scholarly journals Biochemical Enhancement of Geotechnical Properties of Marginal Soils

2018 ◽  
Vol 203 ◽  
pp. 03010
Author(s):  
Murtala Hassan Mohammed ◽  
Ado Yusuf Abdulfatah
Keyword(s):  
Hydraulic Conductivity ◽  
Treatment Duration ◽  
Soil Improvement ◽  
Engineering Properties ◽  
Treatment Technique ◽  
Reagent Concentration ◽  
Soil Variables ◽  
Treatment Conditions ◽  
Metabolic Activities ◽  
Marginal Soil

Microbially-induced calcite precipitation (MICP) is a relatively new and sustainable soil improvement technique. This technique utilizes bio-activity of microorganism to precipitate calcite through metabolic activities of the organisms which decompose urea in to ammonium and carbon dioxide. The carbonate so produced combined with the supplied calcium to precipitate calcite. This calcite improves engineering properties of soil through the formation of coating and bonds between soil particles. Preliminary results have proved the feasibility of the isolated bacteria in MICP treatment technique to improve the engineering properties of marginal soil. The main objective of this study is to determine the preference conditions for effective MICP treatment in improving the soil engineering properties (Unconfined Compressive Strength, California Bearing Ratio and Hydraulic Conductivity) of a typical marginal soil. Variables such as; treatment duration (24, 48, and 72hours), reagent concentration (0.1, 0.25, 0.5, and 0.75M), and concentration of the isolates (1×105, 1×106, and 1×107cfu/ml) were considered in the MICP treatment. The results suggested that the preference treatment conditions were 72hours treatment duration, 0.75M reagent concentration, and 1×107cfu/ml concentration of the isolates. The corresponding alterations recorded were 94.86KN/m2 (295%) and 30.8% (92.5%) increment for CBR and UCS while 0.93X10-6m/s (78.95%) reduction was recorded for hydraulic conductivity. The calcite content showed a reasonably good comparison with the improvements in the soil engineering properties. The pH of effluents increased during MICP treatment indicating the presence of urease bio-activity.

scholarly journals Research on Physical and Engineering Properties of Unstabilised Soil

2019 ◽  
Vol 8 (6S4) ◽  
pp. 842-845
Keyword(s):  
Photosynthetic Bacteria ◽  
Soil Improvement ◽  
Sem Analysis ◽  
Engineering Properties ◽  
Calcite Precipitation ◽  
Environmentally Sustainable ◽  
Methane Reduction ◽  
Metabolic Activities ◽  
Living Organisms ◽  
Characteristic Growth

Soil improvement techniques are inevitable due to the severe hazards caused by excessive settlement of foundation, debris flow, destructive landslides and the further softening by means of infiltration of prolonged rainfall. The environmentally sustainable technique that utilizes a biological process for biomineralization is Microbial Induced Calcite Precipitation (MICP). Biomineralization is the process in which living organisms produce minerals. There are different metabolic activities that lead to MICP such as ureolysis, denitrification, ammonification, photosynthesis, sulphate reduction and methane reduction. In this study, the photosynthetic soil-borne bacteria is used to enhance the soil stability. The photosynthetic bacteria is isolated from the soil, the characteristic growth is studied and the most efficient strain is selected to be injected back into the soil. The final properties of the soil are tested and are expected to increase its strength. The initial and final variations in the surface of the soil are studied using SEM analysis and EDAX

Experimental Research on the Engineering Properties of Foam-Improved Red Clay Soil

2011 ◽  
Vol 261-263 ◽  
pp. 1831-1835
Author(s):  
Guo Gang Qiao ◽  
Da Jun Yuan ◽  
Bo Liu
Keyword(s):  
Experimental Research ◽  
Clay Soil ◽  
Soil Improvement ◽  
Engineering Properties ◽  
Screw Conveyor ◽  
Test Results ◽  
X Ray Diffraction ◽  
Shield Tunneling ◽  
Red Clay ◽  
Improvement Measures

