Lime-treated Soil Research Articles

Aggregate size effect on the water retention properties of a lime-treated compacted silt during curing

The main drying paths of the water retention curves of lime-treated soils were measured. Aggregate size effect on the water retention property was emphasised. Four soil powders with different maximum aggregate sizes (Dmax = 5, 2, 1 and 0.4 mm) were prepared and mixed with 2% quicklime (by weight of dry soil). Samples were prepared by static compaction at dry side of optimum water content (w = 17%) with a dry density of 1.65 Mg/m3. Suction measurement was performed by a dew-point hygrometer at different curing periods (t = 7, 28 and 90 days). The results obtained show that: i) aggregate size effect is insignificant on the water retention curve of untreated soil in the studied suction range (ca 500 kPa ~ 55 MPa); ii) lime treatment gradually improves the soil water retention capacity with the increasing of curing time; iii) aggregate size effect on water retention property of lime-treated soil becomes significant in the suction range from ca 860 kPa to 9 MPa on the long curing term: treated soils prepared with smaller aggregate size (S0.4 and S1) have a higher water retention capacity rather than soils prepared with larger aggregate size (S5).

Effects of aggregate size on water retention capacity and microstructure of lime-treated silty soil

Lime treatment is a common technique of improving the workability and geotechnical properties of soils. In this study, the aggregate size effects on the water retention capacity and microstructure of lime-treated soil were investigated. Two soil powders with different maximum aggregate sizes (Dmax = 0·4 and 5 mm) were prepared and stabilised by 2% lime (by weight of dry soil). Soil samples were prepared by compaction at dry side of optimum water content (w = 17%) with a dry density of 1·65 Mg/m3. Suction and pore size distribution were determined after different curing periods. The results obtained show that: (a) the treated soil with smaller Dmax presents relatively smaller modal sizes and lower frequency of macropores (10–330 μm); (b) lime addition effectively improves the soil water retention capacity and decreases both the modal sizes of macro- and micropores gradually over time. Moreover, a higher air entry value and larger water retention capacity were also observed for a smaller Dmax value, in agreement with the pore size distributions.

Shear strength and compressibility behaviour of lime-treated organic clay

Apart from strength characteristics, a review of studies on the compressibility of lime-treated soils is equally important that influenced the stability of soil structures. Due to the fact that no study has been carried out, an investigation on the effects of humic acid on strength and compressibility behaviour of lime-stabilised organic clay is presented in this paper. Unconfined Compressive Strength (UCS) and oedometer tests were carried out at different curing periods of 7, 28 and 90 days. Consolidation data was analysed in terms of changes in void ratio (e), volumetric strain (ε1), compression index (Cc), and coefficient of consolidation (cv) which defines a soil's compressibility. The results showed a similar behaviour when compared to both tests. It can be conclude that the cementation bonding was associated with the fabric arrangement of soil structures.

Mohr–Coulomb failure envelopes of lime-treated soils

The aim of this study is to quantify the influence of amount of lime and porosity in the assessment of the Mohr–Coulomb failure envelope of lime-treated soils based on unconfined compressive strength (σc) and splitting tensile strength (σt) of such materials, without the necessity of carrying out triaxial testing. Based on a previously established concept that the σt/σc relationship is unique for each specific fine-grained soil and lime blend, it is shown that the effective angle of shearing resistance of a given lime-treated soil is independent of the porosity and the amount of lime of the specimen and that effective cohesion intercept is a direct function of σc (or σt) of the improved soil; this in turn depends on the porosity and volumetric amount of lime in the soil–lime blends. Finally, the concepts are successfully tested for clayey sand treated with lime at two distinct curing time periods, considering weak to moderate cementation levels.

