# Presentation: 693003

## Nanotechnology in Building and Construction

*Dr. Joannie W. Chin*

## 30,000 ft view

**30,000 ft view**

## 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).

## Nanomaterials in Construction

**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*, 2008.
- Sales of carbon nanotubes projected to
-    exceed $2B, >103 metric tons annually in the next 4 - 7 years.
- Major use – electronics and _composites_.

## 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 TiO2

- conventional
- glass

- self-cleaning
- glass

## Photovoltaics

- Predominant photovoltaic material is silicon, but an emerging technology involves the use of dye-sensitized nano-TiO2.
- Large surface area of nano TiO2 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

- 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, dale.bentz@nist.gov
- Functionalized carbon nanotubes for nanocomposites and chemical probes –        Tinh Nguyen, tinh.nguyen@Nist.gov
- Nano fire retardants – Jeff Gilman, _jeffrey.gilman@Nist.gov_
- General inquiries – Joannie Chin, joannie.chin@nist.gov, 301 975 6815