Reattaching Loose Or Spalled Limestone

Procedure code:
446007S
Source:
Departmental Auditorium Bldg (Hsr) - Grier, Brown, Renfrow..
Division:
Masonry
Section:
Limestone
Last Modified:
03/03/2017

 

REATTACHING LOOSE OR SPALLED LIMESTONE

 

 

PART 1---GENERAL

 

1.01 SUMMARY

 

A. This procedure includes guidance on reattaching loose or

spalled limestone that is reusable and has not been

extensively damaged.

 

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. American Society for Testing and Materials (ASTM), www.astm.org

 

 

 

PART 2---PRODUCTS

 

2.01 MANUFACTURERS

 

A. Axson Technologies (formerly Akemi Plastics, Inc.)

www.axsontech.us

 

B. Sika Corporation

http://usa.sika.com

 

 

 

2.02 MATERIALS

 

A. Replacement limestone - reuse any loose or fallen stone

fragments that are still sound; re-use such stone in its

original position and location; replacement stone should

match existing limestone in color, texture and type.

 

B. Epoxy Adhesive such as "Sikadur 32 Hi Mod" epoxy adhesive, or

approved equal (Sika Corporation).

 

1. High modulus, high strength, moisture insensitive

   epoxy adhesive with a pot life of 30 minutes at 70

         degrees F.

 

2. Can be applied at temperatures as low as 40 degrees

         F.

 

     3. Colored to match existing limestone.

 

C. A color-matched polyester-based adhesive such as "Limestone Super",(Wood & Stone Company, a Axson Technologies US, Inc. company), or approved equal.

 

     1. 10-12 minute cure depending on ambient temperature; temperatures below 32 degrees F (O degrees C) require heated mixture.

 

     2. Can be applied at temperatures as low as 20 degrees

         F

 

     3. Colored to match existing limestone.

 

D. Permanent coloring agent as required, compatible with

adhesive, and as recommended by adhesive manufacturer.

 

E. Stainless steel rods for reinforcement: 1/4 inch

diameter threaded rods, length as required.

 

2.03 EQUIPMENT

 

A. Stiff bristle brushes (natural fiber or nylon)

 

B. Polyethylene plastic mixing vessel for mixing adhesives

and patching mortar

 

 

PART 3---EXECUTION

 

3.01 ERECTION, INSTALLATION, APPLICATION

 

A. Carefully remove all loose fragments of stone. Set aside

all pieces in good condition for reuse.

 

B. Clean exposed metal anchors. Remove corrosion by

scraping with a stiff wire bristle brush.

 

C. Remove unsound metal anchors and replace with new

stainless steel anchors of similar size and shape. Bed

anchors in epoxy grout.

 

D. Remove dust and debris from building stone and fragments

using a stiff bristle brush.

 

E. For small fragments (.5 cubic feet or less):

 

     1. Coat building stone surface with adhesive such as

         noted above, or approved equal. Be sure to cover the

         entire surface, filling all voids.

 

     2. While adhesive is still tacky, set stone fragment

         in place. Prevent fragment from moving until

         adhesive is fully cured.

 

     3. Clean any residual adhesive from the stone surface

         using water and stiff bristle brush. Wet stone and

         fill any chips with lime-based patching mortar of

         appropriate color, texture and composition. Tool

         surface level with surrounding stone.

 

F. For large fragments (more than 4 inches by 4 inches by 4

inches):

 

     1. Follow procedures in E.1. above.

 

     2. After adhesive has cured, anchor fragments with 1/4

         inch smooth stainless steel rods.

 

           a. Drill 1/4 inch holes at a 45 degree downward

               angle through the face of the newly set stone

               fragment. Drill holes should extend at least

 

     2 inches into the backing stone, 2 inches into

        the fragment and should allow for the rod to

        be countersunk at least 3/4 inches from the

        face of the stone.

 

             b. Space the anchor rods between 3 and 5 inches

                 apart and no less than 2 inches from any edge.

 

     3. Clean any residual adhesive from the stone surface

         using water and a stiff bristle brush. Wet stone

         and fill holes from countersunk rods with patching

         mortar. Tool surface level with surrounding stone.

 

END OF SECTION

 

Last Reviewed 2017-03-03