This paper examines the early hydration of alkali-slag cements activat
ed by different sodium compounds, such as NaOH, Na2CO3, Na2SiO3.5H(2)O
, Na3PO4, Na2HPO4 and NaF, at 25 and 50 degrees C. A conduction calori
meter was used to monitor hydration kinetics. It was found that the in
itial pH of activator solution has an important role in dissolving the
slag and in promoting the early formation of some hydration products.
However, further hydration of alkali-slag cements is dominated by the
reaction of the anion or anion group of activator and the Ca2+ dissol
ved from slag rather than the initial pH of the activator solution. Fi
nally, three models were proposed to describe the early hydration of a
lkali-slag cements based on heat evolution measurements.