chapter 3 for engineering geology

1. IMPORTANT BUILDING STONES
BY : ENG ISMAIL MOHAMOUD ALI

2. Introduction
• Any type of rock that satisfies the properties
of rock that we discussed before may be used
as building stones.
• Some rocks, however, may occur abundantly
whereas others are much rare.

11. • 3. Sandstones:
• Massive sandstones consisting of closely
interlocking angular grains of quartz and free
from structural defects find extensive use as
building stones in all areas where they occur.
Varieties rich in clay and iron are better avoided.
• Quartzites having uniformly distributed siliceous
cement are quite suitable under heavy loads.

13. • 4. Limestones:
• These sedimentary rocks are also very
extensively used as building stones at places
of their occurrence but all varieties are not
suitable for this purpose. Limestones show
great variation in their properties and
appearance.

14. • Use of limestones as facing stones, even if
quite strong; should be avoided in situations
where:
a. The air is polluted with industrial gases, such
as in industrial towns;
b. Along sea coasts where sea-water- rich winds
can attack them directly.

15. • The reason for first precaution is that
sulphuric acid vapours contained in the
industrial gases react with calcium carbonate
of limestone producing calcium sulphate
(gypsum) crystals. This change involves an
increase in the volume and results in the
disintegration of the surface layer of the rocks.

16. • Similarly, salt crystals may be formed from
seawater by absorption and evaporation on
the rock surface and cause disintegration at
the surface.

18. 5. Marble:
• These are metamorphic rocks that are used for
ordinary structural work as well as for decorative,
and architectural designs. Marbles occur in
different colors and textures. Their absorption
value is generally low. They have sufficient
strength to bear building loads and at the same
time can be given any desirable shape because of
their low hardness. Marble can take brilliant
polish.

20. • 6. Slate:
• It is another metamorphic rock characterized
with a perfect slaty cleavage. It is used only as
a paving and roofing stone in ordinary type of
construction in hilly terrain where it may be
available.

23. Thank you