untreated samples. Finally, scanning electron microscopy was used to monitor the packing state of the specimens. The experimental results reveal that the shrinkage and compressibility characteristics of mudstone soils can be significantly improved through NS treatment. In particular, the results demonstrate that the mudstone soils treated with 0.3% NS, regardless of type, had the highest compressive strength. Our results provide insight into the contribution of NS to the hydromechanical properties of mudstone soils and suggest that NS-HPI may be a better treatment than NS-HPO due to its improved ability to strengthen mudstone soils.

Stiffness and strength parameters for the hardening soil model of a reconstituted diatomaceous soil

Centrifuge modelling has been widely used to study the geotechnical behaviour of structures built on soft soils and to calibrate and validate numerical models. In the finite element method (FEM), the mechanical behaviour of the soils is established through a constitutive model, and the correct selection and calibration of its parameters are essential to obtain accurate results. In this article, the mechanical parameters of an artificial reconstituted soft soil proposed for centrifuge modelling are obtained, calibrated and validated for the hardening soil (HS) model based on laboratory test results. The reconstituted soil consists of 50% kaolin clay and 50% diatomaceous soil from Bogotá, Colombia. First, geotechnical characterization of the reconstituted soil is presented. The model preparation technique to generate the effective stress profile for the centrifuge model is described. The strength and compressibility parameters are obtained from CU triaxial tests and a one-dimensional consolidation test, respectively. Finally, the obtained parameters are calibrated via explicit numerical modelling using the FEM and the SoilTest module of Plaxis software. It is concluded that the reconstituted artificial soft soil proposed herein mimics most of the natural lacustrine deposits of soft soils worldwide and can be modelled using the HS model for FEM analyses.

ELASTO-PLASTIC BEHAVIOR OF NATURALLY DEPOSITED CLAY DURING/AFTER SAMPLING

Changes in soil structure and overconsolidation in highly structured natural deposited clay as a result of sampling and setting in laboratory tests, together with their effects on the subsequent mechanical behavior, are numerically simulated in terms of unconventional elasto-plastic mechanics. To describe the mechanical behavior, a Super/subloading Yield Surface Cam-clay model is employed. This model allows a description of the decay of soil structure, loss/ increase of overconsolidation and evolution of anisotropy with ongoing plastic deformation from the process of the soil sampling through the unloading with swelling up to the subsequent tests. The sampled clay subjected to isotropic unloading and/or one-dimensional unloading with swelling down to the first stage of vertical loading level, displays a response to some degree, different from that of the soil at the original sampling site; for example, an overconsolidated sample subjected to isotropic unloading with swelling will display rewinding behavior in a subsequent undrained triaxial compression test, and secondary consolidation/delayed compression in a one-dimensional consolidation test. However, one-dimensional unloading with swelling, which is followed by one-dimensional compression test, will give better prediction of the in-situ consolidation yield stress than isotropic unloading. Artificially disturbed clay subjected to repeated undrained shearing after sampling suffers a significant loss of structure. This results in a drop in peak strength under subsequent monotonic undrained shearing tests, and in the compression index in one-dimensional compression tests, as described by Schmertmann.

Effects of Class C and Class F Fly Ash on Mechanical and Microstructural Behavior of Clay Soil-A Comparative Study.

A large amount of coal fly ash produced in thermal power plants is disposed of in landfills which causes many environmental problems. The utilization of fly ash can be encouraged in geotechnical engineering projects. In this paper, the effects of class C and class F fly ash on the mechanical and microstructural behavior and stabilization of clay soil were evaluated through a program of laboratory experiments. The experiments included compaction, unconfined compressive strength, consolidated-undrained triaxial, one-dimensional consolidation tests, and scanning electron microscopy analysis on samples of fly ash-stabilized clay soil after 1, 7, and 28 days of curing. The tests were conducted on mixtures of clay with class C or class F fly ash, ranging from 0% to 30% of the soil. Experimental results showed that the strength parameters and permeability of the stabilized soil improved while the compression and swelling indices decreased by the addition of fly ash and by the increase of curing days. The results obtained from the mechanical tests agreed with the results from the SEM analysis. Based on the results, the soil could be successfully stabilized by using class C fly ash. The improvements in strength, swelling, and permeability parameters of the stabilized soil were higher with the class C fly ash compared with class F fly ash.

