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formed from the insoluble calcium carbonate with the continued
influence of carbon dioxide and water. Calcium hydrogen carbonate
is very soluble and easily washed away with rainwater. Depending on
weather conditions this process may however take up to two years to
complete.
Snow & Ice Removal
The safest deicers for concrete are also the most common: sodium
chloride-rock salt, and calcium chloride pellets. Sodium chloride,
however, will damage vegetation and corrode metal. Calcium chloride
works better at lower temperatures, has little effect on vegetation but
promotes rust. Ammonium nitrate and ammonium sulfate fertilizers, sold
as safe for grass and shrubs can rapidly attach and disintegrate concrete.
Magnesium chloride chemically disintegrates concrete slowly. Urea in
low concentrations will not damage plants, but will attack concrete.
Manufacturer’s usage recommendations should always be followed to
prevent over applying deicers. Do not use a chemical deicer to melt
every bit of snow and ice. Once the bond between ice and pavement
is broken, the slush and residual deicer should be mechanically removed
using a large rotary brush attached to a small tractor to prevent
refreezing.
Sealers
Uses:
Application of a sealer follows stain removal, efflorescence removal
and overall cleaning. Sealers are used for aesthetic and functional
reasons. Sealers offer many functional advantages.
Sealers for Concrete Pavers
If the panels are sealed, Masons Supply should be consulted prior to
verify that the sealer is compatible and will perform in the environment
planned for its use. Sealers not recommended for use with panels are
acrylics, urethanes, epoxies, alkyds, esters, and polyvinyl acetates.
Somemunicipalities regulate buildingmaterials with high volatile organic
contents (VOC’s). The restrictions usually apply to solvent based sealers.
The VOC level of a sealer refers to the pounds per gallon (or grams per
liter) of solvent which evaporates from the sealer, excluding the water.
VOC’s have been regulated since they can contribute to smog. Most
water based sealers comply with VOC restrictions and some solvent
based products may comply as well. The user should check with the
sealer supplier to verify VOC compliance in those areas which have
restrictions.
Many solvent based products are combustible and emit hazardous fumes.
Therefore, flame and sparks should be prevented in the area to be sealed.
Personsapplyingsealersshouldwearadequatebreathingandeyeprotection.
Never use solvent based sealers in a poorly ventilated or confined area.
Silanes/Siloxanes
Silanes and siloxanes are durable and penetrate concrete well. Silanes
are the simpler form that, when exposed to moisture begin to link up to
other silanes. Siloxanes do the same linking together. Both chemicals
become a polymer, curing as a film in the capillaries of the concrete.
A hydrophobic barrier to moisture is created, preventing moisture
from entering but allowing the concrete to “breathe” or release water
vapor.
Because silanes and siloxanes reduce moisture from entering the
concrete, they can deter efflorescence from appearing on the surface
of concrete panels. They initially enhance colors and produce a flat, no
gloss finish on the panel surface. This makes silanes and siloxanes very
suitable on exterior areas for resisting efflorescence. Silanes and siloxanes
do not resist penetration of petroleum stains unless they have additives
specifically for that purpose. When required, proprietary mixtures with
additives can increase petroleum stain resistance.
Silanes have smaller molecules, so they penetrate farther into the
concrete than larger siloxane molecules. However, they are more
volatile (tend to evaporate) until they bond to the concrete. Silane
sealers generally require a higher percent of solids to counteract their
rate of evaporation. Therefore, silanes tend to be more expensive than
siloxanes. Silanes and siloxanes are typically used as water repellents
for concrete bridge decks, parking garages, and masonry walls. Their
primary use for reinforced concrete structures is to prevent the ingress
of chloride ions from de-icing salts. This intrusion causes reinforcing steel
corrosion in the concrete, and a weakened structure. Their ability to
decrease intrusion of chloride materials makes them useful on panels
subject to deicing salts or salt air, such as walks, streets, parking lots,
plaza roof and parking decks.
Sealing Procedures
All dirt, oil stains and efflorescence must be removed prior to sealing. The
cleaned surface must be completely dry prior to applying most sealers.
Allow at least 24 hours without moisture or surface dampness before
application. The panels may draw efflorescence to the surface, or the
sealer may whiten.
Cover and protect all surfaces and vegetation around the area to be
sealed. For exterior (low-pressure) sprayed applications, the wind should
be calm so that it does not cause an uneven application, or blow the
sealer onto other surfaces. For many sealers, especially those with high
VOC’S, wear protective clothing andmask recommended by the sealer
manufacturer to protect the lungs and eyes.
Sealers can be applied with a hand roller if the area is small (under 1000
ft² or 93 m²). For larger areas, more efficient application methods are a
low pressure sprayer.
Hazardous Materials
The U.S. Federal Government and Canadian Government require
that all shipments of hazardous materials by common carrier must be
accompanied by a Material Safety Data Sheet (MSDS). All chemical
manufacturers must supply sheets to shippers, distributors and dealers
of cleaners and sealers if the materials are hazardous. The MSDS must
accompany all shipments and be available to the purchaser on request.
The MSDS lists the active ingredients, compatibility and incompatibility
with other materials, safety precautions and an emergency telephone
number if there is a problem in shipping, handling or use. The user should
refer to the MSDS for this information.
References
1. Cleaningand Sealing InterlockingConcretePavement - AMaintenance
and Protection Guide.
JAN 2010
-18-
STinTACT
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| mai tenance & pr tection guide