Incorporation of bacteria in concrete: the case against MICP as a means for strength improvement

Lorena Skevi, Bianca Reeksting, Timothy Hoffmann, Susanne Gebhard, Kevin Paine

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Strength improvement of cement-based materials by the addition of bacteria has been reported over the past decade and has been mainly attributed to microbially induced calcite precipitation (MICP 1). However, the ability of bacteria to survive, grow and retain their metabolic activity in concrete is questionable. This research sheds light on the mechanisms involved in the strength enhancement of cementitious materials that contain bacteria. The addition of different concentrations of live and dead cells of Bacillus cohnii in cement mortars led to an increase in flexural and compressive strength for the mortars containing both types of bacteria. Findings of the present study led to exclusion of MICP as the main cause of strength enhancement, disproving earlier theories. Other known hypotheses including the behaviour of bacteria as organic fibres or as nucleation sites are thoroughly discussed, and a new approach is proposed.

Original languageEnglish
Article number104056
JournalCement and Concrete Composites
Early online date10 Apr 2021
Publication statusPublished - 31 Jul 2021

Bibliographical note

Funding Information:
The authors gratefully acknowledge the Material and Chemical Characterisation Facility (MC 2 ) at University of Bath ( ) for the technical support in conducting SEM and TGA measurements. Tsz Ying (Vicky) Hui and Bin Li are thanked for their contribution to the TGA and strength experimental work, respectively. The authors acknowledge EPSRC (Project No. EP/PO2081X/1 ) and Industrial collaborators/partners for funding the Resilient Materials for Life (RM4L) programme grant. Lorena Skevi and Timothy D. Hoffmann were supported by BRE Trust and University of Bath Research Studentship Awards, respectively.


  • Concrete
  • Bacteria
  • Compressive Strength
  • Calorimetry
  • Thermal analysis


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