- INTRODUCTION
- The tile industry has had its share of ceramic tile installations loosing
their bond to various surfaces. Ceramic tile may become loose from their
bond because of the following reasons or combination thereof.
- Improper substrate preparation or specification, i.e.: concrete slab
may have a steel trowel or burnished finish. The standard of the tile
trade requires a steel trowel and a light broom finish. The light broom
finish texture is necessary to provide small pockets for the bonding
mortar to key into the concrete, thus providing a higher shear bond
strength.
- Curing compounds are widely used by contractors in spite of the warnings
and literature forbidding their use to sure concrete. The manufacturers
indicate the compound will oxidize in 30 - 45 days but CTI knows this
is true only under ideal conditions. When the concrete covered with
curing compounds is not exposed to the ultra violet ray of the sun
these curing compounds have been present on slabs nearly two years
old. Some compounds may last longer than two years.
- Lack of or improperly installed expansion joints, cause many tile installations
to fail by tile loosing their bond. Many tile installations require
expansion joints throughout the field. However, all tile installations
shall have expansion joints at the perimeter and especially where the
tile surface abut rigid wall, columns, or dissimilar planes.
- Deflection of substrate contributes its share of problems to tile failures.
The tile industry has established 1/360 of the span as the maximum
amount permissible to assure that the tile will remain bonded.
- Premature traffic over a freshly installed floor will cause a loss in
bind of the tile. The ANSI specifications require to keep traffic off
for at least 72 hours but CTI prefers 7 days because of uncertainties,
in curing time, with the materials and climatic conditions.
- Excessive abuse or misuse of the tile and bonding materials can cause
loss of bond, In some cases a high absorptive tile may not have been
pre-moistened or the concrete has sucked the moisture out of the bonding
mortar too rapidly for proper hydration of the cement in the bonding
mortar. Either condition may result in a failure.
- Contaminates on the substrate while applying the bonding mortar may cause
problems especially to an improperly or untrained mechanic. A trained
mechanics will always clean the surface of contaminates before tiling.
If contaminates are present, the bonding mortar will usually roll up
at the time of application.
- Poor workmanship is also a potential cause but is extremely rare in well
qualified craftsmen. Poor workmanship is more prevalent with the unlicensed
or unschooled mechanic. Many geographical areas in the USA has set
up apprenticeship schools to properly train and educate the mechanics
for our trade.
- Bonding tile to uncured concrete usually will cause a failure. The ceramic
tile institute recommends that the concrete slab shall cure for 28
days before tile are directly adhered to the surface. This time is
necessary for a proper cure and will allow for the slab to shrink to
approximately its maximum amount.
- Of all the ceramic tile installations, an extremely high percentage never
have any problems and provide the most cost effective, beautiful, durable
and functional surface of any other surface material. Therefore, epoxy
injection should not be a crutch or the "ace in a whole" or substitute
for quality installing of quality materials used in compliance to proper
specifications.
- DISCUSSION
- What is Epoxy Injection? Epoxy injection as used in the tile trade and further
discussed within is a means to re-bond a separated tile installation. Cracks
within the concrete slabs or other substrates may also be repaired by filing
and adhering the separated parts with an epoxy resin.
- The epoxy resin adhesive is a two component liquid epoxy containing 100%
solids and specially formulated to be injected, by an epoxy injection
machine, through a nozzle. The epoxy components are mixed in the nozzle
for better control and immediate injection.
- The adhesive is a low viscosity liquid, containing no solvents and cures
at room temperature. At a curing time of 24 hours at about 77 degrees
F. the bond strength is so great that the concrete or tile will usually
break first before the bond fails. The shear strengths are in excess
of 4000 PSI and compression strengths exceeding 15,000 PSI.
- When should epoxy resin adhesive be used?
- Whenever the conditions are favorable to restore the monolithic integrity
of a damaged ceramic tile installation. A determination of the extent
of damage is necessary, i.e.: the separation within the system should
not be excessively wide (preferably less then 1/8"). The surfaces
to be rebonded need to be clean or cleanable and solid (not powdery).
An evaluation as to the cost effectiveness of restoring vs. replacement.
- Whenever the esthetics of the job dictates that replacement is not feasible.
For example, a mural may have a crack caused by an earthquake in its
backing material. The crack could be rebonded and then tessarae carefully
remounted over the crack and blended into the facial image.
- How is it used? Epoxy resin adhesive is installed in a variety of methods.
