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Risk for Mould Growth on Hemp-Lime at Different Relative Humidity

Johansson, Sanne LU ; Strandberg, Paulien LU and Balksten, Kristin (2021) 4th International Conference on Bio-Based Building Materials (ICBBM 2021) In Construction Technologies and Architecture 3. p.588-594
Abstract
Microbial growth often thrives in humid conditions, at high relative humidity. Moulds are complex organisms; many types of mould are able to survive strong variations in humidity and temperature, such as those on building façades. For some building materials a critical relative humidity is determined, which functions as a theoretical threshold; at this (or lower) relative humidity microbial growth will likely not occur. Hemp-lime is a building material that consists of hemp shiv (the woody core parts of the hemp stem) and building lime. It is a material that can be used for walls, and even though it has been used for more than 20 years, thusfar little is known about its critical moisture levels for microbial growth. The aim of this... (More)
Microbial growth often thrives in humid conditions, at high relative humidity. Moulds are complex organisms; many types of mould are able to survive strong variations in humidity and temperature, such as those on building façades. For some building materials a critical relative humidity is determined, which functions as a theoretical threshold; at this (or lower) relative humidity microbial growth will likely not occur. Hemp-lime is a building material that consists of hemp shiv (the woody core parts of the hemp stem) and building lime. It is a material that can be used for walls, and even though it has been used for more than 20 years, thusfar little is known about its critical moisture levels for microbial growth. The aim of this research was therefore to determine at what relative humidity microbial growth occurs on carbonated hemp-lime material, and to study if there is a protective influence of a carbonated lime binder on the hemp shiv. The objective was to study microbial growth on hemp shiv, hemp-lime and on hemp with a thin layer of lime at three relative humidity (75 %, 85 % and 95 %) and at two different temperatures (15°C and 23°C); conditions that could occur naturally in a hemp-lime façade exposed to high rain loads in a northern European climate. Hemp shiv seems to have a relatively low resistance to microbial growth, similar to that of wood. However, because the hemp is protected by lime it can withstand much higher relative humidity without microbial growth occurring on the material. The critical moisture level for hemp-lime seemed to occur between 75 and 85 % RH, while the material was completely without microbial growth at 75 % RH. The lime had a protective effect on the hemp and acted as a mould inhibitor, both over time and with varying temperature and humidity. (Less)
Please use this url to cite or link to this publication:
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organization
publishing date
type
Chapter in Book/Report/Conference proceeding
publication status
published
subject
host publication
Bio-Based Building Materials : Selected peer-reviewed full text papers from the 4th International Conference on Bio-Based Building Materials (ICBBM 2021), June 16-18, 2021, Barcelona, Spain - Selected peer-reviewed full text papers from the 4th International Conference on Bio-Based Building Materials (ICBBM 2021), June 16-18, 2021, Barcelona, Spain
series title
Construction Technologies and Architecture
editor
Amziane, Sofiane and Sonebi, Mohammed
volume
3
pages
588 - 594
publisher
Trans Tech Publications
conference name
4th International Conference on Bio-Based Building Materials (ICBBM 2021)
conference location
Barcelona, Spain
conference dates
2021-06-16 - 2021-06-18
ISSN
2674-1229
2674-1237
ISBN
9783035726992
978-3-0357-3699-1
DOI
10.4028/www.scientific.net/CTA.1.588
language
English
LU publication?
yes
id
8b21a1ea-52e4-4e1b-ba39-a304b682c1b6
date added to LUP
2022-10-11 11:58:53
date last changed
2023-03-21 15:30:43
@inbook{8b21a1ea-52e4-4e1b-ba39-a304b682c1b6,
  abstract     = {{Microbial growth often thrives in humid conditions, at high relative humidity. Moulds are complex organisms; many types of mould are able to survive strong variations in humidity and temperature, such as those on building façades. For some building materials a critical relative humidity is determined, which functions as a theoretical threshold; at this (or lower) relative humidity microbial growth will likely not occur. Hemp-lime is a building material that consists of hemp shiv (the woody core parts of the hemp stem) and building lime. It is a material that can be used for walls, and even though it has been used for more than 20 years, thusfar little is known about its critical moisture levels for microbial growth. The aim of this research was therefore to determine at what relative humidity microbial growth occurs on carbonated hemp-lime material, and to study if there is a protective influence of a carbonated lime binder on the hemp shiv. The objective was to study microbial growth on hemp shiv, hemp-lime and on hemp with a thin layer of lime at three relative humidity (75 %, 85 % and 95 %) and at two different temperatures (15°C and 23°C); conditions that could occur naturally in a hemp-lime façade exposed to high rain loads in a northern European climate. Hemp shiv seems to have a relatively low resistance to microbial growth, similar to that of wood. However, because the hemp is protected by lime it can withstand much higher relative humidity without microbial growth occurring on the material. The critical moisture level for hemp-lime seemed to occur between 75 and 85 % RH, while the material was completely without microbial growth at 75 % RH. The lime had a protective effect on the hemp and acted as a mould inhibitor, both over time and with varying temperature and humidity.}},
  author       = {{Johansson, Sanne and Strandberg, Paulien and Balksten, Kristin}},
  booktitle    = {{Bio-Based Building Materials : Selected peer-reviewed full text papers from the 4th International Conference on Bio-Based Building Materials (ICBBM 2021), June 16-18, 2021, Barcelona, Spain}},
  editor       = {{Amziane, Sofiane and Sonebi, Mohammed}},
  isbn         = {{9783035726992}},
  issn         = {{2674-1229}},
  language     = {{eng}},
  pages        = {{588--594}},
  publisher    = {{Trans Tech Publications}},
  series       = {{Construction Technologies and Architecture}},
  title        = {{Risk for Mould Growth on Hemp-Lime at Different Relative Humidity}},
  url          = {{http://dx.doi.org/10.4028/www.scientific.net/CTA.1.588}},
  doi          = {{10.4028/www.scientific.net/CTA.1.588}},
  volume       = {{3}},
  year         = {{2021}},
}