Flashcards
CONS 280 Exam 2
Cards in this deck (18)
- 1Hydration of Cementwater + cement undergo chemical reactions.
*5 clinker compounds
- water
- new materials(solids)
Hydration products-
1) C-S-H= 50% of hardened cement (blobs)
2) C-H= 20-25% (plates)
3) Ehringite= Remaining(needles) - 2Mineral Admixtures- Added to improve workability or hardened properties
- pozzolanic materials, cementitious materials, and non-reactive materials
- in addition to cement or partial/full replacement - 3Pozzolanic Materials__Natural__
- Volcanic Ash
- Pumice
- opaline cherts
- shale
- diatomaceous earth - 4Why/Rules of Pozzolanic Materials?- sulfate resistance
+heat
-ASR reactivity
= permeability
-no replacement of cement
-less than/equal to 10% cement mass - 5By-Products- Fly Ash
- Silica Fume
- Blast Furnace Slag - 6Fly Ash -Common Types- Powder from burning coal
- Class F (15-20% of cement material)
- Class C (15-40% of cement material) - 7Silica FumeMetal alloy production waste
5-10% of cement material
Increases strength
Decreases permeability - 8Blast Furnace Slag30-40% of cement material
- 9Proportioning- May need to alter water content
- May need to alter the sand content
- if it's replacing some of the cement
-> Blended cement
- Water + CM = normal hydration products + new hydration products - 10Water Content- Fly ash doesn't need as much water, 1-10% less water
- Slag also decreases water demand 1-10%
- silica fume increases demand - 11Heat of Hydration- can take type 1 or 2 to "4"
- 12Workabilityimproving it because of particle shape "ball bearing" like-easy to mix
- 13Air entrainmentfly ash and silica fume decreases air content, adjust air entrainer
- 14Set TimeFly ash and slag slows set time, in cold weather it needs accelerator ad-mix, in hot weather increases time to place and finish
- 15Concrete mix design Main steps1) select materials
2) determine quantities - 16Considerations-Cost
-Use
-structure type
-where
-durability
-strength
-workability - 17ACI Mix Design Method Common Methods1) Arbitrary volume method (cement: Sand: Coarse aggregate)
ACI211__2) Absolute weight method
__________3) Absolute volume method
-ABS weight = assumes/takes known unit weight of concrete
-ABS volume method = takes specific gravity of materials to find unit volume (from there find weight) - 18ACI Mix Design Method Required info.-Type of structure
-Structure specs: size, dimensions, rebar placement spacing
-Target compressive strength
-Cement Req.
-Air content
-Exposure to freeze-thaw
-Exposure to sulfate
-sieve analysis data-(grade) Nom. and Max.
-Unit weight of coarse agg.
-BSG
-Absorption
-MC
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- Engineering Flashcards on CONS 280 Exam 2, created by Aaron Daniels on 30/10/2018.
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- Aaron Daniels
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