Best bonding surfaces
It has been found that a coating bonds
better to a freshly exposed, roughened
concrete surface.
One way of achieving this is by
mechanical means, where the top
part of the concrete is removed by
diamond-encrusted metal plates which
are rotated over the surface like the
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is chemical, where hydrochloric acid is
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the surface of the concrete, which is
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particularly appealing and would
have preferred to just apply the sealer
to the untreated concrete, but the
instructions recommended the etching
with fairly strong hydrochloric acid
(HCl). Concrete is a mixture of various
minerals such as calcium carbonate
(CaCO 3 ) and calcium hydroxide
(Ca(OH) 2 ), both alkaline, which react
with the acid to form salt, water, and
carbon dioxide gas
In the early part of last century, eggs
were preserved for as long as six months
by sealing the eggshell with various
substances. One used in New Zealand
was ‘waterglass’, which is said to be a
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reacts with the eggshell and seals its
microscopic holes, stopping the entry of
air and slowing the deterioration of the
eggs. Waterglass has the same effect on
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calcium hydroxide in the concrete, isstrongly bonded to the concrete, and
makes the concrete impermeable to
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works in a similar fashion. Waterglass
is soluble in water, so the presence of
solvents indicates that there is much
PRUHWR6LOR[D7HNDiluting the acid
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‘Hydro-Etch’ in the Ghostshield system,
is a watery liquid the colour of beer.
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with water to a bit more than one-tenth
of the original concentration before it
can be used to etch the concrete.
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and a litre container and measured
PO RI WKH FRQFHQWUDWHG DFLG DQGTest strip of Siloxa-Tek 8510 being applied