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Summary of parameters describing the failure criteria of biologically cemented sand at low confining stresses (<500 kPa) for different dry densities.
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A new method for ground improvement is being developed: BioGrout, a method based on microbial-induced carbonate precipitation. The feasibility of this method was tested in a field scale experiment: within 12 days 40 m 3 of sand was biologically cemented stretching over a length of 5 m between three injection and three extraction points. In this pap...
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... overview of the derived parameters describing the different failure criteria using both approaches is presented in Table 2. For increasing dry density from 1700 to 1900 kg/m 3 (or CaCO 3 content from 200 to 400 kg/m 3 assuming an initial dry density of 1500 kg/m 3 ) the cohesion increases from 280 to 920 kPa and the friction angle from 39 to 50° when including BTS in the failure criterion (or when BTS is excluded from 270 to 540 kPa Figure 7. Peak strengths (major principal stress) were calculated using correlations in Figure 6 at different confining pressures (minor principal stress: BTS, 0 (UCS), 100 and 500 kPa) for different dry densities of 1700 ( ■ ), 1800 (▲) and 1900 kg/m 3 ( ). ...Citations
... Bacillus pasteurii-also known as Sporosarcina pasteurii, an alkalophilic bacterium with a highly active urease enzyme-is a microbe type commonly used in MICP via bioaugmentation [107]. Important field trials include the stepwise approach devised and implemented by [108]. Figure 16a shows the 0.9 m × 1.1 m × 1 m sand box that received 3500 L of bacterial suspension and 0.5 M urea/CaCl 2 reagent solution in 8 intervals and over a 50-day period. ...
The ground is a natural grand system; it is composed of myriad constituents that aggregate to form several geologic and biogenic systems. These systems operate independently and interplay harmoniously via important networked structures over multiple spatial and temporal scales. This paper presents arguments and derivations couched by the authors, to first give a better understanding of these intertwined networked structures, and then to give an insight of why and how these can be imitated to develop a new generation of nature-symbiotic ground engineering techniques. The paper draws on numerous recent advances made by the authors, and others, in imitating forms (e.g. synthetic fibres that imitate plant roots), materials (e.g. living composite materials, or living soil that imitate fungi and microbes), generative processes (e.g. managed decomposition of construction rubble to mimic weathering of aragonites to calcites), and functions (e.g. recreating the self-healing, self-producing, and self-forming capacity of natural systems). Advances are reported in three categories of Materials, Models, and Methods (3Ms). A novel value-based appraisal tool is also presented, providing a means to vet the effectiveness of 3Ms as standalone units or in combinations.
... The void ratio and thickness of the samples were 0.77 and 20 mm, respectively. The bacteria solution with a volume equal to the soil void volume [47] was then sprayed to the soil surface. The mix was rested for one hour, and then the same volume (as the bacteria solution volume) of the cementation solution was sprayed to the surface of the samples with predefined spraying rates. ...
In this study, the microbially induced calcite precipitation process is introduced to a sandy soil-steel interface. A series of modified direct shear tests designed based on the Taguchi design of experiments method are conducted to examine the bio-cemented soil-steel interface strength parameters. The primary test results are analyzed using the ANOM and ANOVA approaches, and the predictions of the Taguchi method are compared with the test results. The effects of the initial soil moisture content, density ratio of urea/CaCl2, and rate of injection of the cementation solution on the response of the bio-cemented sand-steel interface are scrutinized. Both the ANOM and ANOVA show that the density of the cementation solution is the most influential parameter, while the initial soil moisture content is the least influential factor in the bio-cementation process of the sand-steel interface. The test results show that introducing bio-cementation process to the soil-steel interface is an effective approach in enhancing the interface properties, increasing the sand-steel interface shear strength 3 to 7 times, depending on the normal stress used in the tests. The results also show that the initial moisture content that yields the highest gain in the interface shear strength due to bio-cementation is near the optimum moisture content of the soil obtained from the modified compaction test.
... Thereafter, intensive and comprehensive efforts are being put into MICP. Table 1 reviews the previous studies on MICP, mainly focusing on geotechnical engineering applications [8,11,[49][50][51][52][53][54][55][56][57][58][59][60][61][62][63][64][65][66][67]. ...
This study reviews the fundamental mechanisms of biological soil improvement methods—microbially induced calcium carbonate precipitation (MICP) and biopolymer treatment (BPT). Extensive experimental data on various geotechnical properties of sands treated by MICP and BPT are compiled, including the unconfined compressive strength, Mohr-Coulomb shear strength parameters, and permeability. Furthermore, the variations in these engineering parameters are correlated to calcium carbonate content for MICP and biopolymer content for BPT, which provides insights into the extent of biological modification in engineering properties of sands, potential applications, and limitations.