Mohr–Coulomb failure envelopes of lime-treated soils

Mohr–Coulomb failure envelopes of lime-treated soils

Permeability of lime- and cement-treated clayey soils

The permeability (k) of lime- and cement-treated clayey soils was investigated in the laboratory by flexible-wall permeability tests and oedometer tests. Test results indicate that for the cement-treated soils (with up to 8% cement content by dry weight), the value of k is almost equal to that of untreated soils under identical void ratio (e) conditions, and the k value decreases significantly when the cement content is higher than 8%. For lime-treated soils, the threshold lime content is about 4%. Investigation of the soil microstructure using the mercury intrusion porosimetry (MIP) test and scanning electron microscope (SEM) imaging indicates that when the cementation products formed by the pozzolanic reaction fill mainly the intra-aggregate pores, the value of k is comparable for the treated and untreated samples. When the cementation products begin to fill the interaggregate pores, the value of k of the treated sample becomes smaller than that of the untreated soil sample under the identical e value condition. An indication that the cementation products have filled the interaggregate pores is the rapid increase in strength of the treated soil.

Aluminium uptake and translocation in Al hyperaccumulator Rumex obtusifolius is affected by low-molecular-weight organic acids content and soil pH.

Background and AimsHigh Al resistance of Rumex obtusifolius together with its ability to accumulate Al has never been studied in weakly acidic conditions (pH > 5.8) and is not sufficiently described in real soil conditions. The potential elucidation of the role of organic acids in plant can explain the Al tolerance mechanism.MethodsWe established a pot experiment with R. obtusifolius planted in slightly acidic and alkaline soils. For the manipulation of Al availability, both soils were untreated and treated by lime and superphosphate. We determined mobile Al concentrations in soils and concentrations of Al and organic acids in organs.ResultsAl availability correlated positively to the extraction of organic acids (citric acid < oxalic acid) in soils. Monovalent Al cations were the most abundant mobile Al forms with positive charge in soils. Liming and superphosphate application were ambiguous measures for changing Al mobility in soils. Elevated transport of total Al from belowground organs into leaves was recorded in both lime-treated soils and in superphosphate-treated alkaline soil as a result of sufficient amount of Ca available from soil solution as well as from superphosphate that can probably modify distribution of total Al in R. obtusifolius as a representative of “oxalate plants.” The highest concentrations of Al and organic acids were recorded in the leaves, followed by the stem and belowground organ infusions.ConclusionsIn alkaline soil, R. obtusifolius is an Al-hyperaccumulator with the highest concentrations of oxalate in leaves, of malate in stems, and of citrate in belowground organs. These organic acids form strong complexes with Al that can play a key role in internal Al tolerance but the used methods did not allow us to distinguish the proportion of total Al-organic complexes to the free organic acids.

Influence of Lime on Shrinkage Behavior of Soils

AbstractDamage due to soil shrinkage is a serious problem in many parts of the world. Lime can significantly improve the performance of soils, both in terms of increase in strength and reduced swelling. However, its efficacy in reducing shrinkage of soils has not been studied much. A series of experiments were conducted to develop an understanding of the shrinkage behavior of lime-treated soils. Six different soils covering wide range of plasticity were treated with varied percentage of lime and curing period. Lime increases the shrinkage limit of soils irrespective of their plasticity characteristics; however, it is more in case of high plastic soils than the low plastic ones. Volumetric shrinkage continued to reduce until about 5% of lime content beyond which further reduction was marginal. Hence 5% of lime can be considered as the optimum lime content giving maximum shrinkage reduction. With lime the shrinkage responses of soils were found to have grown flatter indicating that lime can effectively redu...

