Epoxy Patching Cracks In Terrazzo Floors
- Procedure code:
- Tacoma Union Station Courthouse/Tacoma, WA - GSA/PBS
- Last Modified:
EPOXY PATCHING CRACKS IN TERRAZZO FLOORS
A. This procedure includes guidance on patching cracks in
terrazzo with epoxy resin.
B. See 01100-07-S for general project guidelines to be
reviewed along with this procedure. These guidelines
cover the following sections:
1. Safety Precautions
2. Historic Structures Precautions
4. Quality Assurance
5. Delivery, Storage and Handling
6. Project/Site Conditions
7. Sequencing and Scheduling
8. General Protection (Surface and Surrounding)
These guidelines should be reviewed prior to performing
this procedure and should be followed, when applicable,
along with recommendations from the Regional Historic
Preservation Officer (RHPO).
A. NTMA Standards: Comply with specified provisions and
recommendations of the National Terrazzo and Mosaic
Association, Inc. (NTMA)
A. Patching Resin: Manufacturer's standard 2-component
epoxy resin, designed specifically for patching of
1. Tint to match color of existing terrazzo matrix
following manufacturer's recommendations.
B. Aggregate for Epoxy: Natural, sound, crushed marble
chips without excessive flats or flakes, complying with
1. Colors and gradation of aggregate sizes as required
to match existing terrazzo aggregate material.
NOTE: ORIGINAL PLANS OFTEN CONTAIN THE EXACT
2. Aggregate colors should be matched after cleaning
or taken from the interior of core samples
depending upon scope of work.
C. Ammonia or chemical stripper
D. Interior Floor Sealer: Colorless, slip and stain
resistant penetrating sealer with Ph factor between 7 and
10, that does not affect color or physical properties of
E. Clean, potable water
A. Hand sander, small grinding tools
B. Grinding stones: Fine grit emery stones manufactured
specifically for restorative type grinding and surfacing
of terrazzo surfaces (#40 and #80 grit stones).
C. Resurfacing Screens: A fine grit screen manufactured
specifically for restorative type grinding and
resurfacing terrazzo surfaces.
3.01 ERECTION, INSTALLATION, APPLICATION
A. Remove all foreign matter from the void, followed by
routing with a power tool. Remove all sealer from the
surface adjacent to the void with a stripper or ammonia.
B. Blend the resin materials to match the color matrix, by
adding marble dust or pigment.
C. Force mixed resin into the void, making sure it is
pressured into the crack as deep as possible. In some
cases, the supplier will instruct using a primer for
D. If the void is large enough, and the intent is to
disguise the line so it will blend into the rest of the
terrazzo floor, irregularly place marble chips matching
the existing terrazzo blend along the line approximately
one to two inches on center. Be sure to do this,
however, while the patching resin is still in a wet
state. Finally, tool off surface and allow to cure.
E. When the material has hardened, sand surface with a hand
sander or small grinding tool, using fine stones.
1. Use a #40 or finer grit stone for the initial
grinding, exposing the marble chips. Follow with a
fine #80 grit stone before grouting with cement to
fill all pinholes.
CAUTION: DIVIDER STRIPS MAY BE COATED INSTEAD OF
SOLID COMPOSITION. COATED STRIPS SHOULD NOT BE
GROUND. GRINDING MAY CAUSE COATED DIVIDER STRIPS
TO LOSE THEIR COATING AND DISCOLOR.
2. Cover grouted surface with paper or polyethylene
for at least 72 hours.
3. Thoroughly rinse the surface with clean, clear
4. Remove excess rinse water and allow to dry.
5. Final polish with a #80 or finer grit stone. Care
should be taken to limit grinding and polishing to
a small distance beyond the perimeter of the patch.
F. For some time, this area will be noticeable, however,
with normal maintenance, the area will blend into the
balance of the floor.
END OF SECTION