When we think about concrete masonry products' sustainable features, durability, thermal mass, and recycled content come to mind. But pollution control is usually not on the list. With advances in cement technology, concrete products have reached an even greater green potential: staying clean and actually improving air quality.
Italcementi Group has been producing photo-catalytic cement in Europe for a decade. Now Essroc, Italcementi's U.S. subsidiary based in Nazareth, Pa., is making a name for the TX Active brand cement in North America.
TX Active includes two formulations. Self-cleaning TX Arca allows concrete to resist most environmental pollutants that gather on the surface and cause discoloration. TX Aria is also self-cleaning, and actually eliminates significant amounts of pollution from the air, including nitrogen oxide, sulfur oxide, and carbon monoxide.
When UV rays in sunlight contact concrete made with TX Active cement, they accelerate the natural oxidation process that decomposes organic and inorganic pollutants. This photocatalytic process keeps the pollutants from accumulating on the concrete's surface.
The environmental benefits vary. TX Arca attacks soot, grime, mold, mildew, bacteria, and other allergens. This keeps concrete structures clean and eliminates the need for chemical cleaning solutions. TX Aria goes further by actually decreasing harmful air pollution.
The owners of MGA Cast Stone, based in New Gloucester, Maine, were intrigued by the product and followed its development in Europe. When Essroc began producing TX Active in the U.S., the architectural precast and cast stone producer was one of the first American precast producers to adopt it. MGA become certified to use the photocatalytic cement by producing TX Active test panels, which Essroc inspected and approved.
The producer is spreading the word about the product's benefits by showing architects and owners what it can do. One of MGA's most effective demonstrations is to stain a TX Active precast sample with coffee and place it in the sun where it will clean itself within a matter of hours. (Depending on sunlight exposure, the concrete can be noticeably cleaner within six hours, and completely clean within 24 hours.)
Greg Hamann, MGA vice president, admits some specifiers are hesitant about the product's cost, which ranges about 15-20% more than conventional cement. “In the grand scheme of things, it's not a big difference, especially when you consider that buildings with these panels will always maintain their look,” says Hamann. He estimates TX Active cast stone panels pay for themselves within three years, compared with the cleaning costs over a building's lifetime.
Cast stone with TX Active is significant for restoration contractors, especially in polluted cities where buildings age more quickly. “In a full-replacement restoration job the product will represent the original look of a building, and it will never look old again,” Hamann says.
The new product could also give masonry contractors a competitive edge for bidding green projects. If masons understand the benefits of environmentally friendly products such as TX Active cast stone, they can be an important resource for owners or architects. “Even if a mason comes in with a high bid, he can offer more value by using a greener product,” Hamann says.
TX Active cement can help a project earn LEED credits in the categories of Sustainable Sites, Energy and Atmosphere, Materials and Resources, and Innovation in Design, the manufacturer says.