Showing papers on "Soil stabilization published in 2022"

Clayey soil stabilization using alkali-activated volcanic ash and slag

Abstract: Lime and Portland cement are the most widely used binders in soil stabilization projects. However, due to the high carbon emission in cement production, research on soil stabilization by the use of more environmentally-friendly binders with lower carbon footprint has attracted much attention in recent years. This research investigated the potential of using alkali-activated ground granulated blast furnace slag (GGBS) and volcanic ash (VA) as green binders in clayey soil stabilization projects, which has not been studied before. The effects of different combinations of VA with GGBS, various liquid/solid ratios, different curing conditions, and different curing periods (i.e. 7 d, 28 d and 90 d) were investigated. Compressive strength and durability of specimens against wet-dry and freeze-thaw cycles were then studied through the use of mechanical and microstructural tests. The results demonstrated that the coexistence of GGBS and VA in geopolymerization process was more effective due to the synergic formation of N-A-S-H and C-(A)-S-H gels. Moreover, although VA needs heat curing to become activated and develop strength, its partial replacement with GGBS made the binder suitable for application at ambient temperature and resulted in a remarkably superior resistance against wet-dry and freeze-thaw cycles. The carbon embodied of the mixtures was also evaluated, and the results confirmed the low carbon footprints of the alkali-activated mixtures. Finally, it was concluded that the alkali-activated GGBS/VA could be promisingly used in clayey soil stabilization projects instead of conventional binders.

Stabilization of expansive soils using chemical additives: A review

Abstract: Volume instability of expansive soils due to moisture fluctuations is often disastrous, causing severe damages and distortions in the supported structures. It is, therefore, necessary to adequately improve the performance of such soils that they can favorably fulfil the post-construction stability requirements. This can be achieved through chemical stabilization using additives such as lime, cement and fly ash. In this paper, suitability of such additives under various conditions and their mechanisms are reviewed in detail. It is observed that the stabilization process primarily involves hydration, cation exchange, flocculation and pozzolanic reactions. The degree of stabilization is controlled by several factors such as additive type, additive content, soil type, soil mineralogy, curing period, curing temperature, delay in compaction, pH of soil matrix, and molding water content, including presence of nano-silica, organic matter and sulfate compounds. Provision of nano-silica not only improves soil packing but also accelerates the pozzolanic reaction. However, presence of deleterious compounds such as sulfate or organic matter can turn the treated soils unfavorable at times even worser than the unstabilized ones.

Soil stabilization

Abstract: Soil stabilization involves the improvement of soil properties by implementing chemical and mechanical techniques. Binders such as cement and lime enhance stabilization in soils, developing their engineering properties and generating an improved construction material. The current book chapter presents a critical review study regarding the performance of pulverized fuel ash (PFA) as a stabilization agent. Results obtained from the extensive literature review are presented considering the utilization of different types of PFA-binders and their effect on toxic metal-leaching, minerals, as well as the mitigation of geotechnical soil defects. Soil contamination, especially by hazardous toxic metals, substantially contributes to environmental pollution. Remediation of contaminated soils is significantly enhanced using PFA binders, whereas their effects on soil remediation present similar results after long-term curing periods. Unconfined compressive strength (USC) exhibits a positive correlation with the increasing PFA-binders and moisture contents, which increases the soil resistance under static load. The current status of the global legislation framework regarding fly ash utilization is characterized by diverse regulations among the countries of America, Asia, and Europe. Therefore barriers need to be overcome to develop a common regulatory global framework that determines the actions of incorporating fly ash in soil stabilization.

Application of response surface method for optimization of stabilizer dosages in soil stabilization

Abstract: The objective of this paper is to optimize the amount of dosage required for soil stabilization. The low plastic soil (LPS) is stabilized using fly ash-based geopolymer, and its performance was measured in terms of unconfined compression strength (UCS). The fly ash to activator ratio (FAR) varies from 0.6 to 2.0, and curing days (CD) (0, 14 and 28 days) are used to stabilize LPS. A mathematical equation was developed using the response surface method based on a face-centered central composite design for experimental results. Furthermore, an optimization study was carried out to find out the optimum dosage for the stabilization of LPS. The analysis is performed through analysis of variance, and it shows that the developed model gives good agreement with experimental results for all the values of FAR and CD, respectively. Based on optimization analysis, the optimized dosage for FAR is 1.5, i.e., fly ash content varies between 20 and 30% and curing days 22.75, which shows the maximum UCS value (1606.14 kPa). It is believed that the proposed optimization approach could be beneficial to the designers or engineers to have a preliminary estimation of strength before testing. The contribution of different parameters toward UCS value is presented in the form of sensitivity analysis. It was observed that curing days impart more contribution toward the higher value of UCS.

