This chart, which is found in both ACI 305R-91, "Hot Weather Concreting" and
in ACI 308-92, "Standard Practice for Curing Concrete," may be used to
estimate the rate at which water will evaporate from concrete. Note that
the chart relates air temperature, relative humidity, concrete temperature,
and wind velocity to arrive at a predicted rate of evaporation from the
concrete surface.
ACI recommends that if the predicted evaporation rate exceeds 0.2 pounds of
water per square foot per hour (1 kilogram of water per square meter per
hour), then preventative measures ought to be initiated. For silica-fume
concrete, preventative measures are usually required when the predicted rate
of evaporation reaches about one-half of the rate for conventional concrete.
The predictions from the chart are only as good as the data that is
supplied. Calling a weather station miles form the project site may supply
general information, but it is the conditions on the placement site that are
critical.
The Silica Fume Association
38860 Sierra Lane, Lovettsville, VA 20180
Tel: 540.257.4224 Fax: 540.822.9456
