Expert: Stephen Hayes - 6/30/2010

Question
We are in the early planning stage for a large concrete pour during hot summer weather in Middle East (single continuous concreting / pouring for a massive raft foundations 50m x 50m on plan and 5m thick (Total volume: 12500 m³).
The single concreting operation is estimated to continue for 48 hours. The shaded ambient air temperature is expected to reach 46° to 50° Celsius in the afternoon and approximately 30° Celsius during night. The laboratory measured absolute maximum concrete hydration temperature (for C60) is expected to reach 80° Celsius. The relative humidity is very low.
We are concern about the high shaded ambient air and maximum concrete hydration temperature.
Questions:-
If the freshly pour concrete is
a) properly cured and covered to minimized loss of moisture, and
b) all surfaces are properly insulated so that the maximum temperature difference between the outer surface and inner core of the 5m thick raft is maintained below 15° Celsius,
in this case, would the
(a) high ambient temperature (50° Celsius) and
(b) High concrete hydration temperature (80° Celsius) will have any unfavorable effects / cause potential deficiencies to concrete in the hardened state – strength and durability?
(c)-Please guide me about the availability of low heat cement in Saudi Arabia and worldwide and its price difference.

(d)-What will be the effects if cooling is done by chilled water pipes.

(e)-What will be the effect of concreting under shading during day time?

Answer
Hi waseem;Sorry that I do not have the expertise to answer your questions.  I am an expert in floor coverings (carpet, vinyl, tile, hardwood, laminate, rubber, etc.).  HOWEVER, go to the website, <concrete.org>, which is the website for the Concrete Institute.  You should be able to find answers to all your questions, and there is contact information on that website, so you can call them and ask for one of their technical services people to help you.

If you have any problems finding out the information you need, please get back to me for some other contact information.

Cordially,

John Michaels