Effect of Biopolymeric Stabilization on the Strength and Compressibility Characteristics of Cohesive Soil

Sustainable engineering discourages the use of conventional soil stabilizers such as lime and cement owing to their higher carbon emission rates. To address these challenges, many researchers considered biopolymer stabilization, a promising green technique in geotechnical engineering practice for treating expansive soils. This study evaluated the performance of two biopolymers, xanthan gum (XG) and guar gum (GG), in improving the unconfined compressive strength (UCS) and consolidation characteristics of an expansive soil subjected to different testing conditions. The dosage of the biopolymers (XG and GG) was maintained at 0.5%, 1%, 2%, and 4% by weight of dry mass of soil mass. Biopolymer treated samples were subjected to desiccator and natural curing conditions (i.e., specimens were exposed to different temperature and relative humidity conditions) for 7, 14, 28, 45, and 60 days. Results showed that the UCS of biopolymer-treated soil increased with increased dosage up to 2% and 1% for XG and GG, respectively; strength significantly improved during the first 28 days of curing under controlled conditions. Improvement of strength was due to increased adhesive strength between gum strands and soil particles. One-dimensional fixed-ring oedometer consolidation test results indicated that the compressibility and swelling characteristics of biopolymer-treated soil increased due to the hydrophilic nature of gum and an increase in the repulsive forces between negatively charged clay particles and the respective functional groups of XG and GG. Scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR) were performed on both untreated and biopolymer-treated soil to evaluate the interaction mechanism between soil and biopolymer strands. The microlevel studies confirmed the crosslinking of soil particles by gum strands, which aids in the strength improvement.

Analysis of the physical, hydraulic, and mechanical properties of sugar bagasse ash-clay geomaterial

Sugar cane bagasse ash (SA) is the result of the incineration of residues in the production of sugar which has as its final disposal the sanitary landfills generating environmental impacts. The practice of the circular economy for using SA ash as a stabilizer of clay soils in highway bases and sub-bases requires the study of the potential of ash as an alternative cement. Soil stabilization is commonly done with the addition of cement or lime; however, the production of these materials releases CO2 into the atmosphere. This research estimates the potential use of SA ash as a cementing agent considering the physical, hydraulic, and mechanical properties of clay soil mixed with percentages of 6, 8, and 10% of Uncalcined Sugarcane Bagasse Ash (USA) and Calcined Sugarcane Bagasse Ash (CSA). X-ray fluorescence spectrometry (FRX), methylene blue value test, specific gravity, dry unit weight, granulometric analysis, and Atterberg limits tests were carried out to evaluate the physical properties of the mixtures. One-dimensional consolidation tests, soil water characteristic curves (SWCC), standard Proctor compaction, unconfined compression, and direct shear were carried out to estimate the mechanical and hydraulic properties of the mixtures. An improvement in the physical, hydraulic, and mechanical properties was found with the addition of USA and CSA. Finally, based on the analysis of the physical, hydraulic, and mechanical properties of the Soil-USA and soil-CSA samples, it was determined that the best option as an alternative cementitious agent is found in the 8% Soil-CSA mixture due to the improvement in the plasticity index, gravity density, angle of friction, cohesion, and unconfined compressive in comparison with the other samples and the original soil. However, it is essential to mention that this cementitious addition can prejudice the hydraulic properties and consolidation process. It is vital to consider those parameters when realizing any geotechnical design with this mixture.

Primary and secondary compression behavior of dredged clay at low effective stresses

This study presents an experimental investigation on the time-dependent compression behavior of dredged clay samples at high initial water contents under lower effective stress. A series of laboratory one-dimensional consolidation tests with or without aging were conducted on dredged clay samples with various initial water contents. Test results showed that initial water content has a significant effect on the primary compression of dredged clay specimen. All dredged clay specimens follow the same decreasing trend in void ratio with time. Compared with the significant decrease in void ratio in the primary consolidation stage, void ratio decreases less significantly with time in the secondary consolidation stage and tends to level off. The aging strain will not continue increasing as the increase in initial water content more than two times the liquid limit. Aging strain of specimens at different initial water contents consistently increase linearly with the increasing time. The value of secondary compression index is influenced by both aging time and initial water content. It consistently reduces with increasing aging time yet increases with increasing initial water content. We should fully consider the effect of initial water content and aging time on the secondary compression index to predict the secondary compression settlement.