Red clay soil is widely distributed in south China, the microstructure of red clay soil was studied applying scanning electron microscopy (SEM), and the X-ray diffraction analysis (XRD) test found that a large number of swelling inducing minerals, for example, montmorillonite, illite-montmorillonite or chlorite-smectite were contained in the red clay soil. Shield tunneling in this kind of stratum is prone to arising “cake” and “arch” phenomena and it prone to lead screw conveyor device unsmooth dumping, so soil improvement measures must be taken. Foam as the most advanced soil conditioner has been widely used in shield construction. Using self-developed foam agent, experimental research on foam conditioning red clay soil was carried out, test results show that foam can not only significantly reduce the soil shear strength, but also can greatly enhance the soil's compressibility and fluidity, which is significant for the smooth dumping and excavation face stability maintenance.

scholarly journals Feasibility Study of Native Ureolytic Bacteria for Biocementation Towards Coastal Erosion Protection by MICP Method

2019 ◽  
Vol 9 (20) ◽  
pp. 4462 ◽  
Author(s):  
Md Imran ◽  
Shuya Kimura ◽  
Kazunori Nakashima ◽  
Niki Evelpidou ◽  
Satoru Kawasaki
Keyword(s):  
Coastal Erosion ◽  
Urease Activity ◽  
Ground Improvement ◽  
Soil Improvement ◽  
Engineering Properties ◽  
Culture Solution ◽  
Precipitation Trend ◽  
Mediterranean Countries ◽  
Erosion Protection ◽  
Ureolytic Bacteria

In recent years, traditional material for coastal erosion protection has become very expensive and not sustainable and eco-friendly for the long term. As an alternative countermeasure, this study focused on a sustainable biological ground improvement technique that can be utilized as an option for improving the mechanical and geotechnical engineering properties of soil by the microbially induced carbonate precipitation (MICP) technique considering native ureolytic bacteria. To protect coastal erosion, an innovative and sustainable strategy was proposed in this study by means of combing geotube and the MICP method. For a successful sand solidification, the urease activity, environmental factors, urease distribution, and calcite precipitation trend, among others, have been investigated using the isolated native strains. Our results revealed that urease activity of the identified strains denoted as G1 (Micrococcus sp.), G2 (Pseudoalteromonas sp.), and G3 (Virgibacillus sp.) relied on environment-specific parameters and, additionally, urease was not discharged in the culture solution but would discharge in and/or on the bacterial cell, and the fluid of the cells showed urease activity. Moreover, we successfully obtained solidified sand bearing UCS (Unconfined Compressive Strength) up to 1.8 MPa. We also proposed a novel sustainable approach for field implementation in a combination of geotube and MICP for coastal erosion protection that is cheaper, energy-saving, eco-friendly, and sustainable for Mediterranean countries, as well as for bio-mediated soil improvement.

scholarly journals Direct currents stimulate carbonate mineralization for soil improvement under various chemical conditions

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Dimitrios Terzis ◽  
Patrick Hicher ◽  
Lyesse Laloui
Keyword(s):  
Electric Fields ◽  
Textural Properties ◽  
Soil Improvement ◽  
Transport Processes ◽  
Electric Currents ◽  
Electric System ◽  
Beneficial Effects ◽  
Treatment Conditions ◽  
Microbially Induced Carbonate Precipitation ◽  
Chemical Conditions

Abstract The present study integrates direct electric currents into traditional calcium carbonate mineralization to investigate electrochemical interactions and the subsequent crystalline growth of CaCO3 bonds in sand. A specific line of focus refers to the effect of three chemical reactive species involved in the stimulated geo-chemo-electric system, namely CaCl2, Ca(CH3COO)2 and Ca(CH3CH2(OH)COO)2. By altering treatment conditions and the applied electric field, we capture distinctive trends related to the: (i) overall reaction efficiencies and distribution of CaCO3 crystals is sand samples; (ii) promotion of CaCO3 mineralization due to DC (iii) crystallographic and textural properties of mineralized bonds. The study introduces the concept of EA-MICP which stands for Electrically Assisted Microbially Induced Carbonate Precipitation as a means of improving the efficiency of soil bio-cementation compared to traditional MICP-based works. Results reveal both the detrimental and highly beneficial effects that electric currents can hold in the complex, reactive and transport processes involved. An interesting observation refers to the “doped” morphology of CaCO3 crystals, which precipitate under electric fields, validated by crystallographic analyses and microstructural observations.

