Reply #54: To my knowledge yes, both get harder as their cool

[happyslug]

And depending on how much concrete is being used determines how long it will take to "Cool".

This was a problem on Hoover Dam:
http://www.usbr.gov/history/hoover.htm
http://www.usbr.gov/lc/hooverdam/History/essays/concrete.html

"Following the diverion of the river, the floor of the canyon was dredged down to bedrock. Only then could the pouring of the concrete begin. A major problem with a structure as large as the Hoover Dam was the cooling of the concrete. Engineers calculated that the massive amount of concrete would take over one hundred years to cool; when cool the dam would crack, rendering it useless. To avoid this, the dam was poured in rows and columns of blocks. Refrigerated water was pumped through the blocks in pipes, and the pipes were then shot full of concrete, rendering the dam a true monolith--entirely one piece. The dam itself was completed two years ahead of schedule, in 1935. Power generation began in 1936 and turbines continued to be added until 1961, when the last one went on line (Bureau of Reclamation, 53-54)."
http://xroads.virginia.edu/~1930s/DISPLAY/hoover/construction.html

An article advocating that 35 Degree temperture between the core and the surface of Concrete can be exceeded (and that most state DOTs do NOT permit such wide temperture variations):
http://www.ctlgroup.com/dynamic_pdfs/18WB006ConcretePerspectiveArticle.pdf

For more on Concrete:
http://www.concrete.org/general/home.asp