This document discusses the characteristics of good building stones. It defines stones as derived from rocks that form the earth's crust and have no definite shape or chemical composition. Stones are commonly used in construction for buildings, dams, roads, and more. The key characteristics of good building stones discussed are appearance, weight, porosity, grain size, texture, hardness, toughness, crushing strength, density, resistance to fire, ability to be dressed, and durability. Stones suitable for construction should score high on these qualities such as having a high density, low porosity, and high crushing strength to withstand forces.

1. CE8391 CONSTRUCTION MATERIALS
UNIT I STONES – BRICKS – CONCRETE BLOCKS
Presentation By
Mr.P.Selvakumar.,B.E.,M.E.
Assistant Professor,
Department Of Civil Engineering,
Knowledge Institute Of Technology, Salem.
Stones

2. Sub topics
1. Definition
2. Uses of stones
3. Characteristics of good building stones

3. Stones - Definition
• The stones are derived from rocks which form the earth's
crust and have no definite shape or chemical composition
but are mixtures of two or more minerals.
• The mineral is a substance which is formed by the natural
inorganic process and possesses a definite chemical
composition and molecular structure.

4. Stones - Uses
• Construction of residential and public buildings.
• Construction of dams, weirs, harbours, abutment for
bridges, etc.
• Used as road metal and railway ballast.
• Used as aggregate for concrete.
• Used in the form of veneers for decorative front and
interior of buildings.

7. Commonly Used Building Stones
1. Granite
2. Basalt
3. Limestone
4. Sandstone
5. Marble
6. Slate
7. Gneiss
8. Quartzite
9. Laterite
10. Chalk

8. Granite Basalt Limestone
Sandstone Marble Slate Gneiss

10. Characteristics Of Good Building Stones
• Stones find their applications in the construction of heavy
structures such as dams, docks and harbours, weir,
bridge piers, buildings, etc.
• To find the suitability of stones under different
conditions, the following characteristics should be
considered:

11. Characteristics Of Good Building Stones
1. Appearance and colour
2. Weight
3. Porosity and absorption
4. Fineness of grain
5. Texture
6. Hardness
7. Toughness
8. Crushing strength
9. Density
10.Resistance to fire
11. Dressing
12. Durability

12. Appearance and Colour
• The Stones colour used for decoration work should have
uniform and appealing colour.
• Should be free from flaws and clay holes.
• The stones should also have the ability to receive good
polish.

13. Weight
• The weight of the good building stone should be high, as
heavier stones can resist the force of bigger magnitude.
• A heavy stone possess more Compactness and less
porosity.
• Weight of the stones depends on density.

14. Porosity and absorption
• Porosity makes the stone unsuitable for building construction
• Because during rain, water seeping into pores contains acids
and fumes (absorbed from atmosphere) which destroy the
stone.
• When the climate is cold, water entering the pores may even
freeze and split the stone.
• Continuous dampness makes the building unhealthy.

15. Fineness of grain
• The stones which are fine grained are suitable for moulding
works.
• The fracture in the stones should be sharp, even, bright and
clear with grains.
• A dull, chalky and earthly fractures of stones indicates signs
of future decay.

16. Fineness of grain

17. Texture
• A good building stone should have compact fine crystalline
structure free from cavities, cracks or patches of soft or
loose material. The stones with such texture are strong and
durable.

18. Texture

19. Hardness
• The stones must be adequately hard and tough so that they may
resist wear and tear (as in the case of railway ballast, road metal,
etc.).
• Hardness refers to resistance against scratching.
• The coefficient of hardness should be greater 17 for a stone to be used
is road work (High hardness).
• If it is between 14 and 17 is said to be medium hardness
• If it is less than 14, the stone is said to be poor hardness

20. Toughness
• Toughness refers to resistance against deformation.
• In impact test, the Stone is tested for toughness index,
 Below 13 Not tough
 Between 13 to 19 Moderately tough
 Greater than 19 - Toughness is high.

21. Crushing strength
• Crushing strength or compressive strength is required to measure
for load bearing structures.
• For good structural stone, the crushing strength should be greater
than 100 N/mm2

22. Compactness (Density)
• Stone's durability is decided by their compactness or density of
composition.
• A compact stone can withstand the effects of external agencies
effectively.

23. Resistance to fire
• Resistance to fire: For resistance against fire, the stone
• (i) should have homogeneous composition.
• (ii) should be free from calcium carbonate or oxide of iron.

24. Dressing
• The art of shaping a stone is known as dressing.
• Stones should possess uniform texture and softness so that they
may be easily dressed,
• If the stone is too hard, finish will be poor and dressing
uneconomical.

25. Durability
• A stone is more durable in case it is
(i) compact,
(ii) homogeneous and
(ii) free from any material affected by dilute hydrochloric and
sulphuric acids.
• It should also have negligible water absorption.

26. Thank You
Any queries?