Testing Performance-Engineered Mixtures: predicting long-term performance

While concrete has traditionally been accepted based on measurements like strength, slump, and air, these measurements, in their current form, have very limited correlation to future performance, said Abbas Taghavi, Ph.D., P.E., Project Manager at Transtec. “However, recent developments in concrete testing technologies have yielded methods that are better predictors of long-term performance,” he added.

“The goal of the PEM Transportation Pooled Fund—TPF-5(368): Performance-Engineered Concrete Paving Mixtures—is to bring these newer technologies to state agencies and to assist states in the adoption of the test methods that will help them deliver on the promise of durable concrete,” said Taghavi. “It is a coalition of federal, state, and industry leaders dedicated to maximizing pavement performance.”

With advanced testing, owners, contractors, and end-users all benefit from PEM use. These benefits include:

Owners/Agencies

• Get beyond prescriptive determinants of concrete quality (e.g., slump, strength, total air content) to incorporate tests that correlate with service-life durability (e.g., resistivity, box test, unit weight, entrained air).
• Obtain quality control information to confirm the acceptance criteria (i.e., statistical approach for sampling and testing to ensure consistency of material production).
• Define desired characteristics of the product, and allow the contractor to control how to provide it, resulting in a reduced oversight burden on the agency.

Contractors

• Leverage quality control by developing updated practices incorporating the tests (e.g., resistivity, box test, unit weight, entrained air).
• Increase ability to innovate in construction techniques with minimized control restraints from the agency.
• Reduce material (cement) usage by optimizing the mix.

End Users

• Produces durable pavement that results in less maintenance/reconstruction and road closure.
• Reduces cement content, which achieves sustainability goals.
• Improves user experience (e.g., ride quality, fuel usage).

The Federal Highway Administration, 19 state departments of transportation, and four national associations representing the concrete industry have come together to fund the project, which began in October 2017 and is scheduled for completion on December 31 of this year.

This story originally appeared in the 2022 Quarter 2 edition of Concrete Pavement Progress.