July 2007 – Vol. 1 No. 3 Partnering for Roadway Innovation

TERRA E-News is a quarterly electronic newsletter of the Transportation Engineering and Road Research Alliance. TERRA E-News brings you the latest research on pavement, materials, and related transportation engineering challenges, including issues related to cold climates.

Member News

Member Profile: SemMaterials

SemMaterials, a subsidiary of SemGroup, L.P., is one of the largest asphalt producers and marketers in the United States and Mexico. SemMaterials joined TERRA earlier this year for the opportunity to better understand pavement problems and to help bring new strategies and products to the pavement market.

According to SemMaterials’ Dan Wegman, an account manager and the company’s representative on the TERRA board, agency innovations offer exciting new possibilities for addressing road problems. “TERRA is a great opportunity to get exposure to the agencies,” he said, “and do it in a highly research-oriented framework with a lot of substance behind it.”

Wegman explained that roads are either fairly new and in need of preservation to keep them that way, or they are beyond preservation and need rehabilitation. With the TERRA research partnership, SemMaterials hopes to find new solutions and provide new products and materials that will give the “right fix to the right road.”

Wegman also hopes his voice on the TERRA board will allow SemMaterials to participate in the development of pavement strategies to fill gaps in road preservation and repair. “We need to add more tools to our toolbox,” he said.

In many ways, SemMaterials has already become more involved in roadway repair. For instance, Mn/DOT has used SemMaterials products in several locations. Technologies like microsurfacing and ultra-thin bonded wearing courses have been used to extend the life of pavements. In addition, SemMaterials will help with the 2008 reconstruction of the MnROAD mainline using an emulsion base-stabilization process.

Through access to TERRA research and an opportunity for testing new products in the research-oriented MnROAD facility, SemMaterials ultimately hopes to help provide the best products to local agencies. In the end, improved product quality means that roadway repair is minimized and costs are kept as low as possible.

“We are extremely grateful to have this opportunity to work with such an outstanding pavement research group and individuals associated with the TERRA organization,” Wegman said.

Member Highlights

More than 60 people attended the first two MnROAD seminars of 2007, held at the MnROAD facility near Albertville on June 12 and July 9. The events, sponsored by the Minnesota Department of Transportation (Mn/DOT) and the Concrete Paving Association of Minnesota (CPAM), in cooperation with Minnesota Local Technical Assistance Program (LTAP), included sessions on the history and performance of MnROAD, future research, and innovations in design and construction, followed by a field review and site tour of the test sections. City and county engineers, public works officials, design and consulting engineers, as well as others interested in pavements, attended.

Projects and Initiatives

TERRA featured in national TR News

A recent issue of TR News (March-April 2007, #249) (4 MB PDF) highlighted TERRA for its unique work with public and private partnerships to advance new technical capabilities, a new governance structure, and new transportation research. “The Transportation Engineering and Road Research Alliance: Partnering to Advance Pavement and Road-Related Research” (p. 3), written by founding TERRA members Richard Stehr and Fred Corrigan (TERRA co-chair), discusses the innovative relationship among TERRA stakeholders on a state, national, and international scale. The five-page feature article also outlines TERRA’s formation and activities, from the successful implementation of the alliance built around MnROAD to the most recent national and international road research. TR News, published bimonthly by the Transportation Research Board (TRB), features articles on innovative and timely research and development activities in all modes of transportation.

TERRA featured as ‘successful partnership’

TERRA participated in the 2007 Mississippi Valley Conference “People, Partners, Programs,” hosted by the Minnesota Department of Transportation (Mn/DOT), from July 9 to 11 in Minneapolis. During the second day of the conference, TERRA co-chair Fred Corrigan made a presentation about TERRA, one of four organizations highlighted in a concurrent session on successful partnerships. Mn/DOT's Ben Worel also led a lunch tour of MnROAD, one of four Minnesota transportation facilities conference attendees visited.

Conference highlights included keynote addresses by national transportation leaders, updates and perspectives on the work of the National Surface Transportation Policy and Revenue Study Commission (created by Congress in 2005 as part of SAFETEA-LU to examine the condition and future needs of the nation's surface transportation system), tours of state-of-the-art transportation facilities, and a variety of sessions on cutting-edge transportation topics.

The purpose of the annual conference is to foster the development, operation, and maintenance of an integrated and balanced transportation system to adequately meet the needs of those states whose highways serve the upper Mississippi Valley. Mississippi Valley, one of the four regional AASHTO groups, includes Illinois, Indiana, Iowa, Kansas, Kentucky, Michigan, Minnesota, Missouri, Ohio, and Wisconsin.

MnROAD Diary: An inside perspective from a premiere road research facility

Failure is just another bump in the road (or test track)
By MnROAD Forensic Engineer Tim Clyne

MnROAD pavement research

At least Cell 28 made it through the first spring. But this test cell, constructed with materials and methods typical of any low-volume road around the state, is experiencing some major failures.

Cell 28 is on MnROAD’s low-volume road (LVR) test track, a 2.5-mile closed loop with 20 test cells. Built in August 2006, Cell 28 is the control section for Cell 27, which contains a geocomposite capillary barrier drain (GCBD) to remove subsurface moisture from the pavement system. It is a pooled-fund project, TPF-5(126), from TERRA’s earliest days. The Michigan and New York DOTs have contributed funds, and the University of New Mexico and the U.S. Army Cold Regions Research & Engineering Laboratory are performing the research with the Minnesota Department of Transportation.

