SUBJECT:
SEALING OF POROUS CONCRETE MASONRY UNITS (CMU’S), CINDER, SPLIT FACE, ETC., BLOCK
Most of the new CMU block is manufactured using very porous,
lightweight aggregates. This is evident by the weight. Older block, as well as some still
manufactured in Nevada, weigh approximately 38 pounds. The new block can weigh as little
as 23 pounds. This block is difficult to seal due to high porosity and lightweight unless
a secondary process of decreasing the pore structure and increasing the density of the
calcium hydroxide content is used. MOXIE 1500 CONCRETE SEALER is a chemically reactive
sealer in its process and reacts with calcium hydroxide (free lime). Some older block or
stucco may need this step as well, as the hydroxides over the years may have leached out
by rain or run-off.
Hydrated lime (calcium hydroxide) is recommended however,
baking soda may be successfully substituted at approximately two tablespoons per gallon
for this process.
This process is described as follows:
Mix approximately one cup, by volume, of calcium hydroxide in a
five gallon bucket of boiling water and mix thoroughly (two tablespoons per gallon baking
soda).
Allow 24 hours for any calcium hydroxide to settle out of
solution, baking soda will settle within a couple of hours.
Carefully pour off the top of the liquid with the calcium
hydroxide, or baking soda, that has remained in solution, leaving what has
settled in the bucket. This liquid may be poured into a spray bottle for small areas.
Pour this liquid into the water reservoir of a power wash unit.
Power wash the entire surface of the block or spray the area
with the spray bottle containing the suspended calcium hydroxide or baking soda.
Before the surface has dried, apply MOXIE 1500 CONCRETE SEALER
as per application procedures described in the published documentation.
MOXIE 1400 may be applied 24 hours later if the requirement is
to achieve a surface on which water will "bead up". MOXIE 1500 does not produce
a surface on which water "beads up".
NOTE: If the surface is to be acid washed or a fungicide used
make sure the product is thoroughly rinsed off or neutralized prior to the application of
MOXIE 1500 CONCRETE SEALER.
Calcium hydroxide (hydrated lime) may be purchased from local
chemical companies for approximately $16.00 for a fifty pound bag.
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