The skyrocketing cost of petroleum — and by extension, asphalt — is only one of several megatrends that will impact how you do business in the coming year.

by , Contributing Editor

IRVM: New Path for Agencies

Integrated Roadside Vegetation Management is a new paradigm for road agencies charged with maintaining safe roadsides, and was identified in 2005 in NCHRP Synthesis 341, Integrated Roadside Vegetation Management: A Synthesis of Highway Practice, by longtime state vegetation manager and consultant, Bob Berger.

A report on IRVM will also appear in our January issue.

Olympia-based Berger — a founder of the National Roadside Vegetation Management Association — surveys state programs, reviews current literature, finds common practice and contradictions, and elaborates best practice guidelines for the 21st century.

“Poor roadside vegetation management practices have ranged from blatant neglect to routine blanket applications of herbicides,” Berger says. “Roadside vegetation managers for public road systems have recognized the need to better manage the plant communities that will meet identified goals. Just as the highway system serves as a transportation link for movement of people and materials, roadsides serve as a transportation link for the spread of invasive weeds.”

The Texas DOT uses spraying to maintain the initial vegetation-free zone along the road in its Integrated Vegetation Roadside Management program.

The literature review conducted for this synthesis identified the lack of a uniform definition of IRVM,  or the more inclusive term, integrated pest management, Berger says. However, most IRVM definitions identified a decision-making process that integrates the needs of local communities and highway users, knowledge of plant ecology and natural processes, design, construction and maintenance considerations, monitoring and evaluation procedures, government statutes and regulations, and available technologies.

“Alongside these elements are cultural, biological, mechanical, and chemical control methods to economically manage roadsides for safety plus environmental as well as visual quality,” Berger says. Now, investigations into how roadside vegetation affects the integrity and life of the highway infrastructure, specifically pavements, are needed, he adds. The creation of a task force for developing a national database on costs for various types of vegetation management activities could improve the projections of economic impacts among methods of control.

“Also, the creation of a task force for developing a database on assigned dollar values for the benefits of environmentally sensitive methods of managing vegetation would be helpful,” Berger says. “Roadside managers could be assisted in justifying the use of the more costly methods of vegetation management in environmentally sensitive areas.”

Berger’s NCHRP synthesis is available off the Internet in .pdf format; access it at http://gulliver.trb.org/publications/nchrp/nchrp_syn_341.pdf .

A year ago when we reviewed trends to watch in 2005, we discussed the high oil prices of 2004 — petroleum peaking at $55 per barrel — and how it would impact the price of asphalt (see Paths to Progress, 2005: Petroleum Through Roof).

That all sounds naive now, as earlier this year  petroleum peaked around $66.08 a barrel and helped drive inflation in the cost of construction materials.

In addition to materials, users of diesel fuel are suffering, as high diesel prices are trimming contractor profit margins and throwing government operations budgets in turmoil.

At press time, United States crude for December delivery ended the trading session at $61.22 a barrel on the New York Mercantile Exchange. This price still is below record levels when adjusted for inflation. Oil would have to rise to $80 a barrel in today’s prices to meet the peak price, adjusted for inflation, set in 1981. But the significantly higher price of petroleum is rippling through the road-building industry, driving up operating costs, and increasing prices for all construction materials.

Since December 2003, inflation in highway and street construction has far outpaced other construction sectors.

“In general, consumer prices have remained very moderate through the entire period [five years ending September 2005], although they have accelerated in the past two years as oil prices have set new records,” said Ken Simonson, chief economist, the Associated General Contractors. “[But] construction costs have risen dramatically in 2004, 2005, or both, after having moved similarly to the overall [producer price index, PPI] in the previous three years.”

Simonson notes that asphalt prices have risen 10% in the 12 months ending December 2003, just under 12% in the nine months ended September 2004, and over 15% in the nine months ending September 2005.

Diesel fuel price increases have been worse: up 54.4% in 2002, 13% in 2003, nearly 55% in the nine months ending September 2004, and another whopping 51% in the nine months ending September 2005.

