Geoscience Reference
In-Depth Information
Mortar, plaster, and
render
8
construction, it is neither strong nor durable. To satisfy
the demand for dependable structures, stronger and more
durable binders have evolved, the main ones being based
on gypsum, lime, and cement. A brief comparison of the
properties of these different binders is provided in
Table
30
and their development is summarized overleaf.
Mortars are used to embed masonry units as well as
being used as wall finishing materials internally (plaster)
and externally (render). Mud was the first material used
for these purposes and, although it is still used in earth
Table 30
Comparison of the properties of different binders used for mortars, plasters, and renders
Property
Mud/clay
Gypsum
Lime
Portland cement
Heating
Air drying
130-170°C
850-1200°C
1250-1500°C
temperature
for production
Construction
Moderate
Fast
Moderate
Fast
speed
Strength
Very low
Low
Medium-high
Very high
Breathability
High
High
High
Low
Shrinkage
High
Low
Medium
High
Fire resistance
High
High
Medium
Medium
Appropriate
Earth
Internal
Conservation of
Modern masonry structures
applications
structures
plastering
historic buildings
with movement joints
Increasing revival in
Masonry carrying large loads
use for new buildings
(does not require
Extreme exposure
movement joints)
conditions
Inappropriate
All other
External works
Extreme exposure
Conservation of historic
applications
structures
(except for
conditions
buildings
conservation of
existing external
gypsum mortars)