An April 2007 distress survey showed no visible distresses at the pavement surface. But on Friday, June 1, Doug Lindenfelser, the MnROAD LVR truck driver, noticed the beginnings of trouble. A small area—20 feet long—in the 80,000-pound-truck lane (a standard truck weight) showed signs of slippage cracking, shoving, and fatigue cracking. Doug hit it hard with the truck, putting in more than his usual 80 laps per day on Friday and the following Monday. Then, throughout the day Tuesday, the spot blew up.

Specifically, the top 2-inch lift of hot-mix asphalt (HMA) separated/delaminated from the bottom lift, and small chunks of pavement could be pulled out by hand. During construction, an HMA truck locked its breaks and skidded in this area, which may have caused microcracks on the bottom lift since day 1. Subsequent passes of the MnROAD truck easily shoved the pavement from the shoulder, back and forth across the road. Moderate rutting and major fatigue cracking also occurred.

Our forensic investigation the next week found, in simple terms, a big mess. The HMA was so soft (10 months after construction) that when removed and piled up next to the excavation, it flowed like HMA directly out of the plant. The Class 5 aggregate base and clay subgrade layers were excessively wet, partially the result of a 2-inch rainfall over the previous weekend. The subgrade was so soft, in fact, that the dynamic cone penetrometer (DCP), used to estimate the strength of subgrades, penetrated through the entire 7-inch layer with one blow. Falling weight deflectometer (FWD) testing along the entire cell showed deflections that were excessively high and also variable station-to-station.

The excavation was filled in, patched up, and made as good as new … until the next day when Doug made a new hole immediately downstream from the first one.

It seems a perfect storm of poor design and material parameters came together to cause the failures seen so far on Cell 28:

• A soft asphalt binder (PG 52-34) with no recycled asphalt pavement (RAP)
• A thin (6-inch) base layer of marginal Class 5 material (it failed gradation tests during construction)
• The inclusion of wet, sticky clay as a subgrade layer. This layer seemed to catch the water flowing downhill (east to west) from the Cell 29 base material. The water had no place to go, so it just sat there.
• Construction traffic may have caused small distresses from the beginning.

Let’s hope Cell 28 (and Cell 27, which looks much better) can hold together one more year to finish the experiment before it needs to be reconstructed.

The Minnesota Road Research Project, or MnROAD, located on Interstate 94 about 40 miles northwest of Minneapolis, is one of only a handful of research facilities where scientists and engineers can carry out long-term research on materials and construction techniques under real-world conditions, including many related to Minnesota’s climate. The MnROAD facility is a key element in TERRA's comprehensive road research strategy.

Related resources:

• E-mail MnROAD Forensic Engineer Tim Clyne
• TERRA Projects

Announcements

TERRA Innovation Series: Highway 36 open house set for Aug. 29

TERRA, in cooperation with FHWA, FHWA Highways for LIFE, and Mn/DOT, is hosting an open house at the Trunk Highway 36 (TH36) reconstruction project on August 29, 2007, 9:00 a.m. to 3:00 p.m. at the North St. Paul Community Center. The event, “Transforming Highway 36 Through Innovation,” is the first in the new TERRA Innovation Series. This open house features a work site tour led by TH36 project engineers and will showcase in-progress highway reconstruction innovations, such as complete closure and intelligent compaction. In addition, FHWA, Mn/DOT, and TERRA officials, including FHWA administrator Rick Capka (invited) and Lt. Gov. Carol Molnau, Mn/DOT commissioner (invited), will speak. Concurrent panel sessions with federal, state, and industry speakers will address TH36 project technology innovations, accelerated construction, and communications, outreach, and market research. For more information, please visit the TERRA Web site or contact Stephanie Jackson, sjackson@umn.edu, 612-624-8398.

Mid-Continent Transportation Symposium scheduled for Aug. 16 and 17

The Center for Transportation Research and Education (CTRE) at Iowa State University will host the Mid-Continent Transportation Symposium, on August 16 and 17, 2007, in Ames, Iowa. This year's theme is "Partnering to Build America’s Transportation System." Also at the conference, a representative from the TERRA board will make a presentation about TERRA's mission and activities. Details about specific sessions, presentations, and special speakers are available online. For more information about the symposium, contact Judy Thomas, CTRE at Iowa State University, phone 515-294-1866 or e-mail jathomas@iastate.edu.

TERRA Board welcomes new member representative

TERRA welcomes Roberto Ballarini, professor and new department head of civil engineering (CE) at the University of Minnesota, to the TERRA board. Ballarini succeeds John Gulliver, who served as CE department head for 10 years and had represented the department on the TERRA board. Ballarini, a leader in the field of structural engineering and solid mechanics, joined the faculty of the University of Minnesota in the fall of 2006 after more than 20 years at Case Western Reserve University in Cleveland, Ohio. His research focuses on the development and application of theoretical and experimental techniques to study the response of materials to mechanical, thermal, and environmental loads.