Thermo-kinetics of cement hydration: temperature effect and activation energy

Title: Thermo-kinetics of cement hydration: temperature effect and activation energy
Author(s): Yanfei Peng, Will Hansen, Claus Borgnakke, Ivindra Pane, J.C. Roumain, Joseph J. Biernacki
Paper category : conference
Book title: International RILEM Symposium on Concrete Science and Engineering: A Tribute to Arnon Bentur
Editor(s): J. Weiss, K. Kovler, J. Marchand, and S. Mindess
Print-ISBN: None
e-ISBN: 2912143926
Publisher: RILEM Publications SARL
Publication year: 2004
Nb references: 28
Language: English

Abstract: The purpose of this study is to quantify the temperature effect on cement hydration. In this study, long-term ( . 21 days) isothermal heat of hydration rate data is obtained at three different temperatures (15 oC, 23 oC, 35oC) for ordinary portland cement (OPC) and for blends of OPC containing supplementary cementitious materials (SCM). Between 1000 and 2000 data points are obtained for rate of hydration between the ages of 1 hour and 21 days. The results show that the absolute rate decreases by three orders of magnitude as the hydration process gradually becomes diffusion controlled. The cumulative heat of hydration is evaluated using the exponential hydration function of Freiesleben-Hansen. A new rate model for absolute hydration rate is proposed. This model predicts that the rate of hydration is a product of a temperature function (absolute rate constant) and a degree of hydration function (diffusion controlled) that is unique for a given system. The absolute rate, instead of the conventional relative rate, is used so that the effect of temperature on long-term hydration can be incorporated. This model is then used to predict the temperature effect on total rate in the temperature range of 5 to 40°C. Within this range the temperature effect on rate of hydration at 40°C is rapidly decreasing to less than 1% of total peak rate within 3 days, while at 5°C temperature effect is still pronounced at the age of 7 days. During the deceleration stage of hydration the relative temperature sensitivity (i.e. activation energy) is constant at about 50 KJ/mole.

Online publication: 2004-03-25
Classification: Early-Age Measurements
Publication type : full_text
Public price (Euros): 0.00
doi: 10.1617/2912143926.019

>> You must be connected to view the paper. You can register for free if you are not a member