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Concrete Technology - Coggle Diagram

- - - - Normal weight
      - Heavy weight
      - Light weight
  - - - Aggregate mainly retained on a 4.00 mm test sieve*.
      - Specific gravity for granite is around 2.55 to 2.67.
    - - Aggregate mainly passing a 4.00 mm test sieve and retained on a 63 micrometer (or 0.063 mm) test sieve.
      - Specific gravity is around 2.6 to 2.7
    - - mixture of coarse and fine aggregates.
  - - - aggregate from mineral sources which has been subjected to nothing more than mechanical processing.
    - - aggregate of mineral origin resulting from an industrial process involving thermal or other modification.
    - - aggregate resulting from the processing of inorganic material previously used in construction.
  - - - Bone dry from oven set at 1030C for 24 hours.
    - - Surface is dry but pores within the aggregate is filled with water.
    - - Surface and pores within the aggregate is filled with water
  - - - decaying vegetation and etc. retards setting of cement.
    - - chlorides etc corrodes reinforcement steel.
    - - high water demand, low strength and high shrinkage.
    - - Alkali-Silica Reaction (ASR), affects durability of aggregates.
- - - - Versatile
      - Easy to maintain
  - - - Admixture is also added to modify certain propertiest
  - - - 8to20%
    - - 10to25%
    - - 1%
    - - 60to75%
    - - Around 2%
- - - - Hydration : Cement + water
      - The water content of the mix is usually expressed in terms of the water/cement ratio (W/C)
    - - Water reacts with cement to provide the bonding agent for the composite
      - In fresh concrete, it provides the lubricating element in terms of workability
    - - Hydration process from cement forms calcium silica hydrate that bind the elements together.
      - Stronger bond will be formed with more cement; however, lubricating element (workability) will be reduced.
      - Weaker bond will be formed with adding water ; however, lubricating element (workability) will be increased.
      - Hence, need to balance between strength and workability.
- - - - Setting
        
        Stiffening of cement paste
        
        Initial setting time
        
        Minimium 60 minutes
        
        To allow mixing and handling to take place
        
        Final setting time
        
        Maximun 10 hours
        
        To start gain strength before formwork removal take place
        
        Change from fluid to rigid state
      - Hardening
        
        Gaining of strength in cement
  - - - Most common cement
      - Medium rate of setting and hardening
      - suitable for most concrete work
      - specific gravity around 3 to 10
    - - Develop strength faster than OPC
      - Use when early formwork removal is neccessary
      - Construction at low temperature to safeguard against frost damage
      - Should not be used in mass concrete construction due to higher rate of heat development.
      - specific gravity around 3 to 10
    - - Use where sulphates are present in concentration that would damage concrete
      - Higher cost due to special composition of raw materials
      - Typical application for sewage treatment works (Hydrogen Sulfide: produced by breakdown of organic matters from human waste), sub and super structure in contact with seawater including reclaimed ground etc.
      - Specific gravity around 2.97 to 3.10.
    - - Low heat of hydration
      - Typical application includes large gravity dams and large raft slabs to control thermal cracks.
      - Specific gravity around 3.15
    - - Uses for architectural purposes.
      - Colour cement is possible by mixing white cement with colour pigment, however, not commonly use as a fresh coat of paint can be applied on concrete structure
      - White cement are used to fill gaps between floor titles, cover cracks or touch up work for false ceiling, dry wall partition etc.
      - specific gravity around 3.05 to 3.1
- - - - A chemical substance which is added in small amounts during or immediately before the mixing stage of concrete production.
      - Admixture is introduced to concrete to alter or improve the properties of the fresh and hardened concrete.
      - 3 most important properties that normally required to be improved are
        
        Workability
        
        Compressive strength
        
        Durability
      - Accelerators
        
        Used in cold weather concreting.
        
        Expediting demoulding and stripping of formworks.
        
        Suitable for emergency repair work and water leakage.
      - Set-Retarders
        
        used for work which requires a prolonged set-retardation.
        
        used for large pours such as dam, retaining wall.
        
        suitable for hot weather concreting where hot temperatures can reduce the normal setting and hardening times.
        
        prevention of the formation of cold joints between successive lift .
      - Water-reducers (plasticizers)
        
        increase strength by reducing w/c at given workability
        
        reduce cement content at given workabililty and strength.
        
        increase workability for a given w/c ratio and strength
      - High Range Water Reducing (Superplasticizers)
        
        A self-levelling concrete mix is achievable
        
        Very-high strength concrete is achievable with a water reduction of 25 to 30 per cent.
        
        Slumps in excess of 200 mm is achievable with no increase in water content
        
        very suitable for heavily reinforced and inaccessible sections or where rapid placing of concrete is required.
        
        suitable in underwater, bored pile and diaphragm wall concreting using a tremie.
        
        Used to produce self compacting or self consolidation concrete.