Stone: Types, Classification, and Applications in Civil Engineering

What Is Stone?

Stone, encompassing various stone types, is a naturally available building material that has been used since the early age of civilization. It’s available in the form of rocks, which can be cut into the required size and shape and used as a building block.

It has been used to construct small residential buildings into large temples and palaces all over the world. Red Fort, Taj Mahal, Vidhan Sabha in Bangalore, and several palaces of medieval age all over India would be the famous stone buildings.

Type of Stones

Considering the different types of stone, stones used for civil engineering works may be classified in the following three ways:

1. Geological
2. Physical
3. Chemical

1. Geological Classification

Based on their origin and the kinds of stones, they are classified into three main groups

1. Igneous Rocks.
2. Sedimentary Rocks.
3. Metamorphic Rocks.

1.1 Igneous Rocks.

These rocks are formed by cooling and solidifying these rock masses in their molten magmatic condition of the material of the earth. Normally, igneous rocks are strong and durable. Granite, trap, and basalt are the rocks belonging to this category, and Granites are formed by slow cooling of the lava under thick cover on the top.

Hence they have crystalline surfaces. The cooling of lava in the top surface of the earth results in non-crystalline and glassy texture. Trap and basalt belong to this category.

1.2. Sedimentary Rocks.

Because of weathering action of water, wind and frost existing rocks disintegrate. The disintegrated material is carried by water and wind; the water being the most powerful medium. Flowing water deposits its suspended materials in a few points of obstacles to its flow. These deposited layers of materials get consolidated under pressure and by heat.

Chemical agents also contribute to the cementing of these deposits. The rocks so formed are more uniform, fine-grained, and compact within their nature. They represent a bedded or stratified structure in general. Sandstones, limestones, mud-stones, etc. belong to this class of rock.

1.3. Metamorphic Rocks.

Previously formed igneous and sedimentary rocks under go changes because of metamorphic action of pressure and internal heat. For example, because of metamorphic action granite becomes grasses, trap and basalt change to schist and laterite, limestone changes to marble, sandstone becomes quartzite, and mud-stone becomes slate.

2. Physical Classification.

Based on the structure and types of stones and rocks, they may be classified as:

1. Stratified Rocks.
2. Unstratified Rocks.
3. Foliated Rocks.

2.1. Stratified Rocks.

These rocks have a layered structure. They possess planes of stratification or cleavage. They may be easily split along these planes. Sandstones, lime-stones, slate, etc. are examples of this class of stones.

2.2. Unstratified Rocks.

These rocks aren’t stratified. They possess compact and comprehensible grains. They can’t be split into a thin slab. Granite, trap, marble, etc. are examples of this type of rock.

2.3. Foliated Rocks.

These rocks have a tendency to split along a definite direction only. The direction is parallel to each other, as in the case of stratified rocks. This type of structure is very common in the case of metamorphic rocks.

3. Chemical Classification

On the basis of their chemical composition and understanding the stone type, engineers prefer to classify rocks as:

1. Silicious Rocks
2. Argillaceous Rocks
3. Calcareous Rocks

3.1 Silicious Rocks

The main content of these rocks is silica. They are hard and durable. Examples of such rocks are granite, trap, sandstones, etc.

3.2 Argillaceous Rocks

The main constituent of the rocks is argil, i.e., clay. These stones are tough and durable, but they are brittle. They can’t withstand shock. Slates and laterites are examples of this type of rock.

3.3. Calcareous Rocks

The main constituent of the rocks is calcium carbonate. Limestone is a calcareous rock of sedimentary origin, while marble is a calcareous rock of metamorphic origin.

Uses of Stones

Considering the kinds of stone available, stones are used in the following civil engineering constructions:

1. Stone masonry is used for the construction of walls, foundations, arches, and columns.
   
2. Stones are used for flooring.
3. Stone slabs are used as damp proof courses, lintels, as well as roofing materials.
4. Stones with good appearance are used for the face works of buildings. Polished marbles and granite are generally used for face works.
5. Stones are used for paving of roads, footpaths and open spaces across the buildings.
6. Stones can also be used in the construction of piers and abutments of bridges, dams, and retaining walls.
7. Crushed stones together with graved are used to provide a base course for roads. When mixed with tar, they form finishing coat.
8. Understanding the working principle of centrifugal pumps, crushed stones are used in the following works:
   1. As a basic inert material in concrete.
   2. For making artificial stones and building blocks.
   3. As railway ballast.

FAQ: Stone in Civil Engineering

What are the main types of stones used in civil engineering?

The main types of stones used in civil engineering are classified based on geological, physical, and chemical properties. These include:

1. Igneous Rocks: Such as granite, trap, and basalt.
2. Sedimentary Rocks: Including sandstones, limestones, and mud-stones.
3. Metamorphic Rocks: Like marble, quartzite, and slate.

What is the difference between igneous and sedimentary rocks?

1. Igneous Rocks: Formed from the cooling and solidifying of molten magma. They are typically strong and durable, with examples including granite and basalt.
2. Sedimentary Rocks: Formed from the accumulation and consolidation of sediments. They often have a layered structure and include rocks like sandstone and limestone.

How are stones classified physically?

Physically, stones are classified into:

1. Stratified Rocks: Layered rocks that can be split along planes, such as sandstone and limestone.
2. Unstratified Rocks: Compact and non-layered rocks, including granite and marble.
3. Foliated Rocks: Metamorphic rocks with a tendency to split along parallel planes, like slate.

What are the common chemical classifications of rocks?

1. Silicious Rocks: High in silica, such as granite and sandstone.
2. Argillaceous Rocks: Contain clay, making them tough but brittle; examples include slate and laterite.
3. Calcareous Rocks: Composed mainly of calcium carbonate, including limestone (sedimentary) and marble (metamorphic).

What are the primary uses of stones in construction?

Stones are used for:

1. Stone Masonry: Walls, foundations, arches, and columns.
2. Flooring: Various types of stones, including polished marble and granite.
3. Slabs and Roofing: Stone slabs for damp proof courses, lintels, and roofing materials.
4. Face Works: Decorative exterior finishes, especially with polished stones.
5. Paving: Roads, footpaths, and open spaces.
6. Structural Elements: Piers, abutments, dams, and retaining walls.
7. Crushed Stone Uses: Base course for roads, concrete aggregate, artificial stones, and railway ballast.

What are the benefits of using stone in construction?

1. Durability: Stones are strong and long-lasting.
2. Aesthetics: Stones provide a natural and attractive appearance.
3. Versatility: Suitable for a wide range of construction applications.
4. Low Maintenance: Requires minimal upkeep compared to other materials.

How is crushed stone used in construction?

Crushed stone is used for:

1. Concrete Production: As an aggregate material.
2. Base Course: Providing a foundation for roads and pavements.
3. Artificial Stones and Blocks: Manufacturing construction materials.
4. Railway Ballast: Supporting railway tracks and ensuring stability.