Chemical quality of common beans as influenced by genotype and aluminium rates under two soil liming regimes

Soil acidity affects seed yield and crop quality negatively due to aluminium toxicity in most humid tropics where the crop is cultivated for food and cash income by smallholder farmers. This study was conducted to assess the effect of different exchangeable aluminium concentrations on bean chemical quality of two common bean genotypes grown on lime-treated and lime-untreated soils. Factorial combinations of five aluminium rates (0.0, 12.5, 25.0, 50.0, and 100.0 mg Al/ kg soil) and two common bean genotypes (New BILFA 58 and Roba 1) were laid out in a completely randomized design with three replications. For each treatment, four plants were raised per pot in the vegetation hall of Nekemte Soil Laboratory, western Ethiopia. The experiment was established in two sets: lime-treated soil and lime-untreated soil. The results revealed that aluminium toxicity caused major changes in the composition of the common beans. Significant differences (P &lt; 0.01) were found among the different aluminium rates and between the two genotypes for bean crude protein, crude fibre, crude fat, and ash, carbohydrate, calcium, magnesium, and aluminium contents under both liming regimes. The interaction of aluminium and genotype also influenced most of the bean chemical quality attributes negatively. New BILFA 58 (acidic soil tolerant genotype) had better bean chemical quality attributes (except aluminium and condensed tannins contents) than Roba 1 (acidic soil sensitive genotype) under both liming regimes. On the average, lime application increased bean crude protein, crude fat, ash, and calcium contents by 4.1%, 20.7%, 7.9%, and 11.7%, respectively. However, it decreased bean crude fibre and aluminium contents. Bean carbohydrate and condensed tannin contents of the genotypes increased in response to increasing aluminium application under both liming regimes. The total ash, which is an indirect indicator of the mineral content of foodstuffs, was found to be higher for New BILFA 58 than Roba 1 under both liming regimes. In conclusion, the results of this study have demonstrated that increased soil aluminium contents have significant negative effects on common bean quality, but integrated use of tolerant genotypes and application of lime can simultaneously alleviate the problem of low yield and reduced bean nutritional quality of the crop.

Evolution of the properties of lime-treated silty soil in a small experimental embankment

In order to study the evolution of a lime-treated silty soil under in-situ conditions of mixing, laying out, compaction and environment, an experimental dike was built near Rouen, in northwest France; this dike is 25m long, 4m wide at the crest and 1.8m high. While special care was taken to mix the soil and lime very thoroughly, to precisely measure the quantity of water, to compact the soil using a vibrating sheepsfoot roller, the building conditions were those usually used to construct embankments in all other respects. Samples were taken from the dike approximately 1month, 6months and 12months after the completion of the work and underwent triaxial and oedometric testing. To compare the properties of treated soil with those of untreated soil, another smaller “reference” embankment was built nearby under similar conditions with silty soil.Small-strain triaxial tests were performed on unsaturated specimens of treated and untreated soil using an original strain measurement device. The change in axial secant moduli can be described by a power law E=βσ1m, where β is a parameter that depends on curing time and m is nearly constant (m≈0.45).CU and CD large-strain triaxial tests carried out on saturated treated and untreated specimens, consolidated under confining stresses ranging from 10 to 300kPa, showed a definite increase in cohesion as a function of curing time, with nearly unchanged friction angles. The possibility to use a non-linear failure criterion was examined. The compressibility coefficient Ciso, slope of the critical state line (CSL) in the [log(p′), e] coordinate system, is significantly lower in treated than untreated specimens, but its value remains constant whatever the curing time. At the same time, the CSL of the treated specimens is above that of the untreated silt. The brittleness of the material, derived from the peak to residual deviator stress ratio qpeak/qres is the same for treated and untreated specimens and is independent of curing time and confining stress. However, the axial strain corresponding to the peak of CD curves is much higher in untreated than in treated specimens. The permeability of the saturated lime-treated soil (10−9m/s) is the same as that of the untreated soil. The value measured one month after the embankment was constructed, does not change with time or with the confining stress. The results of the present study confirm those of previous studies on laboratory-prepared unsaturated specimens: they have demonstrated the effectiveness of lime-treatment in the much more difficult environment of a real working site and shown that lime-treated samples present a significant gain in their engineering properties, even when saturated, provided that the dosage of lime and water, mixing and compaction conditions are carefully controlled. The new material thus obtained presents lower plasticity, improved workability, increased stiffness and cohesion without any loss of performance in terms of brittleness or permeability.

