Selected Answers

From Jorge Lizarraga of International Paint on March 21, 2011:

     Admixtures in concrete ...read more

     Admixtures in concrete will affect coating adhesion in several ways. One of those ways is due to closing the pores of the concrete to make it watertight, closing capillaries, making concrete surface extremely soft and impermeable for coating application.

      Hardeners don´t allow a suitable profile and  anti-dust additives will also reject the coating.  So, if the additive is on the surface of concrete, we can remove it using highly concentrated tensioctives solutions.

     If the additive is penetrated into the concrete, we must  remove the upper concrete, and replace it with new concrete or an epoxy layer. I can obtain a good surface profile in both softened and hardened concrete by using concentrated solutions of clorhidric acid (35%), checking the attack of the acid, and stopping it by washing when the profile is reached. In this way we can minimize the effect of admixtures to concrete.