Subgrade Stabilization Research Articles

Evaluation of pavement design input parameters of biaxial and triaxial geogrid stabilized flexible pavements overlying soft subgrades

Stabilization of flexible pavement layers using geogrids to improve the mechanical response of pavement layers is gaining importance over conventional stabilization techniques due to their low cost and superior performance. However, the lack of experimental data on quantifying the design input parameters of stabilized subgrades or granular layers limits the extensive use of geogrids in the field. Evaluation of design input parameters such as modulus improvement factor (MIF) or layer coefficient ratio (LCR) would promote the use of geogrids in the pavement, reducing the consumption of natural aggregates and the overall project cost. This study attempts to evaluate MIF and LCR due to geogrid stabilized soft subgrades considering different scenarios. All possible combinations of stabilization of pavement layers using biaxial and triaxial geogrids were considered. This involved stabilization of (a) the subgrade layer alone, (b) base layer alone, and (c) subgrade, subbase, and base layers. Accordingly, an extensive, systematic experimental program consisting of eighteen large-scale model pavement experiments (LSMPE) were conducted in five categories (designated as Series I through V). The stabilization of subgrade and granular layers was carried out using commercially available biaxial (BX1 and BX2) and triaxial (TX1) geogrids overlying soft and moderate subgrades with California bearing ratio (CBR) equal to 2.5 and 4%. Test results showed that stabilized subgrade prepared with existing and prepared subgrade material in conjunction with geogrid improved the effective CBR to as high as 10.9% from effective CBR = 7% corresponding to existing and prepared subgrade material without geogrid. The design inputs of geogrids (BX1/BX2/TX1) stabilized granular layers resulted in the MIF and LCR values ranging from 1.9 to 2.8 and 1.31 to 1.63, respectively, for the tested configuration considered in the study. Based on the findings of the study, inputs on resilient modulus of pavement layers were recommended for similar reinforcement and subgrade conditions considered.

Mix design development for geopolymer treated expansive subgrades using artificial neural network

Expansive soils have been inevitable during road constructions due to its widespread availability. Conventional stabilizers; cement and lime have not been quite reliable in terms of economic, environmental, and durability perspectives. Thus, geopolymer has come into limelight as a sustainable alternative. However, the complexity of geopolymer-soil behaviour makes it challenging to predict their strength development patterns and it requires a large number of trial and error tests in laboratory scale due to the soil specific nature of such mixes. To date, no research has been attempted to develop design charts for geopolymer-expansive soil stabilization field applications. This study proposes design charts using Artificial neural networks (ANN) to predict the 28-day unconfined compressive strength (UCS) of Class F fly ash (FA) based geopolymer stabilized expansive soil (PI = 32% – 46%) to support field implementation of this novel geopolymer based soil stabilization. The model was developed based on a robust collection of literature data; FA/Soil, Activator/FA, Na2SiO3/NaOH, alkaline molarity, and their respective 28-day UCS values. Three contour plots for mix design: FA/soil vs. NaOH molarity, activator/FA vs. Na2SiO3/NaOH, and Na2SiO3/NaOH vs. NaOH molarity were proposed based on the model predictions. The proposed mix design charts were validated through the in-house tests which showed reasonable match in comparison with the predicted 28-day UCS using the contour plots. The proposed mix design charts can be employed for in-situ geopolymer-expansive subgrade stabilization to achieve strengths between 0.6 and 2.1 MPa.

The Effect of the Addition Steel Slag and Bamboo Leaf Ash on the CBR Unsoaked Value in Subgrade Stabilization

The Effect of the Addition Steel Slag and Bamboo Leaf Ash on the CBR Unsoaked Value in Subgrade Stabilization

Analisis Stabilisasi Tanah Dasar dengan Cerucuk Bambu dan Geotekstil

The road plays an essential role as a driving force for development growth in Sukabumi. The access section is an organic clay type with low bearing capacity, so it needs subgrade stabilization. The DCP test obtained a value of 0.76%. The carrying capacity value is in a poor classification. Therefore, it is necessary to strengthen the soil layer using bamboo culms and geotextiles. After that, it is required to do a field CBR. After supporting bamboo culms, the carrying capacity value is 5.63%. This value meets the CBR requirements in medium classification. Thus, it is necessary to add a pavement layer with geotextile. This bearing capacity test obtained a value of 20.59% and is in excellent classification.

