Associate Teaching Professor Chris Senseney was interviewed by Denver7 about the state of bridges in Colorado. Senseney noted that much of our infrastructure in the state and across the United States was built in the 50s and 60s.

 "We're at the point where a lot of bridges are at the end of their useful life," Senseney said. 

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Associate Teaching Professor Chris Senseney recently had a published in "Environmental Research: Infrastructure and Sustainability." The paper,"Recommendations for cradle-to-gate environmental product declarations (EPD) in 'Buy Clean' procurement based on CDOT's experience," is one of the first papers of its kind to discuss green public procurement of construction materials in the United States, Senseney says.

The paper discusses how environmental product declarations (EPDs) work and gives an example from the Colorado Department of Transportation. It also gives advice on how to deal with problems when using EPDs. The goal is to help the government make good choices for the environment when buying materials and to make it easier for them to do it.

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Each time Mija Hubler drives through Denver, she notices bridges patched with concrete and thinks about how these structures might fail.

Hubler, an associate professor in CU Boulder’s Department of Civil, Environmental and Architectural Engineering, envisions a future where concrete cracks are repaired deep within to prevent such failures. She and her team of CU Boulder researchers and partners are developing technology that infuses concrete with self-repair capabilities found in living organisms. 

“Bridges are just patched again and again,” Hubler says. “My dream is to extend the structures’ lifetime by integrating this technology into new and aging construction.”

The project, "Reinforced Concrete Repair by an Evolving Visualized Internal Vascular Ecosystem (RC-REVIVE)" research team, has landed a $10 million grant from the Defense Advanced Research Projects Agency (DARPA) Biorestoration of Aged Concrete (BRACE) program, which draws inspiration from networks of filamentous fungi and human vascular systems. 

The idea is that networks of cracks in concrete can naturally provide a pathway to facilitate internal healing, similar to the veins in human bodies. Creating a biological network within a structure will allow the team to introduce nutrients and organisms for concrete self-repair.

Led by Hubler, the research team includes Associate Professor Wil Srubar, Associate Teaching Professor Chris Senseney and Assistant Professor Srikanth Madabhushi as well as four researchers from Drexel University and North Carolina State University.

Leveraging cracked networks to extend a concrete structure’s lifespan has never been done before, Hubler says. The team’s approach has the potential to transform the maintenance and durability of concrete structures, reducing long-term repair costs, she adds.

The project’s immediate goal is to enhance the longevity of Department of Defense structures and airfield pavements. If successful, the project will not only prevent new damage, but also shorten repair time, reduce maintenance costs and extend the life of infrastructure. 

The 4.5-year research effort consists of a strategic track, focusing on long-term solutions for large, heavy structures such as missile silos and naval piers, and a tactical track for improving rapid airfield damage repair.

Susan Glairon sat down with principal investigator Associate Professor Mija Hubler to find out more about the project.                                                                                                                                                                                                                                
Why is this project important to you?
I have been studying the long term deterioration of large reinforced concrete structures since I was a graduate student. Reinforced concrete structures not only cost dollars, but also lives, because they fall apart much earlier than expected.

This project combines my work developing new living materials for structural applications with my extensive background in studying the deterioration of existing reinforced concrete structures. It’s an exciting project because it merges those two areas.

What’s different about this project?
Compared to other projects I've worked on that utilized bio approaches for engineering applications, this project specifically focuses on vascularization. We draw inspiration from the idea that concrete crack networks naturally provide a pathway, similar to the veins in our bodies. By creating a biological pathway within the structure, we can introduce nutrients and organisms, enabling self-repair capabilities. 

The bacteria will repair cracks through mineral deposition.

Why is the proposed method a better way to repair concrete?
Currently we repair concrete after the damage has reached the surface, but typically the damage begins subsurface. Patching the broken surface is not actually repairing the system. Our method addresses the damage from within, allowing more effective and lasting repairs.

Why are you looking at a bio solution?
Researchers across all disciplines of engineering are realizing the importance of collaborations with biology and bioengineering. In this project, we're exploring a combination of organisms that are either available in the wild or engineered to fulfill a specific purpose. 

How do  these organisms survive?
It depends on which organism. For a photosynthetic organism, light may be sufficient. For non-photosynthetic organisms, additional stimulants can be incorporated into the material to encourage them to grow or respond. You can also promote the growth of certain organisms with an electric field through a current applied to the system. 

How many years might an organism be able to make repairs?
It depends on the organism. We are putting these organisms in an environment they don't like to live in. Concrete is not an ideal habitat for any organism, so we plan to engineer coating and other technologies to help the organisms live longer. Additionally, we might need to periodically check on the vascular system and provide it with additional nutrients to support the organism’s existence. Our approach shifts the focus from yearly surface repairs to monitoring the health of the vascular network.

Is the research focused on repairing existing concrete or is it to prevent cracks in new concrete as well?
The first two years of the project primarily focuses on developing a bio-based repair technique. After this initial stage, the team will explore two potential applications. One application involves the underground repair of aged, reinforced concrete, including filling existing cracks, and mitigating corrosion from rebars. The other application focuses on repairing extensively damaged airfields, which is different because when an airfield is damaged, it results in regions of missing material. So our technology will need to be incorporated into a new repair material that resembles fresh concrete. We have design metrics aimed at determining the capacity of repaired sections to accommodate aircraft landings. CU Boulder is leading both applications. 

