effect of concrete placing temperature on early

Question

Effect of concrete placing temperature on early thermal movement

Rate of hydration of cement paste is related to placing temperature of concrete. Rate of heat production is given by empirical Rastrup function:

H=H₀×2^{r (T-T1)}

H_o = Rate of heat production at a reference temperature

T = Temperature where rate of heat production H

T1 = Temperature where rate of heat production H_o

r = 0.084

A 12^o C increase in placing temperature doubles the rate of reaction of hydration. Henceforth concrete placed at a higher temperature experiences a higher rise in temperature. For example concrete placed at 32^oC generates heat of hydration twice as fast when compared with concrete placing at 20^oC. Therefore high concrete placing temperature has significant effect to problem of early thermal movement.