Properties Of Compacted Soils Research Articles

CBR Correlation with Index and Compaction Properties of Soil

California Bearing Ratio (CBR) is widely used in the design of roads to indicate the bearing capacity of subgrade as well as each layer of the flexible pavement system. However, the procedure for obtaining the CBR value is often considered complicated and time-consuming, thus; some correlations were developed by previous researchers between the CBR value and index properties such as fine content (w), liquid limit (LL), and plasticity index (PI) of the soil, as well as between the CBR value and compaction properties i.e., optimum moisture content (OMC) and maximum dry density (MDD). This study was conducted to evaluate the applicability of the published correlation on the soil obtained in Palembang and the surrounding areas. In this case, 30 sets of secondary data were collected and selected from past projects. In addition, laboratory tests were conducted on five sets of samples for verification purposes. The laboratory tests include a wet sieve to obtain fine content, Atterberg limits to determine soil’s plasticity, and a standard Proctor test to obtain OMC and MDD. Analysis shows that with modifications, some published correlations could be used to predict unsoaked and soaked CBR values for soils in Palembang. Furthermore, two correlations were developed between the CBR values and compaction properties of the soil based on statistical analysis of the collected data.

A Simplified Procedure to Estimate Effects of Soil Lumps on Some Properties of Compacted Soil

The present research attempt to propose a testing methodology, some preliminarily test results and data interpretation method to estimate effects of soil lumps on properties of compacted soil. Lumps of soil with various dimensions, from smaller than 1.18 mm to 37.5mm, are prepared and each dimension of soil lump is compacted with OMC to a cylindrical soil sample which is then compared with the sample obtained from conventional standard compaction test in which all soil lumps are thoroughly broken up before mixing with OMC (ASTM D698 – 12). Therefore effects of the soil lumps with several dimensions on moisture content distribution, dry density and strength of the compacted soil can be investigated. Eventually, data interpretation to estimate effects of lumps on properties of compacted soil is introduced for further application of soil compaction quality control

Compactabilidade de solos coesos dos tabuleiros costeiros do nordeste sob influência de água residuária de mandioca

ABSTRACT Consolidation tests give important insights into soil compactibility. However, it requires equipment that is not always available. The costal tablelands in Northeastern Brazil have extensive areas of cohesive soils where compaction is an expressive problem. This region is a prominent producer of food and fibers with cassava as one of the leading products. Part of the cassava is used for flour production, generating wastewater, which is often applied as organic fertilizer to the soil. This can affect the compaction properties of soil due to its dispersing-flocculating characteristics. Uniaxial-compression tests and mathematical models are the primary methods to measure or estimate soil compaction. This study measured soil compression with a centrifuge, seeking a simple-quick method. We used specific loads (stainless-steel cylinders: mass) and increasing G-force (weight) to simulate the pressure on the samples used in most consolidation apparatus. Soils, sampling layers, and the presence of cassava wastewater (manipueira) were also compared since they may affect compactibility-related attributes. Samples of a Gray Cohesive Argisol and Dystrocohesive Yellow Latosol (depths of 0-0.20 m and 0.20-0.40 m) from the Tablelands of the state of Bahia, Brazil, were used. Wastewater affected water-dispersible clay, aggregate stability, pH, ∆pH, flocculation, and organic carbon, thus influencing compactibility but not the moisture and maximum density measured by the Proctor test. Centrifugation caused lower density than the Proctor test. The results were close to those estimated by the mathematical models, thus considered a promising alternative to estimating consolidation. This method also provides insight into the root growth-limiting density and the moisture content that leads to it.

Discussion: Predicting compaction properties of soils at different compaction efforts

Discussion: Predicting compaction properties of soils at different compaction efforts

Detecting spatial variability of soil compaction using soil apparent electrical conductivity and maize traits