Efficient stabilization of soil, sand, and clay by a polymer network of biomass-derived chitosan and carboxymethyl cellulose

Abstract: Biomass-derived polymers are being increasingly utilized as eco-friendly functional materials in fields ranging from medicine and food to agriculture and environmental engineering. In this report, we developed a novel efficient method for improvement of soil materials based on in situ gelation of a polyion complex formed by biomass-derived carboxymethyl cellulose (CMC) and chitosan (CS). Self-organized network of polymer films and microfibers assembled via electrostatic interactions between oppositely-charged polyions interconnects particles of soil material and imparts the resulted composite with a considerable mechanical strength. Treatment of soil even with a high water content (ca. 30%) by a mixture of CMC and CS at m(CMC + CS)/m(soil) ratio of ca. 1% is sufficient to gain up to 150 kPa compression strength that further increases up to ca. 1 MPa after drying. Similar reinforcement effect by CMC-CS complex was observed for sand, and much higher yield strengths were measured for clay. Mechanical properties of soil materials strengthened by CMC-CS complex depended on structure and stability of CMC-CS polyion network and controlled by the polymerization degrees of macromolecules and the charge ratio between them. Being composed entirely of biomass-derived polymers, the proposed soil treatment system is particularly attractive due to environmental friendliness and sustainability and it can be utilized not only for the soil improvement but also for the construction of functional platforms for soil pollution control and remediation.

Evaluation of lateritic soil stabilized with lime and periwinkle shell ash (PSA) admixture bound for sustainable road materials

Abstract: The indiscriminate disposal of periwinkle shells as agricultural waste at landfills has saddled geo-environmental engineers with the responsibilities of reutilizing these wastes as construction materials for dual purpose of soil stabilization and effective waste disposal. In this research, lime and periwinkle shell ash (PSA) under laboratory conditions were effectively utilized in stabilizing lateritic soil so as to validate its potentials for use as pavement layer materials. Lateritic soil treated with lime at 0–8% and PSA at 0–10% (each at 2% increments) by dry weight of soil was evaluated for index properties, maximum dry density (MDD), optimum moisture content (OMC), California bearing ratio (CBRS and CBRU) and unconfined compressive strength (UCS) using the standard Proctor test. The scanning electron microscope (SEM) and Fourier transformation infrared (FTIR) were also used to determine the morphological changes and functional groups in the stabilized soil. There was a general decrease in consistency limits as the stabilizers increased. Furthermore, MDD decreased with increase in OMC. For the UCS test, peak strength of 895, 1810 and 2670.45 kN/m3 (at 7, 14, and 28 days), respectively, occurred at 8% lime/ 8% PSA. The untreated soil with CBRS and CBRU of 4.3 and 11.5% peaked at 79.3 and 91.2% (8% lime/8% PSA), respectively. SEM resulted in the formation of new microstructural arrangements, while FTIR displayed distinctive functional groups as regards their specific bands for the natural and stabilized soil. The study concluded that the inclusion of lime and PSA could be of economic benefits in improving marginal soils.

Experimental Study of Black Cotton Soil Stabilization with Natural Lime and Pozzolans in Pavement Subgrade Construction

Abstract: This study explores the engineering characteristics of Black cotton soil (BCS) stabilized with natural lime, volcanic ash (VA), and their mixtures. Based on the available literature, the stabilization of VA-BCS is limited. Laboratory tests conducted on stabilized BCS include the Atterbeg limits, the proctor test, the swell percent test, and the California bearing ratio (CBR). The results showed that adding VA and lime greatly improves the engineering characteristics of BCS. BCS stabilized with a mixture of VA and lime showed superior results. Adding 3% lime with 20% VA increased natural CBR values 10.76 times, reduced plasticity by 29%, and reduced swell percent by 88%. Stabilized BCS with 3% lime + 20% VA meets the minimum swell, plasticity, and strength requirements; thus, it can be used as an alternative to cutting and filling.

