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< prev - next > Manufacturing handicraft process industries Mining and Mineral Industries KnO 100362_Gypsum processing and use (Printable PDF)
Gypsum Processing and Use
Practical Action
up only small quantities of plaster and to apply these quickly, unless retarders are used.
A typical mix for wall blocks would be one volume of gypsum plaster to one volume of sand,
two volumes of gravel, and one volume of water. Such blocks would be hard enough to de-
mould after 10 to 15 minutes, before being left to dry for several days. The blocks should
satisfy the standard requirements for building blocks for general internal structural purposes,
and not be used in wet or damp conditions.
Gypsum plaster can also be reinforced with fibres and cast in moulds to produce precast
decorative panels. Certain fibres, such as sisal and conventional glass fibre, will not
deteriorate appreciably in a gypsum medium, although they do deteriorate over time in a more
alkaline Ordinary Portland Cement mix. Note that because of its affinity for water, gypsum
plaster should be stored in a dry place, and never outdoors if there is a risk of rain. If storing
gypsum in bags or in bulk for long periods then it should not be stored directly in contact with
the ground and preferably raised on pallets or slats. Prolonged storage in damp or humid
conditions is not advisable.
FaL-G Bricks and Blocks
Gypsum is a significant ingredient in Fly ash – Lime – Gypsum (FaL-G) bricks and blocks that
have been developed in India. These can be moulded with the same equipment used for
conventional concrete bricks and blocks and cured in water or steam, in the same way as for
concrete. Properties for the bricks and blocks similar to those of conventional concrete can be
achieved and it is claimed that even low grade waste gypsum and lime can be used in the
mixture to make satisfactory products.
Reference and further Reading
Gypsum Plaster: Its manufacture and use, Andrew Coburn, Eric Dudley, Robin
Spence. Practical Action Publishing, 1989
(A manual for potential and existing producers and users of gypsum, covering raw
material identification, properties of gypsum, production and use. Summary
information on a number of case studies from around the world is presented, and a
glossary, selected bibliography and contact addresses are included.)
Guidelines for manufacture of gypsum plaster in Mechanized pan system (IS 13001:
1991), Bureau of Indian Standards
Low Grade Gypsum; Use In Building; Code of Practice (IS 12654: 1989), Bureau of
Indian Standards
Small-scale production of gypsum plaster for building in the Cape Verde Islands, Ray
Smith, in Appropriate Technology, Vol.8 No.4, pp 4-6. Practical Action
Construire en Platre, Marc Nolhier. Editions L’Harmattan, Paris, 1986.
(Comprehensive text on gypsum. Covers both production technologies and the use of
gypsum in building. Many case studies included from around the world as well as a
comprehensive bibliography. Only available in French.)
For information on a small scale gypsum calciner and gypsum board manufacture
for dry lining of walls that has been developed by the Central Building Research
Institute in India contact:
The Director
Central Building Research Institute (CBRI)
Roorkee – 247 667
Tel: +91-1332-272243
Fax: +91-1332-272272
E-mail: [email protected] or [email protected]
For further information on Fly ash – Lime – Gypsum (FaL-G) bricks and blocks
contact the developers of this technology:
Institute for Solid Waste Research &
Ecological Balance (INSWAREB)