AbstractSoil compaction is one of the main limiting factors for sustainable agriculture. Efficient methods for detecting the distribution of soil compaction at a field scale are urgently needed in precision agriculture. We evaluated the possibility to detect soil compaction from measurements of apparent electrical conductivity (ECa) by using electromagnetic induction (EMI) and maize traits at a ~1 ha field parcel. The soil was Luvisol, and soil compaction‐related properties, such as bulk density (BD), penetration resistance (PR), soil texture, soil salinity, soil moisture and maize traits, were measured at ten locations across the field based on ECa variability. In this site‐specific study, no good correlation between soil compaction properties (i.e. BD and PR) and ECa was found but soil clay content was positively related to ECa in the sublayer (P = 0.08). The variation in the unmanned aerial vehicle (UAV)‐derived maize canopy height was significantly negatively correlated with soil compaction and a negative relationship between dry above‐ground biomass and BD and PR existed at 25–50 cm layer. In addition, ECa and UAV‐derived maize canopy height was negatively correlated (Spearman's rank correlation coefficients of −0.67 in the 0–25 cm layer) under the rather dry conditions prevailing during this study. Overall, as could be expected, detecting soil compaction with ECa was challenging under heterogeneous terrains, while maize traits had a better correlation with spatial variability of soil compaction. Owing to its sensitivity to the integral variation of multiple soil properties, ECa was a good indicator of maize canopy height.

Predicting compaction properties of soils at different compaction efforts

Soil compaction is a key operation regarding the construction of, for example, railway and road embankments, earth dams and clay liners for waste disposals. Standard and modified Proctor tests are employed to obtain the optimum compaction properties at different energy levels. The choice of compaction technique depends on the type of compacted earthworks to be carried out. In practice, it is possible that the same material deployed in the past for a certain engineering work has to be reused in different work, requiring a different compaction energy. As compaction tests are time consuming, a preliminary assessment of optimum compaction properties from one energy level to another can be useful in geotechnical applications. Two empirical models linking different compaction energies are presented in this paper. Using the liquid limit, the possibility of evaluating the optimum moisture content and maximum dry unit weight from modified properties was investigated. A database of 49 data sets from the literature was used to build a model, which was validated with 14 other independent data sets. Statistical analysis was carried out and Monte Carlo simulations were also performed. This paper provides an update on knowledge regarding compaction at different energy levels using a larger database.

Prediction of Compaction Parameters from Soil Index Properties Case Study: Dam Complex of Upper Atbara Project

Soil compaction involves concretion and a relative variation of physical and mechanical properties of soils. Determining laboratory compaction characteristics such as maximum dry density (MDD) and optimum moisture content (OMC) could be vital work to manage field compaction for all earth-works structures. There are 3 necessary Atterberg limits: plastic limit (PL), liquid limit (LL), and Plastic Index (PI). The most objective of this paper is to get the relationships between compaction parameters and their Atterberg limits of fine-grained soils and to create reliable correlations. For conducting this work, forty samples are collected from a borrowed space that is found at the bank upstream of Setit watercourse. The tests of soil samples were executed at the laboratory of Dam complex of the upper Atbara project. To perform this work, the Microsoft Office Excel software was exercised for the regression analysis of compaction parameters and Atterberg limits. Several trials were created to get the relationships between Atterberg limits (LL, PL, and PI) with the compaction parameters (OMC, and MDD). From the regression analysis, it's found that OMC and MDD have an excellent relationship with the LL other than the PL and PI. It had been observed that the (OMC) has an excellent correlation with (MDD) other than the remaining parameters. From this work, it's going to be suggested to use the soil compaction properties and Liquid Limits' correlations attributable to their reliable results compared with the other correlations. The result of the paper may be helpful and applicable in numerous civil engineering sectors, particularly for preliminary investigations and prefeasibility studies of various civil engineering works.

Review of soil compaction: History and recent developments

Abstract Compaction of soils is a major construction activity in civil engineering, and particularly in the transport industry. This paper presents a brief historical account of soil compaction development with special emphasis on transport geotechnics. Proctor’s curves and California Bearing Ratio (CBR) are reviewed and the associated state-of-the-art field specifications are discussed. The properties of compacted soil and the typical behaviours of compacted fill under in-service conditions are discussed. Intelligent compaction is being increasingly adopted with a view to increased uniformity in compaction, lack of which is a major cause of premature pavement failure. However, it needs further advancement to make it more intelligent. The current state of the ability to predict compacted soil behaviour is reviewed and the limitations are identified. Of more recent developments, interpretation of compacted soil behaviour with a three-dimensional state boundary surface is highlighted, and simplified behaviour can be interpreted and used in routine practice. Areas that need further advancements in theory and practice are highlighted.

