Agriculture Reference
In-Depth Information
proportions. It is wise, when producing a mate-
rial for use in construction, to specify the mix-
ture according to the properties one is seeking.
Thus, for an interior wall in a home, the acous-
tic absorption of the material will be given pri-
ority. By contrast, an outer wall will benefit
from materials that have been developed for
their thermal resistance. In Table 17.2, the
characteristics of hemp cement are detailed
and compared with those of a number of other
materials used in the construction industry.
superstructure (Fig. 17.16). The frame can
be covered completely in hemp cement or,
alternatively, the timbers can be left visible.
Generally, hemp cement with a density of
approximately 420 kg/m
3
is used for this
purpose.
CONSTRUCTION
.
The hemp cement can be
introduced by pouring it between two panels
that act as a mould. Alternatively, it can be
projected by machine on to a single panel.
When constructed to a thickness in excess of
27 cm, hemp concrete guarantees a uniform
insulation that respects current thermal
regulations.
17.4.5 Applications
Hemp cement, as defined previously, is used to
create walls, insulating floor tiles, rendering or
insulating underlay for roofing (Fig. 17.15).
Each of these uses is described in the following
paragraphs.
Use in floor construction
Hemp cement can be used to produce an insu-
lating slab(s) of concrete sited over ventilated
ballast (Fig. 17.17). Above the ground floor,
it can also be applied to wooden boards
(Fig. 17.18). A density of 500 kg/m
3
is used
for these applications.
Use in wall construction
Hemp cement is used to fill the wall
spaces that exist round the wall's frame or
Table 17.2.
Summary of the technical characteristics of hemp cement compared to other building
materials.
λ
: Thermal
Conductivity
(W/(m.K))
Deformation
(mm)
α
: Acoustic
absorption
Rc (MPa)
E (GPa)
Binder A
4,8
0,01
0,600
0,214
0,23-0,42
Binder C
3
0,01
0,300
0,12-0,22
Roof (low dose of
Binder A)
0,26
0,16
0,003
0,065
0,55-0,90
Wall (intermediate
dose of Binder A)
0,37
0,1
0,020
0,085
0,58-0,80
Tile (intermediate
dose of Binder A)
0,48
0,07
0,028
0,090
0,50-0,80
Rendering (high
dose of Binder C)
0,75
0,05
0,030
0,150
0,29-0,56
Pressure sealed
cellular concreate
5
25.10
−4
2
0,17
0,21-0,32
Panels of wood
0,058
Panels of
compressed straw
0,12
Cement mostar
10
5.10
−4
20
Hydraulic cement
20
1.10
−4
35
0,666
>0,1 (aggregates)
