scholarly journals Sustainability Benefits Assessment of Metakaolin-Based Geopolymer Treatment of High Plasticity Clay

2020 ◽  
Vol 12 (24) ◽  
pp. 10495
Author(s):  
Rinu Samuel ◽  
Anand J. Puppala ◽  
Miladin Radovic
Keyword(s):  
Volume Change ◽  
Expansive Soils ◽  
Expansive Soil ◽  
High Plasticity ◽  
Lime Treatment ◽  
Chemical Additives ◽  
Ambient Temperatures ◽  
New Class ◽  
Stiffness Characteristics ◽  
Strength And Stiffness

Expansive soils are prevalent world over and cause significant hazards and monetary losses due to infrastructure damages caused by their swelling and shrinking behavior. Expansive soils have been conventionally treated using chemical additives such as lime and cement, which are known to significantly improve their strength and volume-change properties. The production of lime and cement is one of the highest contributors of greenhouse gas emissions worldwide, because of their energy-intensive manufacturing processes. Hence, there is a pressing need for sustainable alternative chemical binders. Geopolymers are a relatively new class of aluminosilicate polymers that can be synthesized from industrial by-products at ambient temperatures. Geopolymer-treated soils are known to have comparable strength and stiffness characteristics of lime and cement-treated soils. This study evaluates the sustainability benefits of a metakaolin-based geopolymer treatment for an expansive soil and compares its results with lime treatment. Test results have shown that geopolymers have significantly improved strength, stiffness, and volume-change properties of expansive soils. Increased dosages and curing periods have resulted in further property enhancements. Swell and shrinkage studies also indicated reductions in these strains when compared to control conditions. The sustainability benefits of both geopolymer and lime treatment methods are evaluated using a framework that incorporates resource consumption, environmental, and socio-economic concerns. This study demonstrates geopolymer treatment of expansive soils as a more sustainable alternative for expansive soil treatments, primarily due to metakaolin source material. Overall results indicated that geopolymers can be viable additives or co-additives for chemical stabilization of problematic expansive soils.

scholarly journals Stabilization of Expansive Soil with Polyvinyl Alcohol and Potassium Carbonate

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Fuhai Zhang ◽  
Lei Zhang ◽  
Wangxi Hong
Keyword(s):  
Polyvinyl Alcohol ◽  
Volume Change ◽  
Expansive Soils ◽  
Soil Column ◽  
Ground Surface ◽  
Expansive Soil ◽  
Thick Layer ◽  
Soil Surface ◽  
Compression Tests ◽  
Dense Microstructure

Expansive soils have great volume change potentials with water content changes, which is problematic to facilities. Great efforts have been spent on finding proper methods to stabilize expansive soils, but these stabilizers all had limitations. The Polyvinyl alcohol (PVA) and K2CO3 combination was proposed in this paper. Free swell tests, oedometric tests, unconfined compression tests, and direct shear tests were performed to investigate the effectiveness of the PVA and K2CO3 combination to control the volume change and increase the soil strength. Microstructures of the natural expansive soil and the stabilized soil were also studied with SEM photos. SEM photos showed a homogenous and dense microstructure after stabilization. In addition, a laboratory soil column model was built to study the ability of this stabilizer combination to stabilize expansive soils by directly spraying the solution on the ground surface. All these test results show that the combination of PVA and K2CO3 is able to effectively stabilize the natural expansive soil and increase the shear strength. It is possible to directly spray the stabilizer solution on the soil surface to form a relatively thick layer of the stabilized expansive soil.

