Compaction Curve Research Articles

Compaction Characteristics of Kaolin Reinforced with Raw and Rubberized Oil Palm Shell

This paper presents an attempt to evaluate the suitability of oil palm shell (OPS) and rubberized OPS (ROPS), an alternative bio-material, as reinforcement in kaolin. OPS was surface coated with rubber, and its water absorption potential was studied in 5 media involving water and kaolin samples (with different water contents). The water absorption data measured in the laboratory was used as an indirect measure to verify the degradability of ROPS samples when used as reinforcements in kaolin. The surface treatment of OPS with rubber was found to perform well, with around a fivefold decrease in water absorption, thus making it an ideal treatment procedure to this end. Kaolin-ROPS mixtures with different OPS and ROPS proportions (0, 5%, 10%, 20%, and 30% by weight) were prepared in laboratory to evaluate their compaction behaviors. Both standard proctor compaction and mini-compaction procedures were adopted in this study to ensure applicability of the findings across a wide range of compaction methods adopted in the laboratory. Compaction curves obtained for both kaolin-OPS and kaolin-ROPS mixes showed a decreasing trend in the maximum dry density values with increasing proportions of OPS and ROPS. Optimum water content of kaolin-OPS mixtures did not show a significant variation, while kaolin-ROPS mixture showed a downward trend with increasing ROPS contents, thereby signifying improvement in the compaction characteristics after OPS reinforcement in kaolin.

Practical method to estimate parameters of elasto-plastic constitutive model for unsaturated soils from compaction curve

The input parameters for the hardening law for the elasto-plastic constitutive model of unsaturated soils are generally fitting parameters that control the degree of hardening response and cannot easily be determined without the results of experimental tests in which the changes in suction, water content, and volume are measured or controlled. However, it is next to impossible to complete such precise experimental tests on all the geomaterials comprising the earth structure to be analysed, such as an embankment. It is important, therefore, to establish a method for determining these parameters from more easily attainable data on the material. This paper presents a practical method for estimating the input parameters related to hardening/softening due to desaturation/saturation in the elasto-plastic constitutive model proposed by Ohno et al. (2007a) from a compaction curve, which is frequently obtained and widely used in engineering practice. In the proposed method, the input parameters are estimated by simultaneously solving three theoretical equations, each of which holds for a different point, indicating the statically compacted state on the dry side of the compaction curve, while the approximately represented compaction curve is used instead of a hand-drawn one. The paper demonstrates that the proposed method enables the estimation of the input parameter values within a range small enough so as not to affect the results of the simulation, irrespective of the way in which the points on the represented compaction curve are selected. The validity of the estimated parameters is verified and then discussed through a series of static compaction test simulations.

Understanding Soil Surface Water Content Using Light Reflection Theory: A Novel Color Analysis Technique Considering Variability in Light Intensity

Abstract Accurate measurement of soil surface water content is vital for analyzing evaporation, partition of solar radiation, infiltration, and runoff. Color analysis of soil has already been found to be a nonintrusive, economical, and feasible approach for the measurement of surface water content. However, color contrast within the soil domain was rarely considered in color analysis approaches demonstrated by previous researchers. This color contrast occurs because of the spatial heterogeneity of light intensity in the soil domain. This study aims to demonstrate and validate a new color analysis technique for overcoming the shortcomings of previous approaches. Six series of tests were conducted to analyze the color of red soil at various surface water contents. In addition, six measured dry densities on the compaction curve were selected for validation of the proposed color analysis technique. Soil has been compacted by hand to the desired state of compaction in a small mold. Images of soil samples were captured using a commercially available camera model (NIKON COOLPIX L29, Nikon, Tokyo, Japan). The brightness variation of soil samples was quantified using the change in mean gray value of the images. A white paper was placed below the mold to consider color contrast within the soil samples. Mean gray values of all test samples were obtained using a public domain image processing program called ImageJ. Color contrast within the soil samples was equalized with respect to reference locations considered on the white paper. Mean gray value was found to decrease with the increase in surface water content. Decrement in mean gray value was found to be more significant (i.e., 14–27 %) in saturation and desaturation zones of soil water characteristic curves (SWCCs) as compared to that in the residual zone (i.e., 3–9 %) with a 3–4 % increase in surface water content. A correlation between mean gray value and surface water content was established for the red soil.

