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.
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.
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.
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:
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.