Membership Directory & Resource Guide - 2018 - 27

TECHNICAL BULLETIN NO. 4, 2018 * pg 2 of 3

2. Precipitation of Minerals or Metals
(surface scaling)

allowed to permeate through a cementitious surface coating. Water
chemistry parameters that are not maintained within the "ideal

ranges", as defined by ANSI/APSP to be "balanced"2,3 can become
All materials that are in a water-contact environment are
subject to mineral scale or metal stain precipitation. Concrete,
aggressive to the cementitious surface coating. Allowing such
cementitious coatings, brick, metal, tile, and even glass surfaces
conditions, can result in the dissolving of components of the cement/
are subject to salt scale or staining from minerals or metals
aggregate matrix and the leaching of cement compounds.5,6,10,11 The
precipitating from the water. Surface scaling often exhibits
leaching of the pigment, which is held in place by these cement
itself as a white or light-colored film or layer, which can mute or
compounds, occurs as well.15 Organic pigments have a much smaller
completely mask the intended finish color. Metal precipitation
particle sizing than inorganic pigments, making them more likely to
can often alter the coloration of the surface by staining the finish.
be released from the cement binder and lost, as the binder becomes
For example, copper and manganese can cause a blue, green,
more porous from ongoing deterioration or weathering. Generally,
or black coloration and iron can cause a red, orange, or black
this appears as 'faded', lighter-colored, or white areas across the
coloration. Having the water periodically tested for metals and
surface.
hardness, and taking the necessary precautions to avoid the
accumulation of significant concentrations of metals and mineral
If water is allowed to remain in an aggressive condition for an
salts can avoid this from occurring. Alternatively, sequestering
extended period of time, pigment can be partly or completely
or chelating chemicals may be used. However; once started,
leached up to 1/8" in depth leaving the surface color faded or white
their continued usage becomes necessary as long as significant
2.
Precipitation
of
Minerals
or
(surface scaling)
ifMetals
the pigment
is completely removed. The resulting color loss is
CALCIUM
SALT MIGRATION
DUE TO
CEMENT
HYDRATION
amounts
of mineral or metal
remain
in the water,
or
precipitation
All materials that are in a water-contact environment are subject to mineral scale or metal stain precipitation.
(PIGMENT MASKING)
irreversible.
Theandterm
water"
to befrom
water
Concrete, cementitious coatings,
brick, metal, tile,
even"aggressive
glass surfaces are
subjectistoconsidered
salt scale or staining
of that mineral or metal is likely.
minerals or metals precipitating from the water. Surface scaling often exhibits itself as a white or light-colored2,3,12
film or
that is chemically outside of established balanced ranges.
layer, which can mute or completely mask the intended finish color. Metal precipitation can often alter the coloration

3. Dissolution of Cement Compounds
(pigment loss)

of the surface by staining theAggressive
finish. For example,
and manganese
can cause
a blue, green,
or black
watercopper
is capable
of removing,
dissolving,
or otherwise
coloration and iron can cause a red, orange, or black coloration. Having the water periodically tested for metals and
reacting
with components
of the surface
materials
causing
hardness, and taking the necessary
precautions
to avoid the accumulation
of significant
concentrations
of metals
mineral saltsof
can avoid this from occurring.9,10,11
Alternatively, sequestering or chelating chemicals may be used.
Water chemistry plays an important role in the lifeand
expectancy
This
would
include
water
that
has
low
calcium
deterioration.
However; once started, their continued usage becomes necessary as long as significant amounts of mineral
a cementitious coating. Reactions with the soluble
or cementitious
metal remain in the water, orhardness,
precipitation of
thatpH,
mineral
metal is likely.alkalinity, and/or a combination of
low
loworcarbonate

materials can take place whenever water, or moisture, is

these.4

PRECIPITATION OF MINERALS OR METALS (SURFACE SCALING)

Top View

Precipitation ofCross Section (Detailed)
Minerals or Metals
(Surface Scaling)

Technical Bulletins

Top View

EDS Hyper Map

Cross Section (Detailed)

EDS Hyper Map (Detailed)

Ca = Calcium Si = Silicon Al = Aluminum
EDS Hyper Map

EDS Hyper Map (Detailed)

Ca = Calcium Si = Silicon Al = Aluminum

N PCon li n e .org

http://www.npconline.org/

Table of Contents for the Digital Edition of Membership Directory & Resource Guide - 2018