Scaling Concrete
It's one of the leading
complaints of many homeowners and probably the easiest defect of a concrete
surface to avoid. It's called scaling and it makes concrete deteriorate and
look terrible.
Scaling is primarily found in outside concrete flat work such as sidewalks,
patios and driveways. In most cases it is blamed on de-icing salts used on
the concrete during the winter months. Despite these assertions, the truth
is that properly specified, placed, and cured concrete should be able to endure
the effects of typical de-icing agents.
A 32 MPa concrete mix design with 5-8% air entrainment should provide sufficient
protection against the damages of freeze-thaw. A higher strength concrete
of that kind is required in regions with severe climates (Such as Nova Scotia)
because the concrete is subjected to considerably more freeze-thaw cycles.
Once the proper specification of a concrete mix has been selected, there are
precise methods for the correct installation and finishing of this type of
concrete. The basic finishing specifications call for screeding, floating,
broom finishing, and sealing of the concrete. If all these guidelines are
followed closely there is a minimal chance for concrete scaling to occur.
Repeatedly these specifications are not met because of small common mistakes in finishing. These mistakes include excessive water to the mix, improper steel trowel finishing, finishing concrete prior to elimination of bleed water and/or overworking of the concrete surface. Insufficient or improper curing and lack of sealing can also add to the problem.
Concrete that is well made and well placed will prevent scaling.
V. J. RICE CONCRETE representatives
will assist you in determining the proper mix for your project specifications.