“The weekly average price of on-highway diesel fuel [in late October] reached a new high of $3.15 per gallon, up $0.06 after the record $0.35 jump the previous week,” Simonson said. “Contractors use diesel fuel to power off-road equipment and construction vehicles. Also, contractors face diesel fuel surcharges on deliveries of materials and equipment to job sites.”

There are a number of reasons why diesel prices have skyrocketed:

• Typically, diesel prices go up when cool weather comes because refiners begin to make more heating oil and less diesel.

• Katrina and Rita shut down a number of refineries, which caused a spike in the price of gasoline. Now those refineries are coming back on line and are working hard to produce gasoline, thus lowering the price of gasoline, but boosting the price of diesel.

• There is a heightened competition for diesel fuel with Europe and Asia, where diesel-powered vehicles are much more popular than here, raising prices.

• Also, autumn shipping of harvests puts annual pressure on diesel prices.

Inflation is showing up in other building materials because many of them use oil products as feed stock, Simonson said. Oil is used to make PVC pipe, asphalt modifiers, paving fabrics, waterproofing membranes, tires, and much more. Further, higher fuel prices are reflected in higher delivered prices and fuel surcharges.

In addition to asphalt cement, portland cement also is going up in price. Cement manufacturing is energy-intensive, and concrete is very heavy to transport. To complicate things, Hurricane Katrina — anything but a lady — devastated the Port of New Orleans, once the largest cement import site in the United States, handling 12% of all imported cement in 2004.

“Expect 5 to 8% growth in the PPI for construction materials, compared to 4 to 6% growth in the overall PPI in both 2005 and 2006,” Simonson told a group of surface transportation professionals in May. “In addition, supplies of some materials will be tight. Currently, tire-making capacity is so limited that some construction equipment is reportedly being shipped without tires. Cement is also likely to run out for brief periods in some markets.”

For better or worse, night work has become a fact of life for the road construction industry. More and more states are scheduling construction work at night because of high traffic volumes during the day.

“Nighttime work, however, has its own hazards,” says Gerard E. Kennedy, project engineer, Nova Scotia Department of Transportation and Public Works. “A comprehensive specification can help in adapting to the special circumstances of working at night.”

In 2002, the Nova Scotia Department of Transportation and Public Works developed a specification to address the special concerns of working at night. To develop the specification, NSTPW staff relied on published findings from two recently completed National Cooperative Highway Research Program projects, NCHRP Report 476, Guidelines for Design and Operation of Nighttime Traffic Control for Highway Maintenance and Construction; and NCHRP Report 498, Illumination Guidelines for Nighttime Highway Work.

“NSTPW also obtained comments and specifications from many state and provincial departments of transportation in the United States and Canada that had experience with nighttime construction,” Kennedy said earlier this year. Since 2002, Nova Scotia has updated its specification from experience and on-site observations, he said.

A minimum level of point illumination recently was added to the lighting requirements to reduce the variability of illumination in the work area. The specification defines the following three levels of illumination:

Level 1, 60 lux, general site lighting for workers on foot.

Level 2, 110 lux, for working near certain types of equipment, for example, behind the paver, so quality control personnel can monitor the pavement mat closely.

Level 3, 220 lux — required at stations for traffic-control persons.

Balloon lighting is the new standard for night work illumination.

The contractor must assemble a trial setup of the traffic control and light systems for NSTPW review before work can begin. The specification also establishes requirements for traffic-control devices that will be used. “The construction contractor must submit a detailed night work plan, which includes night-related traffic control plans, site safety rules, and training materials,” Kennedy said. “The plan also must include detailed lighting plans designed by a professional engineer with expertise in lighting.”

TCPs and other workers must receive special training in carrying out their duties at night and must wear high-visibility apparel, he says. TCPs also must have radio communication with other TCPs and staff on the work site. Haul trucks must have reflective signs mounted on the tailgates, directing motorists not to follow into closed traffic lanes. Trucks and heavy equipment also must add reflective material to produce an outline of the vehicle. All vehicles on the site must have rotating incandescent lights.

