Civil Engineering Reference
In-Depth Information
winter gardens etc., it is often natural to lay the stones on earth or sand, without anything
in the joints.
Marble is the only stone that needs proper maintenance. This is carried out with wax or
polish.
Fired clay sheet materials
Fired clay can be used for a whole selection of surface materials for roof, walls
and floors. These can be divided into two main groups: fired clay tiles and
ceramic tiles.
Roof tiles of fired clay were used very early in the history of the
Mediterranean countries. The principle used was that of 'nun' and 'monk' tiles
(see Figure 15.5). The interlocking tile was first made in France in the mid-nine-
teenth century; it provides better waterproofing and increased fire safety. From
around the end of the nineteenth century, all houses in small towns were
ordered to have interlocking roof tiles or slates. Many clay tiles have been
replaced with concrete tiles and metal sheeting, often given a profile to look like
clay tiling.
Brick veneering of inner and outer walls uses bricks of standard sizes which
are placed in mortar on solid concrete or timber frame structures in thin layers.
Brick products can also be used as flooring, laid on sand or in mortar. Ceramic
tiles are used on floors and walls. These are usually square or rectangular in
form, but specially designed tiles of other shapes, e.g. triangular, octagonal or
oval, are also available. Tiles can be glazed or unglazed; unglazed tiles are often
coloured.
A better quality of clay is required for the production of roofing tiles and
ceramic tiles than for bricks. There is, however, an abundance of raw material.
Ceramic tiles and fired clay products used as outside cladding, roof covering
or untreated floor covering should have a very low porosity. This entails firing at
high temperatures, something that results in high primary energy use and pol-
lution levels. Lime cannot be added to reduce the pollution, as this would
increase the porosity of the products. For brick veneers on inner walls, the water-
proofing demands are less.
Fired clay products are an excellent material for the indoor climate. They are
hygienic, do not release gases or dust, and are usually good moisture-regulators,
if they are not highly fired and sintered. The jointing material for ceramic tiles
usually have polymers such as epoxy and polyurethane as ingredients. These can
cause health-damaging emissions into the indoor climate. In Sweden, mastics
with organic constituents have lead to mould problems, especially in bath and
shower rooms. Pure, biologically neutral combined cement and sand alternatives
are far better for both floor and wall.
