Cementitious Patch Repair Of Granite Spalls Or Failed Patches
- Procedure code:
- National Capitol Region Specifications
- Last Modified:
CEMENTITIOUS PATCH REPAIR OF GRANITE SPALLS OR FAILED PATCHES
A. This procedure includes guidance on the removal and
replacement of existing loose or deteriorated
cementitious patches. For guidance on attaching small
granite fragments using epoxy adhesive, see 04465-21-R.
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. Product Data: Submit manufacturer's product literature
for epoxy adhesives or resins.
B. Samples: Submit samples of dowels for patch anchorage.
1.04 PROJECT/SITE CONDITIONS
A. Environmental Requirements: No work in this section
shall be performed when the ambient temperature is less
than 40 degrees F and falling, or higher than 90 degrees F.
B. Existing Conditions:
1. The Contractor shall be responsible for the
protection of all adjacent materials during the
execution of the work.
2. The Contractor shall repair all damage to adjacent
materials caused by the execution of the work of
this section at no expense to the Owner.
A. Jahn Restoration Mortars
B. Sika Corporation
A. Patch dowels: Threaded rods of A.I.S.I. Type 302/304
stainless steel, sizes as required.
B. Cementitious patching material such as "M160 Granite
and Bluestone Repair Mortar" (Jahn Restoration Mortar), or approved
equal, through various vendors.
C. Clean, soft cloths
D. Clean, potable water
E. Epoxy grout: High-modulus, low viscosity, high strength
epoxy grouting/sealing/binder adhesive such as "Sikadur
35, Hi-Mod LV" (Sika Corporation), or approved equal.
A. Stiff natural bristle brushes
B. Stiff wire bristle brushes
A. Temporarily remove and store light fixtures, mounting
brackets, conduit, signs and other building accessories
to facilitate the restoration work. Reinstall all
3.02 ERECTION, INSTALLATION, APPLICATION
A. Cut back to sound stone with chisel and hammer. Score
surface to receive patch with chisel to provide a
mechanical key with patching material.
B. Thoroughly clean all stone dust and debris from areas
that are to be repaired by air and then with a soft brush
C. Clean any exposed metal anchors of all corrosion by
scraping and brushing with stiff wire brushes. Replace
any unsound anchors as necessary with new stainless steel
anchors of same approximate size and shape. Bed new
anchors in epoxy grout.
D. Pre-moisten stone with clean water and a stiff natural
bristle brush to prevent patching mortar from drying out
prematurely. Avoid over wetting stone, which inhibits
adhesion. Prepare test patches as required for approval
by the Contracting Officer's Representative to determine
the correct degree of moistening.
E. First mix the cementitious patching material well in a
dry state, then add water as per manufacturer's
instructions. Patching mortar should be shapable without
using molds and as it is being applied should hold its
shape right away. Do not mix more material than can be
used within 30 minutes.
F. Apply with trowel so that patch is slightly higher than
adjacent surfaces. Jahn repair mortar can be put on
from 3 mm to any required thickness at once. Allow to
harden for 7 days, then carefully cut back and tool to
match adjacent surfaces. Maintain mortar joints; do not
install patch across joints.
G. Keep patches damp for 72 hours after installations.
END OF SECTION