Partial Replacement of Conventional Material with Stabilized Soil in Flexible Pavement Design

Abstract: Due to rapid urbanization and industrialization, the construction of roads increases rapidly for easy and fast transportation. Adequate land is not available everywhere to construct good roads; hence, roads are forcefully built on locally available soil such as loose soil or expansive soil. In this paper, an experimental investigation was carried out on low plastic soil (LPS) to enhance engineering properties by using chemical soil stabilization (fly ash-based geopolymer). The design of flexible pavement thickness was carried out for conventional and stabilized soil material using IITPAVE software as per IRC 37 guidelines. The results show the feasibility of fly ash-based geopolymer significant enhancement of strength were observed in terms of unconfined compressive strength (UCS) for various curing days (0 to 128 days), California bearing ratio (CBR), and Resilient modulus (MR). The microstructural analysis via Scanning Electronic Microscope (SEM) and X-Ray Diffraction Analysis (XRD) was also reveling the formation of geopolymeric gel which leads to the dense matrix to soil mass. The flexible pavement thickness significantly reduces with the application of stabilized low plastic soil. doi: 10.5829/ije.2022.35.05b.07

Low plasticity clay stabilized with cement and zeolite: An experimental and environmental impact study

Abstract: • The effects of cement replacement with zeolite for clay stabilization were studied. • Mechanical, durability, physicochemical and microstructural tests were conducted. • LCA analyses were performed on the binders and their use for road construction. • Porosity parameter was proposed for determining UCS , ALM, consumed energy, and CO 2 emissions. • The durability and mechanical properties of samples having 15% zeolite were higher. To mitigate environmental issues caused by conventional binders and gain superior geotechnical properties, pozzolanic materials can be considered for soil stabilization purposes. Herein, the effectiveness of zeolite for enhanced treatment of cement-stabilized clay was studied by measuring pH, maximum dry unit weight (MDUW), optimum moisture content (OMC), unconfined compressive strength (UCS), and accumulated loss of mass (ALM), as well as carrying out scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses. Then, the life cycle assessment (LCA) analyses were conducted to evaluate the potential environmental impacts of cement and zeolite production and their use as stabilizing agents in clayey soil. The soil was stabilized by 2, 4, 6, and 8% cement contents and 0, 15, 30, 45 and 60% cement replacements with zeolite. Furthermore, 56-day curing time was considered to assure accomplishment of hydration and pozzolanic reactions. Besides, samples were exposed to up to 8 wetting-drying cycles to evaluate durability-based parameters. The environmental impacts of the combination of cement, zeolite, and clay for constructing a one-kilometer pavement subgrade in terms of greenhouse gas (GHG) emissions and energy consumption in production, transportation, and execution were studied using LCA. Finally, Al 2 O 3 , SiO 2 , and CaO components were discussed to react with one another and to participate in the chemical reactions as the active composition (AC). UCS results indicated that up to 15% cement content replacement with zeolite, strength increased whereas it reduced thereafter. UCS and ALM were observed to decrease and increase during wetting-drying cycles, respectively. The efficacy of optimum zeolite percentage was more noticeable in higher cement percentages, both in terms of mechanical and durability tests. LCA confirmed that the efficiency of energy consumption and GHG emissions reduced with increasing zeolite. Also, for the samples containing zeolite and cement, the porosity parameter (n)/AC was nominated as a key controlling parameter for determining the UCS, ALM, consumed energy, and the produced CO 2 . Regarding the experimental program and LCA, the use of zeolite instead of cement is highly recommended both in terms of moisture changes, mechanical properties and environmental aspects.