Challenges to modelling heave in expansive soils

2006 ◽  
Vol 43 (12) ◽  
pp. 1249-1272 ◽  
Author(s):  
Hung Q Vu ◽  
Delwyn G Fredlund
Keyword(s):  
Numerical Modelling ◽  
Volume Change ◽  
Void Ratio ◽  
Expansive Soils ◽  
Ground Surface ◽  
Expansive Soil ◽  
Coupled Analysis ◽  
Coupled Equations ◽  
Mathematical Equations ◽  
Unsaturated Expansive Soils

There are challenges associated with the numerical modelling of unsaturated expansive soils. The challenges are primarily related to the quantification of the void ratio constitutive surface, the characterization of the void ratio constitutive surface at low stresses and (or) suction, and the solution of coupled equations with several nonlinear unsaturated soil property functions. This study suggests that the void ratio constitutive surface of an expansive soil subject to a monotonic wetting path can be estimated from volume change indices obtained from conventional laboratory tests. The constitutive surfaces for both the soil structure and the water phase can be described using mathematical equations that allow net normal stress and suction to be reduced to zero. The solutions for two typical volume change problems are presented using both a coupled approach and an uncoupled approach. The first example problem simulates water leakage from a pipe under a flexible cover. The second example problem simulates the infiltration of water at ground surface. The results of the analyses are in accordance with anticipated behaviour. The results also show that the answers from an uncoupled analysis compared well with those from a coupled analysis. It is suggested that an uncoupled analysis may be adequate for most prediction of heave problems involving unsaturated expansive soils.Key words: heave prediction, numerical modelling, expansive soil, constitutive surface, uncoupled analysis, matric suction.

Model for the simulation of swelling-pressure measurements on expansive soils

1998 ◽  
Vol 35 (1) ◽  
pp. 96-114 ◽  
Author(s):  
Fangsheng Shuai ◽  
D G Fredlund
Keyword(s):  
Pore Water ◽  
Volume Change ◽  
Unsaturated Soil ◽  
Pore Water Pressure ◽  
Expansive Soils ◽  
Water Pressure ◽  
Expansive Soil ◽  
Swelling Pressure ◽  
Oedometer Test ◽  
Free Swell

Numerous laboratory swelling tests have been reported for the measurement of swelling pressure and the amount of swell of an expansive soil. These test methods generally involve the use of a conventional one-dimensional oedometer apparatus. Few attempts, however, have been made to formulate a theoretical framework to simulate the testing procedures or to visualize the different stress paths followed when using the various methods. The simulation of the oedometer tests on expansive soils is required to fully understand the prediction of heave. The correct measurement of swelling pressure is required for an accurate prediction of heave. It is further anticipated that some information on unsaturated soils property functions may be approximated from the back-analysis of the data. A theoretical model is proposed to describe the pore-water pressures with time and depth in a specimen as well as the volume changes during various oedometer swell tests. The model is formulated based on equilibrium considerations, constitutive equations for an unsaturated soil, and the continuity requirement for the pore fluid phases. The transient water flow process is coupled with the soil volume change process. The model can be used to describe the volume-change behaviour, pore-water pressure, and vertical total stress development in an unsaturated soil during an oedometer test performed by any one of several test procedures. The model has been put into a finite element formulation using the Galerkin technique. All the parameters required to run the model can be obtained by performing independent, common laboratory tests. The proposed model was used to simulate the results from free-swell, constant-volume, constant water content, and loaded-swell oedometer tests. Computed values of volume change, vertical total stress, and pore-water pressure are in good agreement with measured values.Key words: unsaturated soil, expansive soil, swelling pressure, theoretical simulation, constant-volume oedometer test, free-swell oedometer test, loaded-swell oedometer test.

scholarly journals Strength, Hydraulic, and Microstructural Characteristics of Expansive Soils Incorporating Marble Dust and Rice Husk Ash

2021 ◽  
Vol 2021 ◽  
pp. 1-18
Author(s):  
Fazal E. Jalal ◽  
Sultani Mulk ◽  
Shazim Ali Memon ◽  
Babak Jamhiri ◽  
Ahsan Naseem
Keyword(s):  
Rice Husk ◽  
Rice Husk Ash ◽  
Expansive Soils ◽  
Expansive Soil ◽  
Sensitivity Analyses ◽  
Waste Materials ◽  
Strength Development ◽  
High Plasticity ◽  
Preconsolidation Pressure ◽  
Marble Dust

