Introduction
Materials which are required for construction of buildings are referred as building materials.
Building materials are classified into three types
- Natural Materials: - These are naturally occurring materials namely wood, stone, mud or clay etc.
- Artificial materials: - These are man-made materials namely bricks, cement, glass & steel.
- Composite materials: - These are combination of two or materials namely concrete,
plywood etc.
Objective
To study different types of building materials used for construction of buildings
Stones
Introduction
Stones are naturally occurring building materials which is widely use in construction of buildings. Nowadays it has become an important source of aggregate (coarse & fine) for manufacturing concrete. Most of the historic monuments that remain even today are made of stones. These are permanent in nature and prices go up if you change the shape and texture of stone.
Sources of stone are rock which is not homogeneous in nature, no definite chemical composition and shape. Therefore we can conclude, stones are one of the important building materials that all the Civil Engineers should be familiar with it.
Classification of rocks
Stones used for civil engineering works may be classified in the following three ways:
- Geological Classification
- Physical Classification
- Chemical Classification
- Geological Classification
Based on their origin of formation stones are classified into three main groups
(i) Igneousrocks
(ii) Sedimentary rocks and
(iii)Metamorphic rocks
(i) Igneous Rocks: The inside portion of the earth‟s surface has high temperature so as to cause fusion by heat at even ordinary pressures. The molten or pasty rock material is known as the magma occasionally tries to come out to the earth‟s surface through cracks or weak portions. The rocks which are formed by cooling of magma are known as the igneous rocks.
Different types of igneous rocks are
Plutonic rocks, hypabyssal rocks and volcanic rocks.
(ii) Sedimentary Rocks: These rocks are formed by the deposition of products of weathering on the pre-existing rocks. All the products of weathering are ultimately carried away from their place of origin by the agents of transport. Such agents are frost, rain, wind, flowing water etc.
(iii) Metamorphic Rocks: These rocks are formed by the change in character of the pre-existing rocks. The igneous as well as sedimentary rocks are changed in character when they are subjected to great heat and pressure. The process of change is known as the metamorphism.
2. Physical Classification
Based on the structure, the rocks may be classified as: i. Stratified rocks
ii. Unstratified rocks iii. Foliated rocks
i. Stratified Rocks: These rocks are having layered structure. They possess planes of Stratification or cleavage. They can be easily split along these planes. Sand stones, lime stones, slate etc. are the examples of this class of stones.
ii. Unstratified Rocks: These rocks are not stratified. They possess crystalline and compact grains. They cannot be split in to thin slab. Granite, trap, marble etc. are the examples of this type of rocks.
iii.Foliated Rocks: These rocks have a tendency to split along a definite direction only. The direction need not be parallel to each other as in case of stratified rocks. This type of structure is very common in case of metamorphic rocks.
3. Chemical Classification
On the basis of their chemical composition engineers prefer to classify rocks as:
1) Silicious rocks
2) Argillaceous rocks and
3) Calcareous rocks
Silicious rocks: The main content of these rocks is silica. They are hard and durable. Examples of such rocks are granite, trap, sand stones etc.
Argillaceous rocks: The main constituent of these rocks is argil i.e., clay. These stones are hard and durable but they are brittle. They cannot withstand shock. Slates and laterites are examples of this type of rocks.
Calcareous rocks: The main constituent of these rocks is calcium carbonate. Limestone is a calcareous rock of sedimentary origin while marble is a calcareous rock of metamorphic origin.
Quarrying of Stone
Quarrying is the process of extracting natural stones from the earth's crust for use in construction, decorative purposes, and other applications. Here's an overview of the quarrying process:
1. **Site Selection:** A suitable site is chosen based on factors like the type of stone desired, accessibility, proximity to markets, and environmental considerations.
2. **Clearing and Preparation:** Vegetation and topsoil are removed from the site to expose the underlying rock formations. This can involve excavation, cutting trees, and leveling the land.
3. **Drilling and Blasting:** Holes are drilled into the rock using specialized machinery. Explosives are then placed in these holes and detonated to break the rock into manageable sizes.
4. **Extraction:** Once the rock is fragmented, it is either hauled out using heavy machinery or broken into smaller pieces for easier transportation.
5. **Transportation:** Large pieces of stone are transported from the quarry to processing plants using trucks, conveyor belts, or even by rail in some cases.
6. **Processing:** At processing plants, the stone is cut, shaped, and finished according to its intended use. This can involve cutting into slabs, shaping into blocks, or creating specific architectural pieces.
