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Focus on Floors
Concrete Technology
Home > Concrete Design &
Construction >Durable Floors
DURABLE FLOORS
 Durable
concrete floors begin with quality materials, good design, and proper
workmanship. Beyond these essentials, measures can be taken to ensure
your concrete floor is protected. If deterioration occurs, understanding
its cause can help with the repair and prevention.
 Many
concrete slab surface defects (delamination, dusting, etc) and problems
with floor flatness can be attributed to the quality of the material
and/or the placing and finishing techniques. Retaining an expert
installer who knows his/her locally available concrete material
can be an important step in achieving good quality concrete floors.
As an installer, having the right concrete mix for the job and sufficient
labor and equipment to properly place, consolidate, and finish the
fresh concrete is crucial.
Beyond quality floor construction, implementation of surface or
penetrating sealers can improve the wear resistance or protect concrete
from chemical attack. There are a wide variety of surface sealers
for use on concrete slabs. If your application is to protect a stained
interior residential floor or prevent excessive wear and abrasion
on an industrial slab, the appropriate surface treatment will vary.
A discussion of the available sealers is given below.
 When
slab defects do arise, understanding their cause can help in repairing
and preventing them in the future. These defects may be scaling,
random cracking, crazing, or a delamination.
For more information on concrete durability, click
here.
Resources
Concrete Slab
Surface Defects (IS177)
Effects of Substances
and Guide to Protective Treatments (IS001)
Popouts: Causes,
Prevention, Repair (PL852)
Control Driveway
Deicer Scaling by Avoiding Lean Concretes (PL942)
Avoiding Slab Delaminations
Delaminations are separations in a slab,
parallel to and generally near the upper surface, that result from
bleed water and air being trapped below the prematurely closed (densified)
mortar surface. The primary cause is finishing the surface before
bleeding has occurred.
Delaminations are more likely to occur when factors that
extend the bleeding time of concrete, such as:
- a cold subgrade
- a vapor retarder directly under the slab
- thick slabs
- a high water content
- entrained are air combined with factors that accelerate
setting of the concrete surface, such as:
- high wind velocity
- low relative humidity
- rising air temperature
- exposure to direct sunlight
To avoid delaminations, consider the following:
- Do not use concrete with a high slump, excessively
high air content, or excess fines.
- Use appropriate cement contents in the range of
515 to 565 lb/cubic yard (305 to 335 kg/cubic meter).
- In cold weather, warm the subgrade before placing
the concrete.
- Avoid placing a slab directly on the vapor retarder
(see above).
- Avoid overworking the concrete, especially with
vibrating screeds, jitterbugs, or bullfloats.
- Do not attempt to seal (finish) the surface too
soon. Use a wood bullfloat on non-air-entrained concrete to avoid
early sealing. Magnesium or aluminum tools should be used on air-entrained
concrete.
- Reduce evaporation over the slab by using a fog
spray or slab cover.
- Avoid using air contents over 3% for interior
slabs.
Reference:
Concrete Slab
Surface Defects (IS177)
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Protecting Floors from
Chemical Attack
Although portland cement concrete is durable in most natural environments,
it is sometimes used in areas such as chemical processing plants
where it is exposed to substances that can attack and deteriorate
it.
Various surface protection options are available to
protect concrete in even the most aggressive environments. Here
are the advantages and disadvantages of several options:
| |
Advantages |
Disadvantages |
| Epoxies |
Strong bond
Low shrinkage
Moisture tolerant |
Not UV resistant |
| Urethanes |
Fast cure
Good toughness |
High cost |
| Methyl Methacrylates |
Very fast cure |
Cure inhibited by air
Strong odor |
| Polyesters/Vinyl Esters |
Good chemical resistance
High service temperatures |
High shrinkage/
thermal expansion |
| Potassium Silicates |
Very good acid resistance
Very high service temps |
Poor alkali resistance
Rigid/requires membrane |
| Acid Brick |
Very good acid resistance
Very high service temps |
Permeable/need membrane
High cost |
| Sulfur Concrete |
Good acid resistance
Fast strength gain |
Specialized mixing/transport
Rigid/requires membrane |
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