Influence of subtitle base stabilization with geogrids on the deformability of the earth bed during thawing

In this research papers, several fundamental questions connected with the assessment of the influence of subgrade stabilization using the geogrid reinforcing method on deformability of subgrade during thawing are considered, as also the basic provisions of methods of calculation of the stress-strain state of subgrade reinforced by geogrids during thawing. Several practically significant tasks, such as reduction of general deformability, reduction of uneven distribution of deformations, increase of bearing capacity, and ensuring the stability of earth bed during thawing, can be solved by using modern geomaterials in the construction of earth bed. In order to determine the degree of change in the deformation characteristics of the ground reinforced with planar geomaterials under varying factors of structural, operational, and technological nature, a series of laboratory stamping tests were performed. The test outcomes showed an increase in the total deformation modulus of reinforced soil, depending on the realized variant of reinforcement, under the condition of full inclusion of geomaterial in the work under load, and being the most essential for recompacted soils. The paper proposes a method of accounting for the influence of reinforcing layers of geomaterial on the deformability and bearing capacity of the earth bed during thawing using a conventionally homogeneous equivalent layer with parameters determined by the outcomes of die tests. The proposed method of calculating the stress-strain state of an earth bed reinforced with geogrids during thawing is based on the use of the finite element method and is an effective tool for solving practical tasks of railway construction, including permafrost conditions.

Investigating the Effect of Lime Stabilization of Subgrade on the Fatigue & Rutting Lives of Flexible Pavements Using the Nonlinear Mechanistic-Empirical Analysis

Investigating the Effect of Lime Stabilization of Subgrade on the Fatigue & Rutting Lives of Flexible Pavements Using the Nonlinear Mechanistic-Empirical Analysis

Sustainable utilization of sugarcane bagasse ash in highway subgrade- a critical review

Pavement subgrade stabilization is one of the major problems in the transportation industry due to the diversity in the type of soil. Sometimes, weak soils are encountered, which are inadequate for carrying the self-weight of the pavement layers and traffic load, compromising the stability of highways. In this instance, either they are replaced with more suitable material or modified to increase their load capacity. Former is a costlier affair if the material is not locally available. Various modification techniques, such as chemical modification, can be done using traditional or non– traditional additives. The cement and lime are commonly used to provide sufficient strength of the subgrade soil, but due to their high cost of production and a negative impact on the environment in the form of greenhouse gas emissions, these must be replaced by a more sustainable and eco-friendlier substitute. This study reviews the suitability of by-products of sugarcane industry, i.e., sugarcane bagasse ash (SCBA) for subgrade stabilization, focussing on its sustainable use and analysing engineering properties of different types of weak subgrade and its mechanism involved in stabilisation. It can be concluded from the literature that the use of bagasse ash is a less expensive and sustainable solution compared to traditional one. So, SCBA needs to be promoted to improve and enhance engineering properties of subgrade material.

Effect of Axle Overloading on Pavement Structural Behaviour with Improved Clayey Subgrade Using PET Fibres

Clayey subgrade soils are considered to have a lower bearing capacity, which may develop early pavement failure due to diverse axle loading. To avoid such failure issues, these soils must be treated prior to the beginning of the construction work. In the recent past, soil stabilization with plastic waste has become popular to reduce waste and improve soil behaviour. The current study aimed to use polyethylene terephthalate (PET) waste bottles to improve clayey subgrade soil for pavement construction. The PET fibre content varied between 1% and 5% by weight of the dry soil to investigate its influence on compaction, California bearing ratio (CBR), unconfined compressive strength (UCS), and tri-axial shear strength. The modified soil matrix with PET was further stabilized using Terrasil (0.1%) in order to improve the strength properties of the treated soil with ageing. Overall, the influence of the addition of the PET fibre on the structural behaviour of flexible pavement under diverse axle loading conditions was evaluated using Finite Element (FE) techniques. The pavement model is computationally implemented in ANSYS to study pavement structural behaviour in terms of surface deflection, vertical stress and strain on the subgrade layer, maximum shear strain in the bituminous layer, and tensile strain at the base of the bituminous layer under standard loading and overloading by 1.25 and 1.5 times. The test results indicated that the addition of PET fibres in subgrade soil significantly increases the CBR, UCS, and internal friction angle and decreases the compaction characteristics. The use of PET fibres in subgrade stabilization can result in a significant reduction in pavement thickness. FE analysis results compare pavement rutting performance and show that overloading reduces rutting life.