How will you assess the longevity of internal repairs?
We will assess the mechanical and chemical condition of the concrete along with the effectiveness of the biological repair system. That information will be used by our modeling experts to develop a numerical model that predicts the structure’s lifetime.

Will this technology be used just for military applications, or will the research be used to improve civilian roads and bridges?
While DARPA projects are often inspired by military needs, most technologies initially developed for one purpose may be used for other purposes as well. Although the project intends to address an array of challenges faced by the military, the resulting product could be utilized for civilian infrastructure as well.  

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Associate Teaching Professor Christopher Senseney received the 2023 American Society of Civil Engineers Region 7 Outstanding Faculty Advisor award.

"It’s a great honor, and nice to know that the students nominated me, he said.

Outstanding Faculty Awards are given each year by ASCE's committee on student members to faculty advisors who have demonstrated outstanding leadership and support to their ASCE student chapter. ASCE will honor Senseney at a local meeting on Sept. 28.  

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Christopher Senseney spoke to the Denver Post in a new article focusing on cost pressures for the I-70 Floyd Hill project.

Senseney, an associate teaching professor in the Department of Civil, Environmental and Architectural Engineering, is an expert on construction engineering and project delivery.

The I-70 project, slated to cost at least $700 million, is designed to tackle bottlenecks on the interstate in the mountains west of Denver. Rising inflation, supply chain disruptions, and labor shortages are driving concerns that costs could grow. A new "rough estimate" by the project contractor pegged the cost at $800 million.

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The safety of travelers through Glenwood Canyon on Interstate 70 will require innovative solutions to deal with the power of water and gravity for the foreseeable future.

When the highway was built, sections were elevated on pylons to pass water, as well as to provide animals with access to the river underneath the roadway. But not at Blue Gulch, where the worst of the damage from the July 31 and Aug. 1 torrential rainstorms that caused mud and rocks, some the size of small cars, to come cascading down the gulch from 1,800 feet above.

While there are options for mitigation of mudslides like this, they all will be very costly, says Chris Senseney, professor of civil engineering at the University of Colorado.

“One of them is to construct openings under the roadway so that the debris could potentially flow under the road through a culvert or something like that," he said. “Another option that I've heard of is to construct some kind of basin the debris could flow into and be collected. Whenever that happens, you could get crews up there to remove that debris and maintain that area.”

There might be room for catchment basins high up in Blue Gulch, but getting equipment up there to build and maintain them would require building a road to get there, and that’s not a likely option given the rugged, steep terrain.

“I guess a third would be something like you see in some really bad avalanche areas where you have a shed that carries debris over the roadway,” Senseney said.

None of these possible engineering solutions will be in place any time soon, he said.

“I think that the moral to the story is there is no quick fix to this problem.”

Engineering a reliever and bypass route is no less daunting and probably about as expensive.

Cottonwood Pass between Gypsum and Glenwood Springs has become a popular bypass for locals commuting from the Eagle area to and from jobs in the Roaring Fork Valley.

Cottonwood Pass is not as rugged as other forest roads in the mountains that bypass the canyon, but Garfield County Sheriff Joe Vallario is adamant that tourists and people unfamiliar with the area not try to use it as an alternative to the approved northern detour, especially not semi-trucks with trailers. To prevent truckers from trying, Eagle and Garfield counties have stationed workers at each end of the pass road to stop oversized vehicles from attempting it.

Cottonwood Pass is a steep, narrow gravel road with sharp curves that is unsuitable for large trucks, motorhomes and RV trailers. Besides the grade and width, there are sections that are completely impassible when wet due to extremely slippery mud.

GLENWOOD, COLORADO - AUGUST 5: Recent mudslides have I-70 in Glenwood Canyon closed on August 5, 2021 in Glenwood, Colorado. (Photo by RJ Sangosti/The Denver Post) RJ Sangosti

Improving the pass as a usable bypass option for Glenwood Canyon has been discussed for decades. Cost is the major obstacle. Garfield County Commissioner Tom Jankovsky said, “There would have to be federal funding for that. It’s in excess of probably $50 million. I don’t think we can get it to the point where semis can travel over it, but I do think we can get it to the point where it can be a two-lane country road that could handle some of the traffic from I-70.”

Senseney said, “They need land on both sides of the road in order to widen it. They don't own that land. So, the one big issue is obtaining the right of way.”

Most of the route passes through private property, and in the past, proposals to widen and pave the road have been met with stiff opposition from residents along the route, as well as community members in Glenwood Springs. However, the state can acquire the necessary right of way using the power of eminent domain if landowners balk at the project.

Gov. Jared Polis included a request for $10 million to study upgrading Cottonwood Pass in a letter to the Federal Highway Administration on Monday as part of a $116 million disaster assistance program request to get I-70 back open and mitigate future mudslides.

"Further, the ongoing vulnerability due to the severe erosion described above will likely require improvements to diversion routes such as Cottonwood Pass to be able to withstand heavier traffic in the future while providing resiliency," the letter states. "Prior estimates concluded that improvements to Cottonwood Pass are upwards of $50 million ... subject to further assessment which could increase this number."

The Federal Highway Administration responded Tuesday to the request, one business day later, with a grant of $11.6 million under its quick-release process, 10% of the total Polis requested.

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