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Historic Preservation - Technical Procedures

Spectitle:

Patching Spalled Concrete

Procedure code:

0373204R

Source:

National Capitol Region Specification - Agriculture Building

Division:

Concrete

Section:

Concrete Repair

Last Modified:

02/24/2012

Details:

Patching Spalled Concrete



PATCHING SPALLED CONCRETE


PART 1---GENERAL

1.01 SUMMARY

    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

         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 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.


PART 2---PRODUCTS

2.01 MANUFACTURERS

    A.   Sika Corporation
         201 Polito Ave.
         Lyndhurst, NJ  07071
         201/933-8800

    B.   General Polymers

    C.   Master Builders

2.02 MATERIALS

    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
         matter.

2.03 EQUIPMENT

    A.   Trowels

    B.   Chisels

    C.   Stiff bristle brushes (non-metallic)


PART 3---EXECUTION

3.01 PREPARATION

    A.   Protection:

         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
              restoration work.

         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.

3.03 ADJUSTING/CLEANING

    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
         permitted.

                         END OF SECTION