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Historic Preservation - Technical Procedures

Spectitle:

Regrouting Deteriorated Joints In Marble

Procedure code:

0445505R

Source:

Tacoma Union Station Courthouse/Tacoma, Wa - Gsa/Pbs

Division:

Masonry

Section:

Marble

Last Modified:

07/02/2012

Details:

Regrouting Deteriorated Joints In Marble



REPOINTING DETERIORATED JOINTS IN MARBLE


PART 1---GENERAL

1.01 SUMMARY

    A.   This procedure includes guidance on repointing
         deteriorated joints in marble.  

    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

    B.  American National Standard Institute (ANSI)
         www.ansi.org (use most reecent versions).


PART 2---PRODUCTS

2.01 MATERIALS

    A.   Setting Materials:  Joints should be filled to match
         existing mortar or marble color, as directed by Regional
         Historic Preservation Officer (RHPO).

         1.   Portland Cement: ANSI/ASTM C 150, Type I, except
              complying with staining requirements of ASTM C 91
              for not more than 0.03% water soluble alkali

         2.   Hydrated Lime:  ANSI/ASTM C 207, Type I

         3.   Sand:  ANSI/ASTM C 144, non-staining, except graded
              with 100% passing the No. 166 sieve for 1/4" and
              narrower joints

              a.   For white pointing mortar and grout, furnish
                   natural white sand or ground white stone
                   complying with specified requirements

              b.   For colored pointing mortar and grout, furnish
                   ground marble, granite or other sound stone,
                   meeting specified grading requirements for
                   sand, of color required to match existing
                   mortar and grout color

         4.   Clean, potable water

         5.   Dry-Set Mortar:  Factory-sanded Portland cement and
              additives complying with ANSI A 118.1, of type
              approved by mortar manufacturer and marble supplier
              for application indicated

    B.   Molding Plaster:  ANSI/ASTM C 59

    C.   Clean, potable water

2.02 EQUIPMENT

    A.   Masonry Drill

    B.   Hacksaw Blade

    C.   Chisel and mallet for removing deteriorated grout

    D.   Brushes:  Soft bristled nylon only

    E.   Hand-held Water Bottle

    F.   Steel Trowel


PART 3---EXECUTION

3.01 PREPARATION

    A.   Protection:  Prevent mortar used in repointing
         and repair work from staining face of surrounding marble
         and other surfaces.  Remove immediately mortar
         in contact with exposed marble and other surfaces.

3.02 ERECTION, INSTALLATION, APPLICATION

    A.   Carefully remove deteriorated mortar from
         joints by hand with a chisel and mallet and other hand
         tools, unless otherwise indicated and approved by RHPO.

    B.   Clean marble surfaces within raked-out joints to provide
         reveals with square backs and to expose marble for
         contact with pointing mortar.  Brush, vacuum or flush
         joints to remove dirt and loose debris.

         CAUTION:  BE CAREFUL NOT TO SPALL EDGES OF MARBLE UNITS.
         EPOXY PATCH ANY EXISTING MARBLE UNITS WHICH BECOME
         DAMAGED.  SEE 04455-03-R FOR EPOXY PATCHING PROCEDURES.

    C.   Fill joints in marble unit with new mortar of color to match
         existing mortar color or to match marble color as directed, except at
         expansion and control joints indicated to be filled with
         sealant.  Color of mortar shall be established in mock-ups.  
        Finish mortar flush with finished surface of marble, or replicate the original pointing style of         mortar.
         
    D.   Fill all gaps and skips to produce a finished joint which
         is uniform in color, smooth and without voids, pinholes,
         or low spots.

    E.   Remove mortar spillage from face of marble as work
         progresses.

    F.   Cure mortar by maintaining in a moist condition for 7
         days.

    G.   For Regrouting Stone Floors:  Do not permit traffic
         during setting of units or for at least 24 hours after
         final grouting of joints.

                         END OF SECTION
 


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