Komparativna analiza učinkovitosti otpada od orezivanja palmi i geotekstila na stabilizaciju posteljice

This paper proposes a novel and environmentally friendly solution for subgrade stabilization that not only contributes towards waste material recycling but also enhances the bearing capacity of subgrade soil. Laboratory plate load tests were conducted under static loads to evaluate the potential use of palm tree pruning waste (PTPW) as a soil reinforcement material instead of commercially manufactured geotextiles, as well as to analyse the impact of the reinforcement depth, number of reinforcement layers, and the relative density of the subgrade material. The results revealed that as the number of reinforcements increased, the load-bearing pressure behaviour of the reinforced subgrades improved. Furthermore, when the reinforcement depth decreased, the load-bearing pressure behaviour improved significantly. All PTPW-reinforced subgrades performed better than geotextile-reinforced subgrades under the same conditions. Additionally, the bearing capacity improvement in the reinforced subgrades was evaluated based on the bearing capacity improvement factor (BCIF). The highest BCIF was obtained when the PTPW was used as a reinforcement with two layers at a sand subgrade relative density of 80 %.

Subgrade soil stabilization using marine debris: A literature review

The use of different marine residues found in the great biodiversity of the Peruvian coast, such as crushed mollusk shells or fan shells, can be used as mechanical stabilizers for clay soils due to a change in granulometry. In this article, we reviewed 74 research studies indexed in different databases such as Scopus, Scielo, Ebsco, Proquest, Springer Link, and ScienceDirect, whose publication has not exceeded seven years, with the objective of carrying out a systematic review of the use, effect and influence of marine debris as soil stabilizers. For this purpose, the analyses of the mechanical and also physical properties of such mixtures in different marine debris were reviewed compared to the various types of stabilizers currently used. These evaluated results indicate, that the Pacific razor clam shell offers a lower bearing capacity compared to the fan shell when stabilizing clayey soil. However, the shredded output of both types of marine debris can meet the need for clay subgrade stabilization. Based on the review, it was determined that the addition of different types of shredded marine debris reduces water absorption by capillarity, increasing the resistance and bearing capacity of the soil.

Application of eco-friendly and smart materials in geotechnical engineering for subgrade stabilization: a review

The performance of road pavement mainly depends upon the properties of subgrade soil. The failures occur in case of road pavement is due to poor strength characteristics and high volume change behaviour of subgrade soil. Thus, considering the performance criteria, subgrade soil needs to be treated so as to make it suitable for the construction of road pavement. It was observed that, soil stabilization using various admixtures is more effective and commonly used practice for enhancing the properties of subgrade soil. The previous research shows that subgrade soil stabilization can be achieved with the application of various environmental friendly (Bio – Enzymes) and smart materials (Agricultural and Industrial waste) in required quantity to enhance the physical, strength and volume change characteristics of natural soil. It was also observed that, the combined use of such materials makes the subgrade soil more suitable for the construction of road pavement. From the experimental investigations of various available research works on subgrade stabilization, it was observed that strength and volume change properties such as California Bearing Ratio (CBR), Unconfined Compressive Strength (UCS) and Swell Pressure of subgrade soil can be effectively changed with the help of use of such materials. It was also observed that use of conventional methods has negative impact on environment. Thus, subgrade can be stabilized with eco – friendly and cost effective materials to achieve both economic and serviceability criteria.

GEOSYNTHETICS USED TO STABILIZE THE SUBGRADE

The repetitive, high, and targeted stresses placed on pavements, whether bound or unbound, may hasten the ageing and collapse of the road structure. The main aim of the study is stabilization of subgrade using geosynthetics .Soil stabilization is a process of treating a soil to maintain, alter or improve the performance of the soil as a construction material and very importantly to minimize the cost of earthworks. In order to determine the preliminary and engineering (strength) testing of the samples, analysis were carried out. In this study, the results of studies on the performance of nonwoven geotextile within subgrade are carried out experimentally utilizing the California Bearing Ratio(CBR) testing arrangement.The experimental results give a clear indication that the presence of geotextiles increases the CBR value of the soil thus, geotextile should be employed as a modernized form of improving road construction on poor soils and to reduce the layer thickness of pavements

Incorporation of Mixing Microbial Induced Calcite Precipitation (MICP) with Pretreatment Procedure for Road Soil Subgrade Stabilization.

