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 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.

Innovative Approach for Addressing Coastal Erosion Protection Using Microbial Induced Carbonate Precipitation

2020 ◽  
Author(s):  
Md Al Imran ◽  
Kazunori Nakashima ◽  
Niki Evelpidou ◽  
Satoru Kawasaki
Keyword(s):  
Coastal Erosion ◽  
Global Climate ◽  
Bacterial Species ◽  
Environmental Parameters ◽  
Soil Improvement ◽  
Sediment Supply ◽  
Sand Sample ◽  
Carbonate Precipitation ◽  
Culture Duration ◽  
Erosion Protection

<p>Considering the global climate change and the ensuing sea level rise, the subsequent acceleration of coastal erosion is evident. Phenomena of coastal erosion, coastal flooding and shoreline retreat are expected to show a significant increase in frequency and intensity, in global level. The effects of coastal erosion are worsened by storms, and the reduction of sediment supply associated with global warming and anthropogenic modification of rivers and coastlines. As a countermeasure to coastal erosion, this work focuses on the development of coastal artificial in-situ rocks. We developed a new method that encompasses microbes and the related mechanism is called “Microbial Induced Carbonate Precipitation” (MICP). We successfully isolated three microorganisms, Micrococcus sp., Pseudoalteromonas sp., and Virgibacillus sp., from the selected area, and investigated their effectiveness in order to make a solidified sand sample. The precipitated bounding material has also been confirmed as calcite by XRD and XRF analysis. We successfully demonstrated that all of these bacterial species are very sensitive with certain environmental parameters, such as temperature, pH, culture type, culture duration, etc. In laboratory scale, we successfully obtained solidified sand by syringe (d = 2.3 cm, h = 7.1 cm) solidification method bearing UCS (Unconfined Compressive Strength) up to 1.8 MPa using 0.5 M CaCl<sub>2</sub> and urea as cementation solution at 30°C. In addition, we propose a new sustainable approach for field implementation of this method through a combination of geotube and MICP mechanism, which will contribute to coastal erosion protection. The proposed approach is more economic, energy-saving, eco-friendly, and sustainable for bio-mediated soil improvement.</p>

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 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.

Urease Activity of Ureolytic Bacteria Isolated from Six Soils in which Calcite was Precipitated by Indigenous Bacteria

2012 ◽  
Vol 29 (4) ◽  
pp. 389-395 ◽  
Author(s):  
Malcolm B. Burbank ◽  
Thomas J. Weaver ◽  
Barbara C. Williams ◽  
Ronald L. Crawford
Keyword(s):  
Urease Activity ◽  
Indigenous Bacteria ◽  
Ureolytic Bacteria

scholarly journals Causes of Ground Settlements in Upper Reservoir of Hydro-Wind Plant of El Hierro and Method Implemented for Soil Improvement

Proceedings ◽  
2018 ◽  
Vol 2 (23) ◽  
pp. 1468
Author(s):  
Fabiola Fernández-Baniela ◽  
Daniel Arias ◽  
Álvaro Rubio-Ordoñez
Keyword(s):  
Ground Improvement ◽  
Soil Improvement ◽  
El Hierro ◽  
Engineering Problems ◽  
Mobile Dune ◽  
Ground Settlements ◽  
Design And Construction

This article exposes one of the main engineering problems in the design and construction of the upper reservoir of El Hierro hydro-wind plant, relative to the high settlement of the bottom in the southeast area. The high settlements measured during the construction phase are consequence of the geological-geotechnical settings of the site, a natural depression of a volcanic crater occupied by highly deformable soils derived from the weathering of volcanic materials. Ground improvement was carried out by partial preloading (mobile dune), preceded by the execution of a trial embankment in the southeast area of the reservoir, where the greatest thickness of deformable soils was identified.

The Strength of Fly Ash-Bottom Ash (FA-BA) Mixtures as Backfill Material in Ground Improvement Works

2013 ◽  
Vol 465-466 ◽  
pp. 937-943
Author(s):  
Abd Rahim bin Hj. Awang ◽  
Wan Hilmi bin Wan Mansor ◽  
Ahmad Yusri Bin Mohamad
Keyword(s):  
Shear Strength ◽  
Fly Ash ◽  
Specific Gravity ◽  
Ground Improvement ◽  
Bottom Ash ◽  
Friction Angle ◽  
Soil Improvement ◽  
Geotechnical Properties ◽  
Raw Material ◽  
Fa Composition

In Malaysia, coal has been used as a raw material to generate electricity since 1988. In the past, most of the wastage of coal burning especially the bottom ash was not managed properly as it was dumped in the waste pond and accumulated drastically. This research has been conducted to explore the physical characteristic and geotechnical properties of fly ash-bottom ash (FA-BA) mixtures that consist of 30% FA, 50% FA, 70% FA and 90% FA by weight. The physical characteristics, that include the specific gravity, particle size distribution and compaction, were tested for each mixture without any curing. However, the geotechnical properties of the mixtures that include the permeability and shear strength had been studied at various curing periods (0, 14 and 28 days) to review the effect of time on the geotechnical properties of the mixtures. The results show that mixtures with higher FA composition have lower value of specific gravity, well-graded, and need less moisture to be compacted efficiently compared to those mixtures with lower FA composition. The results also show that mixtures with higher FA composition have less drainage characteristics but can be improved by prolonging the curing period. The maximum shear strength was obtained at mixture with 50%FA and the value increased with curing periods. The friction angle obtained ranged from 270to 370. It is also found that the mixtures with lower FA composition are more compressible compared to the mixtures with higher FA composition. The results obtained could be used by others to determine the suitability of different FA-BA mixtures for various usage in Geotechnical Engineering work such as for soil improvement work in weak soils or as backfill materials in embankment construction.

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