Experimental Investigation of Unconfined Compression Strength and Microstructure Characteristics of Slag and Fly Ash-Based Geopolymer Stabilized Riverside Soft Soil

Abstract: To solve the issues of insufficient early strength of cement stabilized soil and high resource cost, high reduction cost, and high environmental cost induced by the application of cement, the slag and fly ash-based geopolymer was adopted as the stabilizer to treat riverside soft soil. This study mainly investigated the effects of stabilizer content, slag-to-fly ash ratio, and alkaline activator content on the strength of geopolymer stabilized soils with different curing ages. Unconfined compressive strength (UCS), scanning electron microscope (SEM), and X-ray energy spectrum analysis (EDS) tests were carried out. The results show that the stabilizer content, slag–fly ash ratio, and alkaline activator content have a decisive influence on the UCS of geopolymer-stabilized soil. The mix-proportions scheme of geopolymer stabilized riverside soft soil, with a geopolymer content of 15%, a slag–fly ash ratio of 80:20, and an alkaline activator content of 30%, is considered optimum. It is proven by SEM that the uniformly distributed gelatinous products formed in the geopolymer-stabilized soil bind the soil particles tightly. Moreover, the EDS analysis confirms that the gelatinous products are mainly composed of C-S-H gel and sodium-based aluminosilicate (N-A-S-H).

Impact of Strength-Enhancing Admixtures on Stabilization of Expansive Soil by Addition of Alternative Binders

Abstract: Abstract In this study, the stabilization process is introduced to a clayey expansive soil collected in southern Sweden. The tests examined strength parameters of expansive soil stabilized by different binders using combination of both traditional binders (cement and lime) and alternative materials (slag Merit 5000, fly ash from SCA Lilla Edet and fly ash from coal combustion, ISO certified). The practical goal was to find a binder mixture that is optimized for soil stabilization with respect to technical properties of stabilizing agent as an inert ballast material. The strength of soil stabilized by various binders was examined by velocity of the P-waves propagating through specimens. The results show that introducing slag Merit 5000 as an admixture to cement and lime is an effective approach in enhancing strength properties in weak soil, which increases bearing capacity of soil for planned construction works. The results also shown that a mixture of lime and bio ash yields a better effect in the stabilization of a clay. Soil stabilized with cement, cement/slag and lime/slag becomes resistant to freeze-thaw cycles, which is crucial for construction of roads and building foundations.

Small-scale laboratory test on expansive soil stabilized by CCR-Fly ash columns

Abstract: Volumetric changes in expansive soils due to seasonal moisture changes can seriously damage foundations. In the small-scale laboratory study reported in this paper, the effect of inserting columns made from calcium carbide residue (CCR) and fly ash (FA) to reduce the swelling potential of expansive soil was examined. An attempt was made to determine the mineralogical changes in the soil and to identify newly generated reaction products by X-ray diffraction (XRD). The strength gain of the stabilised soil was investigated using unconfined compressive strength tests. It was found that the heave of the soil with columns of CCR and FA installed by in situ mixing and compaction reduced by up to 88% and 57%, respectively. The compressive strength of samples increased up to two-fold, and around the same level, for both installation methods after 90 d of curing. This increase in strength was an outcome of soil modification and stabilisation. The XRD results indicated the change in soil mineralogy. Further studies are required to study the cyclic swell–shrink behaviour of the stabilised expansive soil.

Feasibility of lime and biopolymer treatment for soft clay improvement: a comparative and complementary approach

Abstract: Abstract Highway pavement infrastructure projects which involve soil improvement should be executed, ensuring environmental sustainability. In the present study, guar gum (GG) and lime were assessed for the purpose of soft clay stabilization. The experimental program for the soil stabilization employed a two-stage process. The initial stage involves treatment of the soil with various percentages of lime (3, 5, 7, and 9%) and GG (0.6, 1.0, 1.4, and 1.8%), maintaining the same material acquisition cost and considering curing (0, 7, 14, and 28 days) for the unconfined compressive strength (UCS). In the second experimental stage, a complementary approach in which 3% lime was combined with GG at various percentages (0.1, 0.2, and 0.3%) was employed. The tests conducted include UCS, California bearing ratio (CBR), and strength loss resistance (SLR). Results show that the sole use of lime and GG resulted in significant improvement in the UCS, albeit lime was better. While UCS improved with curing time for the lime-stabilized soil, UCS gain for GG occurred only for up to 7 days curing because biodegradation of GG by microbes in the soil ensues on further curing. Lime-GG stabilization resulted in better UCS and CBR improvement with curing than lime stabilization; however, lime stabilization yielded better SLR. The optimum additive content for strength improvement was obtained at 3% lime + 0.3% GG. Microstructural analysis indicated cementation in the stabilized soil. Predictive models for the UCS were developed based on regression methods. Model evaluation revealed that Gaussian process model provided the best UCS prediction.