... This increase is consistent with the results of soil cementation by other materials, such as Portland cement (Clough et al. 1989;Schnaid et al. 2001). It should be noted that all of the specimens were stiff and brittle, which is consistent with the results of other studies of biologically cemented sands (DeJong et al. 2006;Van Paassen et al. 2010b). ...
An indigenous non-spore-forming urease-positive bacterium, Staphylococcus pasteuri was isolated from the soil to reduce the risk of variation in the microbial flora of soil after bio-cementation and was evaluated for its potential to strengthen sands by microbial-induced calcite precipitation (MICP). Its effectiveness and survival time were compared to those of Sporosarcina pasteurii, a well-known bacterium that is commonly used for MICP. The results revealed that S. pasteuri has no viability in the soil for more than 10 days, whereas Sp. pasteurii remained in the soil for more than 30 days because of spore formation. The unconfined compressive strength of soil, after the bio-cementation by both bacteria, reached about 2.3 MPa at the strain rate of 0.005 mm/s. The hydraulic conductivity of soil columns treated with S. pasteuri and Sp. pasteurii was reduced from 13 to 7.5 m/day and 6.8 m/day, respectively. Finally, using either bacterium resulted in achieving the same geotechnical properties. Therefore, according to the results, a non-spore-forming indigenous bacterium with low viability, such as the one isolated here, could be applied for soil improvement applications to reduce the environmental impacts.
... Applications of various biological-induced processes in engineering have received much attention in recent years; biological clogging of porous materials (Nemati and Voordouw 2003;Rusu et al. 2011) biological remediation of contaminated environment (Fujita et al. 2000;James et al. 2000;Warren et al. 2001;Fujita et al. 2010;Li et al. 2013), wastewater treatment (Hammes et al. 2003) biological remediation of concrete and cement mortar (Ramachandran et al. 2001;Abo-El-Enein et al. 2012 and microbial-induced cementation of porous materials (Rong et al. 2012;Cheng et al. 2014;Montoya and DeJong 2015;Sel et al. 2015) are a few of the more recent attempts to utilize this potential for the advancement of technology. Promising results of the accelerated calcification through microbial-induced calcite precipitation (MICP) methods have emerged from the studies of a number of researchers (Whiffin 2004;DeJong et al. 2006;Dick et al. 2006;Whiffin et al. 2007;Al-Thawadi 2008;Sarda et al. 2009;van Paassen et al. 2009b;Meyer et al. 2011;Cheng and Cord-Ruwisch 2012;DeJong et al. 2013;Achal and Kawasaki 2016;Salifu et al. 2016). The immediate aim of the latter references has been to improve the mechanical properties of porous materials. ...
... In the recent year, a number of different processes have been tested by researchers including urea hydrolysis, 1 aerobic oxidation of calcium acetate, iron/sulfate/nitrate reduction, and deamination 2 of amino acid. Possible biochemical reactions proposed for soil stabilization to date are listed in Table 1 (DeJong et al. 2010;van Paassen et al. 2010a;Akiyama and Kawasaki 2012a, b). ...
... Bacterial suspension with reactant agent also permeates readily in sandy soils at low hydraulic heads since its viscosity is close to water, and all constituents are in the order of micrometer (Vos et al. 2011;Whitman et al. 2012). However, early bacterial activity upon introduction of the bacteria suspension together with the reagent solution causes premature calcium carbonate precipitation and consequence clogging especially at the point of injection (Al-Thawadi 2008;van Paassen et al. 2010a) that hinders free diffusion of the stabilizing fluid, result in non-homogeneity of calcium carbonate precipitation. Hence, although attaining complete uniformity may not be possible, it is important to develop a method to achieve the highest possible relative homogeneity. ...
Biocalcification is a developing method in the realm of bio-geotechnics, potentially invaluable for soil stabilization. The method is based on microbial-induced calcite precipitation. Hydrolysis of urea by the urease enzyme discharging from bacteria in the presence of Ca2+ is one of the most notable methods for calcium carbonate precipitation. However, partial clogging may occur as a result of premature bacterial activity that hinders free flow of the mixture, prohibiting spatial homogeneity of the sediment formation, thus limiting the extent of calcification. In order to circumvent clogging, bacterial activity was suppressed in this study prior to injection by lowering the temperature of the suspension and the reaction to 3 °C prior to mixture, delaying CaCO3 precipitation and thus allowing more uniform dispersion of the mixture. Sporosarcina pasteurii and Arthrobacter crystallopoietes were cultured in two different media and injected with reactant agent into samples of non-cohesive sand. The effect of culture media and temperature was studied on the rate and volume of CaCO3 precipitation. Furthermore, the effect of cementation of each batch on the shear strength of the treated soil was evaluated in unconfined compression test. Compressive strengths in excess of 400 kPa were recorded for samples that were injected in two phases, an hour apart. Whereas the highest compressive strength obtained from a single-phase injection at room temperature was approximately 80 kPa. By lowering the temperature of the bacterial suspension and the reactant solution prior to injection, the compressive strength of the sample treated in a single phase was increased to 230 kPa.
