- In order to decrease the curing time,
gypsum, lime or cement can be added.
As these additives also make the mixture
leaner, the shrinkage is reduced. The disad-
vantages while adding these substances
might be that the binding force and the
compressive strength are reduced.
Joints and cracks in internal elements
can be filled with a mixture of 1 part loam,
0.5 to 1 part hydraulic lime and 0.5 to
1 part gypsum.
If the joints are exposed to weather, gyp-
sum should not be used, but cement, high-
hydraulic lime or a mixture of these totalling
from 8% to 20% can be used as an addi-
tive. Instead of these binders 4% to 7%
double-boiled linseed oil can also be added.
This filler stays plastic for several weeks.
Application of filler
In order to get a good bond between the
old loam surface and the filler material,
cracks should be opened up to 1 cm with
loose particles brushed away and the edges
of the joints sufficiently moistened so that
the loam swells and gets plastic on the sur-
face. When double-boiled oil loam is used
as filler for repairing, the surface has to be
treated with linseed oil.
The plastic filler is first applied with a knife
to both sides of the joint, and the opening
then filled with a drier mixture of the same
filler, tamped or hammered into the joint
(see 8.29). It is advisable that the joint is
filled with more material than is necessary,
so that when after the filler shrinks on dry-
ing, it can be compacted again when still
slightly moist.
Repair of cracks and joints with other
fillers
The repair of cracks and joints with a loam
filler is very time-consuming and requires
some experience. However, other fillers
which show less shrinkage and better
bonding qualities and require less labour
and skill are described in this chapter.
Mixtures
As an alternative to loam fillers, all materials
that can be commonly used for plasters
can be used as fillers. High-hydraulic lime,
cement, gypsum, casein, cellulose and
double-boiled linseed oil can be used as
binders. Silt, sand, and gravel as well as
organic aggregates like cork, sawdust, cereal
and rice husks, and shredded newspaper
can be used as fillers. When repairing exter-
nal joints, organic matter should not be
used except when the mix has a high
pH-value (which prevents growth of micro-
organisms). Acrylic or silicone elastic syn-
thetic mixes can also be used as fillers.
Silicone bonds with loam, provided the joint
surface is dry and free of loose particles
before application.
Repairing larger areas of damage
Repairing with loam
Larger eroded or flaked areas should be
repaired by scraping off all loose loam and
then wetting the surface before applying
new loam, as described in chapter 11 on
loam plasters.
In order to reduce shrinkage, each layer of
loam plaster should not be thicker than
1 to 1.5 cm. If the damage is more than
2 cm deep, it is advisable to scrape the area
to a depth of 4 to 6 cm. This is then filled
with broken adobes and lean mortar. In
areas prone to frost, green bricks are not
advisable as they are not frost-resistant.
Coatings
If the coating of a loam surface is to be
repaired, the old coating should first be
scraped off. The area is then primed before
the new coating is applied. For this, lime-
casein milk can be used, as described in
chapter 12, p. 99.
If the surface is very sandy and soft, a
primer of lime-casein glue is better. This is
prepared from 1 part hydraulic lime and
5 parts fat-free cheese mixed intensively for
two minutes without the addition of water.
The mixture is allowed to stand for a while
105 Repair of loam components
- 2
13 .1Pumping light-
weight mineral loam
- 2Additional interi-
or thermal insulation
layer of lightweight
Loam in bathrooms
timber frame wall
