Sunday, June 15, 2014

2014 EPO Award nominations! Self-cleaning cement

Copyright © Françoise Herrmann

 Dreaming of cleaner city… with cleaner buildings… less pollution… The EPO award nomination disclosing self-cleaning cement may make a part of your dreams come true!
And for those living in the San Francisco Bay Area… there are patents in the New Bay Bridge’s sparkling white appearance!

Self-cleaning cement is an Italian invention based on the principles of photocatalysis, discovered in the 1970s. Photocatalysis is a light driven chemical reaction that decomposes and transforms a wide range of pollutants and contaminants into harmless or potentially beneficial matter, in particular via the chemical reaction of the sun and titanium dioxide (TiO2).  Other uses of the principles of photocatalysis using TiO2 are invoked in a wide variety of applications such as solar water purification (Salih, F, 2004); asphalt pavements for the mitigation of vehicle emissions (Hassan et. al, 2013), or micro particles in various applications intended for the oxidation of organic contaminants (Venugopal, Tezier and Tezier, 2009).
In this EPO nominated invention concerning “self-cleaning cement”, the principle of photocatalysis using TiO2 was transferred to cement (in the right proportions and after extensive experimentation in the 1990s, involving 85 patents). The cleansing and brightening effects of the reaction are mixed in with the cement which is then used for construction.
One of the first constructions using this titanium dioxide-enriched cement was the Dives in Misericordia Church in Rome, designed by American architect Richard Meier [Dives, Italicimenti]. After construction of the church, scientists discovered that the air next to the church was also cleaner, and that harmful substances in the air surrounding the church also oxidized faster. It follows then, that a photocatalytic city, that is, one where all the buildings are covered with photocatalytic titanium dioxide-enriched cement, paint or plaster, could potentially reduce the levels of harmful substances by means of the sunlight.
Adding a titanium-enriched surface to a building increases construction costs 15%, but it is also estimated that it decreases pollution by 20% in the immediate vicinity. The cement, plaint or plaster repels dirt and cleanses the air, using sunlight! This is also the reason why the New San Francisco-Oakland Bay Bridge might retain its sparkling white color, while creating a better work environment for maintenance crews, and perhaps for the Toll Plaza workers also (Hassan, 2009; Lence et. al, 2014).
The following three patents awarded to Luigi Cassar et. al and the Italian firm Italicimenti, are cited as part of the nomination of this invention:
  •  EP0946450 titled Hydraulic binder and cement compositions containing photocatalyst particles
  •   EP2242806 titled Titanium dioxide photocatalytic composites and derived products on a metakoalin support
  •   EP2282203 titled Method of measuring the photocatalytic activity of cementitious material
An mage of the Dives in Misericordia Church (Rome, Italy) built with titanium-dioxide-enriched and photocatalytic materials is included above, and to the right a detail of the sparkling San Francisco – Oakland Bay Bridge….
Now… stop dreaming… and start building a photocatalytic city!
 Hassan, M, Mohammad, L. N., Asadi, S., Dylla, H., and S. Cooperill (2013) Sustainable photocatalytic asphalt pavements for mitigation of nitrogen oxide and sulfur dioxide vehicle emissions. Journal of Materials in Civil Engineering, vol. 23 (3), 365-371.
 Hassan, M. (2009) Life cycle assessment of titanium dioxide coatings. Proceedings of the Construction Research Congress – Building a Sustainable Future, Seattle, Washington, April 5-7, 2009,  – pp. 836-845.
 Lence, A., Hassan, M. Zaylor, A and R. Rupnow (2014) Best practices for maintenance of concrete bridge elements against mold and mildew growth. Proceedings of the Construction Research Congress - Construction in a Global Network, Atlanta, GA, May 19-21, 2014. pp. 1556-1565.
 Nader, M., and B. Mahoney (2013) The New San Francisco-Oakland Bay Bridge. Proceedings of the Structures Congress 2013- Bridging your passion with your profession, in Pittsburgh, PA, May 2-4, 2013.
 Salih, F. (2004) Water purification by a combination of sunlight, titanium dioxide and alum. Proceedings of the  World Water and Environmental Congress, 2004, Salt Lake City, UT, June 27- July 1, 2004, pp. 1-9.
 Venugopal, M., Tezier, J and W. Tezier (2009) Nanotechnology: Benefits, Barriers and Impact on Construction. Proceedings of the Construction Research Congress Building a Sustainable Future, Seattle, Washington, April 5-7, 2009,  pp.447-456.

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