Applying MICP by denitrification in soils: A process analysis

Vinh Pham, Akiko Nakano, WRL van der Star, Timo Heimovaara, Leon van Paassen

Research output: Contribution to journalArticleScientificpeer-review

30 Citations (Scopus)
311 Downloads (Pure)

Abstract

The process of microbially induced carbonate precipitation (MICP) by denitrification was investigated in relation to its potential use as a ground improvement method. Liquid batch experiments indicated that the substrate solution had an optimum carbon–nitrogen ratio of 1·6 and confirmed that combining nitrate reduction and calcium carbonate precipitation leads to an efficient conversion, at which the pH is buffered slightly below 7 and the accumulation of toxic intermediate nitrogen compounds is limited. Sand column experiments confirmed that the volume and distribution of the gas phase strongly depend on the stress conditions. The produced gas volume is inversely related to the pore pressure and can be predicted based on a mass balance analysis, assuming conservation of mass and using theoretical laws of physics. At low pore pressure, the gas formed and accumulated at the top of the column, whereas calcium carbonate precipitation occurred mostly at the bottom near the substrate inlet; an excess amount of gas was produced, which vented from the sand columns and induced cracks in the sand at low confining pressures, which negatively affected the sand-stabilising effect of the calcium carbonate minerals.
Original languageEnglish
Article number15.00078
Pages (from-to)79-93
Number of pages15
JournalEnvironmental Geotechnics
Volume5
Issue number2
DOIs
Publication statusE-pub ahead of print - 2016

Keywords

  • calcium carbonate
  • strength & testing of materials
  • geochemistry

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