III. ACID RESISTANCE
Acids attack concrete by dissolving both hydrated and
unhydrated cement compounds as well as calcareous
aggregates. In most cases the chemical reaction yields soluble
calcium compounds which then leach away by leaving voids
in the concrete. Generally ordinary cement concrete does not
have good resistance to acids. But some weak acids however
can be tolerated particularly if the exposure is very occasional.
Siliceous aggregates are resistant to most acids and chemicals
and are some times specific to improve the chemical resistance
of concrete.