7. **Finishing:** Stones may undergo further treatments like polishing, honing, sandblasting, or flame-texturing to achieve the desired appearance and texture.
8. **Distribution and Usage:** Processed stone products are then transported to construction sites, factories, or other destinations where they are used for various applications, such as building facades, flooring, countertops, and more.
Quarrying operations can have environmental impacts, including habitat disruption, air and water pollution, and landscape alteration. Regulations and responsible practices are often in place to mitigate these effects and ensure sustainable quarrying.
It's important to note that the methods and tools used in quarrying can vary depending on the type of stone being extracted and the technological advancements in the industry.
PROPERTIES OF STONE
1- Physical properties
2- Chemical properties
Physical properties:-
The physical properties of stones, which are important for their use in construction, include:
1. **Density:** The mass per unit volume of a stone. It affects the overall weight of the stone and the structures built using it.
2. **Porosity:** The percentage of void spaces in the stone's structure. Highly porous stones are more susceptible to water absorption and weathering.
3. **Water Absorption:** The capacity of a stone to absorb water. Stones with high water absorption might be prone to cracking or deterioration in freezing conditions.
4. **Compressive Strength:** The ability of a stone to withstand axial loads without breaking. It's a crucial property for load-bearing structures.
5. **Hardness:** The resistance of a stone to abrasion, scratching, and wear. Harder stones are more durable and suitable for areas with heavy foot traffic.
6. **Toughness:** The ability of a stone to withstand impact loads without fracturing.
7. **Abrasion Resistance:** The stone's ability to resist wear caused by rubbing or friction.
8. **Weathering Resistance:** The resistance of a stone to natural weathering processes like erosion, chemical reactions, and temperature fluctuations.
9. **Specific Gravity:** The ratio of the density of the stone to the density of water. It helps in understanding the stone's weight relative to water.
10. **Pore Structure:** The arrangement and size of pores within the stone, which can affect its durability and susceptibility to water damage.
Chemical properties:-
The chemical properties of stones are important for understanding their reactivity and how they might interact with various substances over time. Here are some key chemical properties of stones used in construction:
1. **Acid Resistance:** How well a stone can withstand exposure to acidic substances without undergoing chemical reactions or deterioration.
2. **Alkali Resistance:** The ability of a stone to resist the effects of alkali substances, which can cause swelling or other forms of damage.
3. **Chemical Composition:** The elemental makeup of a stone, which influences its reactivity and behavior under different conditions.
4. **Weathering:** Stones can react with atmospheric gases, moisture, and pollutants over time, leading to chemical changes that affect their appearance and durability.
5. **Carbonation:** The reaction between carbon dioxide in the air and minerals in the stone, which can result in changes to the stone's surface and structure.
6. **Sulfate Attack:** Some stones can react with sulfates present in soils or water, leading to a weakening of the stone's structure.
7. **Mineral Reactions:** Stones composed of various minerals might undergo chemical reactions due to exposure to water, acids, or other chemicals.
8. **Color Changes:** Chemical reactions can cause color changes in certain stones, affecting their aesthetic appearance.
9. **Hydration:** In the context of concrete and cement-based materials, hydration is the chemical reaction between cement and water that leads to hardening.
10. **Efflorescence:** The migration of soluble salts to the surface of a stone, often resulting in white deposits. This can occur due to the interaction between the stone and moisture.
Requirements of good building stones
1) Crushing Strength: For a good building stone, the crushing strength should be greater than 100N/mm2.
2) Appearance: The stones which are to be used for face work should be decent in appearance and they should be capable of preserving their color uniformly for longtime.
3) Durability: A good building stone should be durable. The various factors contributing to durability of a stone are its chemical composition, texture, resistance to atmospheric and other influences, location in structure etc.
4) Facility of dressing: The stones should be such that they can be easily carved, moulded, cut and dressed.
5) Fracture: for a good building stone, its fracture should be sharp, even, bright and clear with grains well cemented (means bonded) together.
6) Hardness: The co-efficient of hardness, as worked out in hardness test, should be greater than 17 for a stone to be use in road work. If it is in between 14 and 17, the stone is said to be medium hardness. If it is less than 14, stone is said to be poor hardness and such stones are not fit for road work.
7) Percentage wear: If wear is more than 3%, the stone is not satisfactory. If it is equal to 3%, stone is just tolerable. For a good building stone, the wear should be equal to or less than3%.
8) Resistance to fire: The minerals composing stone should be such that shape of stone is preserved when fire occurs. The failure of stone in case of fire may be due rapid rise in temperature, sudden cooling and different coefficients of linear expansions of minerals.
