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|Table of Contents|

微生物注浆固化粉土的微观结构与作用机理(PDF/HTML)

《南京林业大学学报(自然科学版)》[ISSN:1000-2006/CN:32-1161/S]

Issue:
2017年02期
Page:
129-135
Column:
研究论文
publishdate:
2017-03-23

Article Info:/Info

Title:
Microstructure and mechanism of microbial cementation silt treated by bio-grouting
Article ID:
1000-2006(2017)02-0129-07
Author(s):
SHAO Guanghui12 YOU Ting1 ZHAO Zhifeng12 LIU Peng12FENG Jianting1
1.School of Civil Engineering, Nanjing Forestry University, Nanjing 210037, China;
2.Jiangsu Province Key Laboratory of Soil and Water Conservation and Ecological Restoration, Nanjing 210037, China
Keywords:
silt cementation bio-grouting unconfined compressive strength microstructure
Classification number :
TU411
DOI:
10.3969/j.issn.1000-2006.2017.02.019
Document Code:
A
Abstract:
【Objective】 Determining the behavior of microbial cementation silt treated by bio-grouting, based on the technology of microbial induced carbonate precipitation(MICP), could provide a basis for developing the MICP technology and applying it for dredger fill silt. 【Method】 Experiments were conducted for cement dredger fill silt specimens by microbial grouting. Unconfined compressive tests, X-ray diffraction analyses(XRD), scanning electron microscope(SEM)observations, mercury intrusion porosimetry(MIP)and some chemical analyses were performed to investigate the difference in strength, mineral component, cementing CaCO3 content, soil microstructure and pore size distribution of untreated and treated dredger fill silts. 【Result】 After injecting 1 to 6 rounds of Sporosarcina pasteurii(A600=1.2)and a cement solution containing a mixture of CaCl2 and urea(0.1 mol/L)under constant pressure, the unconfined compressive strength of the treated silt specimens increased by 26.8%, 33.0%, 36.4%, 39.6%, 59.8% and 61.8% after the rounds 1 to 6, respectively, compared to the untreated silt specimen. The strength of the treated silt specimens increased with the number of rounds of injection. The cementing CaCO3 from the microbial grouting was mostly in the calcite phase, which filled the soil pores and cemented the soil particles. The CaCO3 content had a dominant effect on the strength of the treated silt. The more the CaCO3 precipitated from the microbial process in the silt, the higher was the strength of the silt. Furthermore, there was a sensitive threshold for CaCO3 content with respect to strength variation. The cementing efficiency increased significantly when the CaCO3 content was higher than the threshold, which varied with the genetic type or sedimentary environment of the silt. Compared to the untreated silt, the treated silt had significantly different pore diameter distribution characteristics. After the bio-grouting treatment, the pores in the range 10-300 μm in the silt reduced sharply, and the pores smaller than 10 μm remained almost unchanged. 【Conclusion】 Bio-grouting is an effective method that can be applied for cementing dredger fill silt. The strength of the dredger fill silt treated with microbial grouting is influenced by the CaCO3 content, and there is a sensitivity threshold for CaCO3 content with respect to strength variation. The pore size of the dredger fill silt is large enough for the microbial cells of Sporosarcina pasteurii migration. In the dredger fill silt treated by bio-grouting, there is a large reduction in the number of pores with a size over 10 μm.

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Last Update: 2017-03-23