Some mix the two components and pour the liquid. Other installers use
various materials to bridge over the surface of the crack and then pump
the liquid through a tube attached to the crack. Still others drill holes
at random and pump liquid into these holes until the liquid flows out
at some unknown destination.
The best method that CTI has observed is
to strategically locate the areas that have separated, identify these
areas and mark the boundaries, precisely drill a minimum of small holes
in the grout joints between the tike, inject the two component resin
with the proper equipment, monitor the flow of the liquid in the void
by continuous sampling, clean up all excessive resin before it has a
chance to harden (Acetone will clean off liquid), and properly refinish
the surface which would include the re grouting of the holes to blend
with the existing grout color and texture.
For the extended workability
of the epoxy resin adhesive the two components are to be mixed in the
nozzle. The components may also be slightly heated to allow additional
penetration. The components may be purchased in colors to assist the
installer in evaluating the proper mix at the nozzle, i.e.: Component
A is available with a yellow dye, B with blue dye therefore properly
mixed will result in a green mixture.
- What are the costs?
- The epoxy resin adhesive is a medium priced epoxy. Related to the conventional
materials used in the tile trade, epoxies are generally expensive.
- The storage of the raw materials are expensive because of the short shelf
life (approximately 1 year).
- The installation by a competent epoxy injection contractor can vary between
a tenth to one-half the cost of reinstalling the ceramic tile system.
Cost estimates are recommended to determine the cost effectiveness.
The cost of removal of the damage system plus the cost of scarification
of the substrate and/or repair to substrate plus the inconvenience
cost to all parties due to the time delays for repairs plus the relocation
cost of equipment or furniture if the area was inhabited and finally
the cost of replacement of the tile. Any failure is a very costly event
to all parties including the tile industry. The actual "out-of-pocket"
cost for epoxy injection is extremely difficult to determine until
a complete analysis of the failure is obtained.
- What are the dangers?
- In addition to the potential physical danger to individuals there is the
possibility that the voids that are to be rebonded are heavy with contaminants
and not cost effective to get out.
- The possibility that the surfaces are not in a bondable condition. The
epoxy manufacturers insist that the surfaces to receive adhesive shall
be clean, free of dirt, loose particles, oil, grease, asphalt, tar,
paint, wax, rust, waterproofing, curing and parting compounds, membrane
materials and other contaminants which might prevent satisfactory bond
and/or epoxy cure.
- Dermatitis may be caused by exposure to the epoxy resins. The manufactures
print important warnings, "should skin contact with epoxy occur, immediately
wash with soap and water, then rinse thoroughly with water for several
minutes. NEVER try to remove epoxy from skin by using any kind of solvent.
Good protection can be provided by the use of clean rubber gloves,
disposable gloves, or skin creams, Special care should be taken to
protect the face and eyes, flush for 10 minutes with water and secure
immediate medical attention. Good ventilation is required when applying
epoxy in indoor areas." The long tern effects from continuous contact
may not be apparent.
- The damage caused by spills to the tile and surrounding materials is difficult
to determine due to the workmanship of the installer and any accidents
that may occur. The cleaning up shall be immediate with proper materials
to minimize the potential material damage.
- Are there any guarantees or warranties? Very limited at best!
- The manufacturer of the material usually will print their warranties or
as in one case their non-warranty, "this product is sold without warranty
and no implied warranty is to be raised from circumstances accompanying
sale or use thereof. Results obtained by the use of our products depends
on workmanship and conditions under which the materials are used, and engineering
and inspection, over which we have no control.
Therefore, the only guarantee
that is given by us is to replace such goods that are defective in manufacture,
or give credit at our option. Under no circumstances are we responsible
for any damages beyond the price of the material, and no charge for labor,
expense, or consequential damages will be allowed. If materials prove to
be defective, the measure of damage is the price of the defective material.
Our salesmen or representatives have no authority to extend any guarantee
beyond that outlined above."
- The epoxy injection contractor may warranty their work depending upon the
factors dealing with the rebonding of the failure. We suggest that all
warranties be written and all intents of the specifications be thoroughly
understood and mutually agreed upon.
- CONCLUSION
- The best of all worlds when installing ceramic tile is to use quality materials,
write proper specifications, draw detailed methods on the plans, use certified
quality tile contractors, allow ample time for the mechanics to install
the tile and provide adequate supervision.
- If a bond loss occurs and conditions warrant then epoxy injection may be
the next best solution in lieu of removal and replacement.
- Contact the Ceramic Tile Institute of America for the company names of the
epoxy injection contractors who are recognized by the trade for their quality
performance.
|