Compressibility and consolidation properties of Santos soft clay near Barnabé Island

A geotechnical study based on characterization tests and seventy incremental loading one-dimensional consolidation tests was carried out on high-quality undisturbed samples taken from Santos Harbor Channel subsoil near to Barnabé Island, where a pilot embankment was built. The characterization profiles revealed a stratigraphy following the pattern described by Massad (2009), with a 9 m-thick fluvial-lagoon-bay sediments (SFL) clay layer. The consolidation tests were performed following two loading criteria. In criterion A (series one tests), a new loading was applied whenever the strain rate (ε) reached 10-6 s-1, the highest integer power of 10 after the “end of primary” consolidation for double drained 2 cm thick specimens. In criterion B (series two tests), the standard procedure of 24 hour-long stages was adopted. Criterion A reduced the total duration of the consolidation tests from ten to about three days. The preconsolidation (yield) stress (σ’p) and the compressibility parameters Cc and Cr obtained from “e versus σ’v (log)” compression curves of all tests are provided. Series two tests showed that the 24-hour “e versus σ’v (log)” compression curves are translated to the left of the ε = 10-6 s-1 “e versus σ’v (log)” compression curves, keeping Cr and Cc average values unchanged, but decreasing σ’p by about 8%. The SFL clay Cc/(1+e0) values obtained herein are higher than those presented by Massad (2009) due to the higher-quality samples tested in this study. It is shown that it is feasible to carry out a high-quality laboratory test program for design purposes following current standards.

Controlling Conditions of the One-Dimensional Consolidation Test on Peat Soil

This paper studies the changes in the loss on ignition (LOI), total nitrogen content (TN), and strain in a one-dimensional consolidation test on peat soil. The effects of small-range fluctuations in the ambient temperature and changes in the sample height on the consolidation process of peat soil are proposed and verify the inhibitory effect of thymol on the decomposition of organic matter. The results show that when the ambient temperature fluctuates in a small range, the consolidation rate is significantly affected. Under a low load, the ambient temperature increases by 1–2 °C, and the consolidation rate can be increased by up to 10 times. This study presents the changes in loss on ignition (LOI) and total nitrogen content (TN) during consolidation, which proves that soaking the samples with a thymol solution can effectively control the decomposition of organic matter in peat soil. The strain of peat soil at a height of 30 mm is greater than or equal to that of other height samples, while that of mucky soil is 20 mm. Therefore, 30mm is the recommended sample height for peat soil for the one-dimensional consolidation test.

CONSOLIDATION CHARACTERISTICS OF A SILTY CLAY: CONCERNING THE EFFECT OF SOIL DISTURBANCE

In this paper, undisturbed specimen of a silty clay constituting of Phu Bai formation (ambQ21-2 pb) was collected from boreholes in Hue city and surrounding areas. The soil, under both undisturbed and disturbed conditions, was then subjected to standard one-dimensional consolidation tests with 7 loading increments. It is shown from the experimental results that the time to the end of primary consolidation (EOP), determined by Log Time method (tLT) and 3-t method (t3T), decreases with the load increment and under the same vertical stress, the primary consolidation of disturbed silty clay finish at a shorter time than those of the undisturbed one. The coefficient of secondary consolidation (Cα) increases with the vertical stress and reaches the maximum values before decreasing. The obtained values of Cα = 0.005 - 0.020 suggest a relatively low secondary compressibility of the silty clay constituting of Phu Bai formation.

