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Historic Preservation - Technical Procedures

Spectitle:

Poulticing Curing Compound Stains From Concrete

Procedure code:

0371014R

Source:

Hstrc Concrete: Investigation & Rpr/Pre-Conf Training - 1989

Division:

Concrete

Section:

Concrete Cleaning

Last Modified:

02/24/2012

Details:

Poulticing Curing Compound Stains From Concrete



POULTICING CURING COMPOUND STAINS FROM CONCRETE


THE CLEANING OR REMOVAL OF STAINS FROM CONCRETE MAY INVOLVE THE
USE OF LIQUIDS, DETERGENTS OR SOLVENTS WHICH MAY RUN OFF ON
ADJACENT MATERIAL, DISCOLOR THE CONCRETE OR DRIVE THE STAINS DEEPER
INTO POROUS CONCRETE.  USE THE PRODUCTS AND TECHNIQUES DESCRIBED
HERE ONLY FOR THE COMBINATIONS OF DIRT/STAIN AND CONCRETE SPECIFIED.


PART 1---GENERAL

1.01 SUMMARY

    A.   This procedure includes guidance on poulticing stains on
         concrete resulting from curing compounds.

    B.   Curing compounds often disappear from concrete with the
         effects of natural weathering.  However, if this is not
         aesthetically acceptable, chemical agents may be used to
         assist in stain removal.

    C.   Safety Precautions:

         1.   DO NOT save unused portions of stain-removal
              materials.

         2.   DO NOT store any chemicals in unmarked containers.

         3.   EXCELLENT VENTILATION MUST BE PROVIDED WHEREVER ANY
              SOLVENT IS USED.  USE RESPIRATORS WITH SOLVENT
              FILTERS.

         4.   No use of organic solvents indoors should be
              allowed without substantial air movement.  Use only
              spark-proof fans near operations involving
              flammable liquids.

         5.   Provide adequate clothing and protective gear where
              the chemicals are indicated to be dangerous.

         6.   Have available antidote and accident treatment
              chemicals where noted.

    D.   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).

    E.   For additional information on poulticing, see 04455-02-R.


PART 2---PRODUCTS

2.01 MATERIALS

    NOTE:  Chemical products are sometimes sold under a common
    name.  This usually means that the substance is not as pure as
    the same chemical sold under its chemical name.  The grade of
    purity of common name substances, however, is usually adequate
    for stain removal work, and these products should be purchased
    when available, as they tend to be less expensive.  Common
    names are indicated below by an asterisk (*).

    A.   For Curing Compounds Made of Sodium Silicate:

         1.   Scouring Powder or detergent

    B.   For Curing Compounds Based on Wax, Resin or Chlorinated
         Rubber:

         1.   Benzene (C6H6):

              a.   A colorless, volatile, flammable, toxic,
                   liquid, aromatic hydrocarbon used in organic
                   synthesis, as a solvent and as a motor fuel.

              b.   Other chemical or common names include Benzol;
                   Benzole; Phene; Phenyl hydride; Coal naphtha*;
                   Motor benzol*.

              c.   Potential Hazards:  FLAMMABLE.

              d.   Available from automotive supply distributor,
                   chemical supply house, dry cleaning supply
                   distributor, hardware store or paint store.

              e.   Benzene and benzine should not be confused.
                   Benzene is a distinct chemical compound
                   obtained from coal tar.  Benzine is a mixture
                   of aromatic hydrocarbons of similar boiling
                   points derived from petroleum.

         2.   Ethylene Chloride (C2H5Cl):

              a.   A colorless pungent flammable gaseous or
                   volatile liquid used especially as a local
                   surface anesthetic.

              b.   Other chemical or common names include 1,2-dichlorethane;
                    Ethylene dichloride; Glycol dichloride.

              c.   Potential Hazards:  TOXIC AND FLAMMABLE.

              d.   Available from automotive supply distributor,
                   dry cleaning supply distributor, or paint
                   store.

         3.   Methyl Acetone:

              a.   A mixture of various proportions of acetone
                   (47 to 51%), methyl acetate (27.5 to 31%) and
                   methyl alcohol (20 to 25%).

              b.   Potential Hazards:  FLAMMABLE.

              c.   Available from chemical supply house, paint
                   store, or photographic supply distributor (not
                   camera shop).

         4.   Filler material such as diatomaceous earth or talc

         5.   Mineral water

    C.   Clean dry towels for blotting the area after treatment

    D.   Clean, potable water

    E.   Accessible source of water, soap and towels for washing
         and rinsing in case of emergencies associated with the
         use of chemicals

2.02 EQUIPMENT

    A.   For Poulticing:

         1.   Glass or ceramic container for mixing the solution

         2.   Wooden utensil for stirring the ingredients

    B.   Wood or plastic spatula

    C.   Stiff bristle brushes (non-metallic)


PART 3---EXECUTION

3.01 PREPARATION

    A.   Protection:

         1.   Provide adequate wash solutions (i.e. water, soap
              and towels) before starting the job.

         2.   Whenever acid is used, the surface should be
              thoroughly rinsed with water as soon as its action
              has been adequate.  Otherwise it will continue
              etching the concrete even though the stain is gone.

3.02 ERECTION, INSTALLATION, APPLICATION

    NOTE:  DO NOT TRY MORE THAN ONE TREATMENT ON A GIVEN AREA
    UNLESS THE CHEMICALS USED FROM PRIOR TREATMENT HAVE BEEN
    WASHED AWAY.

    A.   For Curing Compounds Made of Sodium Silicate:  Remove by
         scrubbing vigorously with clear water and scouring
         powder.

    B.   For Curing Compounds Based on Wax, Resin or Chlorinated
         Rubber:  

         1.   Mix together 10 parts methyl acetone, 25 parts
              benzene and 18 parts ethylene chloride.  Mix with
              the whiting or filler material to achieve the
              desired consistency and quantity of poultice.

         2.   Thoroughly wet the concrete surface to be treated
              with clean, clear water.

         3.   Apply the poultice mixture to the stained area
              using a wood or plastic spatula and allow to dry.
              Be sure to spread the poultice well beyond the
              stained area.  The liquid portion of the paste will
              migrates into the concrete where it will dissolve
              some of the staining material.  Then the liquid
              will gradually move back beyond the concrete
              surface and into the poultice, where it will
              evaporate, leaving the dissolved staining material
              in the poultice.  Leave the poultice in place for
              30 to 50 minutes.

         4.   When the poultice has dried, brush or scrape it off
              with a wooden scraper.

         5.   Using a stiff bristle brush, scrub the surface with
              a detergent and clean water to remove any residual
              staining.

         6.   Thoroughly rinse the area with clean, clear water
              and allow to dry.

         7.   Repeat the process as necessary to achieve the
              desired level of cleanliness.

         8.   If the stains are old, it may be very difficult to
              completely remove them.  It will be important to
              determine how clean the area must be, because
              sandblasting or light grinding may be the only way
              to remove old stains.

                         END OF SECTION