Requirements of Good Building Stones
1. Strength:
Building
stones must possess adequate strength to withstand the loads exerted upon them.
This is particularly critical for structural elements like foundations,
columns, and load-bearing walls. For example, granite is often chosen for its
high compressive strength about 96.5- 310 MPa.
2. Durability:
Stones
should be resilient against environmental factors such as rain, wind,
temperature variations, and chemical effects. A durable stone like sandstone,
when used in monuments, ensures longevity even in harsh weather conditions.
3. Hardness:
Stones
employed in flooring or pavements need to resist wear and tear caused by
traffic and friction. For instance, basalt is commonly used in pavements due to
its excellent abrasion resistance.
4. Toughness:
The
stone must be tough enough to endure stresses caused by vibrations or dynamic
loads, such as those experienced in machinery foundations or near railway
tracks. Basalt and trap rocks are ideal for such applications.
5. Specific Gravity:
A
good building stone typically has a specific gravity ranging between 2.4 and
2.8, indicating its density and compactness. Higher specific gravity often
correlates with greater strength, making granite a popular choice.
6. Porosity and
Water Absorption:
Stones
with minimal porosity are less likely to absorb water, reducing susceptibility
to damage from freeze-thaw cycles or chemical reactions. For instance, marble,
being non-porous, is often preferred for damp environments.
7. Dressing:
The
process of shaping stones into the desired size and form is referred to as
dressing. Stones that are easy to dress, such as limestone, are economical for
construction, especially in ornamental works.
8. Appearance:
When
stones are used for aesthetic purposes, such as in facades, their visual appeal
becomes crucial. Factors like color, texture, and the ability to take a
polished finish are important. For example, polished marble is highly valued
for its elegant appearance in decorative applications.
9. Seasoning:
Stones
should be adequately seasoned to eliminate quarry sap—a moisture content
present in freshly quarried stones. For instance, laterite stones require an
aging period of 6 to 12 months before use to enhance their strength and
stability.
Each of these factors
plays a vital role in selecting suitable building stones for specific
construction purposes, ensuring not only functionality but also aesthetic and
economic feasibility.