Suitability of Rice Husk Ash (RHA) with lime as a soil stabilizer in geotechnical applications

Abstract: Abstract Soils containing significant levels of silt or clay generally exhibit unacceptable engineering properties (i.e. low strength, high compressibility and high level of volumetric changes) when exposed to variation in moisture content. Chemical stabilizers such as cement and lime which are currently practiced, are often high-priced and unhygienic in terms of environmental sustainability. The prevailing study intended to explore the potential of the local Rice Husk Ash (RHA) which is an agricultural waste, with lime as a soil stabilizer. This experimental study was conducted on clayey soil with high plasticity. Different mixture proportions of RHA (i.e. 5%, 10%, 20% and 30%) and lime (i.e. 10% and 20%) were used to treat the parent soil. Observations were made for variations in index (i.e. liquid limit, plastic limit, sieve analysis, etc.) and mechanical properties (i.e. compressibility, permeability and shear strength) of treated soils soon and 28 days after mixing. It was found that 10% of RHA and 20% of lime by dry soil weight as the optimum dosage for the treatment. This optimum dosage increases the unconfined compressive strength and internal friction angle by 54.05% and 60.48%, respectively and reduces plasticity index by 56.67% at 28 days after mixing. It could be identified that RHA and lime mixture was capable of improving index and mechanical properties of soil, positively.

Stabilization of Soil Using Fly Ash

Abstract: Abstract: Soil is the basic foundation for any civil engineering structures. It is required to bear the loads without failure. In some places, soil may be weak which cannot resist the oncoming loads. In such cases, soil stabilization is needed .Numerous methods are available in the literature for soil stabilization, But sometimes, some of the methods like chemical stabilization; lime stabilization etc. adversely affects the chemical composition of the soil. In this study, fly ash mixes with clay soil to investigate the relative strength gain in terms of unconfined compression, bearing capacity and compaction. The effect of fly ash on the geotechnical characteristics of clay-fly ash was investigated by conducting standard Proctor compaction tests, unconfined compression test, CBR tests and permeability test. The tests were performed as per Indian Standard specifications. Index Terms: Soil, Fine Fly Ash Mixture, Soil Stabilization.

Improving Weak Subgrade Soil Using Different Additives

Abstract: Weak subgrade is the main problem facing most highway projects. Therefore, this study focuses on trying to improve the properties and increase the strength of weak, clayey, swelling soil for use as a subgrade for pavement structural sections. This trial was developed using a mix of granular and chemical stabilization for the soil. Granular stabilization was applied firstly by mixing natural sand at different percentages of 20%, 35%, and 50% of the total weight of clayey, swelling soil samples to find the minimum percentage that could be added to improve it to sandy, clayey soil, which is acceptable as a subgrade according to the Egyptian highway specification code. Secondly, chemical stabilization was applied to enhanced sandy, clayey soil to increase its strength properties. This was performed by adding chemical additives (lime, cement kiln dust (CKD), fiberglass, Addicrete 11, and gypsum) at different ratios of 2%, 4%, and 6% of the total weight of the samples of enhanced sandy, clayey soil. An experimental program was conducted consisting of characteristics and consistency tests, the California bearing ratio (CBR) test, a proctor test, and a consolidated-drained (C-D) tri-axial shear test. The results showed that 50% sand was the minimum percentage that could be mixed with swelling, clayey soil for granular stabilization to be enhanced and become sandy, clayey soil, which is accepted as a subgrade layer according to the Egyptian highway specification code. In addition, using a mix of granular and chemical stabilization increased the compressive strength of this enhanced subgrade by adding 6% lime or cement kiln dust (CKD) of the total sample weight. They enhanced the strength of the soil and reduced its plasticity. Adding 6% fiberglass and polymers could slightly enhance the desired properties; however, it is not recommended to use them due to their slight effect and economic cost. In addition, it is not recommended to use gypsum at more than 4% due to its negative effect on CBR.

