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Historic Preservation - Technical Procedures
Patching Spalled Concrete
National Capitol Region Specification - Agriculture Building
Patching Spalled Concrete
PATCHING SPALLED CONCRETE
A. This procedure includes guidance on patching spalls and
holes in concrete with a cementitious patching material.
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 Precaution= s
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 QUALITY ASSURANCE
A. Masonry and Concrete Repair: Prepare sample panels of
size indicated for each type of masonry material
indicated to be patched, rebuilt or replaced.
A. Sika Corporation
201 Polito Ave.
Lyndhurst, NJ 07071
B. General Polymers
C. Master Builders
A. Concrete Patching Material: One component, early strength, cementitious patching material "SikeTop 222 or
223" (Sika Corporation); "TPM 723" (General Polymers);
"Vertipatch" (Master Builders), or approved equal.
B. Water: Clean, free of oils, acids, alkalis and organic
C. Stiff bristle brushes (non-metallic)
1. Protect persons, motor vehicle= s, surrounding
surfaces of building whose masonry surfaces are
being restored, building site, and surrounding
buildings from injury resulting from masonry
2. Erect temporary protection covers over pedestrian
walkways and at points of entrance and exit for
persons and vehicles which must remain in operation
during course of masonry restoration work.
3. Contractor shall test those areaway drains, window
well drains, etc., which will be used to assure
that drains are functioni= ng properly prior to
performing masonry restor= ation operations in those
areas. The Contractor shall report immediately to
the Construction Engineer the location of drains
which are found to be stopped up or blocked.
4. Prevent grout or mortar used in repointing and
repair work from staining face of surrounding
masonry and other surface= s. Remove immediately
grout and mortar in conta= ct with exposed masonry
and other surfaces.
5. Protect sills, ledges, windows, and projections
from patching material droppings.
3.02 ERECTION, INSTALLATION, APPLICATION
A. Remove deteriorated concrete at spalls to sound material.
Grind, chisel or saw cut =AB" deep undercut around
perimeter of patch. Clean with compressed air. Thoroughly
remove any concrete showing traces of oils or grease.
B. Thoroughly wet patched area prior to casting concr= ete
patching material. If cement patching material
manufacturer recommends a different procedure, such
procedure is to be followed and executed in accordance
with published instructions and in accor= dance with
approved test patch.
C. Install cement patching material in strict accorda= nce
with manufacturer's published instructio= ns.
D. Finish surface to match surface being patched, by
grinding, troweling, sacking, or brushin= g.
A. After mortar has fully hardened, thoroughly clean exposed
masonry surfaces of excess mortar and foreign matter
using stiff nylon or bristle brushes and clean water,
spray applied at low pressure.
B. Use of metal scrapers or brushes will not be permi= tted.
C. Use of acid or alkali cleaning agents will not be
END OF SECTION