ACI 211.1-91, Reapproved 2009, states: "Concrete
proportions must be selected to provide workability,
consistency, density, strength, and durability, for the
particular application.
• Workability: The
property of the concrete that determines its capacity
to be placed and consolidated properly and be
finished without harmful segregation.
• Consistency: It
is the relative mobility of the concrete mixture, and
measured in terms of the slump; the greater the slump
value the more mobile the mixture.
• Strength: The
capacity of the concrete to resist compression at the
age of 28 days.
• Water-cement (w/c) or
water-cementitious (w/(c+p)) ratio:
Defined as the ratio of weight of water to the weight
of cement, or the ratio of weight of water to the
weight of cement plus added pozzolan. Either of these
ratios is used in mix design and considerably
controls concrete strength.
• Durability:
Concrete must be able to endure severe weather
conditions such as freezing and thawing, wetting and
drying, heating and cooling, chemicals, deicing
agents, and the like. An increase of concrete
durability will enhance concrete resistance to severe
weather conditions.
• Density: For
certain applications concrete may be used primarily
for its weight characteristics. Examples are
counterweights, weights for sinking pipelines under
water, shielding from radiation, and insulation from
sound.
• Generation of heat:
If the temperature rise of the concrete mass is not
held to a minimum and the heat is allowed to
dissipate at a reasonable rate, or if the concrete is
subjected to severe differential or thermal gradient,
cracking is likely to occur."
