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Smart
Concrete
The Need
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Concrete has been widely used for
many years as a composite material for various types of structures. One of the weakness of
concrete is that it cannot withstand tension which can cause cracks easily. There has
been a huge demand to monitor concrete structures cracking and preventing them
from propagating further. These efforts are important for timely repair, safety and long-term
durability of critical structures. Non-destructive evaluations, such as attaching or
embedding sensors into structures, have been used in many ways to accommodate the demand,
yet the tests are considered expensive. |
The Technology
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Smart concrete was developed Dr.
Deborah D.L. Chung from State University of New York at Buffalo. Smart concrete is
reinforced by carbon fiber as much as 0.2% to 0.5% of volume to increase its sense ability
to strain or stress while still has good mechanical properties. By adding small amount of short carbon fiber into concrete with a
conventional concrete mixer, the electrical resistance of concrete increases in
response to strain or stress. As the concrete is deformed or stressed, the contact between
the fiber and cement matrix is affected, thereby affecting the volume electrical
resistivity of the concrete. Strain is detected through measurement of the electrical
resistance. So, the smart concrete has the ability to sense tiny structural flaws before
they become significant, which could be used in monitoring the internal condition of
structures and following an earthquake.
In addition, the presence of the carbon fibers also controls
the cracking so that the cracks do not propagate catastrophically, as in the case of
conventional concrete.
Some of the application of smart concrete are:
- The use of smart concrete for the purpose of weighting vehicle
on the highway. The highway made by this concrete could be able to determine where each
vehicle was, and what its weight and speed were. Vehicles could be weighed while traveling
normally on the highway.
- The use of smart concrete for real-time vibrations sensing of
bridges or other highway structures. It could also be used in buildings to dampen
vibrations or reduce earthquake damage.
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The Benefits
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- Even by adding carbon fibers, the extra cost of material will
increase about 30%, this expense is still significantly cheaper than attaching or
embedding sensors into structures.
- Smart concrete is stronger than conventional concrete by the
use of carbon fibers.
- It takes greater force for smart concrete to bend, and it
absorbs more energy before fracture.
- Monitoring can be a real-time and continuous effort.
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Status
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Dr. Deborah Chung has patented this technology
and performed several further researches and tests for potential application, such as a
lab test of the use of smart concrete for weighing moving vehicles. Several papers
regarding this technology have been published in several journals and magazines. |
Barriers
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Although this technology has been through
extensive laboratory testing, it still needs field testing and it is not yet available in
the market. |
Points of Contact
- Deborah D. L. Chung, Ph. D, Niagara Mohawk Chair
Professor of Material Engineering, Furnas Hall, Room 608, Department of
Mechanical and Aerospace Engineering, State University of New York at Buffalo, Buffalo, NY
14260-4400, Phone: (716) 645-2593 x2243, Fax: (716)
645-3875, E-mail: ddlchung@acsu.buffalo.edu
References
- "During an Earthquake, Smart Concrete
Could Fare Better Than Conventional Materials", University at Buffalo News, January
26, 1994,
- Pu-Woei Chen and D.D.L. Chung, "Carbon Fiber Reinforced
Concrete as an Intrinsically Smart Concrete for Damage Assessment During Static and
Dynamic Loading," ACI Mater. J. 93(4), 341-350 (1996).
- "Smart Concrete Would Determine Weight
of Trucks as They Travel on a Highway", University at Buffalo News, May 19, 1999,
Disclaimer Statement
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Neither the Construction
Industry Institute nor Purdue University in any way endorses this
technology or represents
that the information presented can be relied upon without further investigation. |
MA19
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