... This is why the cemented sand in this study shows lower strength compared with previous researches. For instance, Van Paassen et al. achieved an unconfined compressive strength of 12 MPa from samples of microbially-grouted sand [12]. ...
Most traditional soil improvement methods are time consuming, expensive, require heavy machinery and are environmentally detrimental. As a more environmentally favorable ground improvement method, the bio-cementation of soil offers an alternative to traditional soil improvement techniques. This method is based on microbial precipitation of calcium carbonate. The role of bacteria is producing urease enzyme to catalyzing the hydrolysis of urea. In the presence of calcium ions, the produced carbonate ions in hydrolysis of urea react with the calcium ions and calcium carbonate sediment is formed. This paper investigates the applicability of the bio-remediation of dry loose sand by surface percolation. To evaluate the success of treatment, a series of laboratory experiments was conducted, including, shear wave velocity, unconfined compressive strength, Brazilian tensile strength, calcium carbonate content and etc. The study revealed that the bio-remediation technique causes the improvement of soil strength as a result of the cementation of sand particles. Furthermore, the surface percolation method has the potential of cementation and stabilization of loose sand with desirable depth. Increase in soil strength and calcium carbonate content decreases with increase of depth. Results also showed that increase of strength due to bio-improvement depends to calcium carbonate content, its spatial distribution in pores and particle-to-particle binding numbers.
... The use of greater bacterial concentrations provides faster rates of ureolysis and produces larger and less soluble crystals (Phillips et al., 2013). Generally, an optical density (OD) between 0.8 and 1. to evaluate the strength of the biocemented soils (Mujah et al., 2017;Cheng et al., 2013;van Paassen et al., 2009;Al Qabany and Soga, 2013;Zhao et al., 2014;Ivanov et al., 2015b). Most of these studies have shown an exponential evolution of UCS with the amount of calcite. ...
The biocementation process is considered as a promising technique for strengthening loose and weak soils. This technique has shown very good efficiency for several types of soil through laboratory tests and large scale models. On the other hand, it has shown a high sensitivity to the treatment conditions such as reactant concentrations, bacteria, injection rate, type of soil, temperature, etc….These factors influence mainly the spatial distribution of the precipitated calcite, its shape and morphology, which subsequently influences the effective properties of the treated soils. This thesis is part of the French research project BOREAL, which aims at reinforcing old dykes and earth dams with this technique against internal erosion of the core and liquefaction of foundations. The objective of this thesis is to study the evolution of the physical and mechanical properties of biocemented sands (permeability, mechanical strength) by performing mechanical tests and permeability measurements in the laboratory and linking this evolution to microstructural changes by using quantitative 3D X-ray imaging tools. To do this, this work began with biocementation tests on Fontainebleau sand to verify the feasibility of the biocementation process in the laboratory. After these feasibility tests, drained triaxial tests have been carried out on the biocemented sand in order to estimate the evolution of its resistance parameters such as cohesion and friction angle. Small sub-samples of biocemented sand with different calcite contents have been then extracted and observed using X-ray micro-tomography at ESRF at a very high resolution (0.65 μm / pixel). Quantitative methods of 3D imaging have been developed to compute mean microstructural properties (amount of calcite, porosity, specific surface area and specific surface area of calcite) and contact properties (contact surface area, coordination
number, type of contacts, contact orientation, etc…) for the different observed sub-samples. This study has shown a strong evolution of the resistance of biocemented sand (non-linear evolution of the cohesion, quasi-linear evolution of the friction angle, a slight increase of the residual resistance, etc...) and a decrease of the permeability by the precipitation of the calcite inside the sample. The quantitative study of the evolution of the microstructure has shown a stability of the specific surface area of the calcite beyond a certain level of calcification, a strong quasi-linear evolution of the cohesive contact surface between the grains as well as a slight evolution the coordination number (creation of new contacts). The comparison of these evolutions with those obtained considering a simple cubic periodic arrangement using two precipitation scenarii (uniform and localized at the contact) has shown that the precipitation of the calcite mainly occurs in the zones of inter-granular contact. This microstructural information has been then used successfully in micromechanical models to estimate the effective properties of biocemented sand (cohesion, permeability, elastic moduli). Finally, the same tools have been used to study the chemical durability of biocemented sand. This study has shown a degradation of sand resistance by dissolving calcite within the samples. The quantitative measurements on the 3D images have shown a degradation of the contact surface area without hysteresis with respect to the evolution of these contact surfaces during the biocementation process.
