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Hemp concretes : mechanical properties using both shives and fibres

Strandberg, Paulien LU (2008)
Abstract
Hemp (Cannabis sativa) is an agricultural crop that can be used as a building material in combination with lime and cement. A composite building material that combines a cementitious binder (building limes and cement) with hemp shives, the woody core of the hemp stalk is generally referred to as hemp concrete (HC). However, industrial facilities to separate hemp shives and fibres are currently not available in Sweden. HC has many advantages as a building material but it is not load-bearing and must be used in combination with a load-bearing wooden frame. The aim of this research was to elucidate the feasibility of using both hemp shives and fibres in a HC to determine an optimal mix of the different binding agents and to investigate if... (More)
Hemp (Cannabis sativa) is an agricultural crop that can be used as a building material in combination with lime and cement. A composite building material that combines a cementitious binder (building limes and cement) with hemp shives, the woody core of the hemp stalk is generally referred to as hemp concrete (HC). However, industrial facilities to separate hemp shives and fibres are currently not available in Sweden. HC has many advantages as a building material but it is not load-bearing and must be used in combination with a load-bearing wooden frame. The aim of this research was to elucidate the feasibility of using both hemp shives and fibres in a HC to determine an optimal mix of the different binding agents and to investigate if adding undensified microsilica to the mix and using calcinated gypsum as a binder would improve mechanical strength of the material. The effects on compressive strength of pre-mixing the binder or creating perforations in the test specimens were also investigated. Cube and cylinder specimens cured for 40 days in a carbonation room (4.5 vol% CO2) were tested for mechanical properties, water sorption and frost resistance. Including more hydraulic lime or undensified microsilica in the mix did not significantly affect mechanical strength, whereas adding more cement to the mix increased mechanical strength. Calcinated gypsum as a binder gave mechanical properties of the same magnitude of a contemporary HC. Pre-mixing the binder created a more homogeneous material but it did not seem to play an important role in final mechanical properties. The perforations created in some of the test specimens produced a material with a lower Young’s modulus and higher deformation at rupture. Using both shives and fibres in a hemp concrete may be a suitable approach in Sweden until facilities for separating hemp fibres from shives become available. (Less)
Please use this url to cite or link to this publication:
author
publishing date
type
Thesis
publication status
published
subject
keywords
carbonation, gypsum, cement, lime, building material, hemp, shives, silica, lime-hemp concrete.
pages
46 pages
publisher
Sveriges Lantbruksuniversitet
ISBN
978-91-85911-87-5
language
English
LU publication?
no
id
22ac9b48-d2da-4052-8db4-78b596414fb5 (old id 1717272)
alternative location
http://publikationer.slu.se/?pubid=P30423&sprak=e
date added to LUP
2010-11-16 15:34:05
date last changed
2016-09-19 08:45:02
@misc{22ac9b48-d2da-4052-8db4-78b596414fb5,
  abstract     = {Hemp (Cannabis sativa) is an agricultural crop that can be used as a building material in combination with lime and cement. A composite building material that combines a cementitious binder (building limes and cement) with hemp shives, the woody core of the hemp stalk is generally referred to as hemp concrete (HC). However, industrial facilities to separate hemp shives and fibres are currently not available in Sweden. HC has many advantages as a building material but it is not load-bearing and must be used in combination with a load-bearing wooden frame. The aim of this research was to elucidate the feasibility of using both hemp shives and fibres in a HC to determine an optimal mix of the different binding agents and to investigate if adding undensified microsilica to the mix and using calcinated gypsum as a binder would improve mechanical strength of the material. The effects on compressive strength of pre-mixing the binder or creating perforations in the test specimens were also investigated. Cube and cylinder specimens cured for 40 days in a carbonation room (4.5 vol% CO2) were tested for mechanical properties, water sorption and frost resistance. Including more hydraulic lime or undensified microsilica in the mix did not significantly affect mechanical strength, whereas adding more cement to the mix increased mechanical strength. Calcinated gypsum as a binder gave mechanical properties of the same magnitude of a contemporary HC. Pre-mixing the binder created a more homogeneous material but it did not seem to play an important role in final mechanical properties. The perforations created in some of the test specimens produced a material with a lower Young’s modulus and higher deformation at rupture. Using both shives and fibres in a hemp concrete may be a suitable approach in Sweden until facilities for separating hemp fibres from shives become available.},
  author       = {Strandberg, Paulien},
  isbn         = {978-91-85911-87-5},
  keyword      = {carbonation,gypsum,cement,lime,building material,hemp,shives,silica,lime-hemp concrete.},
  language     = {eng},
  pages        = {46},
  publisher    = {ARRAY(0x8a3ed28)},
  title        = {Hemp concretes : mechanical properties using both shives and fibres},
  year         = {2008},
}