September 28, 2021

Calumet County, Wisconsin Helping to Create Longer Lasting, Safer Roads

Many states are looking for methods to improve longitudinal joint performance of their pavements, since these joints often fail before the rest of the surface. With the inherently lower density at the longitudinal joints we often see pavements fail by cracking, raveling, and potholing. Lower density is synonymous with higher air voids which leads to premature failure of pavements due to the intrusion of air and water. Studies have shown that longitudinal joints in pavements are often the weakest areas of a road. (1)

A picture of a pavement’s longitudinal joint with significant damage.

Several state DOTs (Department of Transportation) are now using a materials approach to seal the longitudinal joint region by filling these air voids with asphalt content from the bottom up.

The materials approach is referred to as VRAM(2), a Void Reducing Asphalt Membrane.  VRAM is a highly polymer-modified asphalt cement that is placed at the location of a longitudinal joint before paving. As mix is paved over it, the VRAM melts and migrates up into voids in the low-density mix, making the mix impermeable to moisture while sealing the longitudinal joint itself.

Think of this materials approach and application as putting VRAM down first (asphalt content), to fill air voids in the HMA mat, AFTER the HMA has been placed. This is the innovative nature and chemistry of VRAM and why it has been helping roads last longer in more than 20 states in the United States. 

This particular project covers 10,560 feet in Calumet County, Wisconsin from US 151 to Honeymoon Hills Road.

Illinois Department of Transportation (IDOT) test pavements were evaluated after 12 years and found to have longitudinal joints that exhibited significantly better performance than the control joint sections and were in similar or better condition than the rest of the pavement. Laboratory testing of cores showed decreased permeability and increased crack resistance of mix near joints with VRAM as compared with similar mix without VRAM. The life extension of the joint area is approximately 3–5 years, and the benefit is calculated to be three to five times the initial cost.

You will note the test section (above the white line) does not have VRAM, while the section below did use VRAM. This is 15 years AFTER the VRAM was placed under the HMA at time of construction.

This project’s VRAM application began at 8:05pm with ProTack operating the 05-distributor shooting from the driver’s side. They started at address N3362 in the eastbound lane. Ambient temperature was 61F and existing pavement was 80F. ProTack applied a straight and consistent line throughout the project. VRAM width was measured with an average of 18 inches. (3)

An 18 inch application of VRAM.

The paving crew started at 11:40.  Paving equipment consisted of a Volvo P7170B paver, Sakai SW850-II – 12-ton breakdown roller and a Volvo DD25B-5-ton finish roller. Width was 12 feet.  Mix temp was 275F under the screed.

HMA is placed over the VRAM. The heat and pressure of the HMA cause the VRAM material to migrate upwards 50-75% into the HMA, filling voids with asphalt content.

J-Band® is a VRAM product from Asphalt Materials, Inc. and was created in the labs of the Heritage Research Group.

J-Band has been helping roads last longer since 2002. VRAM has been used in 20 states and the District of Columbia. 

Notes:

  1. Materials Approach to Improving Asphalt Pavement Longitudinal Joint Performance. National Academy of Sciences: Transportation Research Board 2021 Article: https://doi.org/10.1177/03611981211044451 
  2. Editor’s Notes: VRAM, Void Reducing Asphalt Membrane is referred to in Illinois as LJS, Longitudinal Joint Sealant.
  3. Depending on the situation VRAM can be sprayed at different width’s. This article notes 18” which is a typical application width for centerline applications.

Keywords: Infrastructure, Void Reducing Asphalt Material, Longitudinal Joints, J-Band, binder specifications, pavements, design and rehabilitation of asphalt pavements, asphalt, construction, asphalt pavement construction and rehabilitation, materials, binders, Asphalt Materials, The Heritage Group, Milestone, HC&M, Heritage Research Labs.

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Jeff Ball0 commentJob Success, Product-Highlight, Specialty Products
September 24, 2021

What is a Sustainable Rehabilitation Technique for Asphalt Materials?