... Available results in the literature reported that the lowest recorded UCS value was 150 kPa, whereas the highest value was 34 MPa, at different MICP treatments (Whiffin 2004). van Paassen et al. (2010b) revealed an exponential relationship between the CaCO 3 content and UCS values of biocemented soils. This indicates that despite having the same amount of CaCO 3 precipitated crystals, the mechanical response of MICP treated soil can vary significantly depending on the effective CaCO 3 precipitation mechanism. ...
Bio-cementation is a recently developed new branch in Geotechnical Engineering that deals with the application of microbiological activity to improve the engineering properties of soils. One of the most commonly adopted processes to achieve soil bio-cementation is through microbially induced calcite precipitation (MICP). This technique utilizes the metabolic pathways of bacteria to form calcite (CaCO3) that binds the soil particles together, leading to increased soil strength and stiffness. This paper presents a review of the use of MICP for soil improvement and discusses the treatment process including the primary components involved and major affecting factors. Envisioned applications, potential advantages and limitations of MICP for soil improvement are also presented and discussed. Finally, the primary challenges that lay ahead for the future research (i.e. treatment optimization, upscaling for in-situ implementation and self healing of bio-treated soils) are briefly discussed.
... Current exploitations of MICP technology have been mostly tested in water logged soils via using submersed flow (saturated flow) (DeJong et al. 2006;Whiffin et al. 2007;van Paassen et al. 2009avan Paassen et al. , 2009bvan Paassen et al. 2010), requiring heavy machinery and hydraulic injection of the cementation Downloaded by [Curtin University Library] at 00:41 18 May 2015 solution and physical extraction of waste solution. The feasibility of such water-saturated treatment method has been demonstrated in 100 m 3 large-scale experiment, which indicated varied strength of products from loosely cemented sand to moderately strong rock with unconfined compressive strengths of 0.7 -12 MPa (van Paassen et al. 2010). ...
This study has contributed to the technology of soil stabilization via biocementation based on microbially induced calcite precipitation. The newly described method of in-situ soil stabilization by surface percolation to dry soil under free draining environment is tested for its up-scaling potential. 2 m columns of one-dimensional trials indicated that repeated treatments of fine sand (< 0.3 mm) could lead to clogging closed at the injection end, resulting in limited cementation depth of less than 1 m. This clogging problem was not observed in 2 m coarse (> 0.5 mm) sand columns, allowing strength varying between 850 to 2067 kPa along the entire 2 m depth. Three-dimensional fine sand cementation trials indicated that relatively homogenous cementation in the horizontal direction could be achieved with 80% of cemented sand cementing to a strength between 2 to 2.5 MPa and to a depth of 20 cm.
A simple mathematical model elucidated that the cementation depth was dependent on the infiltration rate of the cementation solution and the in-situ urease activity. The model also correctly predicted that repeated treatments would enhance clogging close to the injection point. Both experimental and simulated results suggested that the surface percolation technology was more applicable for coarse sand.
... This increase is consistent with the results of soil cementation by other materials, such as Portland cement (Clough et al. 1989;Schnaid et al. 2001). It should be noted that all of the specimens were stiff and brittle, which is consistent with the results of other studies of biologically cemented sands (DeJong et al. 2006;Van Paassen et al. 2010b). ...
In this study, an indigenous bacterium was isolated from soil, identified as Staphylococcus pasteurii HF 2011by 16s rRNA sequencing method and registered in EMBL with Accession Number of FR839669. This facultative aerobic microorganism was employed as a urease positive bacterium for calcite precipitation of sandy soils. The 40mm height and 70 ×70 mm2 cross section area PVC cubic sample was positioned and packed with sandy soil (from Sistan desert) to a dry density of 1.53 g/cm3. Each end of the cubic was fitted with scotch for preventing disturbance of soil particle through the injection of bacterial suspension and reactant solutions. Fluid reservoirs containing the injected fluids were placed at the top of the cubic. Bacterial cell growth and urease activity were determined by spectrophotometer and conductivity method, respectively. After 30 days, the mechanical behaviors of the packed soil were determined from the interpretation of the results of XRD and unconfined compressive strength tests. The compressive strength of the brick was obtained as 8 MPa, which is appropriate for building construction material.
