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Historic Preservation - Technical Procedures

Spectitle:

Removing Grease Stains From Concrete

Procedure code:

0371001R

Source:

Hspg Prepared For Nps - Sero

Division:

Concrete

Section:

Concrete Cleaning

Last Modified:

02/24/2012

Details:

Removing Grease Stains From Concrete



REMOVING GREASE 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 removing grease
         stains from concrete by washing with an alkaline
         compound, or poulticing with 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.

              NOTE:  SOME OF THE SOLVENTS LISTED ARE KNOWN
              CARCINOGENS AND MAY BE BANNED IN SOME STATES.

         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

    CAUTION:  THE USE OF STRONG ACIDS CAN ETCH AND DISINTEGRATE
    THE CONCRETE SURFACE.

    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 Washing:

         1.   Masonry Cleaner suitable for use on concrete:  

              a.   Adequate surfacants and emulsifiers to loosen
                   soil and to keep it in solution until rinsed
                   away

              b.   May contain the active ingredient hydrofluoric
                   acid - its reaction with soil is often a gas
                   rather than a salt

              NOTE:  INGREDIENTS WHICH PRODUCE SALT SOLUTIONS,
              SUCH AS SULFURIC ACID SHOULD NOT BE PRESENT, THOUGH
              MANY COMMERCIAL CLEANERS CONTAIN THIS INGREDIENT.

         2.   Sodium Orthophosphate:

              a.   Other chemical or common names include
                   Tribasic sodium phosphate; Trisodium
                   orthophosphate; Trisodium phosphate; TSP*;
                   Phosphate of soda*.

              b.   Potential Hazards:  CORROSIVE TO FLESH.

              c.   Available from chemical supply distributor,
                   supermarket, grocery, or hardware store.

         3.   Scouring Powder

         -OR-

         4.   Sodium Metasilicate - powder (Na2SiO3):

              a.   A toxic corrosive crystalline salt used
                   especially as a detergent or as a substitute
                   for phosphates in detergent formulations.

              b.   Other chemical or common names include sodium
                   silicate; Liquid glass; Silicate o soda;
                   Soluble glass; Water glass.

              c.   Potential Hazards:  CORROSIVE TO FLESH.

              d.   Available from chemical supply house,
                   construction specialties distributor, or
                   hardware store.

    B.   For Poulticing:  

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

              Trisodium Phosphate:

              NOTE:  THIS CHEMICAL IS BANNED IN SOME STATES SUCH
              AS CALIFORNIA.  REGULATORY INFORMATION AS WELL AS
              ALTERNATIVE OR EQUIVALENT CHEMICALS MAY BE
              REQUESTED FROM THE ENVIRONMENTAL PROTECTION AGENCY
              (EPA) REGIONAL OFFICE AND/OR THE STATE OFFICE OF
              ENVIRONMENTAL QUALITY.

              a.   Strong base-type powdered cleaning material
                   sold under brand names.

              b.   Other chemical or common names include Sodium
                   Orthophosphate; Tribasic sodium phosphate;
                   Trisodium orthophosphate; TSP*; Phosphate of
                   soda*; (also sold under brand names such as).

              c.   Potential Hazards:  CORROSIVE TO FLESH.

              d.   Available from chemical supply house, grocery
                   store or supermarket or hardware store.

              -OR-

              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.

              -OR-

              Carbon Tetrachloride (CCl4):

              a.   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.

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

              c.   Potential Hazards:  TOXIC.

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

              -OR-

              Chloroform (CHCl3):

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

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

              c.   Potential Hazards:  TOXIC.

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

              -OR-

              Mineral Spirits:

              a.   A petroleum distillate that is used especially
                   as a paint or varnish thinner.

              b.   Other chemical or common names include
                   Benzine* (not Benzene); Naphtha*; Petroleum
                   spirits*; Solvent naphtha*.

              c.   Potential Hazards:  TOXIC AND FLAMMABLE.

              d.   Safety Precautions:

                   1)   AVOID REPEATED OR PROLONGED SKIN CONTACT.

