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Repairing Spalled Granite Using Epoxy Adhesive

Technical Procedures Disclaimer

Prior to inclusion in GSA’s library of procedures, documents are reviewed by one or more qualified preservation specialists for general consistency with the Secretary of Interior Standards for rehabilitating historic buildings as understood at the time the procedure is added to the library. All specifications require project-specific editing and professional judgement regarding the applicability of a procedure to a particular building, project or location. References to products and suppliers are to serve as a general guideline and do not constitute a federal endorsement or determination that a product or method is the best or most current alternative, remains available, or is compliant with current environmental regulations and safety standards. The library of procedures is intended to serve as a resource, not a substitute, for specification development by a qualified preservation professional.


We’ve reviewed these procedures for general consistency with federal standards for rehabilitating historic buildings and provide them only as a reference. Specifications should only be applied under the guidance of a qualified preservation professional who can assess the applicability of a procedure to a particular building, project or location. References to products and suppliers serve as general guidelines and do not constitute a federal endorsement nor a determination that a product or method is the best alternative or compliant with current environmental regulations and safety standards.



  1. This procedure includes guidance on repairing minor cracks and spalls in granite. This includes those smaller than 6"x6". For larger fragments, see 04465-28-R.
  2. 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. Product Data: Submit manufacturer's product literature for epoxy adhesives or resins.
  2. Samples:
    1. Submit samples of dowels for patch anchorage.
    2. Sample Stone Repair: Reattach stone fragments and patch stone at locations selected by the RHPO using methods specified. Provide one sample each material.



  1. Akemi Plastics, Inc. www.akemi.de; info@akemi.de
  2. Sika Corporation www.usa.sika.com


  1. Epoxy Based Stone Repair Adhesive, such as "Akepox" (various "Akepox" products from Akemi), "Sikadur Hi-Mod" (Sika Corporation), or approved equal.
  2. Clean, soft cloths
  3. Acetone (C3H6O):
    1. A volatile fragrant flammable liquid ketone used chiefly as a solvent and in organic synthesis.
    2. Other chemical or common names include Dimethyl ketone; Propanone
    4. Available from chemical supply house or hardware store.
  4. Clean, potable water


  1. Stiff natural bristle brush
  2. Trowel
  3. Chisel
  4. Putty knife



  1. Surface Preparation: Temporarily remove and store light fixtures, mounting brackets, conduit, signs and other building accessories to facilitate the restoration work. Reinstall all removed items.


  1. Carefully remove loose stone fragments from building. Re-use all pieces of broken stone that are in sound condition, without serious cracks or flaws.
  2. Clean any exposed metal anchors of all corrosion by scraping and brushing with stiff wire brushes.
  3. Clean surfaces to be laminated of grease and dust. Surfaces should also be dry.
  4. Mix hardener with mastic as per manufacturer's instructions.
  5. Apply adhesive evenly and completely to surfaces to be laminated. Set stone while adhesive is still tacky. Secure stone fragments in place against movement until adhesive is cured.
  6. Clean any residual adhesive from the stone with acetone.
  7. Pieces larger than 6"x6" should be further anchored with rods drilled through the fragment and into the back-up stone. See 04465-28-R.