Hydro-mechanical coupled B-spline material point method for large deformation simulation of saturated soils

Numerical simulation for large deformation problems of saturated soil poses an ongoing challenge since it requires the capabilities of modeling large deformations, interactions between solid skeleton and pore water, as well as fluidization behaviors. A hydro-mechanical coupled B-spline material point method is developed to simulate large deformations of saturated soils. Based on Biot's mixture theory, a single set of material particles is adopted to represent saturated soils where Darcy's law is employed to govern the motion of pore water and the momentum conservation of the mixture is used to govern the motion of solid skeleton. The convergence and effectiveness of the proposed method are examined by one-dimensional consolidation tests and quasi-static footing penetration into two-dimensional elastic saturated soils. The capability of simulating practical engineering for the proposed method is demonstrated by reproducing the dynamic process of three-dimensional saturated soil slopes with a strain-softening Drucker-Prager constitutive model. Results show that the coupled BSMPM well reveals the overall dynamic process of saturated soil slope involving evolution of shear bands, formation of graben and horst, and fluidization of progressive failures with improved computational accuracy and enhanced convergence, which demonstrates the proposed method is a promising approach for large deformation problems of saturated soils.

Effect of calcium bentonite clay and fly ash on the stabilization of organic soil from Alberta, Canada

This paper presents findings of the effect of calcium bentonite (Ca-bentonite) and pulp mill fly ash (PFA) on the compressibility behavior, and microstructural evolution of organic soil. A natural soil consisting of 26% organic matter was collected from the wetlands in the Wabasca region, Northern Alberta, Canada. A various mix design was prepared for the laboratory tests with the addition of 5%, 8%, 10%, 12%, 15%, and 20% Ca-bentonite with constant 30% PFA. One-dimensional consolidation tests were carried out to evaluate compressibility behavior of the stabilized organic soil. In addition, fall cone tests were conducted to evaluate change in undrained shear streth of soil after stabilization. A series of scanning electron microscope (SEM) tests with energy dispersive X-ray (EDS) and X-ray diffraction (XRD) experiments were conducted to investigate the microstructural and chemical aspects of the organic soil treated with Ca-bentonite and PFA. The results showed that a mixture of 10% Ca-bentonite with 30% PFA was the optimum dosage for improving compressibility of organic soil regardless of the curing method. Microstructural and chemical analysis revealed that the mineralogical and morphological contents of the stabilized organic soil were affected due to the pozzolanic reaction. The results showed that Ca-bentonite and PFA were able to considerably improve the strength and compressibility of the selected organic soil.

Compressibility behaviour and engineering properties of North Borneo Peat Soil

It is known that peat soil is highly compressible. A constituent of peat soil from Klias, Sabah covering a wide range of index properties of fiber contents, specific gravity, organic contents and moisture contents were subjected to one-dimensional consolidation tests. This paper presents the engineering properties and compressibility behavior of sapric type of tropical peat soil. In this role, the high compressibility of Klias peat stands out as a most significant engineering property. With this intention, the purpose of this paper is to provide a simple and analytical means for predicting the consolidation settlement of sapric peat deposit under loading. The rate of primary compression, after a certain time. Increases with the logarithm of time. Loading applied from low stress to high stresses started from 2, 6.25, 12.5, 25, 50, 100 and 200 kPa resulting in high compression index, Cc and ratio, C’c. The Klias peat soil represented sapric type of tropical peat with organic content is 98.43% and lower fiber content which is about 18% of the specimen. Compressibility index Cc, Coefficient of consolidation Cv, and Compression index, Cc, was identified as a crucial component of parameters in determination of settlements behaviour of peat soil. The coefficient of consolidation, Cv, was determined within the range of 1.264 to 12.911 cm2/min and requires special considerations in laboratory testing procedures and interpretation of results.

Stress-dilatancy responses of recovered plastics and demolition waste blends as a construction material

This research study focuses on the stress-dilatancy and compressibility responses of recovered plastics (RP) when used as a supplementary material in blends with construction and demolition (C&D) materials. RP is comprised of different types of waste plastics with a diverse range of shapes, colors, and sizes. The compressibility and collapse potential of RP/C&D blends were assessed through a series of one-dimensional consolidation tests. The stress-dilatancy responses and shear strength of RP/C&D blends were also evaluated via a series of monotonic drained triaxial tests. The RP content was the governing factor affecting the compressibility of blends with limited effect on the collapse potential of C&D aggregates. Moreover, the stiffness and strength of RP/C&D blends decreased with the increase in RP content. The inclusion of RP enhanced the energy absorption of the blends through the increase in total work input upon shearing. Stress-dilatancy properties of the RP/C&D blends were also found to be governed by the total work input parameter. The dilatancy of blends was also modeled within the scope of critical state soil mechanics with the use of dilatancy parameters correlated with the total work input.

