Specification:Removing aluminum stains from concrete

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=GENERAL=

SUMMARY
 This procedure includes guidance on removing aluminum stains from concrete using a mixture of hydrochloric acid and water. Aluminum stains appear white on the concrete surface. 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> </ol> These guidelines should be reviewed prior to performing this procedure and should be followed, when applicable, along with recommendations from the State Historical Preservation Officer (SHPO).

=PRODUCTS=

MATERIALS
<ol type="A">

Hydrochloric acid (30-35%): <ol> A strong corrosive irritating acid.</li> Other chemical or common names include Chlorhydric acid; Hydrogen chloride; Muriatic acid* (generally available in 18 degree and 20 degree Baume solutions); Marine acid*; Spirit of salt*; Spirit of sea salt*.</li> Potential Hazards: TOXIC, CORROSIVE TO FLESH; CORROSIVE TO CONCRETE, STEEL, WOOD OR GLASS, FLAMMABLE.</li> Available from chemical supply house, drugstore or pharmaceutical supply distributor, or hardware store.</li> </ol> </li> Clean, potable water</li> Plenty of water, soap and towels for washing and rinsing in case of emergencies associated with the use of chemicals</li> </ol>

EQUIPMENT
<ol type="A"> <li>Nylon 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 solution of 1 part hydrochloric acid in 4 to 9 parts water. For colored concrete, dilute the acid with more water to avoid altering the color. Begin with 1 part acid to 19 parts water and make stronger or weaker as necessary.</li> <li>Saturate the surface with clean, clear water.</li> <li>Using a stiff bristle brush, scrub the stained area with the solution.</li> <li>Thoroughly rinse the surface with clean, clear water and allow to dry.</li> <li>Repeat as necessary to achieve the desired level of cleanliness.</li> </ol>