Advanced Mathematical Models to Predict the Compaction Properties of Coarse-Grained Soils from Various Physical Properties

An essential task in the process of construction is the determination of compaction properties of soils. Many years of laboratory test experience strengthen our belief in the existence of predictive equations that govern the compaction characteristics of soils. An advanced mathematical model developed in this research in order to uncertain the governing equations. An advanced mathematical model developed in this research in order to uncertain the governing equations. Through a comparative study among a Multiple Linear Regression (MLR) model, an Artificial Neural Network (ANN) model, Extreme Learning Machine (ELM) and a Support Vector Machine (SVM) model, the best predicting model was determined. For this purpose, Six hundred and six (606) samples collected and split into a dataset used for training the models and another used for validation of the derived model. 8 neural networks with a varying number of hidden layers and a varying number of nodes in hidden layers were employed. In ELM 1 hidden layer with varying number of units were employed. It was found that the equations derived from the ELM models described the relationship with superiority over multiple regression, ANN and SVM models for Maximum Dry Density and MLR models described the relationship with superiority over ANN, ELM and SVM models for Optimum Moisture Content.

Toward a better understanding of the effects of cement treatment on microstructural and hydraulic properties of compacted soils

This study deals with the problem of the experimental characterization of cement-treated compacted soils in terms of microstructural and hydraulic properties. Some tests are conducted on two different types of soil: silty sand and clay as fine soils and gravelous sand and alterite as granular soil. Some samples are mixed with 5% of cement and compacted at different levels (i.e., 85%, 95%, 100% and 105% of the maximum dry density, respectively, as achieved using the standard compaction method). The results of the mercury intrusion porosimetry (MIP) tests performed on these cement-treated soils reveal significant changes as regards macropores due to the combined effects of treatment and compaction. Consequently, a decrease in the permeability is clearly observed for all the tested soils when the degree of compaction increases. This decrease is significantly greater in fine soils, which are more sensitive to compaction effects than granular soils.

Assessment of soil compaction properties based on surface wave techniques

Soil compaction plays an important role in every construction activities to reduce risks of any damage. Traditionally, methods of assessing compaction include field tests and invasive penetration tests for compacted areas have great limitations, which caused time-consuming in evaluating large areas. Thus, this study proposed the possibility of using non-invasive surface wave method like Multi-channel Analysis of Surface Wave (MASW) as a useful tool for assessing soil compaction. The aim of this study was to determine the shear wave velocity profiles and field density of compacted soils under varying compaction efforts by using MASW method. Pre and post compaction of MASW survey were conducted at Pauh Campus, UniMAP after applying rolling compaction with variation of passes (2, 6 and 10). Each seismic data was recorded by GEODE seismograph. Sand replacement test was conducted for each survey line to obtain the field density data. All seismic data were processed using SeisImager/SW software. The results show the shear wave velocity profiles increase with the number of passes from 0 to 6 passes, but decrease after 10 passes. This method could attract the interest of geotechnical community, as it can be an alternative tool to the standard test for assessing of soil compaction in the field operation.

Correlation of Maximum Laboratory Dry Density and Optimum Moisture Content of Soil with Soil Parameters

The correlation of compaction properties of soil with various soil parameters are investigated in this study. These correlations were derived through graphically analysis. Soils samples were collected from ten cities of Punjab, Pakistan. The maximum dry density and optimum moisture content (O.M.C) are the compaction properties of soil, which is related to many of soil parameters that included Atterberg index (liquid limit (LL), plastic limit (PL), and plastic index (PI)), percentage of fines (silt, sand), coefficient of uniformity (Cu) and coefficient of curvature (Cc). The relationship of maximum dry density and percentage of fines (silt, sand), optimum moisture content and percentage of fines are the most important relations. These relationships provide a key role in the construction of highways. The effect on the maximum dry density of various kinds of soil, quantity of fines, and types of fines and distribution of the grain size become decided through a sensitivity evaluation that measured the effect of those parameters on acquired maximum dry density By measuring these correlations some unique behavioral developments have been analyzed and we conclude that properly-graded soils have better dry density than poorly graded when the soils have the equal fines content, further it became discovered that plastic fines have a tendency to boom the maximum dry density.

