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The type of soil known as expansive soil is capable of changing its volume through swelling
and contracting. These types of soils are mostly composed of montmorillonite, a mineral with the
capacity to absorb water, which causes the soil to heave by increasing its volume. Due to their capacity
to contract or expand in response to seasonal fluctuatio...
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... Notably, the highest strength for all lime concentration levels is consistently observed with longer curing durations. This is because lime serves as a stabilizing agent that enhances the engineering characteristics of soils by boosting their strength and diminishing their compressibility [20,50,51].Etim et al. [52] pointed out that the rise in UCS values mainly resulted from alterations in the microstructure and the creation of cementitious compounds: calcium silicate hydrate (C-S-H) and calcium aluminate hydrate (C-A-H) due to pozzolanic reactions [53], which play a crucial role in strength development, particularly throughout the curing period. Additionally, the curing time permits the lime and clay particles to engage in chemical reactions, leading to the enhanced soil consolidation. ...
This article proposes a predictive model for the compressive strength (UCS) of lime-stabilized clay soils reinforced with polypropylene fibers (PPF) using the extreme gradient boosting (XGBoost) algorithm. The research indicates that the developed model is highly effective and can serve as a reliable tool for anticipating the UCS of these specific soils. A comparison between experimental data and model predictions suggests that it can effectively elucidate the impact of the combined effect of lime and PPF on the compressive strength of clay soils, thus avoiding the need for new experiments to formulate new compositions. Furthermore, a parametric analysis reveals the benefits of fiber incorporation, particularly at an optimum lime content of 6% dosage. The results also show that an optimal fiber content of 1.25% and a length of 18 mm are essential for achieving satisfactory results. These
findings have significant implications for the planning and implementing fibre treatments, allowing for considerably enhancing soil strength. They provide a solid foundation for more precise and effective interventions
in the lime stabilization of clay soils, thus paving the way for more efficient practices in this area of research.
... The results showed that, in addition to the physical characteristics of expansive clay soil that is susceptible to swelling, the steel fiber and plastic waste material considerably improved the soil strength and volume changes. Al-Gharbawi et al. [27] investigated the laboratory study of stabilizing expansive soil using three percentages of lime, cement, and silica fume (5%, 7%, and 9%), and the work used a consolidation test to record the free swell and swell pressure for the untreated and treated soils, and the grouting technique is used as a process that can be applied in the field to maintain the improvement in the bearing capacity. It was determined that, in comparison to virgin soil, soil stabilized with various concentrations of lime, cement, and silica fume shows a reduction in both free swell and swelling pressure of about 65% and 76%, respectively. ...
Expansive clayey soils (CSs) expand and become softer as moisture content increases, but they get harder and stronger as they dry out. The earth’s swelling and shrinkage characteristics under varying moisture conditions make roads built on expansive CS, in particular, vulnerable to early degradation. In this investigation, coffee husk ash (CHA), gypsum, and a blend of the two additives (G-CHA) were used in experimental tests to treat expansive CS. This study aims to evaluate experimentally the potential of expansive soil stabilization using different additives: CHA, gypsum, and a combination of gypsum and CHA. Five different percentages of CHA (5%, 10%, 15%, 20%, and 25%), three percentages of gypsum (3%, 6%, and 9%), and variable percentages of their combinations were used to stabilize the soil for pavement subgrade application. Atterberg limits, compaction, linear shrinkage (LS), swelling, unconfined compressive strength (UCS), and California bearing ratio (CBR) tests were performed on treated and virgin soil specimens at 3, 7, 14, 28, and 56-day curing times. Results showed that CHA additives effectively reduced the plasticity, LS, and swell potential in addition to increasing the maximum dry unit weight, UCS, and CBR. It was determined that the UCS and CBR values for the 6% stabilized gypsum soil increased by 28.95% and 19.54%, respectively, and reduced by 41% of the plastic index parameter after the addition of 15% CHA. Based on the evaluation of the results, an optimum mixture of 6% gypsum and 15% CHA (SG6C15) stabilized soil can be used in pavement subgrade applications as it achieved the minimum strength target. The performance of CHA-treated samples as subgrade material is superior to that of untreated virgin soil. Because of the stronger subgrade, smaller pavement layers result in a thinner pavement structure.
... During road construction projects in southern Brazil, encountering unsuitable soils along the alignment that cannot serve as subgrade due to their inadequate properties, which fail to ensure stability for the pavement structure, is a common occurrence [1]. Lime in soils, especially clayey soils, leads to a decrease in the liquid limit (L.L.), an increase in the plastic limit (P.L Consequently, this leads to a reduction in the plasticity index (P.I.)), and a decrease in the expansion percentage [2]. While there are instances where the application of lime to fine soils decreases density, it is noteworthy that lime substantially augments the soil's bearing capacity and enhances its shear strength [3]. ...
... Laboratory investigations have illustrated that proper incorporation of lime into soils improved its strength and alleviate some undesirable soil properties such as reducing their shrinkage and swelling potential (Khemissa and Mahamedi 2014;Yi et al. 2015;Ahmed et al. 2020;Aldaood et al. 2021;Al-Gharbawi et al. 2023). Abdi et al. (2021) examined the effects of using lime on the compressive and shear strength properties of kaolinite clay reinforced with fibers. ...
