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Historic Preservation - Technical Procedures

Spectitle:

Removing Chewing Gum From Concrete

Procedure code:

0371010R

Source:

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

Division:

Concrete

Section:

Concrete Cleaning

Last Modified:

02/24/2012

Details:

Removing Chewing Gum From Concrete



REMOVING CHEWING GUM 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 removing chewing gum
         and its residual staining left on concrete using freezing
         agents and chemical solvents.

    B.   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.


    C.   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).

    D.   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.   Ice

         -OR-

         Aerosol Freezing Agents

    B.   Use one of the following solvents in a poultice (see
         Section 3.02 below for related procedures):

         Denatured Alcohol:

         1.   Other chemical or common names include Methylated
              spirit*.

         2.   Potential hazards:  TOXIC AND FLAMMABLE.

         3.   Available from hardware store, paint store or
              printer's supply distributor.

         4.   Denatured alcohol, which carries no liquor tax,
              should be a satisfactory substitute for ethyl
              alcohol for stain removing purposes.

         -OR-

         Chloroform (CHCl3):

         1.   A colorless volatile heavy toxic liquid with an
              ether odor used especially as a solvent or as a
              general anesthetic.

         2.   Other chemical or common names include Methylene
              trichloride; Trichloromethane.

         3.   Potential Hazards:  TOXIC.

         4.   Available from chemical supply house, dry cleaning
              supply distributor, drugstore or pharmaceutical
              supply distributor, or paint store.

         -OR-

         Carbon Disulfide (CS2):

         1.   A colorless flammable poisonous liquid used as a
              solvent for rubber and as an insect fumigant.

         2.   Other chemical or common names include Carbon
              bisulfide*; Carbon sulfide*.

         3.   Potential Hazards:  TOXIC AND FLAMMABLE.

         4.   Available from chemical supply house, drugstore or
              pharmaceutical supply distributor, garden and lawn
              supply center, hardware store, or paint store.

         -OR-

         Carbon Tetrachloride (CCl4):

         1.   A colorless, nonflammable, toxic liquid that has an
              odor resembling chloroform and is used as a solvent
              (as in dry cleaning) and a fire extinguisher.

         2.   Other chemical or common names include
              Perchloromethane; Tetrachloromethane.

         3.   Potential Hazards:  TOXIC.

         4.   Available from chemical supply house, dry cleaning
              distributor, hardware store, paint store or
              photographic supply distributor (not camera shop).

    C.   Filler material such as whiting, diatomaceous earth or
         talc

    D.   Mineral water

    E.   Clean dry towels for blotting the area after treatment

    F.   Clean, potable water


    G.   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.   Use a manufactured freezing agent or ice to make the gum
         brittle and easier to remove.  


    B.   Scrape off as much gum as possible using a wood or
         plastic spatula.

    C.   To remove any residual staining, apply a poultice made
         with denatured alcohol, chloroform, carbon disulfide or
         carbon tetrachloride (see Section 2.01 above).

         1.   Mix whiting material from Section 2.01 with
              denatured alcohol to create a thick paste.  Select
              the amount of whiting or filler material to make a
              poultice of the required size.  Add denatured
              alcohol to obtain the proper paste-like
              consistency.

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

         3.   Apply the 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.

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

         5.   Wash the surface thoroughly with hot water
              containing sodium orthophosphate.

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

         7.   Repeat the process as necessary to sufficiently
              remove the stain.

    D.   If treatment with denatured alcohol does not sufficiently
         remove the stain, try poulticing with chloroform, carbon
         disulfide or carbon tetrachloride (follow procedures for
         Section 3.02 C.1-7. above).

                         END OF SECTION