Bartholomew County, Indiana

Full Depth Reclamation (FDR) is a cost effective and sustainable rehabilitation technique that combines the entire bituminous pavement thickness and a predetermined portion of the underlying aggregate material into a flexible, homogenous stabilized base layer utilizing an asphalt emulsion to provide mixture cohesion and water resistance. FDR is a solution for rehabilitating roads that have poor structure. The FDR is typically followed with an overlay of hot mix asphalt.

This full depth reclamation project took many parties from start to finish. Milestone Contractors, Inc. submitted the bid, Asphalt Materials, Inc. supplied the engineered emulsion and Heritage Research Group provided the sampling, mix design and quality control. 

This particular project was on Hartman Drive in Bartholomew County, Indiana. It consisted of an eight-inch (8″) full depth reclamation on one thousand, one hundred feet (1,100′) of existing recycled asphalt pavement (RAP) road and one hundred – 70 feet (70′) of existing asphalt road. A 3″ hot mix overlay laid in 2 lifts of 1 ½” each was then placed on the new recycled roadway base. 

The County collected and placed the RAP at a depth of 8-9” from another project in the area to build the new roadway base. Milestone then pre-pulverized and graded the entire roadway at a depth of 8”. A second pass was made with the reclaimer and the engineered emulsion was injected and the emulsified material was graded and compacted. After the final cure the recycled base was overlaid with two 1 ½” lifts of HMA (Hot Mix Asphalt), striped and opened to traffic. 

Asphalt Materials Inc., is a proud member of The Heritage Group and brings nearly 65 years of experience to the asphalt industry and road construction projects. Our teams of professionals are dedicated to creating longer-lasting, safer roads with quality, reliable asphalt materials.

Our family of companies want to ensure we are leaving the world in a better place for future generations. As The Heritage Group continues to expand capabilities and investments in the sustainability space, the AMI team is also focused on sustainability in a number of different areas. We will be reporting on these in future articles.

#FDR #Infrastructure #STEM STEMEducation #Sustainability #LongerLastingRoads #HotMixAsphalt

[Note: Bids for this project opened on March 29, 2021]

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Jeff Ball0 commentConstruction, Job Success, Product-Highlight
September 22, 2021

DuPage County Illinois Finds Success Protecting Pavements

Studies have shown that longitudinal joints in pavements are often the weakest areas of a road. Typically the joints are low in density, high in voids and thus are highly permeable. These areas become conduits to air and water infiltration which leads to damage and premature pavement failure. (1)

During the 2016 construction season a new method of longitudinal joint construction was specified in Illinois. This new method is a materials approach and is referred to as VRAM(2), a Void Reducing Asphalt Membrane. Applying VRAM at the time of construction helps fill the pavement voids, thus reducing the permeability in this most critical area.

As part of their evaluation, DuPage County ensured that test cores were taken on different joint constructions, such as VRAM and joint heater. DCT, I-FIT, density, and asphalt binder grading tests were performed to compare the different joint construction methods. The report summarized that the addition of the VRAM contributes to a more durable joint by partially filling the joint and adjacent mat air voids. The joint will be much less permeable and less likely to allow water infiltration.

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Jeff Ball0 commentJob Success, Testimonial
July 12, 2021

Success Story: CMS in Iowa

Cationic Emulsions are made up of three major classifications of emulsion grades: rapid-setting, medium-setting, and slow-setting. The terms “rapid,” “medium,” and “slow” relate to the amount of time it takes for the emulsion to cure and the amount of mixing that can be performed before the emulsion breaks. Emulsions that allow for the longest mixing times generally take the longest to cure, while emulsions that allow for very little mixing time are those that set and cure most rapidly.

Chemical surface-active agents, serving as emulsifiers, are classified by the electrochemical charge that is attained when they dissociate in a water solution. In the case of cationic emulsions, the chemical charge is positive. The chemical type and quantity of surface-active agents used in the manufacturing process governs the properties of the emulsion and in what applications the resulting asphalt emulsion can be used.

As many people know, Asphalt Materials, Inc. is made up of a large family of companies. One of these companies, Bituminous Material and Supply, with plant locations in Tama and Des Moines, Iowa, was approached by Denco Construction regarding an interest in using scrub seal in Iowa. This is an emulsion seal that is not often seen in Iowa. A scrub seal is an application that is very similar to a chip seal treatment. The only difference is that the asphalt distributor pulls a broom sled that houses a series of brooms placed at different angles. These brooms guide or “scrub” the emulsion into cracks to help ensure the road’s surface is sealed.

