सिविल इंजीनियरिंग बिल्डिंग मटेरियल

Civil Engineering Building Materials

• Civil Engineering Building Materials covers essential topics for JE exams.
• The course is presented by Chadha Sir, aimed at providing a trusted learning platform.
• Focus areas of study include cement, stones, bricks, timber, paints, varnishes, lime, mortars, plasters, glass, cast iron & steel, tiles & ceramics, and asbestos.
• Building Materials is a significant portion of the technical exams, with a weightage of 12-15%.

What are Building Materials?

• Building materials are substances used in the construction of structures.
• Structures include buildings, bridges, roads, dams, and other infrastructure.
• Material choice is based on properties, cost, availability, and suitability for applications.
• Labour and transport play a key role in material selection.

Types of Building Material

• Natural building materials include stone, wood and soil.
• Artificial manufactured materials include concrete, steel and cement.
• Other artificial manufactured materials include bricks, glass, tiles, asbestos and plastic.
• Modern materials include composites and geotextiles.

Selection Criteria for Building Materials

• Strength and durability is important for withstanding loads and environmental conditions.
• Workability affects ease of shaping, cutting, and installation.
• Cost and availability includes local accessibility and economic feasibility.
• Sustainability involves environmental impact and recyclability.
• Compatibility relates to how well materials interact within the structure.

Cement

• Cement is a commonly used binding material in construction
• It is gotten by burning a mixture of calcareous (calcium) and argillaceous (clay) material at high temperature.
• The resulting clinker is then ground into a fine powder.

Cement Components

• Calcareous products contain calcium carbonate (CaCO3) or lime (CaO).
• Calcareous products are derived from limestone, chalk, or marble.
• Argillaceous products are rich in clay minerals or alumina (Al2O3).
• Argillaceous products primarily come from clay.
• Clay is silica tetrahedral.

Importance of Cement

• Cement is important because of its binding properties, versatility, and durability
• It is easy to use and cost effective
• It has a wide range of applications
• Applications include buildings, roads and canals

Cement Properties

• Cement acts as a binding agent.
• Cement sets and hardens stones, bricks, tiles etc.
• Hardening results in gain of strength.
• China is the largest producer of cement.
• India is the second largest producer of cement.
• USA is the third largest producer of cement.
• Cement paste is a mixture of cement and water.
• Setting is when cement loses its plastic behavior.

Manufacturing of Cement

• Manufacturing of cement involves burning raw materials
• After the raw materials undergo burning, clinker is produced
• Clinker is an intermediate product in the production of cement
• Clinker then needs to be ground to produce cement powder

The manufacturing process

• The manufacturing of cement involves steps of selection and mixing of raw materials
• Next burning must occur at 1400-1500 degrees
• The materials are burnt in a rotary kiln
• Grinding occurs in mills
• Storage follows grinding

Raw Materials

• Significant raw materials in cement include: lime, silica, alumina, iron oxide, magnesium oxide, sulphur trioxide, and alkalis.
• Lime has a range of 60-65%.
• Silica has a range of 17-25%.
• Alumina has a range of 3.5-9.0%.
• Iron oxide has a range of 0.5-6.0%.
• Magnesium oxide has a range of 0.5-4.0%.
• Sulphur trioxide has a range of 1-2.0%.
• Alkalis have a range of 0.4-1.3%.

Selection & Mixing of Raw Materials

• Lime (62%) and silica (23%) constitute large proportions of raw materials

Raw Material Roles

• Lime provides strength.
• Silica imparts strength.
• Alumina imparts quick setting.
• Iron oxide offers strength, hardness, and grey color.
• Gypsum increases setting time.
• Magnesia offers hardness.
• Sulphur trioxide provides sound.

Influence of Raw Materials

• Lime (CaO): Is present in OPC from 60-67% and provides strength and durability
• Excess lime can cause cracking, while insufficient lime can weaken the cement.
• Silica (SiO2): Is present in OPC from 17-25% and contributes to long-term strength of cement.
• Alumina (Al2O3): Is present in OPC from 3-8% and enhances the early strength of cement
• Gypsum (CaSO4·2H2O): Present in OPC from 3-5% and control the setting time of cement.
• Iron Oxide (Fe2O3): Is present in OPC from 0.5-6% and provides color.
• Magnesia (MgO): Is present in OPC from 0.1-4% and improves strength and hardness.
• Sulfur Trioxide (SO3): Is present in OPC from 1-3% and regulates the setting time of cement.
• Alkalis (Na2O and K2O): Is present in OPC from 0.3-1.2% and improves the workability of cement and prevent excessive alkali reactions.

Key Terms

• C3S (Tricalcium Silicate): Is responsible for early strength
• C2S (Dicalcium Silicate): Is responsible for ultimate strength
• C3A (Tricalcium Aluminate): Influences the setting time for cement.
• Flash setting is when the cement hardens prematurely.

Manufacturing Processes

• Cement can be manufactured through wet or dry processes
• The method depends on whether raw materials are mixed and grinded in wet or dry conditions
• For many years, the wet process remained popular, which is replaced by the dry process as it consumes less fuel for burning.

Wet Process

• Involves preparing raw materials like limestone and clay and crushing the raw materials
• These materials mix with water to create a slurry
• This is then homogenized before being burned to form a clinker
• After cooling, the clinker is grounded to produced cement

Dry Process

• Crushing and grinding raw materials into fine particles.
• Mixing raw materials to form a homogeneous raw meal.
• Preheating the raw meal using kiln exhaust gases.
• Calcination to decompose the raw meal into clinker.
• Cooling the clinker.
• Grinding the clinker with gypsum to form cement.
• Packaging the cement for distribution.

Wet vs Dry Process

• In the wet process, the material is a slurry and in the dry process, the material is a dry powder.
• The wet process requires less energy and generates more dust
• The dry process is the opposite, generating more energy but less dust
• Raw materials must be high-moisture for the wet process and dry for the dry process
• The wet process produces a more consistent slurry

Step 2 - Rotary Kiln

• Involves burning of raw materials, which occurs at temperature 1400-1500 degrees.
• The length of kiln is 100-180 meters, with a rotation speed of 60-90 revolutions per hour.
• Raw materials are fused at this time to make clinkers.

Types of Cement

• Hydration
• Testing