Microbial induced carbonate precipitation (MICP) provides an alternative method to stabilize the soil. To further improve the reinforcement effect, this study aims to propose a strategy by incorporating the mixing MICP method with pretreatment procedure. A series of laboratory tests were performed to investigate the preparation parameters (including the moisture content and dry density of the soil, the concentration of urea and CaCl2 in cementation solution), the engineering properties, the CaCO3 distribution as well as the mineralogical and micro structural characteristics of pretreatment-mixing MICP reinforced soil (PMMRS). Based on the orthogonal experiment results, the optimum preparation parameters for PMMRS were determined. The UCS of PMMRS was more strongly dependent on the moisture content and concentration of CaCl2 than the concentration ratio of CaCl2 to urea. Moreover, it was testified that incorporation of pretreatment procedure improved the stabilization effect of traditional mixing MICP method on the clayed sand (CLS). The UCS of PMMRS specimen was increased by 198% and 78% for the pure CLS and the simple mixing MICP reinforced soil, respectively. Furthermore, the CaCO3 products generated consisted of the aragonite, calcite and vaterite, which distributed unevenly inside the specimen no matter the lateral or vertical direction. The reason for the uneven distribution might be that oxygen content varied with the regions in different directions, and hence affected the mineralization reaction. In addition, the mineralization reaction would affect the pore structure of the soil, which was highly related to the stabilization effect of MICP reinforced soil.

Laboratory investigation of modified subgrade clay soil mix with steel slag and lime using static and dynamic test approach

ABSTRACT An experimental laboratory program was conducted to understand the feasibility of steel slag and lime in the subgradelayer. The test was conducted on natural clay soil, lime, lime + steel slag stabilizedcohesive subgrade soil. The lime portions were 2%, 4% and 6%, respectively.Similarly, steel slag was added to 20%, 25% and 30%, respectively, by the massof dry soil. The strength of lime soil and lime + steel slag + soil increaseswith increasing curing period. The 7-day unconfined compressive strength (UCS)2% lime soil and soil+20% steel slag + 2% lime is 3.20 MPa and 3.87 MPa,respectively. Eventually, this study supports the use of steel slag and lime inthe construction of subgrade stabilization. Therefore, it is found that a lightweightdeflectometer can be used as a quick strength evaluating tool on modifiedsubgrade soil in the laboratory.

Investigation on use of silica based additive for sustainable subgrade construction

This study presents the potential application of cement and StabilRoad, a silica based additive for subgrade soil stabilization. The coupling effect of soil, cement and StabilRoad additive has been evaluated by compaction characteristics, California bearing ratio (CBR) and Unconfined compressive strength (UCS) at various percentages of cement along with this additive. The underlying mechanism that contributes to the stabilization process was visualized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The result indicates an enhancement in mechanical performances of the soil mixture containing this additive. CBR value and UCS were increased by 72.413 % (soaked condition) and 79.16 % (28 days) on addition of 1 % StabilRoad to the cement modified soil mixture. Meanwhile, different regression models namely, quantile regression (QR), partial least square regression (PSL-R), and linear regression (LNR) models have been developed to establish the relationship of UCS and CBR with routine properties of subgrade soil. LNR model attained the highest predictive accuracy in all cases. An increase in the intensity of C-S-H peaks has been observed with the incorporation of this additive which is responsible for enhanced strength in the modified soil mixture. Subgrade stabilization with this additive also resulted in reducing the overall cost by minimizing the crust thickness of the pavement. Therefore, the present investigation confirms the usability of cement and StabilRoad in subgrade stabilization with significant economic benefits.