Testing

The scrub seal is a process by which asphalt emulsion is applied to a pavement surface by an asphalt distributor. The emulsion is scrubbed into the cracks and voids with a broom before a layer of aggregate is applied over the asphalt. The scrub seal is then rolled with a pneumatic tire roller and is usually ready for controlled traffic in 1 hour or less. The scrub seal process is intended to rejuvenate dry, oxidized, and cracked asphalt pavements in lieu of a micro-surfacing, chip seal or asphalt overlay. This process was tested on roads that interested counties offered as a demo. Below, you’ll find images that were taken during the testing process.

Results

The evaluation of the demo roads showed success, and Bituminous is now focused on sand applications. Denco Construction purchased a sand spreader during the winter season to fulfill the county’s request.

According to Chris Aldama, Plant Manager at Bituminous, “It’s still a pretty fresh process. Denco was able to take approximately 10,000 gallons at the end of June, but needs to make adjustments on sand suppliers. Once sand quality is finalized, I’m confident in the long term success in this area and beyond.”

To learn more about the process, feel free to watch this video:

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asphaltmaterials0 commentJob Success
July 6, 2021

National Air Traffic Control Day: Recognizing Our Work at Coles County Airport

National Air Traffic Control Day was first held on July 6, 1986, on the 50th anniversary of the establishment of the air control system in the United States. According to Senate Joint Resolution 188, which designated the day, it was created to increase public awareness about the United States National Airspace System and to give people a way to “express their gratitude and respect” to “pioneers of the technology of air traffic control” and to all air traffic control personnel.

Many might wonder how National Air Traffic Control Day relates to the work we do here at AMI. The work we do expands far beyond just county roads and highways. We also have experience working with airports because just like with roads, protecting longitudinal joints is also important for airport runways! This past June, we completed a 7,300-foot J-Band project at the Coles County Airport, located near Mattoon, Illinois. The application was scheduled to be 18” wide and 1.51 lb./ft for the 2” surface mix, P401, PG64-22, N40. This was over a recently applied and tacked level binder mix.  J-Band, which is a Void Reducing Asphalt Membrane (VRAM) was measured at 280F after the distributor applied. In total, 7,124 ft and 10,330 lbs. were applied for a total yield of 1.45 lbs./ft. Images of the project can be found below. In Illinois, you may also see VRAM referred to as a Longitudinal Joint Sealant (LJS).

The air control system, created by the United States Bureau of Air Commerce, is the National Airspace System. It works to ensure adequate spacing between airplanes that are flying on routes and to prevent congestion at airports. There are more than 14,000 air traffic controllers, who together with engineers, electronics specialists, and technicians make up the National Airspace System. The system is a model for the world aviation community, is known for its safety and efficiency. Over the course of its first 50 years, the volume of air traffic in the United States expanded one hundred and eighty fold. Today, 5,000 aircraft are in the air in the country at any given moment, with millions of flights taking place each year. The country has 5.3 million square miles of domestic airspace and 24 million miles of airspace over the oceans. On National Air Traffic Control Day, we thank all those who work to keep the airways safe as part of the National Airspace System, and we work to make the system stronger. Learn more about National Air Traffic Control Day here.

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asphaltmaterials0 commentJob Success, Specialty Products
June 10, 2021

Pavement Rehabilitation and Conversion

AMI is committed to changing the standard in the asphalt industry. Our companies strive to implement new processes, ideas, services, and products with the goal of creating a more effective solution to your road construction projects. Our dedication to quality often results in improving roads through the process of pavement rehabilitation. Each project contains different conditions and construction histories which may alter the approach to conducting pavement rehabilitation, but there are several processes that can be utilized upon reviewing a pavement individually. In general, pavement rehabilitation is suited for pavement in the C, D and F pavement condition zones. This article will address how and when each process is used.

