BU Concrete

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BU Concrete
2011-02-06 16:13:06
BU Concrete

US Navy Builder Concrete
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  1. Type I cement is used for what applications?
    • Type I is a General Purpose cement, typically sidewalks, re-enforced conc buildings, railways, tanks, reservoirs, culverts, ect.
    • Not in areas where subjected to sulfate attack
    • Most available
    • Reaches design strength in 28 days
  2. Type II cement is used for what applications?
    • Typical applications are: drainage structures where sulfate attack from water or soil is moderate
    • Reaches design strength in 45 days
    • *Temperature rise is an issue in warm weather
  3. Type III cement considered?
    • High early strength concrete
    • Achieves design strength in 7 days
    • **Do not use in structures under 2.5 feet, because of shrinkage.
  4. Type IV cememnt is used in what applications?
    • Used primarily for large structures like dams where temp rise from curing conc (heat of hydration) could damage structure.
    • Reaches design strength in 90 days
  5. Type V cement is used for what applications?
    • Where conc is subjected to severe sulfate attack (siol or ground water)
    • Reaches design strength in 60 days
  6. What is Air Entrained cement?
    A special cement that has a resistance to freeze-thaw action and scaling caused by chemicals used for snow and ice removal.
  7. An Air Entrained Agent can be added to what types of cement?
    • Type I
    • Type II
    • Type III
  8. What is the acceptable amount of Air Entrained agent to add in a concrete mix?
    3% to 7%
  9. What are admixtures when dealing with cement?
    • Materials added other than cement, water, and aggregate
    • Used to improve certain qualities (Workability, Strength, Durability, Watertighness, & Wear Resistance)
    • Also used ot reduce heat of hydration, reduce segregation, or accelerate of retard hardening
  10. What are workability agents?
    • Materials such as hydrated lime & bentonite to improve workability.
    • Increase fines in concrete if aggregate is deficient
  11. What are accelerators?
    • Calcium Chloride is the only acceptable accelerator
    • Used to spped up strength gain
    • Final strength is not affected
  12. What are retarders?
    • Used to reduce the heat of hydration to aid in the placement and consolidation of concrete before initial set
    • Typically fatty acids, sugars and starches
  13. What are Pozzolans?
    • Typically Fly Ash
    • Improves workability
    • Slows the strength rate of concrete
  14. When is Rule 41 used?
    Used to calc conc materials needed when aggregate is less than 1"
  15. When is Rule 42 used?
    Used ot calc conc materials needed when aggregate is less than 2.5 "
  16. Conc Calcs
    1:2:4 (Conc, Sand, Aggregate)
    2" Course aggregate
    • Step 1: Use Rule 42 b/c agg > than 1"
    • Step 2: 1+2+4=7
    • Step 3: 42/7=6 (6 Bags or cu ft of cement)
    • Step 4: 6(2)= 12 Cu Ft of Sand
    • Step 5: 6(4)=24 Cu Ft of Aggregate
    • Step 6: Check 7+6+24=42 (OK)
  17. 1 Bag of Cement weights how much?
    • 94 pounds
    • 1 cu ft
  18. 1 Cu Ft of of <1" Aggregate weights how much?
    105 pounds
  19. 1 Cu Ft of <2.5 weights how much?
    100 pounds