Improving deformation characteristics of sand soils using bio-improvement methods

Tunalı, Mert
Utilizing biological processes is new and innovative method which can be used to improve engineering properties of soils in an environmentally friendly way. In this study, a recently introduced bio-improvement method named microbially induced calcite precipitation (MICP) is used to improve the strength and deformation characteristics of soft soils. For that purpose, ureolytic bacteria were utilized to improve the strength properties of soils. Ureolytic bacteria can induce enzymatic hydrolysis of urea, which results in production of free ammonium (NH4+) and bicarbonate (HCO3-) ions. In case of existence of free calcium (Ca2+) ions in the environment, calcite (CaCO3) precipitation may occur as the result of a reaction between HCO3- and Ca2+ ions. This reaction results in cementation of soil grains, which results in the improvement of engineering properties of soil. Within the scope of the study, both MICP’s applicability and its effect on strength properties of soil were investigated by performing direct shear tests. More specifically, improvement efficiencies of Sporosarcina pasteurii (ATCC 11859), a widely studied bacterium, and Bacillus licheniformis (ATCC 14580), a relatively new introduced bacterium, were examined with samples prepared at different relative densities and with different number of injections. The improvement in the strength values are also supported with the help of sophisticated imaging tools such as Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDS) techniques.


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Duman, Emre; Pekcan, Onur; Department of Civil Engineering (2020-9)
Microbially induced calcite precipitation (MICP) is a recently proposed novel environmentally friendly ground improvement method that is alternating to conventional ground improvement techniques. MICP has been under intense investigation by researchers from different civil engineering sub-disciplines to mitigate problems related to crack propagation of concrete, insufficient soil strength characteristics, soil erosion, asphalt cracks, etc. This study focuses on the effect of MICP treatment on the stre...
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An Experimental investigation for improvement of sands using microbially induced calcium carbonate precipitation
Sarıçiçek, Yılmaz Emre; Pekcan, Onur; Department of Civil Engineering (2016)
The development of innovative solutions to improve the engineering characteristics of sands becomes an emerging field of Geotechnical Engineering, as the environmental aspects, the economic feasibility and application practicability are concerned. In this scope, many improvement methods have been proposed to satisfy sustainability constraints, to reduce the overall the cost of construction and to be applied safely in the field. Among those, the use of biological means as derived from the nature gets popular...
Improvement of Pectinase Production by Co-culture of Bacillus spp. Using Apple Pomace as a Carbon Source
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Increasing interest in using food and agricultural wastes for low cost enzyme production continues in fermentation industry. Bacteria, especially Bacillus subtilis, are known to produce pectinases in synthetic media and media amended with agricultural wastes as a carbon source, whereas the potential of co-culturing Bacillus species to produce pectinases has not been fully studied yet. In this study, co-culture of B. subtilis and B. pumilus was optimized for solid load and pH to maximize pectinase production...
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Gundogdu, A; Yazıcıgil, Hasan; Kirmizitas, H (2000-04-01)
Quantification of groundwater recharge is a basic prerequisite for efficient groundwater management. While there are several approaches to estimating groundwater recharge rates, some of the approaches proposed cannot be applied in basin-wide hydrogeological investigations due to a lack of data. Thus, some conventional recharge estimation techniques for which data are most often available have to be used in estimating groundwater recharge. In this study, water level fluctuation, the precipitation vs water le...
Citation Formats
M. Tunalı, “Improving deformation characteristics of sand soils using bio-improvement methods,” Thesis (M.S.) -- Graduate School of Natural and Applied Sciences. Civil Engineering., Middle East Technical University, 2019.