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).
PROJECT OUTCOMES AND FINDINGS Problem Identification This Small Business Innovations Research Phase I project addresses the problem of organic contamination on porous building materials such as concrete, stone and similar cementitious materials. Contaminants may include automotive fluids to inks to biological agents such as fungi. This research explored a unique new low-cost (~10-cent/sqft) 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." Description of Research Findings The research confirmed various theoretical predictions of durability and effectiveness. We experimentally explored and documented the following: 1) Speed of photocatalysis (demonstrated in days), 2) Significantly reduced organic runoff (reduced by a factor of three) and mold infestation (completely prevented during the six-month project), 3) Low cost (confirmed to be ~10-cent/sqft), 4) Durability – mechanical (over 1500 automobile tire passes during the six-month project), or photocatalytic (oil stains removed over a two-year span, including the six-month project), 5) Pot-Life (demonstrated to be greater than an eight hour work-day) and, 6) Shelf life (confirmed to be over six months) This research demonstrated self-cleaning on auto oil-laden roads and moldy walkways. The researched included designed experiments and substantial outdoor testing and aging that confirmed the findings above. BROADER IMPACTS AND COMMERCIAL POTENTIAL Organic contaminants inflict significant economic cost, in the hundreds of millions of dollars annually, in the United States alone. Examples: 1) Development projects delayed or cancelled due to projected organic runoff into the environment, 2) Homeowners working to clean driveways, 3) Concrete defaced with inks, 4) Concrete harboring unsightly molds; note, about 10% of the general population is allergic to these, and some are toxic. Perhaps one hundred million dollars annually are spent in the United States on concrete sealants that are only partially effective. A more-effective sealant could signal millions of dollars of new economic activity. This "Green Product" was shown to be easy to apply. Desirable surface characteristics, such as wet traction or vapor transmission, are unchanged. 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 was demonstrated to compare favorably with self-cleaning European concretes in both cost – about 1/10 – and performance – i.e., those remain permeable, retain moisture and can draw contaminants into the subsurface where they are more challenging to address. That approach also does little for existing structures, or stone. "This Project Outcomes Report for the General Public is displayed verbatim as submitted by the Principal Investigator (PI) for this award. Any opinions, findings, and conclusions or recommendations expressed in this Report are those of the PI and do not necessarily reflect the views of the National Science Foundation; NSF has not approved or endorsed its content."
