Stormwater runoff from the built environment, often mixed with contaminants, has a damaging effect on local and downstream ecosystems. Porous paving products and vegetated roofing systems result in less rainwater runoff and thereby reduce surface water pollution. Stormwater treatment systems reduce pollutant levels in any water that is released. Again, quantifiable benefit and a strong track record are important determinants here of “green.”
BASF’s pervious concrete is a mix of portland cement, coarse aggregate, water, and proprietary admixtures. The lack of sand or other fine aggregate creates voids of 2–8mm which allow water to filter through the material at drainage rates of 2–18 gal/min/ft2. Applications include parking lots, driveways, sidewalks, road shoulders, and other light-traffic areas. BASF adds proprietary admixtures to its pervious concrete, including polycarboxylates and nitrilotris methylene trisphosphonic acid; the MSDSs for these admixtures state they contain only mild irritants.
Concrete is an integral component of our buildings and infrastructure but production of its key ingredient, portland cement, is a major source of the world’s anthropogenic carbon dioxide emissions and can also lead to emissions other hazardous byproducts such as mercury and nitrogen oxides.
The environmental footprint and performance of concrete can be improved by replacing a portion of the portland cement with fly ash, ground granulated blast furnace slag, silica fume, rice husks, or other supplementary cementitious materials. Recycled concrete, glass, and slag can be used to reduce the impact of mining of virgin aggregate and the amount of construction material sent to landfills. Lightweight aggregate can lower the weight of the structure and some can provide thermal insulation.
Products listed by GreenSpec incorporate recycled content, have improved durability, provide insulation, or have other innovative environmental qualities.
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