9) Seasoning: the stones should be well seasoned before putting into use. Stones should be dried or seasoned before they are used in structural work. A period about 6 to 12 months is considered to be sufficient for proper seasoning.
10) Specific gravity: for a good building stone, its specific gravity should be greater than 2.7 or so. The heavy stones are more compact and less porous and they can be used for various engineering applications like dams, harbours etc.
11) Texture: A good building stone should have compact fine crystalline structure fre from cavities, cracks or patches of soft or loose material.
12) Toughness index: In impact test, if the value of toughness index comes below 13, stone is not tough. If it comes between 13 and 19, stone is said to be moderately tough. If it exceeds 19, the toughness of stone is said to be high.
13) Water absorption: All the stones are more or less porous, but for a good building stone, percentage absorption by weigh after 24hrs should not exceed 0.6. The porous stones seriously affect the durability of stones.
Test for stones
There are several standardized tests used to assess the physical and mechanical properties of stones used in construction. Some of these tests include:
1. **Water Absorption Test:** Measures the percentage of water absorbed by a stone's surface. This helps evaluate its porosity and susceptibility to weathering.
2. **Density and Specific Gravity Test:** Determines the mass and volume of a stone to calculate its density and specific gravity.
3. **Compressive Strength Test:** Measures the maximum load a stone can bear before it fails under a compressive force.
4. **Flexural Strength Test:** Evaluates a stone's ability to withstand bending or flexural loads.
5. **Abrasion Resistance Test:** Assesses the stone's resistance to wear and abrasion caused by friction or rubbing.
6. **Impact Test:** Measures a stone's toughness by subjecting it to impact loads and observing its behavior.
7. **Porosity Test:** Determines the volume of pores in a stone, providing insights into its permeability and water absorption characteristics.
8. **Slake Durability Test:** Determines a stone's resistance to disintegration when exposed to wetting and drying cycles.
9. **Soundness Test:** Evaluates a stone's resistance to disintegration or deterioration caused by exposure to chemical reactions or physical changes.
10. **Modulus of Rupture Test:** Measures a stone's strength when subjected to a bending force.
11. **Weathering Test:** Simulates weathering conditions to assess how well a stone can withstand natural environmental changes.
It's important to note that the specific tests conducted can vary based on the intended use of the stone and the standards followed by the testing laboratory. These tests provide valuable information about a stone's suitability for construction and help ensure the quality and durability of structures.
Uses
Stones have been used by humans for various purposes for centuries due to their durability, versatility, and aesthetic appeal. Here are some common uses of stone:
1. **Construction:** Stones are used for building structures, walls, foundations, and pavements. They provide strength, stability, and a natural appearance to architectural designs.
2. **Monuments and Sculptures:** Many historical and artistic monuments, sculptures, and statues are made from stone. It's a durable and enduring material for creating lasting works of art.
3. **Paving:** Stones are used for paving roads, pathways, driveways, and public spaces. They can withstand heavy traffic and weathering, making them a popular choice for outdoor surfaces.
4. **Cladding:** Stones are used as cladding materials to cover the exterior walls of buildings. This adds both aesthetic appeal and protection from the elements.
5. **Flooring:** Natural stone flooring, like marble, granite, and slate, is used in homes, commercial buildings, and public spaces due to its durability and elegance.
6. **Countertops:** Stones like granite, marble, and quartz are commonly used for kitchen and bathroom countertops due to their durability and aesthetic qualities.
7. **Fireplaces:** Stones are often used to construct fireplaces and hearths due to their heat-resistant properties and decorative appeal.
8. **Landscaping:** Stones are used for landscaping features like garden borders, retaining walls, water features, and decorative elements.
9. **Jewelry:** Certain types of stones, such as precious and semi-precious gemstones, are used in jewelry-making for their beauty and rarity.
10. **Tools and Weapons:** In ancient times, stones were used to craft tools and weapons like arrowheads, knives, and grinding stones.
11. **Grinding and Milling:** Stones were historically used for grinding grain into flour or for milling purposes.
12. **Water Management:** Stones are used in constructing wells, dams, and water reservoirs due to their ability to withstand water pressure.
13. **Art and Craft:** Stones are used in various art and craft forms, from mosaic artwork to stone carving.
14. **Ballast:** Crushed stones are used as ballast in railway tracks to provide stability and distribute the load of the train.
15. **Riprap:** Large stones are used to protect coastlines, riverbanks, and embankments from erosion and wave action.