Application of Urea Formaldehyde Raisin in Pavement Subgrade Stabilization at Hindon Barrage

Proper stabilization of foundation and subgrade is one of the major concerns in modern civil engineering projects. Development of modern infrastructure is causing harmful effect on environment by using chemicals. This situation has caused necessity to discover alternative techniques to achieve desired result without harming environment. Present paper studies use of urea formaldehyde raisin on chemical and physical stability of subgrade. Study was conducted by varying contents of urea formaldehyde by 1%, 3% and 5% and strength, ultimate bearing capacity and other relevant soil strength parameters were determined. At the end, cost benefits analysis was also conducted for the current method with respect to alternate subgrade stabilization techniques.

Stabilization of expansive soil subgrade by waste plastic

Stabilization of expansive soil subgrade by waste plastic

Quantifying the Benefits of Geosynthetics Reinforcement in Flexible Pavement Design Using Cyclic Plate Load Testing

Development of pavement design over the past decades has focused on moving from empirical design equations to more powerful and adaptive design schemes. The AASHTO mechanistic–empirical pavement design guide (MEPDG) has been developed to model pavement structure and predict its service life more accurately. Although MEPDG has been widely implemented to design conventional pavement, it is not yet capable of predicting the service life of pavement reinforced with geosynthetics. Given the above concerns, seven full-scale test sections that were constructed at Louisiana Transportation Research Center-Pavement Research Facility (LTRC-PRF) were devoted to a structural experiment to investigate the performance of geosynthetic reinforced pavements. The benefits of using geosynthetics to enhance the performance of pavements constructed over soft subgrades was evaluated using cyclic plate load testing. Cyclic load at a frequency of 0.77 Hz was applied through a 305 mm diameter steel plate. The test results clearly show the benefits of geosynthetics in significantly reducing pavement rutting. The test section with double geosynthetic layers performed better than the other six sections studied. After eliminating the effect of variations in construction, the benefits of geosynthetic reinforcement are quantified within the context of the AASHTOWare Pavement ME Design Guide. The developed design procedure is capable of quantifying the contribution of geosynthetics in pavements to base reinforcement as well as subgrade stabilization. A design methodology is proposed that falls within the context of MEPDG.

Stabilization of subgrade with expansive soil using agricultural and industrial By-products: A review

Expansive soils cover a large part of India and possess certain undesirable engineering properties such as low bearing capacity and large volumetric changes which causes severe damage to the pavements. Therefore, it is necessary to improve the geotechnical properties of expansive soils so that it becomes easier to construct pavement using these expansive soils. Agricultural and industrial byproduct such as rice husk ash, sugarcane bagasse ash, fly ash, plastic waste, coir pith and fiber, calcium carbide residue, cement kiln dust, silica fume and red mud etc. are found to be useful in pavement construction. Studies have reported that the strength of stabilized soils significantly improved with the use of various types of industrial and agricultural byproduct. If these waste materials are available locally for soil stabilization, it leads to the development of cost-effective and sustainable pavement construction. Further, utilization of these byproduct as a soil stabilizer also solve the problem of their disposal. As a result, the environmental problems caused by these byproducts from industrial and agricultural will be reduced. The research paper provides an overview of the utilization of different byproducts from industry and agriculture that have been used in soil stabilization as strengthening agents.

Unconfined compressive strength of bio–enzymatic treated expansive (BC) soil

The soil stabilization using Bio-Enzymes becomes an innovative approach compared with conventional methods used for subgrade improvement. The application of these bio-enzymes in small dosages with soil can improve its engineering behavior. The factors responsible for total efficiency of enzymatically treated soil will be the amount of dose, soil type, and field circumstances. The present experimental investigation aims to investigate the impact of varying dosages of two different bio-enzymes DZ-2X and TerraZyme on strength characteristics i.e. (UCS) of black cotton soil with ageing period of (1, 7, 14, 24 and 28) days. The investigation will further resulting in finding the ecofriendly and cost effective material with great application in the subgrade improvement. The results of treated soil with different dosages of DZ-2X and TerraZyme was compared with results of untreated soil to investigate the optimum dosages of Bio-enzymes (DZ-2X and Terrazyme) and effect of ageing period in strength gain. The results shows improvement in strength values in both types of enzyme treatment compared to natural soil. The optimum values of DZ-2X and TerraZyme for treatment was found around 0.091 ml/kg and 0.098 ml/kg respectively. The maximum strength increase will be 131.39% and 112.89% when compared to natural soil. The overall approach will lead to sustainability and economy towards subgrade stabilization.