LAYING PROCEDURE OF IMPRINTED CONCRETE.
E F F L O R E S C
E N C E
is a deposit usually white in colour that may
appear on the surface of imprinted and coloured
concrete. One of the preliminary reasons it
occurs is due to water evaporating from the
surface of the concrete leaving behind a white or
grey deposit of soluble salt. Efflorescence
appears just after a structure is completed and
is generally harmless but these deposits can
occur within the surface pores of the material
causing expansion that may disrupt the surface.
two types of efflorescence are PRIMARY and
Efflorescence the water used in the
production of the concrete migrates to the
surface and evaporates leaving behind soluble
Efflorescence is due to the ingress of water
from an external source. this water picks up
soluble salts present in the concrete and
migrates to the surface, evaporating and
depositing the salts on the surface of the
mostly affected by temperature, humidity and
wind. It is most obvious in winter, this is so as
the rate of evaporation is slower in winter,
therefore allowing salts to migrate to the
surface. However Efflorescence may be observed
throughout the year following heavy rains and
drops in temperature. Its appearance can be
light-coloured and blotchy to a white coating but
as the years pass it becomes less extensive
unless there is an external source of salt.
The reduction or
overall elimination of Efflorescence can be
accomplished by certain methods.
To reduce or
eliminate Efflorescence the following are
mixing water free from harmful amounts of
acids, akalis, organic material, minerals and
Apart from these
easy to follow steps there are other methods to
combat Efflorescence. These methods concentrate
mainly on consistency and composition of cement.
admixtures offer only short-lived protection.
Calcium Stearate Dispersion (CSD) is the most
common Efflorescence Control Agent (ECA). It is a
water soluble wax based compound. Its water
repellant and ECA properties offer only temporary
Low absorption of
moisture is the best assurance against
Efflorescence. To achieve maximum watertightness,
concrete must be made with properly graded
aggregates an adequate cement content, a low
water cement ratio and thorough curing.
Efflorescence occurs the source of the moisture
should be determined and corrective measures
taken to keep water out of the structure.
Efflorescence can be removed by the following:
rinising with brushing light
followed by flushing with clean water.
On a mild case an
application of straight vinegar followed by a
thorough rinsing with water can remove the
deposits. The last resource if none of the
mentioned remove the deposits is to apply a
dilute solution of imuriatic acid ( 1 to 2%).
applying an acid solution dampen the surface with
clean water to prevent acid from being absorbed
deeply into the structure where damage may occur.
application area should be no longer than 4sq ft
with a delay of about five minutes before
scouring off the salt deposit with a stiff
3. After this
treatment the surface should be immediately and
thoroughly flushed with clear water to remove all
traces of acid.
Rubber gloves, glasses and other protective
clothing should be worn by crew members using
an acid solution.
To conclude it is
best to try all other possible means before using
acid solution due to the possible adverse on