Expansive/swell-shrink soils exhibit high plasticity and low strength, which lead to settlement and instability of lightly loaded structures. These problematic soils contain various swelling clay minerals that are unsuitable for engineering requirements. In an attempt to counter the treacherous damage of such soils in modern geotechnical engineering, efforts are underway to utilize environmentally friendly and sustainable waste materials as stabilizers. This study evaluates the strength and consolidation characteristics of expansive soils treated with marble dust (MD) and rice husk ash (RHA) through a multitude of laboratory tests, including consistency limits, compaction, uniaxial compression strength (UCS), and consolidation tests. By using X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses, the effect of curing on UCS after 3, 7, 14, 28, 56, and 112 days was studied from the standpoint of microstructural changes. Also, the long-term strength development of treated soils was analyzed in terms of the interactive response of impacting factors with the assistance of a series of ANN-based sensitivity analyses. It is found from the results that the addition of MD and RHA lowered down the water holding capacity, thereby causing a reduction in soil plasticity (by 21% for MD and 14.5% for RHA) and optimum water content (by 2% for MD and increased by 6% for RHA) along with an increase in the UCS (for 8% MD from 97 kPa to 471 kPa and for 10% RHA from 211 kPa to 665 kPa, after 3 days and 112 days of curing, respectively). Moreover, from the oedometer test results, m v initially increased up to 6% dosage and then dropped with further increase in the preconsolidation pressure. Furthermore, the compression index dropped with an increase in the preconsolidation pressure and addition of MD/RHA, while the coefficient of permeability (k) of RHA stabilized soil was higher than that of MD-treated samples for almost all dosage levels. The formation of the fibrous cementitious compounds (C-S-H; C-A-H) increased at optimum additive dosage after 7 days and at higher curing periods. Hence, the use of 10% RHA and 12% MD as replacement of the expansive soil is recommended for higher efficacy. This research would be helpful in reducing the impacts created by the disposal of both expansive soil and industrial and agricultural waste materials.

scholarly journals A Comparative Laboratory Investigation into the Role of Geosynthetics in the Initial Swell Control of an Expansive Soil

2019 ◽  
Vol 29 (4) ◽  
pp. 18-40
Author(s):  
Jijo James ◽  
Sivapriya Vijayasimhan ◽  
Hemavathi Srinivasan ◽  
Jayasri Arulselvan ◽  
Sathya Purushothaman ◽  
...  
Keyword(s):  
Laboratory Investigation ◽  
Volume Change ◽  
Expansive Soils ◽  
Expansive Soil ◽  
Virgin Soil ◽  
Number Of Layers ◽  
Material Orientation ◽  
Effective Role

Abstract Volume change in expansive soils due to the intervention of water causes swell. A laboratory investigation using two different gbeosynthetic materials was designed to minimise the swell characteristics. The influence of three parameters, being geosynthetic material [Secutex (ST) and Combigrid (CG)], orientation (horizontal and vertical), and number of layers (1, 2, and 3) on the swell of an expansive soil was studied to better understand the potential for geosynthetics in swell control. The study on the immediate swell characteristics (limited to 24 hours) helps in gaining confidence in the use of geosynthetics in the swell control of expansive soils. From the investigation results, it was found that all three parameters, being type of material, orientation, and number of layers influenced the swell control of the soil. When two layers of ST and CG were placed both vertically and crossed, they reduced the swell of the virgin soil by almost 60% and 44%, respectively. It can, therefore, be concluded that geosynthetics can play an effective role in the swell control of expansive soils.

