I have white marks appearing on my concrete block paving. What is it and how do I stop it happening?
A. Due to the process of manufacture of concrete blocks, calcium hydroxide will often be transported via capillary action to the surface of the paving (called “blooming”) where it will react with CO2 in the air to form Calcium Carbonate i.e. a white chalky deposit. Simply remove these deposits with RESIBLOCK ER (Efflorescence Remover). To prevent further occurrence seal with RESIBLOCK Superior or RESIBLOCK Superior Natural Matt. For further information on efflorescence please refer to our technical library.