Study on the Design Settlement of Over-Consolidated Clay for a Complex Development

The purpose of this study was to understand the consolidation settlement characteristics of the west coast, where overconsolidation has occurred, and to identify the problems of existing consolidation design through field tests and the re-evaluation of design parameters. The settlement ratio (measurement settlement/design settlement) obtained using the existing design method was calculated to be 56.0%; however, the settlement ratio obtained through the re-evaluation of the preconsolidation stress and compression index suggested in this study was 95.6-96.6%. It was applicable to the west coast region, where the condition of overconsolidation developed. In addition, the consolidation test curve of the low-plasticity silt ground in the west coast region showed a rounded curve with no clear inflection point. It was difficult to determine the preconsolidation stress when applying the Casagrande method, and it tended to be underestimated. Analysis showed that it is preferable to apply the compression index obtained from the compaction curve as it is, rather than to apply Schmertmann's modified compression index.

Effect of Reclaimed Asphalt Pavement Heating Temperature on the Compactability of Recycled Hot Mix Asphalt.

The compactability of an asphalt mixture is related to the heating temperature of the materials, but the heating temperature of reclaimed asphalt pavement (RAP) is limited by the production process of hot-in-plant recycled mixtures. To choose a reasonable heating temperature for RAP according to the compactability, the compaction energy ratio (CER) obtained from the Superpave gyratory compactor compaction curve was developed. The CERs of fourteen kinds of asphalt mixtures made with different RAPs were compared, all of which were different in type, content, and heating temperature. The results indicated that CER is an effective energy index to evaluate the workability of a bituminous mixture, and it considers both the accumulated energy after each gyration and the number of gyrations. It was also found that increasing the heating temperature of the RAP cannot always improve the workability of the recycled mixture, because the higher heating temperature caused more hard-aged bitumen to be blended with soft virgin bitumen during the mixing process. At the same RAP heating temperature, increasing the RAP content made it more difficult to compact the mixture, especially for RAPs with styrene–butadiene–styrene (SBS) modified bitumen, and the recycled mixtures with SBS-modified bitumen were more difficult to compact than those with nonmodified bitumen.

Influence of Energy on Compaction Characteristics of High Expansive Soils

Each soil type has different behavior with regard to determination of maximum dry density and optimum moisture content and therefore any soil type has its own compaction requirements for experimental purposes and for control the compaction in the field. The general purpose of this study is to a better understanding of the compaction characteristics of high expansive soils, with emphasis on the relationships of moisture content and dry density of high expansive soils at a range of compaction energy levels. To achieve this purpose, high expansive soils samples were subjected to Atterberg limit and a set of laboratory compaction tests to find compaction characteristics namely; maximum dry unit weight and optimum water content of high expansive soils at different compaction energy (compaction effort) for different number of hammer blows per each layer range from 10 to 50, which varied the energy per unit volume from 356 KN/m3 to 1188 KN/m3.Rather than single peak compaction curves, the most achieved compaction curves are an irregular one and half peak compaction curves. According to the comparison results of different compaction energy, it was concluded that the maximum dry unit weight of high expansive soil was not highly affected by gradually increase of applied energy. The results showed that, the maximum dry density of tested expansive soils sample increased from 1.48g/cm3 to 1.6g/cm3 with increase of compaction energy from 356 KN/m3 to 1188 KN/m3.

Visualization and quantification of lab vibratory compacting process for aggregate base materials using accelerometer

Although being widely used as the quality control for field compaction, neither the standard nor modified Proctor tests match the compaction effort of existing field compaction machineries commonly used today. More importantly, these methods are incapable of identifying the compactability of soil materials other than maximum dry density and optimum moisture content. With the widespread application of intelligent compaction (IC), there is a need to develop a new laboratory compaction method for soil and aggregate materials in which a detailed compaction process could be visualized or quantified. In this study, a lab scale vibratory compactor, asphalt vibratory compactor (AVC), was adopted to compact an aggregate base material with a mounted accelerometer. Based on dry density-moisture content curves, the AVC compaction was more effective in compacting cohesionless soils than the standard Proctor test, and there existed an optimum AVC parameter setting to acquire the highest dry density of aggregates as well as more stable frequency spectrums. In addition, by using the discrete-time Fourier transform the lab compaction process could be visualized through the frequency-domain spectrums. Two IC parameters, Compaction Meter Value (CMV) and the Compaction Control Values (CCV), were calculated for specimens at different water content. The CCV value had a more stable pattern and two distinct compaction stages could be identified for the lab compaction, which could be used to construct the lab compaction curve. Based on the lab compaction curves, AVC has the potential to identify the moisture content and compactability of soil materials and to guide the field compaction.