Effect of Matric Suction and Density on Yield Stress, Compression Index and Collapse Potential of Unsaturated Granite Soil

Residual granite soil from Malaysia shows some problematic features such as: high void ratio, low natural dry density, and loose of apparent cohesion of the soil immediately after rain due to wetting. This study is aimed to evaluate the influence of suction and density on unsaturated behavior of the residual granite soil e.g., the yield stress (σc), compression and swelling indices (Cc, Cr), and collapse potential (CP). To do that, a modified oedometer was fabricated on the basis of the axis translation technique (ATT). Then, one-dimensional consolidation tests were performed under different suctions using the modified oedometer. The results showed a negligible increase in σc when the applied suctions were less than the air entry value. The σc values of dense soil samples were higher than that of loose soil samples regardless of the matric suction. Besides, the values of Cc appeared in three zones: saturation, desaturation and residual zones, while, Cr was independent of the matric suction. The difference of CP under similar matric suction indicated a hydraulic hysteresis behavior of the residual granite soil. However, the hydraulic hysteresis effect on the maximum CP was negligible.

Empirical Compressibility Index Equations for Artificial Remolded Clay Mixtures

A series of one-dimensional consolidation tests was conducted on reconstituted soil mixtures with different mineral compositions. Test groups were prepared by mixing various proportions of kaolinite, quartz, and montmorillonite in which the initial water contents were equal to the liquid limits of the soils. The focus was on the compression behavior of reconstituted clay mixtures, including the rarely reported triple mixtures, as well as establishing a link between the liquid limit and the clay mineral ratio of the specimens. The intrinsic compression indexes of the soils were highly dependent on the composition of the soils and the initial water contents. New equations were proposed to estimate the compression index based on the clay mineral content, liquid limit, plasticity index, and initial void ratio. A triangular chart was proposed to estimate the compression indexes of reconstituted soils. A simple way to determine the virgin compression lines of reconstituted specimens is described.

Anisotropic elastoplastic response of double-porosity media

We present a continuum framework to simulate fluid flow through anisotropic elastoplastic media with double porosity. Two effective stress measures σ′ and σ′′ emerge from the thermodynamic formulation, which are energy-conjugate to the elastic and plastic components of strain, respectively. Both effective stress measures can be expressed as a combination of the total Cauchy stress σ and the average pore pressure p¯ in the two pore scales. In the effective stress for elasticity, p¯ is scaled with a rank-2 Biot tensor, whereas the effective stress for plasticity follows the Terzaghi form in which p¯ is scaled by the Kronecker delta. The Biot tensor and storage coefficients are derived as functions of elasticity parameters and porosities. A mixed finite element formulation is introduced to discretize the domain and solve initial boundary-value problems. A stabilization scheme is employed on equal-order interpolation for both displacement and pressure fields throughout the entire range of drainage responses. Numerical simulations reproduce the hydromechanical response of Opalinus shale in one-dimensional consolidation tests throughout the range of primary and secondary consolidation under different external loads. Numerical simulations of the consolidation of a rectangular domain subjected to a strip load demonstrate the efficacy of the proposed stabilization scheme, as well as illustrate the impacts of stress history, mass transfer, and different pore systems on the hydromechanical response.

Numerical simulation with hardening soil model parameters of marine clay obtained from conventional tests

