Question

 What causes surface scaling? What are the precautionary measures for surface scaling?

Answer 1

Surface scaling means the peeling or flaking off of the top surface of the concrete.

Surface scaling is caused due to:

• Freezing and thawing of the water in the porous non air entrained concrete i.e if non air entrained concrete is used , then it doesn't allow air to pass through the concrete which is necessary for the protection from thawing and freezing.

• Due to the application of excessive amount of calcium or sodium chloride , deicing salts on concrete.

Deicing salts particularly those containing ammonium sulfate or ammonium nitrate can cause scaling on the concrete surface.

• Insufficient curing i.e due to insufficient curing, the concrete doesn't reaches its full strength and due to that the top surface scales when exposed to freezing and thawing.

Precautionary measures for surface scaling are:

• Air entrained concrete should be used where the concrete is exposed to freezing and thawing.

• Avoid the use of deicing salts such as calcium and sodium chloride in the first year after placing the concrete.

• Proper curing should be done in order to make the concrete reach its full strength.

• Finishing operations should be carried out only when all the water from the surface has been removed or evaporated.