Lateritic Soil Treated with Waste Wood Ash As Liner in Landfill Construction

2019 ◽  
Vol 25 (2) ◽  
pp. 127-139 ◽  
Author(s):  
Johnson R. Oluremi ◽  
Adrian O. Eberemu ◽  
Stephen T. Ijimdiya ◽  
Kolawole J. Osinubi
Keyword(s):  
Compressive Strength ◽  
Hydraulic Conductivity ◽  
Unconfined Compressive Strength ◽  
Wood Ash ◽  
Engineering Properties ◽  
Volumetric Shrinkage ◽  
Lateritic Soil ◽  
Waste Wood ◽  
K Value ◽  
British Standard

ABSTRACTInherent variability in engineering properties of lateritic soil in relation to its plasticity, permeability, strength, workability, and natural moisture content, has made it an unpredictable material for use in civil engineering works, resulting in the need for its treatment by stabilization. A lateritic soil classified as A-6(6) and CL, according to American Association of State Highway and Transportation Officials and Unified Soil Classification System of ASTM (2011), was treated with up to 10 percent waste wood ash (WWA). Compaction was carried out using four energies, namely, reduced British Standard light, British Standard light (BSL), West African Standard, and British Standard heavy, on samples, which were then examined for hydraulic conductivity, volumetric shrinkage, and unconfined compressive strength as major criteria for use as liner and for the development of acceptable zones. Specimens with 4 percent WWA content compacted with a minimum BSL energy satisfied the maximum hydraulic conductivity (k) value of 1 × 10−9 m/s, maximum volumetric shrinkage strain of 4 percent, and minimum unconfined compressive strength value of 200 kN/m2 required for use as liner in engineered landfills. The overall acceptable zone was enlarged for up to 4 percent WWA content, thereby accommodating higher moulding water content, but the minimum compactive effort required to achieve it became reduced. The beneficial treatment of lateritic soil with up to 4 percent WWA will perform satisfactorily as liner and covers in waste containment application and will minimize the pollution and environmental impact of wood waste disposal.

scholarly journals Review on biological process of soil improvement in the mitigation of liquefaction in sandy soil

2018 ◽  
Vol 250 ◽  
pp. 01017 ◽  
Author(s):  
Abubakar Sadiq Muhammed ◽  
Khairul Anuar Kassim ◽  
Muttaqa Uba Zango
Keyword(s):  
Biological Process ◽  
Soil Improvement ◽  
Emerging Technology ◽  
Biological Processes ◽  
Reagent Concentration ◽  
Calcite Precipitation ◽  
Cyclic Resistance ◽  
Environmental Friendly ◽  
Long Time ◽  
Cyclic Resistance Ratio

Recently, the concept of using biological process in soil improvement otherwise called bio-mediated soil improvement technique has shown greater prospects in the mitigation of liquefiable soils. It is an environmental friendly technique that has generated great interest to geotechnical engineers. This paper presents a review on the microorganism responsible for the biological processes in soil improvement system, factors that affect biological process, identifying the mechanism of liquefaction and commonly adopted method to mitigate liquefaction. Next, the effect of microbial induced calcite precipitation (MICP) on the strength and cyclic response were also analyzed, where it was identified that higher cementation level leads to formation of larger sized calcite crystals which in turn leads to the improved shear strength, stiffness and cyclic resistance ratio of the soil. However, the effects of various bacteria, cementation reagent concentrations amongst other factors were not fully explored in most of the studies. Finally, some of the challenges that lay ahead for the emerging technology are optimizing treatment factors (bacteria and cementation reagent concentration), upscaling process, training of researchers/technologist and long – time durability of the improved soils.

Bearing Capacity Improvement of Shallow Foundations Using Cement-Stabilized Sand

2016 ◽  
Vol 723 ◽  
pp. 795-800 ◽  
Author(s):  
Habib Rasouli ◽  
Hana Takhtfirouzeh ◽  
Abbasali Taghavi Ghalesari ◽  
Roya Hemati
Keyword(s):  
Bearing Capacity ◽  
Soil Stabilization ◽  
Cement Content ◽  
Experimental Tests ◽  
Dry Weight ◽  
Soil Improvement ◽  
Reinforced Soil ◽  
Shallow Foundation ◽  
Engineering Properties ◽  
Suitable Material

