This Small Business Innovation Research Phase I project addresses the problem of organic contamination on porous building materials such as concrete, stone, and related cementitious materials. Contaminants on these materials range from automotive fluids to inks to biological agents, such as fungi. This research explores a unique low-cost (~10 cents/square foot) patent-pending treatment that achieves significant photocatalytic breakdown of common organic surface contaminants over a time span of days. This durable, surface-modifying, self-cleaning nanotechnology both permanently seals pores and makes surfaces photoactive. This combined effect keeps contaminants at the surface and there breaks them down, or makes them more accessible to conventional cleaners. Treated surfaces are consequently inimical to molds - without using a biocide - and largely "take care of themselves". Our research objectives include confirming various theoretical predictions of durability and effectiveness. This project will experimentally test and optimize the following characteristics, among others: 1) speed of photocatalytic reactions, 2) effectiveness regarding organic runoff and mold infestation, 3) mechanical and photocatalytic durability, 4) pot life and 5) shelf life. Pilot research has demonstrated preliminary success on auto oil-laden roads and moldy walkways; the Phase I research will result in further confirmation of, and expanded confidence in, these preliminary data. The broader impact/commercial potential of this project is large since organic contaminants inflict hundreds of millions of dollars of damage annually in the United States alone. These damages are manifested in the form of projects delayed or cancelled due to projected organic runoff, the defacing of buildings or other surfaces, or the growth of unsightly molds, to which about 10% of the general population is allergic. Perhaps $100 million dollars is spent annually in the United States on concrete sealants that are only partially effective; a more effective sealant could create millions of dollars of new economic activity. This "green product" is easy to apply and desirable surface characteristics, such as wet traction or vapor transmission, are unchanged by its application. Others have proposed surface-membrane coatings with more-costly organic excipients that are less compatible with inorganic substrates and less durable, or are themselves susceptible to photocatalytic breakdown. This new method ensures both materials compatibility and low cost. This method also compares favorably with self-cleaning European concretes in both cost (they are ten times as expensive) and performance (i.e., the competing materials remain permeable, absorb moisture, and can draw contaminants into the subsurface where they are more challenging to address).