Experimental Research on the Mechanical Behavior of Lime-Treated Soil under Different Loading Rates

In order to study the mechanical behavior of lime-treated soil under different loading rates, a series of monotonous three-axial compression tests are carried out under different lime contents, different loading rates, and different curing periods. The test results indicate that the lime content can significantly improve the mechanical behaviors of soil, such as shear strength and elastic modulus. On the other hand, three-axial compression test of soil is carried out under the loading rate ranging from 0.1%/min to 8%/min. Experimental results indicate that the mechanical behavior of lime-treated soil is sensitive to loading rate. Besides, the corresponding relationship between internal friction angle, cohesion, lime content, and loading rate is discussed. The results indicate that the loading rate almost has no influence on internal friction angle but significant influence on lime content. Cohesion is affected by lime content and loading rate. Shear strength, elastic modulus, and cohesion all increase with the increase of loading rate. Longer curing period is associated with greater parameter value. Shear strength, elastic modulus, and internal friction angle all firstly increase and then decrease when lime content increases, which all reach the maximum at 6%.

Influence of Compaction Energies on the Strength Characteristics of Lime-Treated Oil-Contaminated Lateritic Soil

Abstract Used lubricating oil–contaminated soil was treated with up to 6 % lime content by dry weight of soil. Specimens of artificially contaminated and treated lateritic soil were compacted using two compaction energies, namely, standard proctor (SP) and West African standard (WAS) or “intermediate.” Samples were subjected to compaction and strength [unconfined compressive strength (UCS) and California bearing ratio (CBR)] tests. The results of laboratory tests show that the strength characteristics of treated soil improved with higher compaction energy. The UCS values increased with increased compaction energy; for instance, for samples containing 2 %, 4 %, and 6 % oil content and treated with 2 % lime content, compacted with SP compaction energy, the UCS values obtained were: 446, 563, and 581 kN/m2. Whereas for samples containing the same mix compacted with WAS compaction energy, the UCS values obtained were: 607, 616, and 625 kN/m2. On the other hand, the peak unsoaked CBR values recorded for the same soil–oil–lime mixtures are 35 %, 27 %, and 19 % for samples compacted with SP energy and 40 %, 30 %, and 30 % for samples compacted with WAS compaction energy.

Free swell potential of lime-treated gypseous soil

Lime treatment generally enhances the geotechnical properties of the soils. However, some studies have reported an adverse effect, especially in the presence of gypsum. To develop an understanding of the underlying mechanisms, a study of fine-grained soil with different amounts of gypsum was carried out. The influence of curing conditions (curing period and curing temperature) and wetting-drying cycles on the swell potential of fine-grained soil with (0, 5, 15 and 25%) gypsum was investigated to assess the long-term behavior of this type of soil (i.e. gypseous soil) when used in the construction of road and pavement structures. Mineralogical and microstructural studies (porosimetry, X-ray diffraction and scanning electron microscopy) were carried out to evaluate the cementitious materials and the presence of ettringite. The results show that increasing the gypsum content decreased the swell potential of the untreated soil samples. On the other hand, the swell potential values of soil samples started decreasing after the first wetting–drying cycle then reached equilibrium. Lime treatment results show that the suppression of swelling in lime-treated soil samples without gypsum was partly lost after the first cycle, especially for short curing periods and for both temperature values (20°C and 40°C), while long-term curing periods (more than 28days) gave good results with respect to the suppression of swell potential values. Lime treatment of gypsum-containing samples showed an adverse effect on swell potential. The swell potential values increased with curing period and curing temperature, due to the formation of ettringite. Lastly, wetting–drying cycles caused an increase in the swell potential values of gypsum-containing samples, cancelling out the beneficial effect of lime treatment to control swell.

