building construction (type of partition)

1. Asbestos cement partition
• Partition walls constructed from asbestos
cement sheeting or galvanized sheet fixed
to wooden or steel members are mostly
adopted in works of temporary character.
• For superior type of asbestos cement
sheet partition walls, specially
manufactured slabs of the other materials
are used.
• Each slab consists of core or corrugated
asbestos cement sheet with the plain
asbestos cement sheet attached to it on
either side

2. MERITS
• Asbestos is non-flammable even
at very high temperatures and is
extremely flexible and durable
• It is fibrous and crystalline, elastic
and brittle
• Newer garages that are part of the
house can have asbestos sheet or
fibro to assist in hindering the
spread of fire if a fire were to start
in the garage.
• It has good heat and sound
insulation properties.
• These walls are economical, light
and fairly rigid if constructed
properly.

3. PROBLEMS
•
Problems may be classified into two broad categories:
1) Natural or inherent
2) Vandalism and human-induced problems
NATURAL CORROSION
a. The zinc coating on galvanized iron and steel develops a
natural carbonate on its surface by exposure to the
atmosphere and by the action of rainwater.
b. Since the zinc coating on the iron or steel is very thin, it
can corrode up to the base metal exposing the base to the
atmosphere as well.
c. In industrial atmospheres, the zinc carbonate coating can
be broken down by the same acids that attack zinc
d. These acids often staining the adjacent building elements.

4. CHEMICAL CORROSION
a. Galvanized iron and steel have good corrosion
resistance to: Concrete, mortar, lead, tin, zinc and
aluminum.
b. Galvanized iron and steel have poor corrosion
resistance to: Plasters and cements containing chlorides
and sulfates.
c. Acidic rainwater run- off from roofs with wood shingles
moss, or lichen, condensation on the underside of zinc
plates.
GALVANIC (ELECTROCHEMICAL) CORROSION
a. This type of corrosion is an electrolytic reaction between
the zinc coating and dissimilar metals when in the presence
of an electrolyte such as rain, dew, fog or condensation.
b. Galvanized iron and steel are corrosive to all metals
except lead, tin, zinc and aluminum.

5. HUMAN-INDUCED PROBLEMS
It consist of Mechanical or Physical Deterioration
1. Abrasion: Causes removal of the protective metal surface.
2. Fatigue: A type of deterioration caused by cyclical expansion
and contraction of sheet metal features.
a. Zinc is very vulnerable to fatigue failure because it has
a relatively high coefficient of thermal expansion.
b. Fatigue failure may also occur when the metal sheets are
too thin to resist buckling and sagging.
3. Creep: The permanent distortion of a soft metal which has
been stretched due to its own weight.
4. Distortion: Permanent deformation or failure may occur when
a metal is overloaded beyond its yield point because of
increased live or dead loads, thermal stresses, or structural
modifications altering a stress regime.

6. RISK
Products which contain asbestos can generate fibres when they are damaged,
disturbed, weathered or old: in these circumstances, fibres are released into the
atmosphere and asbestos exposure through respiration can occur.
It is widely believed that exposure to asbestos contained in buildings presents a
relatively small risk.
PREVENTION
A. Applying a protective coating such as paint to galvanized iron and steel will
alleviate the problems caused by corrosion of the protective zinc coating.
B. To prevent the corrosion of the zinc coating due to galvanic action, contact
between galvanized items and copper or pure iron or steel should be avoided.
C. Creep may be prevented by the use of properly sized individual sheets and bays,
properly designed joints, and an adequate number of fasteners.
D. Galvanized iron and steel's resistance to corrosion depends largely
on the type and thickness of the protective zinc coating and the type of corrosive
environment; so it should be kept in mind while doing galvanization.

7. EXAMPLES
• Toilet cisterns can comprise asbestos
molded products either above the
toilet or behind walls in cavities
whilst
• toilet cubicle partitions can
commonly comprise 20 mm thick
compressed asbestos cement sheet
• External garages can contain asbestos
cement walls, eaves and corrugated
asbestos roofs.
• Partition walls constructed from
asbestos cement sheeting or
galvanized sheet fixed to wooden or
steel members are mostly adopted in
works of temporary character.