Performance of soil stabilizzed with biopolymer materials – Xanthan gum and guar gum

Abstract: Biogeotechnology is a subfield of geotechnical engineering that utilizes microbial approaches to improve the engineering parameters of soil. The use of biological processes in the soil reclamation process shows great potential in terms of sustainability and environmental friendly compared to treatment using chemicals such as cement and lime. These additives are recognized to have less ideal environmental impacts due to, in particular, the high quantities of greenhouses that are typically created during production. In this case, one of the potential environmentally friendly and sustainable material options is to use biopolymers obtained from living organisms for soil stabilization, especially in tropical residual soils. However, the physical characteristics of biopolymers fluctuate significantly depending on their types and compositions. The primary purpose of this research is to examine the effects of small quantities of biopolymers on the physical parameters of residual soil (1%, 2%, 4%, and 5%), namely xanthan gum and guar gum. Atterberg limits, optimum water content, maximum dry density, pH, and specific gravity are among the parameters discussed in this research. The shear strengths of both treated and untreated soil at various curing times were experimentally investigated by performing an unconfined compressive strength test. A small amount of biopolymers increased the pH values, reduced the maximum dry density, improved the optimum moisture content, decreased the specific gravity, and also increased the plasticity index. Furthermore, the unconfined compressive strength results highlight that the strength of the soil tends to improve with the addition of biopolymers, highlighting its promising potential for sustainable engineering.

Estimating the subgrade reaction at deep braced excavation bed in dry granular soil using genetic programming (GP)

Abstract: Modulus of subgrade reaction (Ks) is a simplified and approximated approach to present the soil-structure interaction. It is widely used in designing combined and raft foundations due to its simplicity. (Ks) is not a soil propriety, its value depends on many factors including soil properties, shape, dimensions and stiffness of footing and even time (for saturated cohesive soils). Many earlier formulas were developed to estimate the (Ks) value. This research is concerned in studying the effect of de-stressing and shoring rigidity of deep excavation on the (Ks) value. A parametric study was carried out using 27 FEM models with different configurations to generate a database, then a well-known “Genetic Programming” technique was applied on the database to develop a formula to correlate the (Ks) value with the deep excavation configurations. The results indicated that (Ks) value increased with increasing the diaphragm wall stiffness and decreases with increasing the excavation depth.

Experimental Study on Stabilized Expansive Soil by Blending Parts of the Soil Kilned and Powdered Glass Wastes

Abstract: This experimental study explores the utilization of glass wastes mixed with kilned soil for weak soil improvement. Expansive soil remains a reason for a lot of road and building damage through settlement and cyclic volume change. Replacing or stabilizing the soil can minimize the risks associated with the soil type. Cement and lime have been the major stabilizers. However, the cost of these materials is raised. Among many stabilizing materials, parts of the expansive soil burned and mixed with glass powder are investigated to fulfill the major requirements. It is proved that the soil sample taken requires improvement. Parts of the soil kilned and mixed with powdered glass waste have 75% of expansive soil kilned and 25% of glass waste powder, which are then added in expansive soil with percentages of 5%, 15%, and 25% to test the change that occurred on liquid limit, plastic limit, free swell, unconfined compression, compaction, California bearing ratio (CBR), and mineral composition. Maximum dry density (MDD) improved from 1.33 g/cm3 to 1.61 g/cm3, optimum moisture content (OMC) reduced from 40% to 21.3%, plastic index reduced from 58.79% to 19.91%, California bearing ratio (CBR) increased from 0.95% to 12.08%, and unconfined compressive strength (UCS) changed from 216 kPa to 910 kPa on 14 days of curing period. Similarly, the addition of 15% and 25% of the stabilizer improved the free swell of expansive soil to 36% and 14%, respectively. CBR swell values significantly improved from 7.16% to 0.22%. Changes in mineral contents from X-ray diffraction (XRD) test are observed: montmorillonite and illite minerals disappeared, and the nonexpansive minerals are observed abundantly in stabilized soil. The addition of 15% to 25% of the stabilizer in expansive soil improved the physical and chemical properties as to be in the appropriate range for road subgrade construction use.