The specification continues to undergo updates and improvements each year. Notable  changes in the latest revision include using only drums to channelize roads with higher traffic volumes; tightening the spacing between channelization devices; setting minimum values for point illumination; and requiring an internal traffic control plan for each work zone, setting out a strategy for the safe operation of construction vehicles on the site.

For more information contact Kennedy at kennedge@gov.ns.ca.

Electrically conductive concrete may help fight snow and ice while preserving bridge deck reinforcing steel. A demonstration project in Nebraska has weathered storms of two winters and continues to be observed this winter and next.

Conductive concrete is placed in summer 2002 at Roca Spur Bridge, Nebraska.

“Conductive concrete is a cementitious admixture containing electrically conductive components to attain stable and high electrical conductivity,” say Sherif A. Yehia, Western Michigan University, and Christopher Y. Tuan, University of Nebraska-Lincoln. “Due to its electrical resistance and impedance, a thin conductive concrete overlay can generate enough heat to prevent ice formation on a bridge deck when connected to a power source.”

In 1998, in research sponsored by the Nebraska Department of Roads, Yehia and Tuan developed a conductive concrete mix specifically for bridge deck deicing. In this mix, steel shavings with particle sizes ranging between 0.007 and 0.19 inches and steel fibers with four different aspect ratios from 18 to 53 were added to the concrete as conductive materials.

Junction boxes among rebar energize the conductive concrete deck.

Over 150 trial mixes were prepared to optimize the volumetric ratios of the steel shavings and fibers in the mix proportioning, they said. The optimized mix was evaluated in accordance with ASTM and AASHTO specifications, and met requirements.

Due to problems in use of steel shavings exclusively, in spring 2001, Yehia and Tuan developed a conductive concrete mix using graphite and carbon products to partially replace steel shavings. Ten trial mixes with seven carbon and graphite products were included in the preliminary experiments.

All mixes contained 1.5% of steel fibers per volume of conductive concrete, in addition to the carbon and graphite products, which amounted to 25% per volume of the trial mixes.

In 2001, the Nebraska Department of Roads approved a demonstration project at Roca. The Roca Spur Bridge is a three-span slab-type bridge with a 150-foot-long and 36-foot-wide concrete deck with conductive inlay. Slab thickness is 12 inches. The conductive concrete inlay is 117-feet long, 28-feet wide, and 1-inch deep, consisting of 52 4- by 14-foot conductive concrete slabs.

Conductive concrete does its job on Roca Spur Bridge, Nebraska.

Temperature sensors and a microprocessor-based controller system were installed to monitor and control the deicing operation of the inlay. The construction was completed and the bridge was opened to traffic in spring 2003. Data from the first deicing event showed that an average of 46 watts per square foot was generated by the conductive concrete, to raise the slab temperature about 16 degrees F above the ambient temperature.

The deicing controller system was completed in March 2003 and was tested successfully under snow storms in January and February 2004. The system was activated in 2003 for an early April storm with less than 0.25 inches of sleet. The slush on the bridge deck was melted during the storm period. Temperature distribution was uniform across the bridge. The controller system kept the slab temperature about 16 degrees F above the ambient temperature.

The Nebraska Department of Roads approved a five-year plan for monitoring the conductive concrete overlay. This promising new technology  should prove to be a valuable tool in the fight against icy conditions on roadways. More information is available at www.conductive-concrete.unomaha.edu.

November was the completion date for a remarkable bridge deck project that will field-test Engineered Cementitious Composites, a next-generation composite material that combines the strength of portland cement concrete with the ductility of metal.

This ECC slab is carefully finished in southeastern Michigan.

In cooperation with the Michigan Department of Transportation, HNTB Engineering Consultants, Midwest Bridge Contractors, and Clawson Concrete Company, construction of a demonstration ECC link slab bridge began in July 2005. The southeastern Michigan project site is Grove Street over I-94 in Ypsilanti, approximately 45 minutes from Detroit.