Over the last decades, numerical modelling has gained practical importance in geotechnical engineering as a valuable tool for predicting geotechnical problems. An accurate prediction of ground deformation is achieved if models that account for the pre-failure behaviour of soil are used. In this paper, laboratory results of the consolidated drain (CD) triaxial compression tests and one-dimensional consolidation tests of marine clay were used to determine the hardening soil model (HSM) parameter for use in Plaxis 3D analyses. The parameters investigated for the HSM were stiffness, strength and advanced parameters. The stiffness parameters were secant stiffness in CD triaxial compression test (E_{50}^{text{ref}}), tangent stiffness for primary oedometer loading test (E_{text{oed}}^{text{ref}} ), unloading/reloading stiffness (E_{text{ur}}^{text{ref}}) and power for the stress-level dependency of stiffness (m). The strength parameters were effective cohesion (c_{text{ref}}^{text{'}}), effective angle of internal friction (phi^{text{'}}) and angle of dilatancy (psi^{text{'}}). The advanced parameters were Poisson’s ratio for unloading–reloading (ν) and K0-value for normal consolidation left( {K_{circ}^{text{nc}} } right). Furthermore, Plaxis 3D was used to simulate the laboratory results to verify the effectiveness of this study. The results revealed that the stiffness parameters E_{50}^{text{ref}} , E_{text{oed}}^{text{ref}} , E_{text{ur}}^{text{ref}} and m are equal to 3.4 MPa, 3.6 MPa, 12 MPa and 0.7, respectively, and that the strength parameters c_{text{ref}}^{text{'}}, phi^{text{'}}, psi^{text{'}} and K_{circ}^{text{nc}} are equal to 33 kPa, 17.51°, 1.6° and 0.7, respectively. A final comparison of the laboratory results with the numerical results revealed that they were in accordance, which proved the efficacy of the study.

Effect of compaction delay on the strength and consolidation properties of cement-stabilized subgrade soil

Soil compaction is a considerable construction activity to ensure safety and durability, notably in the transportation industry. Compaction delay (CD) occurs because of unpredictable cases which may be related to the climatic, environmental, and logistics reasons. Since the time delay in compaction process affects the engineering properties of the materials in road construction, the current study evaluates the effect of CD on mechanical and consolidation characteristics of cement-stabilized subgrade soil. To achieve this purpose, a set of experimental tests including standard compaction, unconfined compressive strength (UCS), and one-dimensional consolidation tests are performed. Samples are mixed with 1.5, 3, 6, and 9% Portland cement on their maximum dry density (MDD) considering different ranges of CD up to 120 min. Delayed samples show a reduction in MDD (3.46–5.43%), and UCS (11.31–37.25%) compared with those of non-delayed ones. Morphological findings from scanning electron microscope (SEM) analysis confirmed that the CD has a destructive effect on the mechanical characteristics of the soil–cement samples even in the long run. Correspondingly, delayed samples show lower secant modulus (1.81 times) rather than immediate compacted ones. Furthermore, higher CD yields mixtures with higher compression index and void ratio. Finally, laboratory test results are used to develop MDD and UCS regression models considering the CD parameter. The sensitivity analysis, based on regression models, shows that the MDD and UCS are noticeably influenced by cement content variations.

Experimental Investigation on the Strength and Deformation Aspects of Thixotropic Aging in Reconstituted Clays

This study is aimed at comprehending the effect of thixotropic aging on strength and deformation response of natural clays reconstituted in the laboratory. Three clays have been collected and samples were prepared at a moisture content of corresponding liquid limits. Prepared soil specimens were subjected to a thixotropic aging (constant moisture, constant volume and constant temperature conditions) period of 7, 14, 21, 28, 35 and 42 days. Unconfined compressive strength and direct shear tests were performed to assess thixotropic strength recovery. Thereafter, one-dimensional consolidation tests were conducted on the thixotropically aged samples to assess the compressibility characteristics. Interpretation of the responses from unconfined compression test, direct shear test coupled with Scanning Electron Microscopy imaging analyses suggest that thixotropic strength recovery is dependent on activity, percentage of clay fraction, and initial grain structure. Thixotropic strength ratio obtained from unconfined compression test and direct shear test are noticed to be different, although the trend is similar. Interpretation of 1-D consolidation test data suggest that as the thixotropic aging period increased, samples tend to provide higher yield stress compared to the unaged samples. All the void ratio-effective vertical stress responses for the clays at different thixotropic aging periods tend to converge at a same void ratio at a consolidation stress of > 1000 kPa, indicating no effect of thixotropic structuration at high consolidation stresses. In addition, it was observed that thixotropically active clays swell more than the inactive clays during the thixotropic aging period. In addition, a proportional relationship between thixotropic strength ratio and plasticity index was also noticed.