Specification:Removing creosote stains from concrete

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=GENERAL=

SUMMARY
 This procedure includes guidance on removing creosote staining from concrete using a poultice containing benzene. Safety Precautions:  DO NOT save unused portions of stain-removal materials. DO NOT store any chemicals in unmarked containers. EXCELLENT VENTILATION MUST BE PROVIDED WHEREVER ANY SOLVENT IS USED. USE RESPIRATORS WITH SOLVENT FILTERS.

No use of organic solvents indoors should be allowed without substantial air movement. Use only spark-proof fans near operations involving flammable liquids. Provide adequate clothing and protective gear where the chemicals are indicated to be dangerous. Have available antidote and accident treatment chemicals where noted.</li> </ol> </li> See Specification:General project guidelines for general project guidelines to be reviewed along with this procedure. These guidelines cover the following sections: <ol> Safety Precautions</li> Historic Structures Precautions</li> Submittals</li> Quality Assurance</li> Delivery, Storage and Handling</li> Project/Site Conditions</li> Sequencing and Scheduling</li> General Protection (Surface and Surrounding)</li> </ol> </li> These guidelines should be reviewed prior to performing this procedure and should be followed, when applicable, along with recommendations from the State Historic Preservation Officer (SHPO). For additional information on poulticing, see 04455-02-R.</li> </ol> =PRODUCTS=

MATERIALS
<ol type="A">

Benzene (C6H6): <ol> A colorless, volatile, flammable, toxic, liquid, aromatic hydrocarbon used in organic synthesis, as a solvent and as a motor fuel.</li> Other chemical or common names include Benzol; Benzole; Phene; Phenyl hydride; Coal naphtha*; Motor benzol*.</li> Potential Hazards: FLAMMABLE.</li> Available from automotive supply distributor, chemical supply house, dry cleaning supply distributor, hardware store or paint store.</li> 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.</li> </ol> </li> <li>Filler material such as hydrated lime, talc or whiting</li> <li>Mineral water</li> <li>Clean dry towels for blotting the area after treatment</li> <li>Scouring powder</li> <li>Clean, potable water</li> </ol>

EQUIPMENT
<ol type="A"> <li>Glass or ceramic container for mixing the solution</li> <li>Wooden utensil for stirring the ingredients</li> <li>Wood or plastic spatula</li> <li>Stiff bristle brushes (non-metallic)</li> </ol> =EXECUTION=

PREPARATION
<ol type="A"> <li>Protection: <ol> <li>Provide adequate wash solutions (i.e. water, soap and towels) before starting the job.</li> <li>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.</li> </ol> </li> </ol>

ERECTION, INSTALLATION, APPLICATION
<ol type="A">

<li>Mix a poultice by selecting the quantity of hydrated lime, powdered talc or whiting needed to cover the affected area. Add Benzene and mix to form a thick paste.</li> <li>Thoroughly wet the concrete surface to be treated with clean, clear water.</li> <li>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.</li> <li>When the poultice has dried, brush or scrape it off with a wooden scraper.</li> <li>Using a stiff bristle brush, scrub the surface with scouring powder and clean water to remove any residual staining.</li> <li>Thoroughly rinse the area with clean, clear water and allow to dry.</li> <li>Repeat the process as necessary to sufficiently remove the stain.</li> </ol>