Performance Evaluation of Cement and Slag Stabilized Expansive Soils

2018 ◽  
Vol 2672 (52) ◽  
pp. 164-173 ◽  
Author(s):  
Masrur Mahedi ◽  
Bora Cetin ◽  
David J. White
Keyword(s):  
Expansive Soils ◽  
Expansive Soil ◽  
Atterberg Limits ◽  
Type I ◽  
High Plasticity ◽  
Swelling Potential ◽  
Laboratory Test Results ◽  
Addition Rate ◽  
Sulfate Salts ◽  
Type V

Swelling, shrinking, and subsequent low strength of expansive soil poses significant damage to structures if it is considered as foundation or fill material. Recently, the use of cement has become very prevalent in stabilizing these problematic soils owing to its effectiveness. However, the swelling potential of expansive soil is not always adequately resolved by cement. The presence of sulfate salts aggravates the situation impairing the effectiveness of cement, leading to the need to reassess its performance. In this study, the effectiveness of different stabilizers was investigated in stabilizing high-plasticity soil. Two types of soil with variable sulfate content were treated with slag, Type I/II, and Type V Portland cement, and their performances were evaluated based on Atterberg limits, pH, unconfined compression, and volumetric swell tests. A total of 312 samples were prepared for 18 different soil–stabilizer blends tested after 7, 28, and 90 days of curing period. Laboratory test results indicated that strength gain performance was attenuated and swelling potential increased due to the presence of sulfate salts. Adding stabilizers improved the strength of soils by a factor of 4–10 and decreased the swelling potential to < 1%. Atterberg limits decreased initially and then slightly increased with the increase of additive dosages. Additives increased the pH up to a maximum value of 11–12, which could be used as an indicator of target stabilizer addition rate. Finally, slag improved the performance of cement significantly and has proven to be a better option for treating high sulfate expansive soils.

scholarly journals An Experimental Study on the Geotechnical, Mineralogical, and Swelling Behavior of KPK Expansive Soils

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Bakht Zamin ◽  
Hassan Nasir ◽  
Khalid Mehmood ◽  
Qaiser Iqbal ◽  
Asim Farooq ◽  
...  
Keyword(s):  
Expansive Soils ◽  
Clay Fraction ◽  
Expansive Soil ◽  
Vital Role ◽  
Maintenance Cost ◽  
High Plasticity ◽  
Swell Potential ◽  
Overall Stability ◽  
Swelling Characteristics ◽  
Arid And Semiarid

Expansive soils are found in numerous regions of the world explicitly in arid and semiarid zones. These soils expand when absorbed moisture and shrink when released water. Such soil is viewed as a characteristic risk for infrastructures due to the shrink and swell behavior. These soils become more problematic when lightly or moderately loaded structures are built on them. The swelling and shrinkage in these soils chiefly happen due to the presence of montmorillonite minerals. The mineralogical and swell behavior of foundation soils is playing a vital role in the overall stability of a structure. These parameters are often ignored in the geotechnical report writing stage specifically in small projects, due to which, the durability and service life of the facilities are reduced and the maintenance cost is increased. To mitigate the potential damages in structures constructed on expansive soil, it is necessary to assess the mineralogical and swelling characteristics of expansive soil. The current study aims to determine the geotechnical, mineralogical, and swell behavior of the local expansive soils. Based on the results, the Karak soil has the highest plasticity index (PI) of 37% with a clay fraction of 28%, while the D.I. Khan soil has the least PI of 23% with a clay fraction of 17%. Similarly, Karak’s soil contained a higher percentage of montmorillonite (Rp = 8.9%). The maximum values of swell pressure, swell potential, and 1D deformation are 280 kPa, 12.5%, and 1.92 mm for the Karak soil, 6.45% 150 kPa, and 1.38 mm for D.I. Khan soil, and 10.5%, 245 kPa, and 1.64 mm for Kohat soil, respectively. This concludes that Karak’s soil has high plasticity and swell characteristics than Kohat and D.I. Khan soil. The swell characteristic of expansive soils increases with the increase in the percentage of the fine specifically the clay fraction. Furthermore, the Karak soil is more critical than Kohat and D.I. khan soil for lightly loaded structures.

scholarly journals Swelling Potential of Clayey Soil Modified with Rice Husk Ash Activated by Calcination for Pavement Underlay by Plasticity Index Method (PIM)

