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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
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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
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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.
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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
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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
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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.
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An Air Entrained Agent can be added to what types of cement?
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What is the acceptable amount of Air Entrained agent to add in a concrete mix?
3% to 7%
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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
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What are workability agents?
- Materials such as hydrated lime & bentonite to improve workability.
- Increase fines in concrete if aggregate is deficient
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What are accelerators?
- Calcium Chloride is the only acceptable accelerator
- Used to spped up strength gain
- Final strength is not affected
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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
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What are Pozzolans?
- Typically Fly Ash
- Improves workability
- Slows the strength rate of concrete
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When is Rule 41 used?
Used to calc conc materials needed when aggregate is less than 1"
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When is Rule 42 used?
Used ot calc conc materials needed when aggregate is less than 2.5 "
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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)
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1 Bag of Cement weights how much?
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1 Cu Ft of of <1" Aggregate weights how much?
105 pounds
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1 Cu Ft of <2.5 weights how much?
100 pounds
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