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Historic Preservation - Technical Procedures

Spectitle:

Epoxy Patching Cracks In Terrazzo Floors

Procedure code:

0940005R

Source:

Tacoma Union Station Courthouse/Tacoma, Wa - Gsa/Pbs

Division:

Finishes

Section:

Terrazzo

Last Modified:

02/24/2012

Details:

Epoxy Patching Cracks In Terrazzo Floors



EPOXY PATCHING CRACKS IN TERRAZZO FLOORS


PART 1---GENERAL

1.01 SUMMARY

    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

         3.   Submittals

         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).

1.02 REFERENCES

    A.   NTMA Standards:  Comply with specified provisions and
         recommendations of the National Terrazzo and Mosaic
         Association, Inc. (NTMA), 3166 Des Plaines Avenue, Ste.
         132, Des Plaines, IL  60018, 800/323-9736 or 708/635-
         7744, FAX (708) 635-9127.


PART 2---PRODUCTS

2.01 MATERIALS

    A.   Patching Resin:  Manufacturer's standard 2-component
         epoxy resin, designed specifically for patching of
         terrazzo materials.

         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
         NTMA requirements.

         1.   Colors and gradation of aggregate sizes as required
              to match existing terrazzo aggregate material.

              NOTE:  ORIGINAL PLANS OFTEN CONTAIN THE EXACT
              TERRAZZO MIX.

         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
         terrazzo surface.

    E.   Clean, potable water

2.02 EQUIPMENT

    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.


PART 3---EXECUTION

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
         their materials.

    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
              water.

         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