Concrete Mix Design
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Concrete Mix Selection
• Ready Mix Provider: Choosing and
working with a mix provider that
utilizes knowledge, technology and
responsibility in concrete batching
and delivery is a key component of
providing quality concrete.
• Mix Selection: In Kansas City with frequent freeze-thaw cycles, mix designs should meet a minimum compressive strength of 4000 psi at 28 days and recommended to be a minimum 564 cementitious content per cubic yard.
Water/Cement ratios should not exceed .45. Water reducing admixtures * may be utilized to increase slump* without diluting the mixture to less than its desired strength. Unnecessary addition water increases the risk of shrinkage cracks, freeze/thaw damage, and resistance to de-icers.
Admixtures: Type F Fly ash* and ground blast furnace slag* are binders that provide protection against ASR-Alkali-Silica Reaction *
• Mix Selection: In Kansas City with frequent freeze-thaw cycles, mix designs should meet a minimum compressive strength of 4000 psi at 28 days and recommended to be a minimum 564 cementitious content per cubic yard.
Water/Cement ratios should not exceed .45. Water reducing admixtures * may be utilized to increase slump* without diluting the mixture to less than its desired strength. Unnecessary addition water increases the risk of shrinkage cracks, freeze/thaw damage, and resistance to de-icers.
Admixtures: Type F Fly ash* and ground blast furnace slag* are binders that provide protection against ASR-Alkali-Silica Reaction *
Retarders* can be utilized in hot or
windy conditions to slow the set
time of concrete for proper strength
gain. Surface retarders are
utilized in hot or windy conditions
to temporarily slow the surface set
time of the concrete.
Aggregates:* Clean, sound aggregates such as the use of State DOT paving aggregates or higher quality aggregates such as Granite or Quartzite ensure fewer surface issues such as pop-outs.
Air Content: *Air Entrainment admixtures are necessary for attaining the 6%-8% required for the Kansas City area.
Slump:* Should be 4 inches, +/- 1 inch. The slump should not exceed 5 inches for durable concrete. Anything more than 6 inches is too wet to use.
Aggregates:* Clean, sound aggregates such as the use of State DOT paving aggregates or higher quality aggregates such as Granite or Quartzite ensure fewer surface issues such as pop-outs.
Air Content: *Air Entrainment admixtures are necessary for attaining the 6%-8% required for the Kansas City area.
Slump:* Should be 4 inches, +/- 1 inch. The slump should not exceed 5 inches for durable concrete. Anything more than 6 inches is too wet to use.
AVOID THESE PROBLEMS:
SCALING
ALKALI- SILICA REACTIVITY
PLASTIC SHRINKAGE CRACKS