Swelling Behavior of Unsaturated Expansive Soil

To investigate the effect of the changes of the soil suction on volume changes, small-scale experiments were conducted for pure bentonite and bentonite mixed with sand of proportion 30%, 40%, and 50% at different initial water contents and dry unit weights that were chosen from the compaction curves. In addition, a large-scale model with soil dimensions 700 × 700 × 650 mm was used for the same initial water content and dry unit weight to show the effect of water content changes on swelling with time and soil suction. It was concluded that the swelling potential decreases from 14 to 2.4% with an increase of sand content by adding 50% sand to pure bentonites. The swelling percent found from the large-scale model is higher than that obtained from the oedometer swelling test for the same soil. This result applies well on BS5 (50:50, bentonites:sand) soil sample for which the swelling potential from the large-scale model is 8.3% and from the conventional swelling test is 3.6%. The measured swelling pressure from the swelling test at small soil samples is much higher than that measured from the large-scale model. For soil sample BS3 (60:40, bentonite:sand), the swelling pressure decreases from 50 kPa in the swelling test to 23.2 kPa in the large-scale model. The swelling potential decreases with an increase of the soil suction for all types of soil subjected to different periods of saturation.

Collapsible Behavior of Lateritic Soil Due to Compacting Conditions

Soil collapse is a major geotechnical problem that causes architectural and structural damage to buildings and engineering infrastructure. Losses due to soil collapsibility have an economical aspect and the study of these soils is very important due to the large occurrence of collapsible soils around the world. In this research, conventional oedometer tests and suction-controlled oedometer tests were conducted to study the benefit of compaction as a method of improving the behavior of a lateritic soil that is particularly susceptible to collapse after soaking. The results offer practical information to minimize problems arising from collapsible soils. The soil water content before the sample is inundated affected the soil collapsible behavior. Soil specimens less dense when compacted at the dry side of the compaction curve exhibited volume variation under loading less than 4% and collapse deformations up to about 11% when exposed to flooding, while soil specimens compacted at optimum moisture content showed volume variation under loading around 10% and a maximum collapse deformation by about 6%. The collapse deformations changed significantly with inundation stress for the soil compacted especially for stresses above 100 kPa. The collapse deformations were almost insignificant when the lateritic soil had a relative compaction of 90% with values almost always less than or equal to 2%, proving that the compaction process is a soil improvement technique that can significantly reduce the collapse induced by inundation.

An investigation of sulfate effects on compaction characteristics and strength development of cement-treated sulfate bearing clay subgrade

ABSTRACT For road construction on sulfate (saline) soil, whether cement stabilisation could be effectively used must be determined. This study improves understanding of strength reduction characteristics for cement-stabilised sulfate soil subjected to variations in water content, cement content, and curing time. A series of laboratory tests to examine soil properties and compressive strength characteristics of soil-cement mixtures in conjunction with microstructural observations were performed. The compaction curves of cement-stabilised sulfate bearing clay and cement-stabilised high plasticity clay (a benchmark material) were established as nearly identical. This indicated minor effects of sulfate on the compaction characteristics of soil. The experimental results also showed that the rate of compressive strength loss escalated with an increase in cement content and curing time. While producing test samples through the compaction process, a series of unconfined compressive strength (UCS) tests on both materials exhibited a bell-like relationship with a peak at the optimum moisture content (OMC). The UCS of both study materials while compacted with water content below the OMC was lower than that while compacted with water content higher than the OMC. The microstructure observations in this study also supported this characteristic.

Influence of compaction times and pressures on rheological properties of kaolin and sawdust powder mixtures

In this research, the compacting process and rheological properties of kaolin and bio-original additive (sawdust) mixtures were investigated based on compaction pressures and times. Relative compaction curves as a function of forming pressure and time were determined, the authors enabled to precisely specify the changes of the rheological models and rheological characteristics of these powder mixtures which have variable particle compactions and size distributions. varying the compression pressure and changing the composition ratio of the kaolin and sawdust powder mixtures leads to considerable changes in the rheological properties of the prepared mixture.

Compaction Dynamics during Progenitor Cell Self-Assembly Reveal Granular Mechanics

Summary We study the self-assembly dynamics of human progenitor cells in agarose microwells that are used for production of chondrogenic organoids. Using image analysis on time-lapse microscopy, we estimate the aggregate area in function of time for a large number of aggregates. In control conditions, the aggregate radius follows an exponential relaxation that is consistent with the dewetting dynamics of a liquid film. Upon introducing Y-27632 Rho kinase inhibitor, the compatibility with the liquid model is lost, and slowed-down relaxation dynamics are observed. We demonstrate that these aggregates behave as granular piles undergoing compaction, with density relaxation that follows a stretched exponential. Using simulations with an individual cell-based model, we construct a phase diagram of cell aggregates that suggests that the aggregate in presence of Rho kinase inhibitor approaches glass transition.

