Use and Care Manual
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Efflorescence is a white haze that may
appear on the surface of pavers sometime
after installation. It forms as a result of a
natural chemical reaction that occurs when
the lime or water soluble calcium oxide,
produced by the cement contained in the
pavers, reacts with water. When the water
enters the microscopic capillaries in the
pavers, calcium hydroxide is formed. The
calcium hydroxide rises to the surface
of the paver, reacts with the carbon dioxide
in the air, and forms a white haze of calcium
carbonate when the moisture evaporates
from the surface. The appearance of
efflorescence stops when there isn’t any
more calcium hydroxide available to move
to the surface. This process sometimes
can take several months.
Efflorescence does not damage pavers.
However, it can be unappealing. The white
haze may give the impression that the
paver color is fading but this is not the
case. Efflorescence may occur randomly
or be concentrated in certain areas. Dark
colored pavers show efflorescence more
than lighter-colored ones. If efflorescence
does occur, it can be removed with cleaners
specially made for concrete pavers. Care-
less or improper cleaning can result in
damage and discoloration to the concrete
paver surfaces.
One way to moderate the rate of color
change is by cleaning and sealing the
surface of the concrete pavers. Besides
enhancing their color, sealers can prevent
dirt from lodging in the surface.
Color in concrete pavers is achieved by
adding pigment to the concrete mix during
production. The cement in the concrete
mix holds the pigments in place. They are
very stable, showing little change in their
properties over time. As the paver wears
from traffic or weather, the cement and
pigment particles gradually erode causing
a color change over time. Like all pave-
ments, concrete pavers receive dirt from
foot or tire traffic which also changes the
surface color.
Settlement is often caused by inadequate
soil or base compaction. Other factors can
be water in the base or soil, too thick a layer
of bedding sand, or washed out bedding
and joint sand. Loose or inadequate edge
restraints cause pavers to move apart
and can also contribute to settlement. If
the base or soil has settled and is stable,
remove the pavers and bedding sand,
place and compact additional base material
to the correct level, then add bedding
sand. The removed pavers can then be
reinstated with no wasted paving materials
or unsightly patches. Concrete pavers can
be removed for access to underground
utilities, and reinstalled after repairs. When
utility repairs are complete, fill the trench
with base material and compact it. Remove
about 18 in. (0.5 m) of pavers on either side
of the opening, level the bedding sand and
replenish as necessary. Reinstall the pavers,
compact, fill the joints with sand and compact
the surface again, filling joints as needed.
Concrete pavers aren’t damaged by oil
leaking from cars, but the stains can be
difficult to remove. Stains should be treated
as soon as possible since the longer they
remain on the surface, the deeper they
penetrate making removal harder. Wipe
excess oil from the surface as soon as
possible and apply liquid detergent. Allow
it to soak for several minutes. Then scrub
and wash the pavers with hot water.
Several treatments may be necessary for
particularly stubborn stains. In some cases,
it may be simpler to replace the stained
pavers with new ones. Cleaning and sealing
concrete pavers early in their life can make
removing stains easier since sealers prevent
stains from soaking into the surface.