THURSDAY, FEBRUARY 1, 2024
Engineers at the U.S. Army Engineer Research and Development Center recently unveiled a new technique to help strengthen concrete against cold environments during construction.
According to a release from the ERDC, the Additive Regulated Concrete for Thermally Extreme Conditions (ARCTEC) method could allow workers to use commonly available concrete additives as alternative protection in frigid conditions.
About the Method
Fresh concrete can be severely damaged in cold temperatures by internal freezing before the right strength has developed. Additionally, the rate at which this required strength develops is slowed.
The release states that industry-standard cold weather protection measures are often laborious, expensive and time-consuming. In cold regions, more conservative approaches like active heating are reportedly the typical choice, which has subsequently caused a rise in added cost.
Because of this issue, researchers at the ERDC developed ARCTEC to allow for the use of common concrete additives as alternative freeze-protection in cold conditions. ARCTEC reportedly builds upon work performed at ERDC over the last several decades, aiming to improve user-friendliness, economy and utility of the technology.
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| U.S. Army Engineer Research and Development Center |
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Engineers at the U.S. Army Engineer Research and Development Center recently unveiled a new technique to help strengthen concrete against cold environments during construction. |
Dr. Ben Watts and Danielle Kennedy, research civil engineers at the ERDC Cold Regions Research and Engineering Laboratory (CRREL) in Hanover, New Hampshire, have reportedly been refining and adding to ARCTEC applications.
“ARCTEC addresses the problem of protecting concrete from freezing during winter construction, which normally requires energy, labor and resource-intensive measures such as heated enclosures,” Watts said. “These methods slow the pace of construction, create additional CO2 emissions, and fail to fully leverage the heat released by concrete naturally.”
A major part of ARCTEC is guidance to recommend the necessary dosage of additives for a good concrete placement. This recommendation is reportedly dependent upon multiple aspects of a placement, including geometry, mixture proportions, ambient temperature, wind and time of placement.
The number of unique cases needed for general guidance prevents physical testing of every possibility, so a temperature rise model was built to mimic the effects of placement characteristics on the evolving thermal behavior of concrete placed at several additive dosages.
Inputs for this model were reportedly received through laboratory characterization of the thermal and mechanical behavior of concrete at multiple curing temperatures and additive dosages.
When added to synthetic daily temperature profiles, variable convective boundary conditions, multiple placement geometries and constructions, and maturity-informed success criteria, these inputs reportedly caused the ability to define the additive dosage over a wide range of possible placement configurations.
“ERDC developed ARCTEC through collaborations with USACE Great Lakes and Ohio River Division, Pittsburgh District, and the Maine Army National Guard, to provide a process to quantify and regulate the natural heat release of curing concrete, combined with a methodology to evaluate the effects of changing heat release on the behavior of concrete placements in cold environments,” Kennedy said.
“The ARCTEC methodology accounts for differences in placement size and shape, mixture design and ambient temperature and provides the user with an additive dosage recommendation to protect from freezing in those conditions.”
According to the release, another benefit to using ARTEC is that it can be used in any situation where concrete construction in cold weather is required.
“In the near future, ARCTEC research is focused on the refinement of generic guidance for end users; publication of simple, standardized testing procedures for heat-release measurement; and the incorporation of ARCTEC methods into industry-standard cold-weather concrete guidance,” Watts said.
At the moment, ARCTEC is reportedly being studied for military engineering to use in extreme cold applications. Within this research area, future efforts will reportedly focus on building novel additives and extreme cold placement techniques.
ERDC states that CRREL is now in place to meet the challenges presented in some of Earth’s harshest and most austere cold environments.
“ARCTEC is a tool which enables cost and schedule savings for construction and repair of civil and military infrastructure,” Watts said. “Decades of research and collaborative partnerships went into development of ARCTEC, which we believe will be a game changer for construction in cold weather.”
Previous ERDC Research
In late 2022, the ERDC announced that its Cold Regions Research and Engineering Laboratory created three new testing facilities to test coatings to withstand and mitigate ice adhesion and corrosion. The facilities are located in Hanover, New Hampshire; Fairbanks, Alaska; and Treat Island, Maine.
“These are enduring assets that will help us understand the durability of new coatings and surface treatments to transition these technologies to protect real assets in the field,” said Dr. Emily Asenath-Smith, research materials engineer and lead of the Ice Adhesion Facility at ERDC’s CRREL.
“We’ll be tracking the weather, and we’ll have camera monitoring at each site, so researchers will have visual and meteorological data to pair with data on coating performance at each location.”
According to the release from the U.S. Army Corps of Engineers, Asenath-Smith collaborated over several years with ERDC’s Paint Technology Center of Expertise to establish the new facilities. Located in Champaign, Illinois, the Center at the Construction and Engineering Research Laboratory was led by Dr. Rebekah Wilson.
Planning for the facilities at three locations started in 2019. The first prototype rack was reportedly deployed on Treat Island located in the Bay of Fundy off the coast of Eastport, Maine, in 2021.
Asenath-Smith described this site as “unique” because it is the U.S.’s northern-most point off the Atlantic coast. Completely exposed to wave action and wind, the tide can change by 22 feet at each cycle with two cycles per day.
Additionally, the cold water gets icy in the winter, providing the opportunity for the coated test panels to be exposed to cyclic immersion in salt water, freezing and thawing conditions and solar irradiance. Asenath-Smith reported that common estimates indicated that one year on Treat Island was equivalent to six years inland.
The Army Corps reported that the second improved version, complete with weather and visual monitoring system, was installed in November 2022.
The facilities at Hanover were reportedly deployed in October of that year, while the system was erected in Fairbanks in August. The Army Corps reports that Asenath-Smith and her team already had projects slated for the next few years to take advantage of the new capabilities.
Some of the testing occurring before deploying the panels and after were related to how well the coating adheres to the metal of the panels, or how well the ice adheres to a surface after exposure. The team also reportedly has specimens from the National Institute of Standards and Technology at their Hanover site.
In Alaska, the team used samples to support a study for the Army related to the surfaces of modular, temporary bridging systems that the Army uses. The Improved Ribbon Bridge (IRB) was of particular interest, Asenath-Smith noted.
Tagged categories: Additives; Building materials; Coating Materials; concrete; Concrete coatings and treatments; Construction; Engineers; Government; Infrastructure; Infrastructure; Program/Project Management; Research; Research and development; U.S. Army; Weathering
