What is the effect of concrete placing temperature on early thermal movement?
Posted in Concrete Engineering |
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The rate of hydration of cement paste is related to the placing temperature of concrete. The rate of heat production is given by the empirical Rastrup function:
H= Hox 2r(T-T1)
Ho = Rate of heat production at a reference temperature
T = Temperature where rate of heat production H
T1 = Temperature where rate of heat production Ho
r = 0.084
An 12oC increase in placing temperature doubles the rate of reaction of hydration. Hence, concrete placed at a higher temperature experiences a higher rise in temperature. For instance, concrete placed at 32oC produces heat of hydration twice as fast when compared with concrete placing at 20oC. Hence, high concrete placing temperature has significant effect to the problem of early thermal movement.
This question is taken from book named – A Self Learning Manual – Mastering Different Fields of Civil Engineering Works (VC-Q-A-Method) by Vincent T. H. CHU.
