How to get rid of wall saltpetre on finished products (street furniture made of concrete)?

First, check the cement. It is better to use non-neat cement such as or Portland cement  500 without admixture. Second, check the sand and crushed stone for limestone. It is preferable to use aggregates from dense rocks and without organic (sludge). Apply the D-5 admixture (3% of cement weight) and exclude all other admixtures and plasticizers. It binds free lime released during cement hydration. Free lime is the main reason for the appearance of salts.

The addition of D-5 admixture during the production of pressed bricks eliminates the problem of salts.