Influence of moisture content on intelligent soil compaction

The intelligent compaction (IC) technology has been demonstrated as a powerful tool for soil compaction. However, the correlation between IC measurement values (ICMV) and in-situ tests has not been always consistent due to the influence of moisture content. The same density can be obtained at two different moisture contents on either side of the optimum moisture content, whereas without the same modulus. In this study, the influence of moisture contents on ICMV and in-situ point measurement values were examined by both in-situ and laboratory tests. By using the compaction curves from the gyratory compactor and field compaction, the impact of different moisture contents on soil modulus was identified, and the sensitivity of ICMV on the soil density and deflection due to varying moisture contents was explained. Another laboratory test, the vibratory compaction, could offer the target ICMV value from a modulus versus water content curve. Based on the test results in this study, an improved IC soil compaction system including laboratory test validations was suggested to identify the soil compactability and the target value at varying moisture contents.

A novel approach to evaluating the compaction control of soils

Soil compaction is an important operation during the construction of road embankments, railway subgrade, earth dams and compacted clay liners for waste disposal. Soil compaction is usually controlled based on the ratio of the dry density of the soil to the soil water content. However, this relationship presents problems in both the laboratory and in the field when using excess compaction energy levels in cohesive soils with a high natural water content, including differences in the compaction energy levels and a reduction in strength as a result of over-compaction. The compaction curve, which considered the compaction energy levels, is usually unknown in the field and the main factors influencing the stiffness and strength of compacted soils are the dry density and the degree of saturation. We show here compaction results for soils in terms of the dry density and degree of saturation and introduce the concept of an optimum compaction line.

Effect of silica fume on engineering properties of expansive soil

Rapid growth of urbanization and industrialization has led to drastic industrial waste which has become a giant threat to our nature. Minimizing industrial waste now days posing a serious problem in the present scenario. To tackle the problem now a days many innovative and non-traditional researches on waste utilization is gaining importance. The primary purpose of this experimentation is to evaluate the suitability of using the low-cost material i.e. Silica fume as a soil stabilization material. This project work presents the study of expansive soil stabilized with silica fumes which was assembled from an idyllic area named Kalatunga located in Kendrapada district of Odisha state. Soil stabilization was done with various percentages of silica fumes (10 to 100%). The differential free swell (DFS), Atterberg’s limits, standard proctor compaction, california bearing ratio (CBR), unconfined compressive strength (UCS) test and unconsolidated un-drained triaxial (UU) test were carried out on natural and silica fume stabilized soils. Results display that addition of SF scales down the DFS. The compaction curves point out that addition of silica fume results in an increase in optimum moisture content (OMC) and decrease in maximum dry density (MDD). The addition of stabilizers (i.e. silica fumes) escalates the cohesion (C) values in UCS along with an in increase in cohesion and angle of shearing resistance (Ø) in UU triaxial test demonstrating progress in the strength properties of soil.

Water retention characteristics of iron ore fines

Evaluations of water retention characteristics of typical iron ore fines (IOF) were presented, which was part of experimental works for the estimation of liquefaction potential of IOF heaps. The water retention tests were conducted in a suction range from 0.1 to 106kPa on two IOFs and two artificial soils with various testing techniques. It is observed that water retention characteristic curves of one IOF (IOF-B) converge in terms of the relationship between suction (S) and water content (w) regardless densities of specimens when S exceeds a threshold value (Sth). Based on this finding, water retention characteristics are divided into density and materials affected zones. It is also found that IOFs generally have higher water retention ability than the two artificial soils, from which discussion is made on the effect of specific surface area and mineralogy on water retention characteristics of IOF. Finally, water retention characteristics are linked to compaction curves, from which, with the consideration that degree of saturation at peaks of compaction curves is relatively constant, a safety margin of a recently proposed regulation for maritime transportation of IOF is discussed.

