It is well known that fly ash and blast furnace slag are the concrete admixtures
that are expected to promote sulfate resistance of concrete by its pozzolanic activity or
its latent hydraulic property. The purpose of this study is to predict the deterioration of
concrete containing these admixtures under a sulfuric acid environment. Accordingly, the
laboratory sulfuric acid solution soaking test was carried out, and the neutralization
depths of concretes were measured.
The test results showed that the neutralization depth of plain concrete changes
its tendency at about pH 1. The lower the water cement ratio in case of strong acid
range and the higher the ratio in case of weak acid range, the higher values of
neutralization depths were observed. Moreover, the concrete containing Carbon-free Fly
Ash (CfFA), while the content was less than 30% had more sulfate resistance than the
plain concrete did. When the CfFA content was more than 30%, however, the depth of
neutralization became larger. In case of incorporating ground granulated blast furnace
slag (GGBFS) at 27% to 67% content, the higher the slag content, the less the
Then, the prediction formula for the neutralization depth of the concrete
containing CfFA or GGBFS under a sulfuric acid environment was studied. As a result,
the main influential factors to the resistance against sulfuric acid attack of the concrete
containing CfFA or GGBFS were the concentration of sulfuric acid (pH), the cementwater
ratio (C/W) and the content rate of admixture.
Finally, the predicted values calculated by the proposed formula were examined
and showed comparatively good consistency with the experimental data that have been
reported in Japan.