Compressibility Behavior of Dunkirk Structured and Reconstituted Marine Soils

Oedometer tests were performed to determine the compression behavior of Dunkirk structured and reconstituted marine soils. The cement-/lime-treated soils can be considered as “artificially structured marine soils” that show “false over-consolidation.” The effect of additive on the compression curves and yield consolidation stress was investigated. For marine soils with a water content of 90.9%, cement content should be larger than 2% to form artificially structured soils. Cementing additive leads to a higher initial void ratio at compression starting point. increases with cement content, but a lime addition higher than 2% can not significantly increase . From the curves, Cc peaks at 4–6 times of and finally stabilizes with higher . For Cc-ωL, Cc-ω0, and Cc-e0, the relationships as Cc = 0.036(ωL − 50), Cc = 0.027(ω0 −50), and Cc = 0.9(e0 −1.48) can be found for structured marine soils. For Cc-ωL of eight clays, the upper and lower boundary can be found and expressed as Cc = 0.015(ωL −19) and Cc = 0.006ωL. To identify the effect of soil structure, the concept of Δe was introduced. Δe increases with until the maximum at , and then decreases with higher . Different intrinsic state lines were found for soils with different additives. Test data of cement-treated reconstituted soils fit the Burland's equations better than lime-treated soils.

Weathering of a lime-treated clayey soil by drying and wetting cycles

Lime treatment induces several time-dependent physico-chemical processes (cation exchange, pozzolanic reactions, etc.) that result in the bonding of soil particles. This treatment can reduce the swelling properties of clays and improve their strength. Nevertheless, these positive effects of lime-treatment could be altered by weathering in the very long term. In this paper, the effects of successive drying/wetting cycles on the hydro-mechanical properties of a lime-treated clayey soil are considered.Quicklime-treated samples were subjected to successive controlled-suction (osmotic technique) drying/wetting cycles; and also severe hydric cycles corresponding to an alternation of oven drying and saturation. The effect of quicklime dosage and curing time were considered. The results show a progressive increase of the swelling properties of the material and a progressive loss of strength with increasing number of drying/wetting cycles. The extent of the degradation is directly related to the amount of added quicklime and the amplitude of the suction cycles. Mercury intrusion porosimetry tests show that successive cycles lead to a progressive change of the micro-fabric, thus explaining partly the degradation of macroscopic properties.This study shows that weathering by successive drying/wetting cycles is likely to significantly alter the properties of a lime-treated soil, thus weathering effects should be accounted for the long term design of treated soil structure.

Assessing Failure Envelopes of Soil–Fly Ash–Lime Blends

AbstractThis study aims to establish the influence of curing time and the amount of lime and porosity in the assessment of the Mohr-Coulomb failure envelope of fly ash–lime-treated soils based on unconfined compressive strength (σc) and splitting tensile strength (σt) of such materials. Founded on the concept that the σt/σc relationship is unique for each specific fine-grained soil, fly ash, and lime blends, it is shown that the angle of shearing resistance of a given lime-treated soil is independent of the porosity and the amount of lime of the specimen and that cohesion intercept is a direct function of σc (or σt) of the improved soil, which depends of the porosity and volumetric amount of lime of the soil–fly ash–lime blends. Finally, the concepts are tested with success for a sandy soil treated with fly ash and lime at distinct curing time periods, considering moderate to strong cementation levels.

Soil Stabilization Using Lime: Advantages, Disadvantages and Proposing a Potential Alternative

This study is an overview of previous studies on lime (quick and hydrated) -treated soil. Lime is the oldest traditional stabilizer used for soil stabilization. The mechanism of soil-lime treatment involves cation exchange, which leads to the flocculation and agglomeration of soil particles. The high pH environment then causes a pozzolanic reaction between the free Ca⁺² cations and the dissolved silica and alumina. Lime-treated soil effectively increases the strength, durability and workability of the soil. Such treatment also improves soil compressibility. A fluctuation behavior was observed on the influence of lime on soil permeability. However, the factors affecting the permeability of the soil-lime mixture should be extensively studied. Nonetheless, lime treatment has a number of inherent disadvantages, such as carbonation, sulfate attack and environment impact. Magnesium oxide/hydroxide are thus proposed as a suitable alternative stabilizer to overcome at least some of the disadvantages of using lime in soil stabilization.