Conventional concrete used in transportation infrastructure can be brittle and tends to crack, resulting in a lack of durability and frequent repair needs. But a new, ultra-ductile cementitious composite, which is highly crack resistant, may offer new options to structural designers and providers of concrete, say Victor C. Li and Michael Lepech, Advanced Civil Engineering Materials Research Laboratory, University of Michigan-Ann Arbor.

This new material, dubbed Engineered Cementitious Composites, has a tensile strain capacity over 300 times that of normal concrete.

“ECC is a new class of cementitious materials, and ECC meets nearly every major characteristic sought by highway engineers for a highly durable concrete repair material,” Li and Lepech say. “This type of ultra-ductile, high-performance, fiber-reinforced cementitious composite exhibits ductility similar to metals, along with inherently tight crack widths for excellent durability and corrosion protection. Additionally, this material shows excellent  performance in durability testing.”

A finished ECC slab cures in July 2005.

The most distinctive characteristic separating ECC from other concrete repair materials is an ultimate strain capacity between 3 and 5%, depending on the specific ECC mixture. This strain capacity is realized through the formation of many closely spaced microcracks, allowing for high strain capacity.

These cracks, which carry increasing load after formation, allow the material to exhibit strain hardening, similar to many ductile metals, as seen in a typical uniaxial tensile stress-strain curve.

“This is uniquely different from typical concretes or fiber-reinforced concretes, which form a single crack when loaded,” Li and Lepech say. “In the case of normal concrete, the crack opens wide with a rapid drop in load capacity. In the case of FRCs, the crack opens with a gradual drop in load, exhibiting a tension-softening behavior. While the mechanism behind con-crete and FRC deformation is similar to ECC in that it cracks, all deformation is localized at a single section (i.e., the crack face) and the concept of gauge length, and consequently strain, ceases to exist.”

While the components of ECC may be similar to FRC, the distinctive ECC characteristic of strain hardening through microcracking is achieved through micromechanical tailoring of the components — that is, cement, sand, and fibers — along with controlled interfacial properties between components. “Fracture properties of the cementitious matrix are controlled through mix proportions.”

ECC has undergone durability and performance tests, such as restrained shrinkage tests, fatigue and bonding tests, freeze/thaw exposure, wearing/abrasion tests, and accelerated environmental tests. Also, the long-term strain capacity and early-age strength development of ECC were investigated.

More information on ECC technology and applications can be found at www.engineeredcomposites.com.

There’s a promising future for reclaimed and recycled asphalt pavement as an additive to crushed angular aggregate or pit-run granular soils in Montana, according to new research released in July by Montana State University.

In research prepared for the Montana Department of Transportation, Evaluation of the Engineering Characteristics of RAP/Aggregate Blends, by Robert L. Mokwa and Cole S. Peebles, Department of Civil Engineering, Montana State University-Bozeman, research and tests were conducted to evaluate the suitability of such RAP blends. To this prosaic material were applied lab tests, including grain-size analyses, specific gravity tests, modified Proctor compaction tests, relative density tests, Los  Angeles abrasion tests, direct shear tests, permeability tests, R-value tests, and X-ray CT scans.

The study examined changes in the engineering properties of aggregate materials when mixed with RAP. In addition to a thorough evaluation of published literature on the subject, an extensive suite of laboratory tests were conducted using four different aggregates blended with asphalt millings over a broad range of mix percentages.

Laboratory investigations suggest that the engineering properties of RAP-blended soils are comparable with those of virgin aggregates, they say.

“Gradation analyses indicate that the addition of RAP to virgin materials does not significantly change the particle size distribution,” Mokwa and Peebles say.

Montana laboratory tests are validating reuse of RAP.