In order to attain a satisfactory level of safety and stability in the construction of structures on weak soil, one of the best solutions can be soil improvement. The addition of a certain percentage of some materials to the soil may compensate for its deficiency. Cement is a suitable material to be used for stabilization and modification of a wide variety of soils. By using this material, the engineering properties of soil can be improved. In this study, the effect of soil stabilization with cement on the bearing capacity of a shallow foundation was studied by employing finite element method. The material properties were obtained by conducting experimental tests on cement-stabilized sand. Cement varying from 2% to 8% by soil dry weight was added for stabilization. The effect of reinforced soil block dimensions, foundation width and cement content were investigated. From the results, it can be figured out that by stabilizing the soil below the foundation to certain dimensions with the necessary cement content, the bearing capacity of the foundation will increase to an acceptable level.

scholarly journals The Influence of the Addition of Plant-Based Natural Fibers (Jute) on Biocemented Sand Using MICP Method

Materials ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4198 ◽  
Author(s):  
Md Al Imran ◽  
Sivakumar Gowthaman ◽  
Kazunori Nakashima ◽  
Satoru Kawasaki
Keyword(s):  
Fiber Length ◽  
Natural Fibers ◽  
Construction Materials ◽  
Soil Improvement ◽  
Fiber Content ◽  
Microbial Interactions ◽  
Engineering Properties ◽  
Precipitation Trend ◽  
Calcareous Sand ◽  
Jute Fibers

The microbial-induced carbonate precipitation (MICP) method has gained intense attention in recent years as a safe and sustainable alternative for soil improvement and for use in construction materials. In this study, the effects of the addition of plant-based natural jute fibers to MICP-treated sand and the corresponding microstructures were measured to investigate their subsequent impacts on the MICP-treated biocemented sand. The fibers used were at 0%, 0.5%, 1.5%, 3%, 5%, 10%, and 20% by weight of the sand, while the fiber lengths were 5, 15, and 25 mm. The microbial interactions with the fibers, the CaCO3 precipitation trend, and the biocemented specimen (microstructure) were also evaluated based on the unconfined compressive strength (UCS) values, scanning electron microscopy (SEM), and fluorescence microscopy. The results of this study showed that the added jute fibers improved the engineering properties (ductility, toughness, and brittleness behavior) of the biocemented sand using MICP method. Furthermore, the fiber content more significantly affected the engineering properties of the MICP-treated sand than the fiber length. In this study, the optimal fiber content was 3%, whereas the optimal fiber length was s 15 mm. The SEM results indicated that the fiber facilitated the MICP process by bridging the pores in the calcareous sand, reduced the brittleness of the treated samples, and increased the mechanical properties of the biocemented sand. The results of this study could significantly contribute to further improvement of fiber-reinforced biocemented sand in geotechnical engineering field applications.

scholarly journals Experimental Investigation of Consolidation Properties of Nano-Bentonite Mixed Clayey Soil

2020 ◽  
Vol 12 (2) ◽  
pp. 459 ◽  
Author(s):  
Gang Cheng ◽  
Hong-Hu Zhu ◽  
Ya-Nan Wen ◽  
Bin Shi ◽  
Lei Gao
Keyword(s):  
Clayey Soil ◽  
High Stress ◽  
Soil Improvement ◽  
Soil Samples ◽  
Engineering Properties ◽  
Soil Consolidation ◽  
Water Drainage ◽  
Coefficient Of Consolidation ◽  
Test Soil ◽  
Permeability Increase

As a new soil improvement method, adding nano-bentonite can enhance the engineering properties of soil. To study the stabilization effect of nano-bentonite on soil consolidation properties, a series of one-dimensional odometer tests were conducted on a clayey soil with different nano-bentonite mixing contents (i.e., 0.5%, 1%, 1.5%, and 2%). The effects of nano-bentonite on the coefficient of consolidation and permeability of the test soil were analyzed. The results show that adding a certain amount of nano-bentonite does not significantly affect the original consolidation characteristics of soil samples, but displays a notable effect on accelerating water drainage. Among all the soil samples, when the nano-bentonite mixing content is 0.5%, the final compression amount is the largest and the final void ratio is the smallest. The coefficients of consolidation and permeability increase with increasing nano-bentonite mixing content under high stress state. The test results indicate that nano-bentonite can facilitate internal cementation of soil particles, which effectively reduces the compressibility of clayey soil.

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