The Effect of Bacteria on Early Age Strength of CEM I and CEM II Cementitious Composites
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BRE Centre for Innovative Construction Materials, Department of Architecture and Civil Engineering, University of Bath, Bath BA2 7AY, UK
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Milner Centre for Evolution, Department of Biology and Biochemistry, University of Bath, Bath BA2 7AY, UK
*
Author to whom correspondence should be addressed.
Academic Editor: Syed Minhaj Saleem Kazmi
Sustainability 2022, 14(2), 773; https://doi.org/10.3390/su14020773
Received: 16 November 2021
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Revised: 5 January 2022
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Accepted: 7 January 2022
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Published: 11 January 2022
(This article belongs to the Special Issue Biomimetic Infrastructure Materials: Towards a Greener Future)
Despite being associated with lower carbon emissions, CEM II cementitious materials exhibit reduced early age strength compared to that of CEM I. Several studies have demonstrated early age strength improvements by incorporating bacterial cells in concrete. In this study, live vegetative bacteria and dead bacteria killed in two different ways were used to explore whether changes in strength are related to the bacteria’s viability or their surface morphology. Compressive and flexural strength tests were performed at mortars with and without bacteria for both CEM I and CEM II cement. Their microstructure, porosity and mineralogy were also examined. No net strength gain was recorded for either CEM I or CEM II bacterial mortars compared to non-bacterial controls, although changes in the porosity were reported. It is proposed that two phenomena, one causing strength-reduction and one causing strength-gain, took place in the bacterial specimens, simultaneously. It is suggested that each phenomenon is dependent on the alkalinity of the cement matrix, which differs between CEM I and CEM II mortars at early age. Nevertheless, in neither case could it be recommended that the addition of bacteria is an effective way of increasing the early age strength of mortars.
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Keywords:
bacterial mortar; low CO2 cement; compressive strength; pore volume
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MDPI and ACS Style
Hui, T.Y.; Skevi, L.; Reeksting, B.; Gebhard, S.; Paine, K. The Effect of Bacteria on Early Age Strength of CEM I and CEM II Cementitious Composites. Sustainability 2022, 14, 773. https://doi.org/10.3390/su14020773
AMA Style
Hui TY, Skevi L, Reeksting B, Gebhard S, Paine K. The Effect of Bacteria on Early Age Strength of CEM I and CEM II Cementitious Composites. Sustainability. 2022; 14(2):773. https://doi.org/10.3390/su14020773
Chicago/Turabian StyleHui, Tsz Y., Lorena Skevi, Bianca Reeksting, Susanne Gebhard, and Kevin Paine. 2022. "The Effect of Bacteria on Early Age Strength of CEM I and CEM II Cementitious Composites" Sustainability 14, no. 2: 773. https://doi.org/10.3390/su14020773
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