“Large-scale constant head permeability tests indicate the permeabilities of RAP blended samples are generally greater than the virgin aggregates. The addition of RAP lowers the specific gravity of the blended material and decreases the dry unit weights. R-value tests indicate that adding recycled asphalt millings to pit run materials results in a higher R-value. For crushed and screened base course materials, the R-values remain essentially unchanged.

“The outlook for the continued implementation of RAP as an additive to granular base and subbase materials for use in highway construction looks promising.

“Results from the extensive suite of laboratory tests indicate that blending asphalt millings with granular cohesionless material like crushed aggregate or pit run cohesionless soil results in only minor changes to the engineering properties of the virgin material.”

Smart fibers, paints, and polymeric coatings... chemiluminescent light sticks...soil-decontaminating nanoparticles...mussels’ glue; they’re part of a laundry list of potentially important new and exotic materials that may have applications for highways, roads, and bridges, as reviewed by the Virginia Transportation Research Council for the Virginia Department of Transportation.

In State-of-the-Art Survey of Advanced Materials and Their Potential Application in Highway Infrastructure, S.R. Sharp and G.G. Clemeña identified 47 materials in various stages of development.

Products with a greater than average rating in terms of their potential for Virginia DOT include biosensors for lead, elastomeric coating for blast protection, Steel and Foam Energy Reduction barrier, urethane coating for cathodic protection, smart fibers, smart paints, and smart polymeric coatings.

Other materials with potential include electrically conductive concrete (see related item in this article), microencapsulated fire-extinguishing agent, piezoelectric paint, self-healing coatings, self-healing concrete, chemiluminescent lightsticks, and soil-decontaminating nanoparticles.

An additional material with potential, mussels’ glue, also was identified. Download the report at www.virginiadot.org/vtrc/main/online_reports/pdf/05-r9.pdf .

Future portland cement concrete pavements can be constructed with optimal smoothness and long life spans, according to new information published by the Federal Highway Administration.

In Achieving a High Level of Smoothness in Concrete Pavements without Sacrificing Long-Term Performance, (FHWA-HRT-05-068), the FHWA ob-serves that smoothness measurements for construction acceptance are usually performed shortly after paving is completed, using either a profilograph or a lightweight inertial profiler.

“However, it is unclear whether the smoothness  of a pavement measured immediately after it is paved truly reflects the initial smoothness of the pavement, because the smoothness can undergo changes over the short term (e.g., within three months) due to curling or warping effects,” the FHWA says.

In other words, a pavement can have a very high smoothness immediately after construction, followed by a decrease in smoothness over a short time period, because of changes in slab shape that occur with curling and warping.

This research project was performed to:

	Assess whether high initial smoothness translates into better long-term performance.
	Identify design features and material properties in PCC pavements that can cause an initially smooth pavement to exhibit detrimental long-term performance.
	Provide guidance on adjustments that can be made to materials properties, design features, and construction procedures in order to avoid these detrimental effects.
	Investigate early age changes in smoothness of PCC pavements.
	Provide recommendations and guidelines regarding smoothness testing.

Experiments showed that pavements that are built smoother retain their smoothness over a longer period than those that are built less smooth, the FHWA says; hence, pavements that are built smoother provide a longer service life and provide road users a better ride quality.

Use of dowels and certain materials must be done along recommended lines. For example, some non-doweled pavements have shown a high increase in upward slab curvature over time. These pavements have a high amount of faulting, and many are showing other distress.

Factors associated with higher amounts of slab curling over time are high values of freezing index, coefficient of thermal expansion, and PCC elastic modulus. Higher values of the following factors were associated with lower curvature: mean annual temperature, annual precipitation, number of wet days per year, and slab thickness. To prevent upward slab curvature, it is recommended that dowels be used for all pavements constructed in freezing areas.

Also, evidence suggests that higher values of coarse-to-fine aggregate ratio in concrete results in pavements that maintain their smoothness over longer periods.

A much longer technical summary of the report is available; download it at http://www.tfhrc.gov/pavement/pubs/05069/.

Reprinted from Better Roads Magazine
December 2005

See also:  Index of all Road Science Articles

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