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Concrete - Coggle Diagram

- - - - Portland Limestone Filler Cement
      - High Alumina Cement (HAC)
      - Off-white and White Portland Cement
        
        https://youtu.be/BSgKStjTJIA?si=H0w9i2XxlGETFLOb
      - Particular properties of HAC
- - - - Compaction - This is the process of removing ENTRAPPED AIR (the bubbles shown in the diagram). If air is left inside, it creates "honeycombs" or holes that significantly weaken the structure
      - Curing - Concrete doesn't "dry" - It undergoes a chemical reaction called HYDRATION. You must keep it moist (usually by spraying water) for several days so it can reach its full design strength
      - Mixing & Transporting - The mix must stay uniform. If it takes too long to transport, the concrete might start to set before it's even poured.
  - - - Heat Generation = Hydration is an exothermic process. The amount and rate of heat depend on the cement type. In smaller structures, this heat dissipates easily.
    - - Low Temperature (e.g., 10C) - Decrease the rate of hydration
      - High Temperature (e.g., 30C) - Accelerate rate of hydration
    - - Property &
        Effect of Higher Fineness
        
        Strength - Faster early strength gain, but ultimate strength remains the same as coarse cement.
        
        Workability - Increased cohesiveness (often called
        "fattiness").
        
        Reaction rate - Faster reaction and faster setting/hardening.
        
        Bleeding - Reduced potential for bleeding (water rising to the surface).
        
        Shrinkage - Increased drying shrinkage and potential for cracking.
- - - - Material Types: In NZ, greywacke is the main aggregate source, derived from river beds (rounded) or quarries (crushed)
    - - Uniformly Graded
      - Gap-graded
      - Continuously Graded
    - - 19mm aggregate - It is used for concrete manufacture are normally designated by the largest particles sizes
      - Maximum size : 37.5mm - Smallest sieve opening
      - Nominal size: 27mm - Whole number above the sieve size
      - Selection Constraints: The maximum aggregate size is limited by physical constraints to ensure the concrete can be placed without "bridging" (getting stuck) or segregating. To prevent these issues, the nominal aggregate size should not exceed the smallest of:
        
        3 S/4: Three-quarters of the clear spacing between reinforcing bars (S)
        
        M/5: One-fifth of the minimum dimension of the section (M)
        
        3 C/4: Three-quarters of the minimum cover over reinforced bars (C)
      - Grading of Fine Aggregate (Sand)
        
        Ideally, sand should be continuously graded, containing a range of particle sizes to fill voids effectively. Whilst NZS 3121 provides specifications, the document notes that sand grading significantly impacts the "workability" of the mix
        
        Uniformly Graded Sand - Results in a mix that is less workable, more prone to honeycombing, and harder to finish to a smooth surface
        
        Coarse Sand (Lack of Fines) - Results in a "harsh" mix that is difficult to place and finish, and more prone to bleeding (water rising to the surface)
        
        Fines - A small proportion of "fines" (very small particles) is desirable to improve workability and surface finish