In this paper, the applicability of equivalent age approach to the estimation of compressive strength of concrete incorporating
blast furnace slag (BS) was discussed based on modified apparent activation energy at the set time, which is derived from
Arrhenius function. Concretes were fabricated with different BS contents from 20% to 80%. According to the results, to obtain
modified apparent activation energy(Ea) during setting time, modification of Arrhenius function proposed by Pinto was done by
substituting ln(1/t) for ln(1/t2) for Y axis. Apparent activation energy derived from Arrhenius function ranged from 30~35 KJ/mol
for plain concrete and it also ranged from 30~45 KJ/mol for concrete incorporating BS. As BS contents increases, apparent
activation energy also increases. Good agreement between predicted strength and measured strength was obtained based on the
estimation of compressive strength applying equivalent age computed from Ea by the authors. This may be due to the fact that
although the cement hydration reaction turns from chemically controlled to diffusion controled, Ea from Pinto's suggestion did not
reflect the temperature sensitivity at the hardening stage.