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Kennedy C. Onyelowe ◽  
Michael E. Onyia ◽  
Diu Nguyen-Thi ◽  
Duc Bui Van ◽  
Eze Onukwugha ◽  
...  
Keyword(s):  
Rice Husk ◽  
Volume Change ◽  
Rice Husk Ash ◽  
Clayey Soil ◽  
Expansive Soils ◽  
Expansive Soil ◽  
Clay Content ◽  
Hydrated Lime ◽  
Plasticity Index ◽  
Index Method

Volume change in expansive soils is a problem encountered in earth work around the world. This is prominent with hydraulically bound structures or foundations subjected to prolonged moisture exposure. This behavior of clayey used as subgrade, foundation, landfill, or backfill materials causes undesirable structural functionality and failures. To prevent this happening, clayey soils are studied for possible volume change potential and degree of expansion. Consequently, the problematic soils are stabilized. In this work, the stabilization of clayey highly expansive soil classified as A-7-6 soil and highly plastic with high clay content was conducted under laboratory conditions. The treatment exercise was experimented using quicklime-activated rice husk ash (QARHA), hydrated lime-activated rice husk ash (HARHA), and calcite-activated rice husk ash (CARHA) at the rates of 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, and 10%. Upon treatment with the three calcium compounds to produce three sets of treated experimental specimens, the plasticity index was observed and recorded and swelling potentials were evaluated using the plasticity index method (PIM). The results showed a consistent improvement on the properties of the treated soil with the addition of the different activated admixtures. While the utilization of CARHA and HARHA improved the clayey soil to medium expansive soil, the treated clayey soil substantially improved from highly expansive soil with a potential of 23.35% to less expansive with a final potential of 0.59% upon the addition of 10% QARHA. Finally, QARHA was adjudged as the best binding composite due to the highest rate of reduction recorded with its utilization.

Improvement of Strength and Volume-Change Properties of Expansive Clays with Geopolymer Treatment

2021 ◽  
pp. 036119812110018
Author(s):  
Rinu Samuel ◽  
Anand J. Puppala ◽  
Aritra Banerjee ◽  
Oscar Huang ◽  
Miladin Radovic ◽  
...  
Keyword(s):  
Volume Change ◽  
Carbon Dioxide Emissions ◽  
Expansive Soils ◽  
Linear Shrinkage ◽  
Plasticity Index ◽  
Specimen Preparation ◽  
Expansive Clays ◽  
Change Behavior ◽  
Volume Change Behavior ◽  
Lower Carbon

Expansive soils are conventionally treated with chemical stabilizers manufactured by energy-intensive processes that significantly contribute to carbon dioxide emissions globally. Geopolymers, which are synthesized from industrial byproducts rich in aluminosilicates, are a viable alternative to conventional treatments, as they are eco-friendly and sustainable. In this study, a metakaolin-based geopolymer was synthesized, and its effects on the strength and volume-change behavior of two native expansive soils from Texas, with a plasticity index over 20 were investigated. This paper elaborates on the geopolymerization process, synthesis of the metakaolin-based geopolymer, specimen preparation, and geopolymer treatment of soils. Comprehensive material testing revealed two clays with a plasticity index over 20. They were each treated with three dosages of the metakaolin-based geopolymer and cured in 100% relative humidity for three different curing periods. The efficiency of geopolymer treatment was determined by testing the control and geopolymer-treated soils for unconfined compressive strength (UCS), one-dimensional swell, and linear shrinkage. Field emission scanning electron microscope (FESEM) imaging was performed on the synthesized geopolymer, as well as on the control and geopolymer-treated soils, to detect microstructural changes caused by geopolymerization. A significant increase in UCS and reduction in swelling and shrinkage were observed for both geopolymer-treated soils, within a curing period of only 7 days. The FESEM imaging provided new insights on the structure of geopolymers and evidence of geopolymer formation in treated soils. In conclusion, the metakaolin-based geopolymer has strong potential as a lower-carbon-footprint alternative to conventional stabilizers for expansive soils.

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