Developing materials for more resilient concrete pavements

Like other phase-change materials, the substance his team is working with is especially effective at absorbing and releasing thermal energy. It means that over a wide range of temperature variations, it can store significantly more heat per unit of volume than water, rock or masonry.

That ability makes this phase-change material a good choice for mixing with concrete to boost its resistance to crack-inducing stresses. For instance, in hot weather the material can absorb much of the heat, thus protecting the concrete from a level of heat that can trigger fracturing.

“The important thing is to have a material that helps concrete pavements cope with different kinds of stresses put on it,” Neithalath said. “You need materials that can melt or solidify in response to varying environmental conditions without weakening the structural integrity of the pavement.”

Goal is to optimize durability
Beyond how well the phase-change material performs in that particular fashion, his team needs to answer other big questions.

What changes in the road design and construction techniques are necessary to optimize the use of the crack-reducing phase-change materials?

What are the most effective ways to embed phase-change material into vast amounts of concrete?

Can the new system provide enough durability to justify additional costs?

How can this phase-change material be safely disposed of when the new road pavements are eventually replaced?

In addition, it will likely be necessary to devise strategies for use of the material on bridge decks that are different than how the material would be used in pavements for roadways built on solid ground.

Finding answers “will require us to more fully understand the properties of the material and how it will behave in a range of situations,” said Neithalath, who is also on the faculty of the graduate studies program in materials science and engineering.

Components for progress in place
ASU notes that fellow ASU civil engineers on the project team, Subramaniam Rajan and Mikhail Chester, will apply their specific expertise to aid Neithalath in pursuit of answers and solutions.

Professor Rajan will provide computer modeling to validate results of extensive experiments with the material.

Assistant professor Chester will perform cost-benefit analysis as well as life-cycle analysis of the new pavement material — a major step in predicting how it will measure up to sustainability expectations.

The project will also provide opportunities for a number of ASU post-doctoral lab assistants and engineering graduate students to get valuable research experience.

“We will have good research teams at each of the institutions in different countries that are partners in this project. We have experts for every component of what we need to accomplish our goal,” Neithalath said. “I think we can take concrete pavements to the next level.”