Aggregates!

Card Set Information

Author:
Marciaho
ID:
269564
Filename:
Aggregates!
Updated:
2014-04-07 18:39:23
Tags:
Aggregates
Folders:
Aggregates!
Description:
Aggregates!
Show Answers:

Home > Flashcards > Print Preview

The flashcards below were created by user Marciaho on FreezingBlue Flashcards. What would you like to do?


  1. 2 Aggregate uses
    Underlying load bearing material for foundations and pavements

    Ingredients in portland cement and ashpalt concrete
  2. Fine agg (sand) dimensions
    Less than 4.75 mm
  3. Coarse agg (stone or gravel ) dimensions
    greater than 4.75 up to 9.5 and 37.5
  4. Concrete Agg minerals (2)
    Mafic and Felsic
  5. Mafic properties
    • Minerals rich in Fe and Mg
    • Dark green, brown, black
  6. Felsic
    • Minerals rich in silicon, aluminium, sodium and potassium
    • Light coloured, i.e grey, white
  7. Coarse aggregate rocks (3)
    • Igneous
    • Sedimentary
    • Metamorphic
  8. Igneous examples and formation
    • Basalt and Granite 
    • formed by cooling and solidifying of magma and lava
  9. Sedimentary examples and formation
    • Greywacke and Limestone
    • Products of erosion, accumulates as sediment then buried, compacted and cemented. Occurs under pressure
  10. Metamorphic examples and formation
    • Marble and Schist
    • formed within earth's crust - transformation of rocks via heat.
  11. Auckland and Dunedin use what rocks
    Basalt and Phenolite
  12. Tauranga and Taranaki use what rocks
    Andesites
  13. Nelson and Invercargill use what rocks
    Mixed gravels
  14. Other types of of aggregate
    Crushed air cooled blast furnace slag

    Natural and manufactured light weight aggregate

    Recycled concrete aggregate
  15. Aggregate Processing (4)
    • 1. Crushing
    • 2. Screening - separates material into sand etc.
    • 3. Washing - removes salt, clay or dust. (affects bonding)
    • 4. Transportation
  16. Evaluation of aggregate sources (4)
    Aggregates selected to meet project requirements

    Continual sample and test materials

    Physical and chemical properties
  17. What does the use of aggregate add to underlying material of base course? (2)
    1. Adds stability - function of inter particle friction between aggregate clay, or silt binder in voids

    2. Provides drainage layer - clay and silt may block drainage paths
  18. Aggregate use in Portland Cement Concrete (4)
    • 1. 60-75% of volume
    • 2. Acts as filler to reduce amount of cement paste
    • 3. Greater volume stability than cement paste
    • 4. Need to maximize volume of agg for economy and quality
  19. Aggregate use in asphalt concrete
    • 1. 80% of volume
    • 2. Asphalt acts as binder to hold aggregate together, not enough strength to lock particles into position. 
    • 3. Strength and stability depend on interparticle friction
  20. Important properties of Aggregate (10)
    • 1. Specific gravity (bulk density) - relates to packing density
    • 2. Porosity -voids
    • 3. Absorption - ability and amount of absorbed water 
    • 4. Moisture content
    • 5. Shrinkage - due to drying
    • 6. Gradation and fitness modulus -size distribution
    • 7. Chemical re activity - durability
    • 8. Particle shape - interlock and water deman
    • 9. Modulus of elasticity 
    • 10. Compressive strength
  21. Aggregate Absorption =
    moisture content @SSD / mass dry aggregate (%)
  22. Abs for coarse aggregate
    0.2-4%
  23. Abs of fine agg
    0.2-2%
  24. MC of coarse agg
    0.5-4%
  25. MC of fine agg
    2-6%
  26. Specific Gravity
    ratio of the mass unit volume of the material to weight of the same volume of water at 23 degrees
  27. Specific gravity Ga =
    Mass of aggregate/ mass of equal volume of water
  28. Unit weight (density ) of aggregate (2 equations)
    Unit weight = Mass of aggregate / volume of aggregate 

    Unit weight = specific gravity Ga times by density of water
  29. Types of specific gravity (3)
    Bulk Specific gravity - volume of pores included

    Apparent Specific gravity - volume of pore excluded

    Effective specific gravity
  30. A B and C equals....
    S equals..
    • A= Dry Mass
    • B = SSD mass OR mass of pycnometer filled with water (sand)
    • C = submerged mass

    S = Mass of sand , SSD
  31. Bulk specific gravity @SSD (Ga)
    Ga = B/(B-C)
  32. Unit weight of SSD
    B/(B-C) times density of water
  33. Bulk Specific Gravity (DRY)
    Gdry = A/ (B-C)
  34. Unit weight (DRY)
    A/ (B-C) times density of water
  35. Apparent Specific Gravity of aggregate
    A/ (A-C)
  36. Apparent unit weight
    A/(A-C) time density of water
  37. Apparent unit weight (density ) of aggregate
    Mass of aggregate/ volume not accessible to water
  38. Effective Specific Gravity equation (Gse)
    What is effective volume
    Gse = dry mass of aggregate (A)/ effective volume

    Effect volume = vol of agg particle + vol of water perm pores not filled with bitumen
  39. Absorption
    S-A/A times 100
  40. Specific gravity in SSD for SAND
    Unit weight?
    Gssd = S/(B+S-C)

    unit weight = above times density of water
  41. Dry specific gravity of SAND
    G dry = A/ (B +S- C)
  42. Bulk density equation
    what does it depend on?
    Mass of dry aggregate / volume of container

    Density depends on S.G of agg, particle shape and surface texture.
  43. Bulk unit weight of normal agg compared to unit weight
    Bulk unit weight 1200 to 1700 kg/m^3

    Unit Weight = 2400 to 2900 kg/m^3
  44. Typical compressive and tensile strengths
    • CS - 65-270 MPa
    • TS - 2 to 15 MPa
  45. Modulus of elasticity of aggregates affects... in concrete
    ranges
    • Magnitude of shrinkage and creep in concrete
    • 9.9 to 69 GPa
  46. Free surface moisture content
    and correction equation
    SM = Mwet-Mssd/Mssd time 100

    W correction = -Mssd times (MC-abs)/ (1+ abs)
  47. Total Moisture equation (SSD)
    Mwet-Mdry/ Mdry times 1000

What would you like to do?

Home > Flashcards > Print Preview