Concrete Innovations

New products, manufacturing methods, and research are developing creative concretes to meet today’s challenges
 
Sponsored by Build with Strength, a coalition of the National Ready Mixed Concrete Association
1 AIA LU/HSW; 0.1 IACET CEU*; 1 AIBD P-CE; 1 IDCEC CEU/HSW; AAA 1 Structured Learning Hour; This course can be self-reported to the AANB, as per their CE Guidelines; AAPEI 1 Structured Learning Hour; This course can be self-reported to the AIBC, as per their CE Guidelines.; MAA 1 Structured Learning Hour; This course can be self-reported to the NLAA.; This course can be self-reported to the NSAA; NWTAA 1 Structured Learning Hour; OAA 1 Learning Hour; SAA 1 Hour of Core Learning

Learning Objectives:

  1. Explain the new technologies used in concrete manufacturing.
  2. Discover how innovative concrete products can improve project performance.
  3. Learn how to implement the latest concrete innovations in building and infrastructure projects.
  4. Demonstrate the importance of incorporating new technologies to enhance resilience and sustainability in the built environment.

This course is part of the Concrete Academy

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Geopolymer Concrete

Although we are likely years away from widespread commercialization, one of the more interesting areas of research and development is on geopolymer concrete, which uses fly ash and/or slag and chemical activators as the binder in place of portland cement. Geopolymer concrete is made by using a source of silicon and aluminum, usually fly ash or slag, and combining it with an alkaline activating solution that polymerizes these materials into molecular chains to create a hardened binder. The more common activating solutions include sodium hydroxide or potassium hydroxide, which liberates the silicon and aluminum.

Compressive strength of geopolymer concrete is comparable to portland cement concrete or higher, and strength gain is generally faster with strengths of 3,500 psi or higher at 24 hours. Compressive strengths at 28 days have shown to be 8,000 to 10,000 psi. Research shows that geopolymer concrete has lower drying shrinkage, lower heat of hydration, improved chloride permeability, and is more resistant to acids. And its fire resistance is considerably better than portland cement concrete, which is already highly fire resistant, making geopolymer concretes ideal for special high-temperature applications.

To date, most of these products have not developed beyond the research and development stage. A company called Ceratech launched geopolymer concrete in in 2002 but later closed. A product called Pyrament was launched in the 1980s but was not successfully commercialized. Some of the drawbacks include the high cost and energy to produce the chemical activator, the difficulty and safety concerns in handling a highly alkaline solution, and the need to control temperature during the curing process. In addition, building code approvals are always a hurdle. Currently the most promising applications are in severe environments, such as precast concrete bridges, or other specialty applications, such as high-acid or high-temperature environments or for rapid repair.

The key to geopolymer concrete commercialization will be to develop low-cost, easy-to-use activators. One promising development is at Rice University, where engineers have developed a geopolymer concrete that requires only a small fraction of the sodium-based activation chemicals used in other geopolymer concretes. According to the researchers, they used sophisticated statistical methods to optimize the mixing strategies for ingredients. This resulted in an optimal balance of calcium-rich fly ash, nanosilica, and calcium oxide with less than 5 percent of the traditional sodium-based activator.

Conclusion

More than 20 billion tons of concrete are produced around the world each year. As a result, concrete construction contributes about 5 percent of global CO2 emissions primarily due to the cement manufacturing process. The demand for concrete will likely continue to grow as the population grows. In addition, the demands on strength, durability, and workability will continue to increase. A combination of traditional and advanced technologies will help meet these new demands. Technologies such as TiO2 cements, SCC, SCMs, and fibers are being used now to varying degrees with outstanding results. Carbon capture and sequestration are in their infancy but show great promise. Fly ash beneficiation will help meet the demand for affordable, high performance concretes, and geopolymer concretes may one day help make concrete carbon neutral without sacrificing performance.

End Notes

1TX Active. Lehigh Hanson. Web. 29 April 2021

2Ductal. Web. 29 April 2021

3First Graphene. Web. 29 April 2021

4CarbonCure. Web. 29 April 2021

5Solidia Technologies. Web. 29 April 2021

6Blue Planet. Web. 29 April 2021

7Greener Cement. Web. 29 April 2021

Build with Strength, a coalition of the National Ready Mixed Concrete Association

Build with Strength, a coalition of the National Ready Mixed Concrete Association, educates the building and design communities and policymakers on the benefits of ready mixed concrete, and encourages its use as the building material of choice. No other material can replicate concrete’s advantages in terms of strength, durability, safety and ease of use.

 

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Originally published in May 2021


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