With civilization and urbanization growth, appropriate construction sites with satisfactory geotechnical conditions become less available. Hence, the chemical stabilization of soil has always been an issue of concern for engineers, applied for ground improvement. The present article discusses the influence of metakaolin on the geotechnical properties of sandy soil treated with lime. For this purpose, Proctor and Direct Shear tests were performed to study the mechanical behavior of both untreated and treated soil specimens. The lime in percentages of 3, 6, 9, and 12% by dry weight of sand was utilized, and the metakaolin was added to partially substitute this stabilizer by 10, 20, and 30% of its weight. The results indicated that the inclusion of lime increased the maximum dry unit weight and decreased the optimum moisture content of the soil. While the metakaolin addition slightly augmented the moisture content of the lime-soil mixtures and improved their maximum unit weights at high contents. The research findings showed that for all the stabilizer contents, the shear strength and shear strength parameters of the soil were improved. Yet, the highest improvement was detected when lime was partly replaced by the metakaolin admixture for some contents. The brittleness index of the soil mixtures augmented with the incorporation of lime or L-MK and reduced by increasing the normal stress.
... The finer the grain size of the soil, the smaller the pore size, and the more pores are almost completely filled with adsorbed water, the better the conditions for the formation of separated ice lenses and the formation of freeze-thaw effects. Poorly expansive soils (also referred to as doubtful soils) contain about 20-30% of particles smaller than 0.05 mm and about 3-10% of particles smaller than 0.002 mm [45][46][47]. Table 2 shows the accepted general division of soils into four groups in terms of their susceptibility to the phenomenon of freeze-thaw effects [48]. Table 2. General classification of soil types with regard to the phenomenon of freeze-thaw effects (symbols of soil names according to [43]). ...
This paper presents the results of a test cycle of two types of silty sand (siSa) with different contents of fine fractions. Fine fractions are understood as soil grains with a grain diameter of less than 63 µm (as the sum of silt and clay fractions). The soils tested had a content of fine fractions of fSi+Cl,1 = 15.14% and fSi+Cl,2 = 20.48%, respectively, before the study. Changes in the content of these fractions after the experiments were analyzed. These experiments consisted of dynamic bar projectile impact loading, and a split Hopkinson pressure bar (SHPB) test stand was used in the study. Changes in the granulometric composition of the silty sands studied were carried out in a laser particle size analyzer, allowing measurement of fractional content in the grain size range from 0.01 µm to 3500 µm. As a result, a summary of changes in soil grain size curves in the range of fine fractions was compiled. Repeated trends were observed in the changes in the granulometric composition of the soil samples as a function of the moisture content of the soil sample (w1 = 0%, w2 = 5%, w3 = 10%, and w4 = 15%) and the impact velocity of the loading bar projectile for SHPB pneumatic launcher pressures (p1 = 1.2 bar → v1 = 12.76 m/s, p2 = 1.8 bar → v2 = 17.69 m/s and p3 = 2.4 bar → v3 = 21.32 m/s). The influence of the initial moisture content of the investigated soil on the value of the optimum moisture content obtained during its dynamic compaction was discussed. The trend in the behavior of the change in the granulometric composition of the tested samples was determined, taking the value of the initial moisture content of the soil in relation to the optimum moisture content of the reference sample as a reference. The largest percentage change in granulometric composition through an increase in the value of the silt and clay fraction relative to the reference sample fSi+Cl for both types of silty sand tested occurs for the same moisture content variant w2 = 5%–for soil fSi+Cl,1 = 15.14% there is an increase in the fine fraction of 11.08% and for soil fSi+Cl,2 = 20.48% there is an increase in the fine fraction of 15.17%. In general, it can be seen that more silty soil is more strongly susceptible to the phenomenon of grain crushing for moisture content w1 = 0% and w2 = 5% less than its optimum moisture content wopt,1 = 8.70%. In contrast, less silty soil is more susceptible to the phenomenon of grain crushing for moisture contents w3 = 10% and w4 = 15% greater than its optimum moisture content wopt,2 = 9.20%. The presented dynamic physical phenomenon of soil behavior is crucial during explosive and impact impacts on structures made of soil, e.g., as ground protection layers.
Expansive soils are susceptible to significant volumetric changes due to the fluctuating moisture levels caused by the infiltration and evaporation of water. This has often resulted in destructive consequences for the structures they support. Various stabilization methods were developed and adopted to enhance their properties and make them suitable for construction purposes. Traditional stabilizers have an adverse impact on the ecosystem by releasing harmful greenhouse gases in the atmosphere and leaching of toxic chemical compounds into the groundwater. Hence, in the past few decades, research on soil stabilization has mainly focused on the utilization of various chemical additives that are environmentally friendly and durable for a longer period of time. This paper is aimed at providing a state-of-the-art review of some of the recent, emerging, and sustainable chemical additives for improving the engineering properties of expansive soil. The efficiency of various additives categorized under industrial by-products, synthetic polymers, biopolymers, geopolymers, and enzymes is discussed here. First, the interaction mechanism between different chemical additives and soil particles during the stabilization process is reviewed. Then, the effect of these additives on some of the crucial geotechnical parameters of expansive soils is discussed in detail. Emphasis is placed on the plasticity characteristics, swell–shrink behaviour, unconfined compressive strength, and compaction properties of expansive soils. The paper also comments on the challenges involved in the utilization of these additives for practical applications. Laboratory test results for various stabilized soils are interpreted by understanding the stabilization mechanism for their successful field application in the future.