Successional biocrust stages on dead shrub soil mounds after severe drought: Effect of micro-geomorphology on microbial community structure and ecosystem recovery

A drought- induced massive shrub death event was observed in a semi-arid region of the Negev Desert, leaving bare soil mounds in place. Hypothesizing that the absence of shrubs would allow biocrust expansion to cover the bare soil mounds, we followed the development of biocrusts on the south and north-facing slopes of the soil mounds over three years. Only after six years, when the mounds were totally flattened, were the water infiltration capacity and soil compaction properties of the developing biocrusts similar to those of the surrounding mature biocrusts. The prokaryotic community structure was exposed by pyrosequencing of 16S rRNA gene amplicons. A principal component analysis indicated that the development of microbial community on the soil mounds was affected at multiple scales, including biocrust successional stage, seasonal effect and the micro-geomorphology of the mound (north vs. south slopes). While the phototroph community structure was most associated with the biocrust successional stage, the heterotroph community structure was mostly season-associated. Compared to the north slope, the south slope exhibited delayed development in all determined parameters; with the addition of lately observed establishment of new shrubs in this site, the results emphasize the importance of the micro-geomorphology in the recovery of the affected ecosystem.

Properties of compacted soil as a function of dry density and the degree of saturation

Properties of compacted soil as a function of dry density and the degree of saturation

Inverse estimation of soil hydraulic properties under oil palm trees

Canopies of forested and agricultural ecosystems can significantly alter rainfall patterns into separate stemflow and throughfall areas. These two areas often have also different organic matter contents and soil compaction properties, and hence also soil hydraulic properties, thus causing further differences in the local infiltration rates close to and away from trees. In this study we analyzed possible differences in the unsaturated soil hydraulic properties of the stemflow and throughfall areas below an oil palm tree. Tension disc infiltrometer experiments were carried out underneath the canopy and in the interspace area of an oil palm tree plantation at successive tensions of 5, 2, and 0cm. Soil hydraulic properties were estimated inversely from the measured data using the HYDRUS-2D/3D software package. Four van Genuchten soil hydraulic parameters (i.e., the residual water content, θr, the shape factors α and n, and the saturated hydraulic conductivity, Ks) were optimized. Saturated water contents, θs, were fixed at their laboratory-measured values. Initial estimates of the optimized parameters were set according to Wooding's solution, which ensured rapid convergence of the inverse solution. The stemflow and throughfall regions exhibited contrasting hydraulic properties as indicated by the estimated hydraulic parameters. Values of θs, α, n and Ks for the stemflow area were all found to be higher as compared to those of the throughfall area. The inverse solution using tension disc infiltrometer data proved to be very useful for rapid characterization of hydraulic properties of soil under the oil palm trees.

Spatial variability in soil compaction properties associated with field traffic operations

Current agricultural practices using heavy machinery are associated with soil compaction.This study was carried out to determine the effects of field traffic operations on the changes in spatial variability of soil aggregate stability (AS), bulk density (BD), total porosity (TP), penetration resistance (PR) and volumetric moisture content (VMC) in the various soil depths as indicators of soil compaction. Soil samples to determine AS, BD and VMC were collected and field measurements of PR at 0–10, 10–20 and 20–30cm depths were taken, respectively from geo-referenced intersections with 25×20m intervals before and after traffic operations. Total porosity was calculated using bulk and particle density values. Both disturbed and undisturbed soil samples were taken from each depth (0–10, 10–20 and 20–30cm) of the intersection points of the grid system, before and after traffic operations. As a total 360 soil samples were taken. Kriging analysis was performed to create spatial variability distribution maps of AS, BD, TP, PR and VMC with 1×1m intervals within the field. Results showed that the AS, BD, TP, PR and VMC were significantly influenced by traffic operation and depth. More significant effects on the AS, BD, TP, PR and VMC were produced at the 0–10cm depth than at the 10–20 and 20–30cm depths. For 0–10, 10–20, and 20–30cm depths, while BD increased in the rates of 14.5, 5.3 and 6.7% it caused a decrease in TP at the rates of 12.1, 5.5 and 6.6%, respectively. Averaged across depth, while the initial AS was 54.1% it decreased to 41.9% with traffic operation. Averaged across depth, the BD (8.6%), PR (43.3%) and VMC (12.7%) increased, with an associated decrease in AS (22.6%) and TP (8.9%) after traffic operation, as compared to their initial values measured before traffic operation. Spatial distribution patterns of AS, BD, TP, PR and VMC values following traffic operation showed significant differences compared to those values of before traffic operation. Among the indicators of compaction, the AS and PR was greatly affected by the traffic operations as compared to BD, TP and VMC. Knowledge on the spatial distribution can be used for development management options that minimize production risks and the harmful impact of traffic.