Utilization of Depolymerized Recycled Polyethylene Terephthalate in Improving Poorly Graded Soil

This study introduced recycled plastic waste as a soil stabilizer and encouraged using it as an alternative material in the improvement of poorly graded soil. The water bottles’ plastic waste was depolymerized and recycled to produce a powder material then used this material as a soil stabilizer. Different percentages (0.0, 0.5, 1.0, 1.5, 2.0%) of the depolymerized recycled polyethylene terephthalate (DRPET) (by dry weight of soil) have been chosen to evaluate its effects on the properties and behavior of poorly graded sandy soil. These effects studied through a series of laboratory tests including scanning electron microscopy. Also, the applicability of DRPET in inundation conditions has been studied using confined compression tests. It was found that untreated and treated poorly graded soil show the same shape of compaction curves, and DRPET filled the pore spaces and affected the compaction characteristics of the soil. The soil treated with 1.5 and 2.0% DRPET exhibited brittle behavior, and the addition of DRPET increased the angle of internal friction and reduced the maximum vertical contractive displacement of the soil. DRPET coated the surface of particles and increased the resistance between soil particles and, therefore, increased the time lag during compression. Finally, under confined compression, poorly graded soil treated with DRPET exhibited small changes in void ratio and slightly influenced by inundation in water.

Effects of temperature, dry density and water content on the thermal conductivity of Genhe silty clay

As an important parameter to consider the thermal stability of road engineering in cold regions, thermal conductivity is largely affected by temperature, water content, dry density, and etc.. When investigating thermal conductivity, setting the dry densities and water contents of soil samples according to compaction curve agrees better with actual engineering conditions because of its compaction characteristic for subgrade soil. Therefore, experiments on thermal conductivity of 9 groups of soil samples corresponding to different water contents at the compaction curve were carried out under −40 ℃~20 ℃. It was found that thermal conductivity decreases linearly with the decrease of temperature in positive temperature range and increases exponentially in negative temperature range, which is closely connected to the variations of thermal conductivity, contents and interactions of every phase with temperature. Multiple linear regression analysis showed that water content has a slightly higher effect on thermal conductivity at positive temperature than that of dry density; however, its effect is about twice of that of dry density at negative temperature. Then, an assessment method combining Root Mean Square Error (RMSE) and Root Mean Square Value (Xrms) was proposed to evaluate the predictive capabilities of two classical models (Johansen’s model and the CK model) effectively.

Evaluation of the Modified Cam Clay model in basin and petroleum system modeling (BPSM) loading conditions

Abstract Basin and Petroleum System Modeling (BPSM) simulates the evolution of sedimentary basins over geological time spans, a highly complex process in which the mechanical representation of rocks is of the utmost relevance. Through geomechanical analyses, it is possible to quantify properties of the porous media (mainly porosity), simulate the formation of seals and traps and understand the propagation of faults and fractures, as well as their roles in fluid flow, all of which can significantly influence the prediction of hydrocarbons accumulations. However, the traditional mechanical model applied in BPSM simulators is an empirical law developed by geophysicist Lawrence F. Athy in the 1930s, based on a series of simplifications about the mechanical problem that may restrict its application in scenarios where geological processes others than one-dimensional compaction are acting. Thus, a constitutive model that accounts for the influence of three-dimensional states of stress and strain on the mechanical behavior of geological materials may represent a more robust solution in BPSM analyses. In that context, this work evaluates the ability of an alternative representation (Modified Cam Clay Model) to reproduce the mechanical behavior of sedimentary rocks in the deposition and compaction processes observed in BPSM using simplified test cases and Athy's compaction curve as reference.

Investigating key factors of intelligent compaction for asphalt paving: A comparative case study

As an innovative technology, intelligent compaction (IC) needs an in-depth investigation to improve its applicability for asphalt compaction. For the same asphalt base layer compaction, the potential for utilizing Compaction Meter Value (CMV) to evaluate the asphalt compaction varies based on different underlying support. In this study, the key factors of IC technology for asphalt compaction including underlying support, asphalt temperature, and roller parameters were investigated based on two asphalt base layer projects conducted in the United States and China. It was found that different underlying supports can affect the sensitivity of CMV with respect to the asphalt modulus. For the project with an untreated aggregate base layer, the lack of relevance between CMV and asphalt temperature (R2 = 0.0) proves that the CMV in this case mainly reflects the stiffness of the underlying support. However, the relevance between CMV and asphalt temperature is significant (R2 = 0.35 ∼ 0.72) for the project with a cement stabilized aggregate base layer, reflecting that CMV is sensitive to the change of asphalt modulus. Changes of roller parameters can also affect the correlation between CMV and asphalt modulus. Based on the analysis, it is suggested that establishing a series of detailed compaction curves corresponding to temperature could be the key to enhance the IC asphalt compaction.