Kinetics of the Reaction of Calcium Hydroxide and Fly Ash.
Kinetics of the Reaction of Calcium Hydroxide and Fly
Ash.
(3018 K)
Biernacki, J. J.; Williams, P. J.; Stutzman, P. E.
Title No. 98-M37;
ACI Materials Journal, Vol. 98, No. 4, 340-349,
July/August 2001.
Keywords:
fly ash; kinetics; hydration kinetics; pozzolans;
pozzolanic reaction; cements
Abstract:
The reaction kinetics of a Type-F fly ash with calcium
hydroxide (CH) has been investigated at temperatures
between 25 {degrees}C and 60 {degrees}C.
Thermogravimetric analysis (TGA) was used to determine
CH consumption and production of hydrates
(non-evaporable water) as a function of hydration
temperature and time for various CH/fly ash ratios. The
results indicate that the reaction rate, reaction
stoichiometry and activation energy are dependent on the
CH/ash ratio. The reaction rate was also found to be a
function of the extent of reaction of both CH and fly
ash phases. Various kinetic models were considered
including those proposed by Knudsen and Avrami. These,
however, were found to have limited applicability. A
model is suggested that provides a broader fit to the
observed data.
