6. Environmental Considerations . 



a. Corrosive and Pollutant Attacks on Exposed Surfaces . 



(1) Bituminous Asphalt . Bituminous asphalt is stable in the 

 presence of nearly all chemically-laden substances; however, because asphalt 

 is refined from petroleum-based products, exposure to petroleum solvents 

 will cause deterioration and disintegration of asphalt. It is normally 

 unaffected by usual concentrations (less than 1 normal) of acids, salts and 

 other waste materials. 



(.2) Preplaced Aggregate Concrete . Preplaced aggregate concrete, 

 like Portland cement concrete, is rarely attacked by solid, dry chemicals. 

 Corrosive chemicals must be in some minimum concentration and usually are 

 sulfates or acids. Also organic acids such as acetic, formic, and lactic 

 can be quite destructive to preplaced aggregate concrete. 



(3) Portland Cement Grout . This grout is attacked by the same 

 chemicals as Portland cement concrete; however, if the grout is not of equal 

 density as concrete then the chemical attack may be more aggressive. 



(4) Soil Cement . Soil cement in its normal use is not attacked by 

 most chemicals except for natural occurring sulfates such as sodium, potas- 

 sium, and calcium. 



(5) Sulfur Cement and Grout . Sulfur cement and grout are not 

 generally affected by pollutants in the coastal or marine environment and 

 they can tolerate chloride and sulfate- containing aggregates. They are 

 highly resistant to the corrosive effects of saltwater (The Sulphur 

 Institute, 1979). 



b. Sunlight Exposure Effects . 



(1) Bituminous Concrete . Bituminous concrete weathers only at the 

 surface when exposed to sunlight and air. The weathering results in the 

 very slow evaporation of solvents near the exposed surface, but because of 

 the impermeability of asphalt the solvent loss is very slow. 



(2) Preplaced Aggregate Concrete . This concrete is not affected by 

 sunlight when properly protected from evaporation of mixing water during the 

 curing period. 



(3) Portland Cement Grout . This grout is not affected by sunlight. 



(4) Soil Cement . Soil cement is not affected by sunlight. 



(5) Sulfur Cement Concrete and Grout . Sulfur cement concrete and 

 grout does not appear to be affected by sunlight; however, being a relatively 

 recent material development, experience is limited. 



c. Water Penetration Effects . 



(1) Bituminous Concrete . This concrete is highly resistant to 

 water penetration because of the impermeability of asphalt. Formulations 



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