Swell and shrinkage characterizations of unsaturated expansive clays from Texas

Expansive soils have long been recognized as problematic because they cause failure to civil structures constructed above them. The main problem of these soils can be attributed to poor understanding of the volume changes caused by moisture fluctuations. Current swell and shrinkage characterization models are limited by both the lack of standardized tests and tests that employ volume changes in uniaxial direction. In the present research, a comprehensive laboratory investigation was undertaken to study the volume change related swell–shrinkage behaviors of five different types of expansive clayey soils sampled from various regions in Texas, USA. Extensive experimental programs consisting of basic, chemical and mineralogical soil properties were first determined. Three-dimensional free swell and shrinkage tests were performed on all soils at various compaction moisture content conditions. Soil–water characteristic curves (SWCCs) of all test soils were determined by studying the suction potentials of these soils over a wide range of moisture contents. Volume change measurements of soils showed a good correlation with soil properties, including plasticity and soil compaction properties. SWCC results also showed a clear variation in SWCC profiles of soils with respect to soil plasticity. Overall, a large database of soil properties was developed and is presented here. It includes physical and mineralogical properties, as well as engineering swell, shrinkage and SWCC test results.

Influence of Soil Suction on Small-Strain Stiffness of Compacted Residual Subgrade Soil

The small-strain stiffness of compacted residual lateritic subgrade soil was determined. A bender element apparatus and the filter paper method were integrated to develop a systematic testing procedure to investigate the influence of matric suction on small-strain stiffness, including small-strain shear wave velocity and small-strain shear modulus, with different wetting paths. Soil specimens were compacted at three moisture contents (optimum moisture content, dry of optimum, and wet of optimum), then wetted to various moisture contents by using an environmental simulation apparatus developed to simulate in-service moisture conditions. Test findings indicate that specimen moisture contents increase gradually and finally attain equilibrium in the wetting process. Suction decreases with increasing moisture content and degree of saturation; consequently, small-strain shear wave velocity and small-strain shear modulus decrease. The specimens compacted at dry of optimum have a much lower small-strain shear wave velocity and small-strain shear modulus than specimens compacted at wet of optimum. Nevertheless, the small-strain shear modulus exhibits higher linearity with matric suction than with moisture content. Results indicate that matric suction is a key parameter for evaluating the dynamic properties of compacted soil.

Analysing the form of the confined uniaxial compression curve of various soils

The soil compaction by vehicles is a major factor responsible for physical degradation of cultivated soils. Uniaxial confined compression tests are usually performed to characterise the compaction properties of soil. Two main forms of compression curve have been observed: (i) the bi-linear curve having an elastic rebound curve at low stresses and a linear virgin compression curve at higher stresses; (ii) the S-shaped curve having deviation of the virgin compression curve at high stresses. In the present work, uniaxial confined compression tests were performed on four soils having various textures and different plasticity. Tests were performed on undisturbed and remould samples, at various initial dry bulk densities and water contents. The S-shaped compression curves were observed more frequently when the clay content and/or the initial water content were high. In addition, the S-shaped curves were observed more frequently on remould soils than on undisturbed soils. The difference between the compression of air-filled pores and that of meso-pores storing water subjected to high capillary forces could explain the observed S-shaped curves.

Compaction characteristics of granular soils in United Arab Emirates

Most of the topsoils encountered in United Arab Emirates and in the Arabian Peninsula are granular soils with small percentages of silt and clay. Determination of the compaction characteristics of such soils is an essential task in preparing for construction work. The accumulating experience over many years of soil testing in our laboratories suggested that there exists an underlying trend that governs the compaction characteristics of such soils. As such, a study was undertaken to assess the compaction characteristics of such soils and to develop the governing predictive equations. For the purposes of this study, 311 soil samples were collected from various locations in the United Arab Emirates, and tested for various including grain-size distribution, liquid limit, plasticity index, specific gravity of soil solids, maximum dry density of compaction, and optimum moisture content following ASTM D 1557-91 standard procedure C. Following the development of the predictive equations, a new set of 43 soil samples were collected and their compaction results were used to test the validity of predictive model. The range of variables for these soils were as follows: percent retained on US sieve #4 (R#4): 0–68; Percent passing US sieve #200 (P#200): 1–26; Liquid limit: 0–56; Plasticity index: 0–28; Specific gravity of soil solids: 2.55–2.8. Based on the compaction tests results, multiple regression analyses were conducted to develop mathematical models and nomographic solutions to predict the compaction properties of soils. The results indicated that the nomographs could predict well the maximum dry density within ±5% confidence interval and the optimum moisture content within ±3%.