                   2)   ALWAYS wear rubber gloves when handling
                        mineral spirits.

                   3)   If any chemical is splashed onto the
                        skin, wash immediately with soap and
                        water.

              e.   Available from construction specialties
                   distributor, hardware store, paint store, or
                   printer's supply distributor.

              -OR-

              Sodium Carbonate (Na2CO3):

              a.   A sodium salt of carbonic acid used especially
                   in making soaps and chemicals, in water
                   softening, in cleaning and bleaching and in
                   photography; A hygroscopic crystalline
                   anhydrous strongly alkaline salt.

              b.   Other chemical or common names include
                   Carbonate of soda*; Sal soda*; Soda*; Soda
                   ash*; Washing soda*.

              c.   Available from chemical supply house, grocery
                   store or supermarket, hardware store, paint
                   store, or water and sanitation supply
                   distributor.

              -OR-

              Trichloroethylene (highly refined solvent):

              CAUTION:  TRICHLOROETHYLENE IS HIGHLY TOXIC AND MAY
              REACT WITH STRONG ALKALIS SUCH AS FRESH CONCRETE TO
              FORM DANGEROUS GASES.

              a.   Other chemical or common names include Ethinyl
                   trichloride.

              b.   Potential Hazards:  TOXIC.

              c.   Available from automotive supply distributor,
                   chemical supply house (both commercial and
                   scientific), dry cleaning supply distributor,
                   paint store, photographic supply distributor
                   (not camera shop), or printer's supply
                   distributor.

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

         3.   Mineral water

         4.   Clean dry towels for blotting the area after
              treatment

    C.   Clean, potable water

    D.   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.   Garden hose and pneumatic spray nozzle

    B.   Stiff bristle brushes (non-metallic)

    C.   Wood or plastic spatulas

    D.   Poulticing Materials:

         1.   Glass or ceramic container for mixing the solution

         2.   Wooden utensil for stirring the ingredients


PART 3---EXECUTION

3.01 EXAMINATION

    A.   Examine the concrete surface carefully to determine the
         cause of staining before proceeding with any cleaning
         operation.

3.02 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.

3.03 ERECTION, INSTALLATION, APPLICATION

    CAUTION:  VOLATILE, FLAMMABLE SOLVENTS SUCH AS GASOLINE SHOULD
    NOT BE USED TO CLEAN OIL OR GREASE STAINS.  THESE OFTEN CAUSE
    THE SOIL TO PENETRATE FURTHER INTO THE CONCRETE.

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

    A.   ALWAYS pre-wet the surface thoroughly before using any
         cleaning solution on a concrete surface.

    B.   Washing Grease Stains:

         NOTE:  DO NOT USE SOAP ON CONCRETE; It reacts with the
         lime in the concrete and forms a scum which will cause
         the concrete to soil more rapidly.

         1.   Using a wood or plastic spatula, scrape excess
              grease from the surface.

         2.   Scrub any remaining stain with scouring powder,
              sodium orthophosphate or detergent, following the
              manufacturer's instructions.

         -OR-

         1.   Mix about 4 oz. of sodium metasilicate powder per
              gallon of water.

         2.   Using a stiff bristle brush, scrub the stained area
              with this solution.

         3.   Thoroughly rinse the surface with clean, clear
              water and allow to dry.

    C.   Poulticing Grease Stains:

         1.   Mix whiting and trisodium phosphate to form a thick
              paste.

              -OR-

              Prepare a poultice using benzene, mineral spirits
              or one of the chlorinated solvents listed in
              Section 2.01 B.  Note Precaution in Section 3.02
              A.3. above.

         2.   Apply the paste to the stained surface in a layer
              1/8" - 1/4" thick and allow to dry.

         3.   Scrape off the dried paste with a wooden spatula.

         4.   Thoroughly rinse the surface with clean, clear
              water and allow to dry.

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

         6.   Scrub the surface again, as needed, with scouring
              powder, sodium orthophosphate, detergent or a
              proprietary cleaner formulated for the purpose.

                         END OF SECTION