Nanotechnology in Building and Construction Dr. Joannie W. Chin

30,000 ft view Why nanotechnology in building and construction? Technical barriers OPPORTUNITIES Emerging nanotechologies in building and construction

Nanostructured Materials Gaining control of materials at the nanoscale brings different laws of physics into play. Traditional materials show radically enhanced properties when engineered at the nanoscale.

Material Needs in Building and Construction Deterioration of the nation’s infrastructure: –Cost of repairs is estimated to exceed $2 trillion (NRC, ASCE). –Housing is plagued with poor material quality and excessive fire losses that have led to premature failure and annual repair costs exceeding $60 billion. Nanotechnology offers tremendous potential for improving building materials.

“The construction industry was the only industry to identify nanotechnology as a promising emerging technology in the UK Delphi Survey in the early 1990s… However, construction has lagged behind other industrial sectors, such as automotive, chemicals, electronics and biotech sectors, where nanotechnology R&D has attracted significant interest and investment from large industrial corporations and venture capitalists.” “Application of Nanotechnology in Construction”, Materials and Structures, 37, 649 (2004).

Strong industry interest in use of nanostructured materials to improve service life and flammability performance of building materials Lack of measurement science capability to predict service life and flammability performance of nanostructured materials. Measurement science research is critical to enable U.S. construction industry to innovate and respond to global competition and new environmental regulations Nanomaterials in Construction

Cement and Concrete Nano silica and clinker used to increase densification and hence mechanical properties and durability of cementitious materials. Service life can be doubled through the use of nano-additive viscosity enhancers which reduce diffusion of harmful agents in concrete (patent pending). Photocatalytic TiO 2 added to concrete to reduce carbon monoxide and NO x emissions on roadways.

Carbon Nanotubes Heralded as one of the “Top ten advances in materials science” over the last 50 years, Materials Today, Sales of carbon nanotubes projected to exceed $2B, >10 3 metric tons annually in the next years. Major use – electronics and composites. Enhanced strength, stiffness and toughness without added weight Improved durability Increased functionality Reduced flammability

Carbon Nanotubes Probes for microscopy and chemical imaging

Coatings - Organic Projected to make up 73 % of nanocomposites market by 2010 (Freedonia Group). Thin film, clear nanocomposites for improved scratch and mar properties. Antimicrobial, self-cleaning surfaces. Smart coatings: Sense pressure, impact, damage, chemicals, heat, light, etc.

Coatings - Inorganic Self-cleaning glass Nano-TiO 2 coated glass transparent TiO 2 conventional glass self-cleaning glass

Photovoltaics Predominant photovoltaic material is silicon, but an emerging technology involves the use of dye-sensitized nano- TiO 2. Large surface area of nano TiO 2 greatly increases photovoltaic efficiency. Also has potential for lower material and processing costs relative to conventional solar cells.

Nanoadditive Fire Retardants Use of nanoadditive fire retardants prompted by bans on halogenated flame retardants enacted in many states. Polymer nanocomposites filled with clay, CNTs, etc., possess improved flammability resistance while maintaining or improving mechanical properties. Reduces heat release rate during fire event by formation of surface char which insulates underlying material. Poor Dispersion Good Dispersion Heat Flux

Challenges Techniques for dispersing nanofillers AND measuring degree of dispersion. Measurement of adhesion and interfacial properties. Chemical and mechanical measurements at the nanoscale. Prediction of nanocomposite properties and service life over a wide range of length scales. Unknown health and environmental effects – virgin, released material.

Opportunities Concrete with 2x service life – Dale Bentz, Functionalized carbon nanotubes for nanocomposites and chemical probes – Tinh Nguyen, Nano fire retardants – Jeff Gilman, General inquiries – Joannie Chin,