Weather conditions can affect the appearance of
Temperature effects the amount of water required to
make the mix workable in cool temperatures, it takes
less water to get a workable mix. But, always
remember that variations in the water-to-cement
ratio have a significant effect on concrete color.
Maintain a consistent water/cement ration throughout
the project and follow ACI guidelines for hot and
cold weather concreting where applicable.
Schedule placing and finishing work to minimize
exposure to hot sun before curing materials are
Consider postponing color concreting until windy
conditions pass, or create a wind barrier to avoid
pour concrete if rain, snow or frost is in the
or black-colored concrete will be exposed to
additional heat during sunny, dry conditions.
Provide extra curing protection to prevent thermal
cracking when this combination is anticipated.
Concrete made from the same supplier can cure to
different colors if pouring or curing takes place
under different climates. Place concrete in similar
conditions if possible.
Maintain concrete temperature between 60F and 80F
in most applications for proper curing to occur
during the crucial first days.
Planning – Site Preparation:
Uniformly grade, compact and dampen the sub-grade.
- Add a
2-3” layer of sand, gravel or crushed stone and
compact with vibrating equipment to insure a
not place concrete if the ground has standing water,
hard or soft spots, ice, frost or muddy areas.
Follow American Concrete Institute (ACI) procedures
for the installation of vapor barriers when
Planning – Forms and Reinforcement:
place formwork to achieve consistent thickness
throughout, to ensure even curing and even color.
vertical applications, seal forms to ensure no
leakage and staining of the surrounding area.
applications where the formed surface is visible,
use form liners or employ a resin coated
high-density overlay, epoxy or urethane coated
Always ensure that the form release agents are
compatible with colored concrete.
Planning – Mix Design:
your ready-mix supplier for recommendations on the
specific components for your mix. Hear are a few
slump should be no greater than 4” unless a Grace
mid-range or high-range water-reducing admixture is
water-to-cement ratios will minimize shrinking and
cracking, maximize concrete strength and produce a
richer, darker color.
Plastic shrinkage fibers will reduce shrinkage
cracking, allowing your work to continue looking
beautiful well into the future.
freeze-thaw issues existing in your area, specify
air contents in the range of 5% to 7%.
Planning – Placing:
water added to fresh concrete at the job site. Water
added to the mixer, pumps or placing tools will cause
the final color to pale.
Discharge the concrete as close as possible to the
final location. Move the concrete with shovels
rather than vibrators.
Protect areas near the pour with plastic sheets.
Splatters con stain adjacent slabs and structures.
Planning – Finishing:
attention to detail and consistency in finishing, will
pay off in your final product allowing your customer to
enjoy your craftsmanship.
adding water to your finishing tools. This will
cause pale streaks discoloring the surface.
float after striking off the slab. Magnesium bull
floats can trap moisture in the surface of the
concrete; use wood floats and derbies when possible.
with regular concrete, wait for the bleed water to
completely disappear before troweling as this can
also trap moisture. Over troweling or late troweling
leads to burns and dark spots. The potential for
discoloration rises as troweling time increases. The
easiest way to achieve color uniformity is to skip
troweling and use a broom or swirl finish. Less time
spent of finishing the concrete is better for
more information on creating finishes, see Finishing
Concrete Slabs with Color and Texture by the
Portland Cement Association.
Planning- Curing and Sealing:
you have applied your skills to getting the proper
finish, complete the job with a membrane-forming cure
and seal formulated for colored concrete. A properly
applied curing compound will assist in achieving
consistent drying and a consistent final color. Lack of
proper curing can lead to shrinkage cracks, dusting and
saw cutting, either decorative or structural, should
take place before sealing materials are applied.
Thoroughly clean all cutting residue before applying
Curing with water sprinkling, membranes, paper,
sodium or fluro silicate-type hardeners and
non-approved compounds can cause discoloration. If
water is used to cure, a lighter color is likely.
Always use curing, sealing, and cure-and-seal
products suitable for colored concrete and follow
the manufacturer’s recommendations for application.
Planning – Efflorescence:
Efflorescence is a salt deposit that forms on concrete,
causing unsightly white stains. Water, concrete
permeability and soluble salt content determine how much
and when efflorescence will occur.
Control efflorescence by mixing with a low
water/cement ration, using a curing compound, and
designing a well-drained sub-grade.
concrete against water penetration and leaks.
de-icing salts away from concrete which is not fully
cured and sealed.
Efflorescence can be removed with a water wash and
stiff bristle broom, if treated early. If not, it
converts to calcium carbonate, which is removed with
dilute acid wash that will affect the surface