mod 2

• Cement is the essential glue that holds the other ingredients in place to create concrete.
• Cement


  One of the most essential building materials acting as a binding agent to set and harden materials like bricks, tiles, stones, etc. Mostly composed of iron ore, bauxite, sand or clay, and limestone
• Uses of Cement

  Used in mortar for plastering, masonry work, pointing, making joints for drains and pipes, water-tightness of the structure, laying floors, roofs, constructing lintels, beams, stairs, pillars, precast pipes manufacturing, important engineering structures, foundations, watertight floors, etc.
• Concrete

  A building material manufactured by properly mixing cement, water, sand, and rock
• Difference between Cement and Concrete


  • Definition, composition, method of operation, purposes, types, etc.
• Roads or driveways construction


  Using concrete for roadways or driveways makes them more durable and stronger than asphalt, requiring less maintenance and having a longer service life
• Uses of Concrete


  • Precast pipes manufacturing
  • Piles
  • Fencing posts
  • Construction of important engineering structures such as bridges, culverts, dams, tunnels, lighthouses, etc.
  • Preparation of foundations, watertight floors, footpaths, etc.
  • Construction of wells, water tanks, tennis courts, lamp posts, telephone cabins, roads, etc.
• Foundation construction

  High-rise or low-rise buildings are usually constructed using reinforced cement concrete for durability and load-carrying capacity
• Concrete is a composite material created by mixing binding material (cement or lime) with aggregate (sand, gravel, stone, brick chips, etc.), water, admixtures, etc. in specific proportions
• Concrete is one of the most popular building materials due to its strength, durability, low maintenance, energy efficiency, and sustainability
• Concrete dams construction

  Concrete is better suited for dam construction due to its high strength-to-weight ratio
• Alkaline


  High amount leads to difficulty in the regulation of setting time, low amount leads to discoloration of cement
• Iron oxide


  Also called Ferric Oxide, responsible for the color of the cement
• Hydration of cement


  Depends upon the water-cement ratio, uniformness, temperature of curing, etc.
• Characteristics of cement include providing strength to masonry, stiffening or hardening early, and possessing good plasticity
• Ordinary Portland Cement is the most widely used type of cement suitable for all general concrete construction
• Rapid Hardening Cement strength at 3 days is similar to 7 days strength of OPC with the same water-cement ratio
• Low Heat Cement is prepared by maintaining the percentage of tricalcium aluminate below 6% by increasing the proportion of C2S
• Chemical properties of good cement

  • Lime
  • Alumina
  • Sulfur Trioxide
  • Iron oxide
  • Silica
  • Alkaline
  • Magnesia
• Magnesia


  If used in high amounts, results in unsoundness and is uneconomical
• Silica


  Provides high compressive strength, abrasion resistance, and bond strength to cement
• Heat generation in cement


  Can affect cement quality because excessive hydration leads to undesired strength
• Types of cement

  • Ordinary Portland Cement
  • Portland Pozzolana Cement (PPC)
  • Rapid Hardening Cement
  • Quick Setting Cement
  • Low Heat Cement
• Properties of concrete

  • Workability
  • Strength
  • Durability
  • Creep
  • Shrinkage
  • Unit weight
  • Modular ratio
  • Poisson's ratio
• Portland Pozzolana Cement is prepared by grinding pozzolanic clinker with Portland cement
• Quick Setting Cement sets earlier while the rate of gain of strength is similar to Ordinary Portland Cement
• Rapid Hardening Cement


  • Gains strength quickly, formworks can be removed earlier
• Sulfates Resisting Cement

  • Used to reduce the risk of sulfate attack on concrete, used in construction of foundations in areas with high sulfate content
• Colored Cement


  • Allows creation of different colors of concrete, produced by mixing mineral pigments with ordinary cement, widely used for decorative works
• High Alumina Cement


  • Obtained by melting mixture of bauxite and lime, used in works subjected to high temperatures, frost, and acidic action
• Expansive Cement


  • Expands slightly with time, used for grouting anchor bolts and prestressed concrete ducts
• Characteristics of good concrete include adequate crushing strength, durability, and resistance to abrasion
• White Cement


  • Prepared from raw materials free from Iron oxide, used for architectural purposes due to its white color
• Ordinary Portland Cement


  • Similar to rapid hardening cement, formworks can be removed earlier
• Hydrographic Cement


  • Prepared by mixing water repelling chemicals, repels water and used for water structures like dams, water tanks, etc.
• Types of Concrete

  • Plain Concrete
  • Reinforced Concrete
  • Ready-Mix Concrete
• Blast Furnace Slag Cement


  • Obtained by grinding clinkers with about 60% slag, resembles properties of Portland cement, used for economic considerations
• Low Heat Cement


  • Prepared by maintaining the percentage of tricalcium aluminate below 6% by increasing the proportion of C2S, used in mass concrete construction like gravity dams to prevent cracking due to heat
• Air Entraining Cement


  • Produced by adding air entraining agents during grinding of clinker, improves workability and frost resistance of concrete
• Lime concrete


  • Uses lime instead of Portland cement in its mix
  • Commonly used in historic restoration and conservation work