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asphaltmaterials0 commentJob Success
June 8, 2021

Comparing Field and Lab CIR Mix Properties: Findings from Indiana SR 234

Any business that has been around for over 65 years should have a strong commitment to innovation. Asphalt Materials is that company. Our teams are focused on helping build longer-lasting, safer roads. To do that, we focus on big challenges as creative problem solvers. We have a unique opportunity available to us and our customers in that we are part of The Heritage Group, which includes the expertise that resides within The Heritage Research Group.

Collaboration is a hallmark of our approach as well. Working with contractors and departments of transportation, we take a collective approach that fosters long-term relationships and mutual trust. A recent project created an opportunity with Indiana State Road 234. The construction project consisted of  126,505 square yards of Cold In-place Recycling (CIR) at a depth of 4-inches. The project length was 10.37 miles with a 22 foot width. The project progression can be seen in the image below.

asphalt project progression

While comprised of similar components to conventional Hot Mix Asphalt, CIR lifts cannot be sampled in the same way to measure and confirm quality of the material. Instead, each CIR candidate pavement is sampled, with the representative materials going through a mix design process designed to closely approximate the CIR construction procedure in the lab. Once the CIR mixture meets or exceeds specified laboratory standards, construction can begin.

Per industry standard, several tests are performed during CIR operations to verify the exact material quantities are added to the mixture per the project’s mix design. In-place density testing is also performed to confirm optimal compaction is reached throughout the placed CIR lift. While this testing method is rigorous for the mixture’s components it does not directly measure mixture performance. The current testing standard reveals opportunities to test the constructed material for performance that is timely from a construction perspective and valuable for agency and contractor customers.

Heritage Research Group designed a field sampling method to sample constructed CIR materials just prior to field compaction, allowing for test specimens to be produced and performance tested, similar to mix design test specimens in the lab.

Additionally, a rare opportunity arose to sample the CIR by coring, shortly after construction and the final HMA overlay was completed. This provided field cores from the project for further analysis that is truly representative of the mixture.

Six, 6-inch cores were collected from eight locations on the project (see example below).

core testing

Based on these testing and material sampling opportunities, a research project was formed as follows:

  • Evaluate sampling procedure for field-collected samples.
  • Compare mix design results to field-collected samples.
  • Quantify impact of delayed compaction of field samples.
  • Compare mix design, field samples to field cores.

The variation in approximated versus representative processes in the three types of CIR samples provide a unique perspective to confirm accuracy of the field sampled mix tests and of the initial mix design test results. A diagram outlining the differentiations between mix design, field samples and field cores can be viewed below.

project truth scale

All of the CIR processes are approximated in the lab to produce a mix design, while field sampled materials contain more accurate versions of these processes because they are sampled from the constructed lift. Finally, cores collected from the project, several months after the CIR was completed, provide the most accurate version of the mixture, all of the CIR processes, including compaction, being true to the constructed CIR. 

After conducting testing to determine air voids in the mixtures, specimens were tested for marshall stability and indirect tensile strength in dry and wet conditions. These results are used to estimate a mixture’s resistance to water damage, rutting, and cracking in tension.

To further understand the long-term performance of the mixture, dynamic modulus testing was performed with small-scale AMPT specimens collected from the CIR pavement cores.

Several findings were determined upon analysis of the test:

  • The sampling method to collect field mix samples for lab compaction and testing could be a method to verify CIR mixture properties in the future.
  • The dynamic modulus test results provide additional data to the industry on the performance qualities of the constructed mixture, which also align with the current industry recommendations for the mastercurves which characterize CIR materials. 

This project is an excellent case study that demonstrates the outcomes that are possible when different groups are all driving to the same goal of creating longer lasting, safer roads.

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asphaltmaterials0 commentJob Success, Our Products
May 30, 2019

Rebuild of County Road 151 recognized with two awards

The rebuild of County Road 151 across three townships has been honored with two awards. 

The Monroe County Road Commission received the national Asphalt Recycling & Reclaiming Association’s 2016 Award for Excellence in full-depth reclamation for the project. In addition, the road commission and Gerken Paving Inc. received an award of excellence from the Asphalt Pavement Association of Michigan. 

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asphaltmaterials0 commentJob Success, Our Products