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Historic Preservation - Technical Procedures

Spectitle:

Removing Surface Dirt From Concrete

Procedure code:

0371015R

Source:

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

Division:

Concrete

Section:

Concrete Cleaning

Last Modified:

02/24/2012

Details:

Removing Surface Dirt From Concrete



REMOVING SURFACE DIRT 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 dirt from
         concrete using a detergent, chemical solvent or steam.

    B.   Dirt encompasses deposits of almost any material in a
         location where it's not wanted, but it usually includes
         fine, dark-colored solid particles, often surrounded by
         some kind of oily film.  It is particularly troublesome
         on architectural and decorative concrete, including
         exposed aggregate surfaces.

    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.   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.

         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).


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.   Hydrochloric Acid:

         1.   A strong corrosive irritating acid.

         2.   Other chemical or common names include Chlorhydric
              acid; Hydrogen chloride; Muriatic acid*; Marine
              acid*; Spirit of salt*; Spirit of sea salt*.

         3.   Available from chemical supply house, drugstore,
              hardware store.

    B.   Detergent:

         CAUTION:  SOME DETERGENTS CONTAIN AMMONIA AND MAY REACT
         VIGOROUSLY WITH HYDROCHLORIC ACID.

    C.   Clean, potable water

    D.   Clean white cloths or towels

2.02 EQUIPMENT

    A.   Steam cleaning equipment

    B.   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.   Brush affected area with water and strong detergent.

    B.   Rinse the area thoroughly with clean, clear water and
         blot the surface dry with clean towels.

    C.   Repeat the treatment as necessary until the desired level
         of cleanliness is achieved.

    -OR-

    A.   Mix 1 part hydrochloric acid in 19 parts water.

    B.   Scrub the concrete surface with this solution.  NOTE:
         THIS IS A STRONG METHOD AND MAY ROUGHEN THE CONCRETE.

    C.   Rinse the area thoroughly with clean, clear water, blot
         the surface dry with clean towels.

    D.   Repeat the treatment as necessary until the desired level
         of cleanliness is achieved.

    -OR-

    A.   Steam cleaning is generally effective and may be used in
         combination with proprietary materials, such as
         detergents for dirt removal.

    B.   If there is oil present in the dirt, follow the procedure
         described for removing lubricating oil, see 03710-31-R
         "Poulticing Lubricating and Petroleum Oil Stains From
         Concrete".

                         END OF SECTION