Site accomplished both objectives with a variety of low-maintenance materials: native plants, Cor-Ten steel retaining walls, and a variable-height seat wall made with terra cotta lintels salvaged from the demolished infirmary, a design that is friendly to senior citizens, but not to skateboarders. Perhaps the most innovative solution is an entry marked by bright white pavers that incorporate a new technology called TX Active. The material, manufactured by Essroc and poured over Unilock Eco-Priora pavers, is a photocatalytic cement that reacts to sunlight and accelerates the oxidation of pollutants, rendering them as harmless salts and thereby reducing the amount of nitric oxide in the air.TX Active has the ability to be mixed with any number of materials, including concrete, paints, mortars, and precast elements and the cost is minimal considering that it can reduce pollution considerably through photo-catalyzation and is applied to the surface, rather than needing to be mixed through the entire material to be used.
Though the permeable pavers clean the air best on sunny days, on rainy days they filter rainwater back into the ground, rather than local sewers. The material is also self-cleaning—it was first used by Richard Meier on the precast concrete exterior of the Jubilee Church in Rome—and doesn’t show the black streaks usually associated with concrete buildings in cities.
The company promoting this material notes that the reaction does not consume the underlying materials, and therefore is durable. It also notes that the material can be incorporated into structures like roads and buildings, meaning that they can help reduce pollution while maintaining aesthetics.