Mohr–Coulomb failure envelopes of lime-treated soils

The aim of this study is to quantify the influence of amount of lime and porosity in the assessment of the Mohr–Coulomb failure envelope of lime-treated soils based on unconfined compressive strength (σc) and splitting tensile strength (σt) of such materials, without the necessity of carrying out triaxial testing. Based on a previously established concept that the σt/σc relationship is unique for each specific fine-grained soil and lime blend, it is shown that the effective angle of shearing resistance of a given lime-treated soil is independent of the porosity and the amount of lime of the specimen and that effective cohesion intercept is a direct function of σc (or σt) of the improved soil; this in turn depends on the porosity and volumetric amount of lime in the soil–lime blends. Finally, the concepts are successfully tested for clayey sand treated with lime at two distinct curing time periods, considering weak to moderate cementation levels.

Multivariate Analysis as a Tool for Indirect Selection of Common Bean Genotypes (&lt;i&gt;Phaseolus vulgaris L&lt;/i&gt;) for Soil Acidity Tolerance under Field Conditions

A field experiment was conducted to evaluate soil acidity tolerance of 25 common bean (Phaseolus vulgaris L.) genotypes on lime-treated and lime-untreated acid soils. The twenty-five common bean genotypes were tested in a randomized complete block design with two replications per treatment in 2009 in western Ethiopia. Morpho-agronomic parameters were recorded to evaluate the genotypes. Multivariate methods, including principal component and cluster analysis were used to assess the patterns of morpho-agronomic variation to group the genotypes into distinct categories. The genotype bi trait (GT) bi-plot was used to identify the best traits that are important to identify tolerant genotype and to know the relationships between traits and genotypes. The principal component analysis indicated that the first three principal components contributed 64.6 and 66.1% of the total variability among the 25 common bean genotypes grown on the lime-untreated and lime-treated soils, respectively. Among the measured traits, plant height, number of pods per plant, days to pod setting, grain yield, days to flowering and maturity, biomass yield, and 100 seed weight were the parameters that most significantly caused the variations among the genotypes. Genotype by trait (GT) bi-plot led to grouping of the tested genotypes into four categories based on PC1 and PC2 values and also enabled to identify traits such as number of pods per plant, plant height, pod length, 100 seed weight, and grain yield, which were found to be the most responsive characters in evaluating the genotypes for tolerance to soil acidity. The cluster analysis led to classification of the 25 common bean genotypes in to four groups, the first group (cluster) of which contained four genotypes of BILFA material (new BILFA 38, new BILFA 58, New BILFA 61, and new BILFA 60) that outperformed genotypes in the other group (clusters) when grown on lime-untreated acid soil. In conclusion, the results of this study have revealed that multivariate analysis can be used as an indirect method of selecting high-yielding common bean genotypes having the most important desirable traits that contribute to soil acidity tolerance.

Stabilization of clay soils using lime and effect of pH variations on shear strength parameters

This paper presents the results of geotechnical and mineralogical investigations on lime treated clay soils from Hamedan City, Iran, and effects of pH variations on their shear strength parameters. Initially, lime was added in different percentages and laboratory experiments were conducted after curing times. The results indicate that these soils can be stabilized satisfactorily with the addition of about 7 % lime. Also, investigation of the relationship between lime-treated geotechnical properties and lime percentage and curing time demonstrates high regression coefficients for the proposed relationships. Several laboratory tests were performed on treated and untreated clay soils with lime mixed with pore fluids with different pH values including 3, 5, 7 and 9. The results of shear strength tests indicated that the undrained shear strength parameters for untreated clays increased considerably if the pore fluid had a high pH (pH = 9) or a low pH (pH = 3). It can also be found that for lime-treated soils, maximum cohesion and friction angle values are achieved at pH = 9.