# Concrete inFocus - Spring 2017 - 44

```concrete temperature as a function of ambient temperature based
on investigations conducted by Ramey and Carden. The concrete
temperature is determined as:

If Ta < 40oF, then Tc = Ta + 10oF (in this case
a warning note stating "Warning: Ambient temperatures require cold weather concrete placement
techniques, see ACI 306R-10 Guide to Cold Weather
Concreting," is provided).
If 40oF < Ta < 55o then Tc = Ta + 10oF
If 55oF < Ta < 85oF then Tc = Ta + 5oF
If 85oF < Ta then Tc = Ta
(in this case a warning note stating "Warning:
Ambient temperatures require hot weather concrete placement techniques, see ACI 305R-10
Guide to Hot Weather Concreting," is provided).
The user can also enter his or her own concrete temperature once
the calculator has completed the initial evaporation rate calculations
and chart, Figure 2. The calculator allows users to create an account,
maintain multiple projects, invite other users or viewers, and request
e-mail notification for future project dates and predictions.
As noted by Uno, Hover and others, the results from this and other
calculators, the nomograph and the equations developed over the

years to determine the evaporation rate of bleed water from a concrete
surface depend on the quality of the input data. Hover emphasizes
the importance of properly obtaining the input data. The original
evaporation equation used to create the nomograph and calculator
was developed using data collected from a free water surface (not
a concrete surface). Wind speed was taken at an elevation of 20"
(0.51 m) above the water surface, air temperature 4 - 6 ft (1.2 - 1.8
m) above and water temperature 1.3 cm below the water surface.
Therefore, to calculate an accurate value for the true evaporation
rate (not an estimate) from bleed water above a concrete surface it
is necessary that the weather data from the immediate vicinity of
the concrete surface be used in the evaporation equation. If this is
not done and standardized weather data are used, Hover notes, the
resulting evaporation rate may be significantly different than the
actual value at the jobsite. Even if the ambient weather conditions
are measured appropriately, they may change in a short time. The
wind may die down or pick up, the sky may cloud up reducing the
air temperature and the temperature of the bleed water (or concrete)
will change over time. Therefore, the nomograph (and any calculator
based upon it) should be used as a way to estimate the evaporation
potential of the ambient conditions, not as a way to determine the
actual evaporation rate from a concrete surface. The source of the
weather data and the effects on the calculator results should be
kept in mind.
The weather data used in the SIUE calculator, provided by
the NDFD, is collected from NWS weather observations (NWSI
10-201) based on zip code. The height of a standard weather station
anemometer is 10 meters (33 feet) above the ground. The standard

Calculator display for Zip Code 62025 for the week beginning on 26 September 2015.
44

ı

SPRING 2017

```

From the President’s Desk
Corporate Suite Column
Enviroscene Column
Strong and Efficient: Insulating Concrete Forms for Multifamily Residential Construction
Cut the Cost of Workers’ Compensation Insurance in the Concrete Industry
Engineering: Specifications for Concrete Construction
Predicting the Potential for Plastic Shrinkage Cracks
2017 Product Preview
Concrete inFocus - Spring 2017 - belly1
Concrete inFocus - Spring 2017 - belly2
Concrete inFocus - Spring 2017 - cover1
Concrete inFocus - Spring 2017 - cover2
Concrete inFocus - Spring 2017 - 3
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Concrete inFocus - Spring 2017 - 9
Concrete inFocus - Spring 2017 - 10
Concrete inFocus - Spring 2017 - From the President’s Desk
Concrete inFocus - Spring 2017 - 12
Concrete inFocus - Spring 2017 - Corporate Suite Column
Concrete inFocus - Spring 2017 - 14
Concrete inFocus - Spring 2017 - 15
Concrete inFocus - Spring 2017 - Enviroscene Column
Concrete inFocus - Spring 2017 - 17
Concrete inFocus - Spring 2017 - Strong and Efficient: Insulating Concrete Forms for Multifamily Residential Construction
Concrete inFocus - Spring 2017 - 19
Concrete inFocus - Spring 2017 - 20
Concrete inFocus - Spring 2017 - 21
Concrete inFocus - Spring 2017 - 22
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Concrete inFocus - Spring 2017 - 27
Concrete inFocus - Spring 2017 - 28
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Concrete inFocus - Spring 2017 - 30
Concrete inFocus - Spring 2017 - Cut the Cost of Workers’ Compensation Insurance in the Concrete Industry
Concrete inFocus - Spring 2017 - 32
Concrete inFocus - Spring 2017 - 33
Concrete inFocus - Spring 2017 - 34
Concrete inFocus - Spring 2017 - 35
Concrete inFocus - Spring 2017 - 36
Concrete inFocus - Spring 2017 - Engineering: Specifications for Concrete Construction
Concrete inFocus - Spring 2017 - 38
Concrete inFocus - Spring 2017 - 39
Concrete inFocus - Spring 2017 - 40
Concrete inFocus - Spring 2017 - Predicting the Potential for Plastic Shrinkage Cracks
Concrete inFocus - Spring 2017 - 42
Concrete inFocus - Spring 2017 - 43
Concrete inFocus - Spring 2017 - 44
Concrete inFocus - Spring 2017 - 45
Concrete inFocus - Spring 2017 - 2017 Product Preview
Concrete inFocus - Spring 2017 - 47
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Concrete inFocus - Spring 2017 - 53
Concrete inFocus - Spring 2017 - Index of Advertisers
Concrete inFocus - Spring 2017 - cover3
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Concrete inFocus - Spring 2017 - divider1
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