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Soil stabilization using additives is considered as one of the sustainable alternative techniques to deal with acute material shortages. Critically reviewing the contemporary works on soil stabilization would help practitioners and researchers to comprehend the merits and demerits of each stabilization method, influential parameters, and associated constraints. Furthermore, the critical analysis might aid the authorities to develop standard protocols about the use of various additives for soil stabilization, which would persuade the industry personnel to adopt sustainable practices. This paper presents a methodical review of the present soil stabilization methods under five key areas namely, underlying chemistry, the influential factors, performance indicators, economic and environmental aspects, and industrial perspectives. Findings of the review indicate that cement-based stabilizers perform well irrespective of soil type and curing conditions, on the contrary, lime-based stabilizers require appropriate temperature and pH for strength development. The degree of stabilization depends mainly on soil type, compaction level, and curing type and condition. Most of the soils treated with different additives exhibited a reduction in plasticity index, and maximum dry density against stabilizer dosage irrespective of soil type. The typical values of unconfined compressive strength and California bearing ratio of inorganic and organic soils except for peat, treated with a 5% dosage of all common types of stabilizers, fall in between 700 and 1,500 kPa and 30–60%, respectively. Cement and cementitious blends exhibited better cost-to-strength, energy-to-strength, and CO 2 emission-to-strength ratios for soils with low plasticity whereas lime-blended stabilizers seemed effective for high-plastic soils.

Clayey soils are usually stiff when they are dry and give up their stiffness as they become saturated. Soft clays are associated with low compressive strength and excessive settlement. This reduction in strength due to moisture leads to severe damages to buildings and foundations. The soil behavior can be a challenge to the designer build infrastructure plans to on clay deposits. The damage due to the expansive soils every year is expected to be $1 billion in the USA, £150 million in the UK, and many billions of pounds worldwide. The damages associated with expansive soils are not because of the lack of inadequate engineering solutions but to the failure to identify the existence and magnitude of expansion of these soils in the early stage of project planning. One of the methods for soil improvement is that the problematic soil is replaced by suitable soil. The high cost involved in this method has led researchers to identify alternative methods, and soil stabilization with different additives is one of those methods. Recently, modern scientific techniques of soil stabilization are on offer for this purpose. Stabilized soil is a composite material that is obtained from the combination and optimization of properties of constituent materials. Adding cementing agents such as lime, cement and industrial byproducts like fly ash and slag, with soil results in improved geotechnical properties. However, during the past few decades, a number of cases have been reported where sulfate-rich soils stabilized by cement or lime underwent a significant amount of heave leading to pavement failure. This research paper addressed the some fundamental and success soil improvement that used in civil engineering field.

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.

Calcium-based binders, such as ordinary Portland cement (OPC) and lime (CaO), are the most common artificial cementitious materials used worldwide for concrete and soil improvement. However, using cement and lime has become one of the main concerns for engineers because they negatively affect the environment and economy, prompting research into alternative materials. The energy consumption involved in producing cementitious materials is high, and the subsequent CO2 emissions account for 8% of the total CO2 emissions. In recent years, an investigation into cement concrete’s sustainable and low-carbon characteristics has become the industry’s focus, achieved by using supplementary cementitious materials. This paper aims to review the problems and challenges encountered when using cement and lime. Calcined clay (natural pozzolana) has been used as a possible supplement or partial substitute to produce low-carbon cement or lime from 2012–2022. These materials can improve the concrete mixture’s performance, durability, and sustainability. Calcined clay has been utilized widely in concrete mixtures because it produces a low-carbon cement-based material. Owing to the large amount of calcined clay used, the clinker content of cement can be lowered by as much as 50% compared with traditional OPC. It helps conserve the limestone resources used in cement manufacture and helps reduce the carbon footprint associated with the cement industry. Its application is gradually growing in places such as Latin America and South Asia.

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.

With increased awareness of environmental protection, the output of traditional curing agents such as cement and lime is less and less, so it is urgent to develop new curing agents with high efficiency and environmental benefits. Thus, this study aims at investigating the application of rice husk ash (RHA) from agricultural waste to the soft soil stabilization. A series of tests are conducted to analyze the strength development process and soil–water characteristics of rice husk ash–lime (RHA–lime) stabilized soils. The results of the strength tests showed that by increasing the content of RHA, the unconfined compressive strength (UCS) and splitting strength of stabilized soils increased first and then decreased. The effective shear strength indexes of the three soil types (soft soil, lime-stabilized soil, and RHA–lime soil) are measured and compared. It is found that RHA can effectively improve the shear resistance and water resistance of stabilized soil. The results of methylene blue test demonstrated that RHA can also promote the reduction of the specific surface area and swelling potential energy of lime-stabilized soil. In addition, the influence of RHA on mineral composition and morphology change in stabilized soils is studied at the microscopic level. The X-ray diffraction tests and scanning electron microscope (SEM) tests showed that strength development and change of soil–water properties of RHA–lime stabilized soil are attributed to enhanced cohesion by cementation and pores filling with agglomerated mineral.

