Soil bio-cementation using a new one-phase low-pH injection method
- 336 Downloads
Soil bio-cementation via microbially induced carbonate precipitation (MICP) has been extensively studied as a promising alternative technique to traditional chemical cementing agents for ground improvement. The multiple-phase injection methods are currently well adopted for MICP treatment, but it is rather complex and requires excessive number of injections. This paper presents a novel one-phase injection method using low-pH all-in-one biocement solution (i.e. a mixture of bacterial culture, urea, and CaCl2). The key feature of this method is that the lag period of the bio-cementation process can be controlled by adjusting the biomass concentration, urease activity, and pH. This process prevents the clogging of bio-flocs formation and thus allows the biocement solution to be well distributed inside the soil matrix before bio-cementation takes effect, allowing a relatively uniform MICP treatment to be achieved. Furthermore, the ammonia gas release would be reduced by more than 90%, which represents a significant improvement in the environmental friendliness of the technology. The new one-phase method is also effective in terms of the mechanical property of MICP-treated soil; an unconfined compressive strength of 2.5 MPa was achieved for sand after six treatments.
KeywordsBio-cementation Ground improvement Microbially induced carbonate precipitation Microscopy One phase
We would like to acknowledge that part of this study is supported by Grant No. SUL2013-1 by the Ministry of National Development and Grant No. MOE2015-T2-2-142 provided by the Ministry of Education, Singapore. The authors would also like to thank Donovan Mujah (Ph.D. candidate) for his assistance in conducting some SEM and UCS tests.
- 2.Al-Thawadi SM, Cord-Ruwisch R (2012) Calcium carbonate crystals formation by ureolytic bacteria isolated from Australian soil and sludge. J Adv Sci Eng Sci Res 2(1):12–26Google Scholar
- 3.ASTM (American Society for Testing and Materials) (2013) D2166: Standard test method for unconfined compressive strength of cohesive soil. ASTM International, West ConshohockenGoogle Scholar
- 13.Fidaleo M, Lavecchia R (2003) Kinetic study of enzymatic urea hydrolysis in the pH range 4–9. Chem Biochem Eng Q 17(4):311–318Google Scholar
- 15.Gomez MG, Graddy CMR, DeJong JT, Nelson DC, Tsesarsky M (2018) Stimulation of native microorganisms for bio-cementation in samples recovered from field-scale treatment depths. J Geotech Geoenviron Eng. https://doi.org/10.1061/(ASCE)GT.1943-5606.0001804 Google Scholar
- 20.Miner JR (1974) Odors from confined livestock production. Environmental protection technology. Ser. EPA-600/1-74.023 U.S. Environmental Protection Agency, WashingtonGoogle Scholar
- 21.Mobley HLT, Hausinger RP (1989) Microbial ureases: significance, regulation and molecular characterisation. Microbiol Rev 53:85–108Google Scholar
- 28.Stumm W, Morgan JJ (1981) Aquatic chemistry, 2nd edn. Wiley, New YorkGoogle Scholar
- 29.Tisdale SL, Nelson WL, Beaton JD (1985) Soil fertility and fertilizers. Macmillan, New YorkGoogle Scholar
- 30.Tobler DJ, Cuthbert MO, Greswell RB, Riley MS, Renshaw JC, Handley-Sidhu S, Phoenix VR (2011) Comparison of rates of ureolysis between Sporosarcina pasteurii and an indigenous groundwater community under conditions required to precipitate large volumes of calcite. Geochim Cosmochim Acte 75(11):3290–3301CrossRefGoogle Scholar
- 32.van Paassen LA (2009) Biogrout, ground improvement by microbial induced carbonate precipitation. Dissertation, Delft University of TechnologyGoogle Scholar