Civil Engineering Reference
In-Depth Information
per cent by weight. The sheets or tiles can usually also be applied to walls, either
flat or corrugated.
Small scale production of corrugated sheeting
The mix for this sheeting is 5 kg cement, 15 kg sand and 0.2 kg fibre, mixed well with
water. The mix is poured into a mould where it hardens over 24 hours. It is then placed in
a damp, solar-warmed plastic case to cure for a month, or laid in water to cure for seven
days. (The curing must not occur in dry air.) After curing the sheets are dried. (Parry,
1984.)
The Intermediate Technology Group (IPDG) in England have developed a produc-
tion system for corrugated roof sheeting which is highly appropriate for small-scale
production. The factory can produce 2000 tiles of 50
25 cm per week and needs
four workers in a floor space of 25 m 2 with a courtyard of about 40 m 2 . A factory that
produces 20 000 tiles a week, employs 30 workers on a factory floor of 400 m 2 with a
courtyard of 350 m 2 . In this way one can produce roofing with low energy production
costs and at three quarters of the price of corrugated metal sheeting. These have
been produced for 20 years, and the life span of the sheeting is estimated at 50 years.
Environmentally speaking, cement roof sheeting can be considered better than
the metal alternative. Roof sheeting is much more economical in terms of mate-
rial use than roof tiles. All of the products can be re-used, but the sheeting can
be more easily damaged under demounting and therefore has a lower re-use
factor.
Floor coverings
Concrete
A normal concrete floor is highly durable and can cope with both water and
chemicals, but on the other hand, it is unpleasant to walk on because it is hard
and cold. This can be compensated for to a certain degree by adding sawdust,
crumbled cork or light expanded clay. A concrete floor will produce a lot of dust
through wear and tear unless it is treated with a waterglass solution, painted
with a robust paint or covered by a strong floor covering. If the floor is to be cov-
ered with totally watertight material, the concrete must be completely dried out
before the floor finish is laid, otherwise there may be alkaline reactions in the
products with possible detrimental emissions into the internal air. Complete cur-
ing of the concrete is best guaranteed if it is well watered in the period after the
concrete work.
Terrazzo concrete causes less dust problems than a pure concrete floor, and
produces a much more hygienic surface. A terrazzo floor is a mixture of cement
mortar and crushed stone of only a few millimetres in diameter, usually marble
or limestone. For a harder floor, granite, feldspar or quartz can be used. The floor
Search WWH ::




Custom Search