Earth materials have been used in construction as safe, healthy and environmentally sustainable. It is often challenging to develop an optimum soil mix because of the significant variations in soil properties from one soil to another. The current study analyzed the soil properties, including the grain size distribution, Atterberg limits, compaction characteristics, etc., using multilinear regression (MLR) and artificial neural networks (ANN). Data collected from previous studies (i.e., 488 cases) for stabilized (with either cement or lime) and unstabilized soils were considered and analyzed. Missing data were estimated by correlations reported in previous studies. Then, different ANNs were designed (trained and validated) using Levenberg-Marquardt (L-M) algorithms. Using the MLR, several models were developed to estimate the compressive strength of both unstabilized and stabilized soils with a Pearson Coefficient of Correlation (R2) equal to 0.2227 and 0.766, respectively. On the other hand, developed ANNs gave a higher value for R2 than MLR (with the highest value achieved at 0.9883). Thereafter, an experimental program was carried out to validate the results achieved in this study. Finally, a sensitivity analysis was carried out using the resulting networks to assess the effect of different soil properties on the unconfined compressive strength (UCS). Moreover, suitable recommendations for earth materials mixes were presented.

This work introduces an optimal performance model for predicting the unconfined compressive strength (UCS) of lime-stabilized soil using the machine (ensemble tree (ET), Gaussian process regression (GPR), and decision tree (DT), support vector machine (SVM)), and hybrid (relevance vector machine (RVM)) learning computational techniques. The conventional (non-optimized) and hybrid (genetic (GA) and particle swarm algorithm optimized (PSO)) RVM models have been developed and compared with machine learning models. For the first time, UCS of virgin cohesive soil has been used as input variable to predict the UCS of lime-stabilized soil. A database of 371 results of lime-stabilized soil has been compiled from the literature and used to create training, testing, and validation databases. Furthermore, the multicollinearity levels for each input variable, i.e., lime content, UCS of cohesive soil, and curing period, have been determined as weak for the overall database. The performance of built-in models has been measured by three new index performance metrics: the a20-index, the index of scatter (IOS), and the index of agreement (IOA). This research concludes that the weak multicollinearity of input variables affects the performance of the non-optimized RVM models. Also, the ensemble tree has performed better than SVM, DT, and GPR because it consists of the number of trees. The overall performance comparison concludes that the PSO-optimized Laplacian kernel–based RVM model UCS16 outperformed all models with higher a20-index (testing = 67.30, validation = 55.95), IOA (testing = 0.8634, validation = 0.7795), and IOS (testing = 0.2799, validation = 0.3506) and has been recognized as the optimal performance model. ANOVA, Z , and Anderson-darling tests reject the null hypothesis for the present research. The lime content influences the prediction of UCS of lime-stabilized soil. The computational cost and external validation results show the robustness of model UCS16.

Soil stabilization using nano-additives is one of the trending developments of the decade. Many novel nano-stabilizers were tested by researchers for ground improvement applications. However, the capability of such materials in soil stabilization needs further detailed practical investigations beyond the controlled research environment. On the other hand, many well-proven nano-based stabilizers have constraints like availability, cost, difficulty in implementation method, and the practical feasibility of such usages. Among many well-established additives, nano-silica is one such material that was under research for over a decade and showed promising results for use as a soil stabilizer. Hence, the present work proposes a comprehensive review on characteristics of nano-silica, including its physical nature; its influence on curing methods and ageing, its behavior upon adding with soil and other additive materials in terms of strength improvement, hydraulic conductivity and compressibility; reaction mechanism in various soil and additives and a discussion on the gaps that need to be addressed to transfer this technology to field practices. Literature studies indicate that nano-silica as a sole-additive improved the soil strength and it acted as a strength enhancer for cement, lime and fiber treated soils. Also, nano-silica helps in reducing hydraulic conductivity and compression index of the soil. Further, an analysis on the minimum strength improvement with nano-silica on various types of soils is discussed based on the reported literature. With promising results from the review, further advancements on eco-friendly and cost-effective biogenic production methods would establish nano-silica as a competitive additive in the field of geotechnical engineering.

This study evaluates a binary mixture of fly ash and lime as a stabilizer for natural soils. A comparative analysis was performed on the effect on the bearing capacity of silty, sandy and clayey soils after the addition of lime and ordinary Portland cement as conventional stabilizers, and a non-conventional product of a binary mixture of fly ash and Ca(OH)2 called FLM. Laboratory tests were carried out to evaluate the effect of additions on the bearing capacity of stabilized soils by unconfined compressive strength (UCS). In addition, a mineralogical analysis to validate the presence of cementitious phases due to chemical reactions with FLM was performed. The highest UCS values were found in the soils that required the highest water demand for compaction. Thus, the silty soil added with FLM reached 10 MPa after 28 days of curing, which was in agreement with the analysis of the FLM pastes, where soil moistures higher than 20% showed the best mechanical characteristics. Furthermore, a 120 m long track was built with stabilized soil to evaluate its structural behavior for 10 months. An increase of 200% in the resilient modulus of the FLM-stabilized soils was identified, and a decrease of up to 50% in the roughness index of the FLM, lime (L) and Ordinary Portland Cement (OPC)-stabilized soils compared to the soil without addition, resulting in more functional surfaces.