Asphalt Emulsion Sealers

Asphalt emulsion sealers are asphalt-based and are popularly known as the environmentally-friendly alternative to protecting your driveway. However, it should also be noted that there are no known research or studies that have proven the pollution or hazards caused by paving one’s road with coal tar-based sealers. Asphalt-based sealants are better in terms of preserving air quality, smell better, prevent oxidization and do not cause skin irritation.

The drawback to applying asphalt emulsion sealers though is that it is prone to staining caused by oil or gas spillage. This sealer type also can only be applied between May to September for best curation time and are especially impossible to work on during the night time when the ambient temperature is at its lowest. The price of asphalt emulsion sealers is also extremely volatile due to the active demand for the product versus the limited amount of supply.

Coal Tar Sealers

Coal tar is the most popular asphalt sealer in the market as it is weather-resistant and provides a long-lasting shiny finishing.  Like its namesake suggests, coal tar sealers contain a substantial amount of coal tar mixed in with other polymers and strengthening additives. This water-based sealant is manufactured by baking coal. Coke is then extracted from the baking process which then becomes the main component of coal tar sealers and is the reason why it is resistant to petroleum-based chemicals.

Unfortunately, coal tar sealers are also believed to have a long term detrimental impact on the health of local occupants as well as harm the environment. In June 2011, the Suffolk County Legislature have joined the states of Texas and Minnesota in officially approved a permanent ban on the sale of coal tar sealers as the sealer is believed to be contributing to water pollution and emits a harmful carcinogenic compound known as polycyclic aromatic hydrocarbon. As at this point of writing, companies such as Home Depot and Lowe’s have also halted the sale of coal tar sealers due to the potential liability.

Fast Dry Sealers

Fast dry sealers are meant to patch up roads with high traffic, such as parking lots and major roads leading to public areas such as gas stations and hospitals. The best thing about using fast dry sealers is that it curates in less than an hour, thanks to the additional geo-textile fibers added into the sealant. However, this also means that fast dry sealers are much costlier compared to other types of asphalt sealers. Purchasing this sealer type in small quantities will also prove challenging as most manufacturers of fast dry sealers deal directly with road works companies. When you do eventually find a source distributing this sealer type, you might want to buy in bulk and share the costs with your neighbours. Due to the high cost of material, you might also want to apply fast dry sealers on critically cracked areas on your pavement, followed by a cheaper type of asphalt sealer.

Acrylic Sealers

Another expensive type of asphalt sealer is known as acrylic sealers, which is the epitome of what the perfect asphalt sealer should be. Acrylic sealers are easily identifiable due to its varying degrees of colour, as it can be shaded in black, red, green or clear colouring. These sealers are typically applied onto outdoor tennis and basketball courts as well as shopping mall parking lots. Acrylic sealers are UV resistant, highly durable and impervious to harsh environmental conditions.

Acrylic sealers also do not contain any petroleum by products, which means that it is environmentally friendly as well. Another great benefit of this sealer is that it only has to be reapplied every seven years as well, thereby contributing to savings in terms of maintenance costs.

Defining Quality Sealers

While it would be tempting to plainly opt for the highest quality sealer with the equally high price tag, a better way of selecting the appropriate asphalt sealer for your own use would be to simply look at the warranty duration. Generally, anything with a five to six year warranty would be a safe bet. If you have an ample budget, you might also want to consider opting for a sealer with additional acrylic polymers thrown in as well, as some of these products come with an impressive seven to ten year warranty.

In terms of pricing, asphalt sealers tend to command higher pricing as it is environmentally safer and lasts longer as well. Although it is possible to get a 5-gallon pail of asphalt-based coating for less than USD10, do keep in mind that this layering will probably only last for one season. On the other hand, a decent quality asphalt sealer should cost you anywhere between USD12 to USD15 with a coverage ranging from 250 to 350 square feet. Regardless of whichever type of asphalt sealer you choose, one thing for sure is that the total cost of maintaining the driveway on your own will save you up to 65% of the cost for professional maintenance.

DIY Asphalt Sealing Advice

If you intend to repair and maintain your own driveway, then you should do your due diligence and take some time to study the instructions on how you can prep the asphalt sealer before application. Some asphalt sealers can be directly applied on to the pathway whereas others may require thinning, special handling or curing before application. When in doubt, it is always best to first seek professional advice before starting on your project.

What is Recycled Asphalt?

In technical terms, the Western United States defines virgin asphalt as a “bituminous substance that is used to bind aggregate together to create asphalt concrete.” Generally, asphalt concrete consists mainly of aggregate in which asphalt only makes up 5 to 7% of the total composition.

Recycled asphalt on the other hand is quite simply asphalt concrete which has been reprocessed by mixing the reclaimed asphalt pavement with new asphalt and aggregates. In some circumstances, a recycling agent is also introduced into the mix to improve the performance of the recycled asphalt by softening and rejuvenating its mechanical properties.

The process of creating recycled asphalt usually begins with cold planing (also known as cold milling). In this procedure, the top layer of the pavement is removed using a cold planning machine. The pavement is usually made from Portland cement concrete which can then be crushed and used as the aggregate to form the recycled asphalt. After the recycled asphalt has been mixed, the composition can then be used to overlay the exposed pavement, thereby completing the recycling process.

Other types of asphalt recycling are known as hot recycling, hot in-place recycling, hot mix-remixing, hot mix-repaving, hot mix-heater scarification and full depth reclamation.

Why Recycle Asphalt?

Despite its elaborate process, recycling asphalt can help local governments save money from having to pave roads with new materials. At the same time, the act of recycling also introduces new business opportunities and will help create a greener environment in the long run as well. In 1990, the California Integrated Waste Management Board concluded that Construction and Demolition materials (including asphalt) made up 28% of the waste stream, totalling up to 11 million tons of waste in that year alone. A much deeper studied discovered that out of the 11 million tons of waste, 8.2 million tons were found to consist of asphalt, dirt, concrete, brick and other rubbles, out of which only 57% was recycled.

As asphalt also contains a high amount of oil, the price of virgin asphalt has also dramatically increased in line with the drastic oil price hike. With oil prices now hovering around the USD90 range, the demand for recycled asphalt is also growing in tandem as recycled asphalt is cheaper and yet just as durable as virgin asphalt.

Even if costing is not a problem, we are all obliged to protect the Earth’s natural resources for the sake of sustaining future generations. The repeated creation of asphalt is also known to contribute to environmental pollution, which is why recycling such toxic material is an effective method of reducing toxin production around the globe.

The creation of materials such as asphalt is also believed to contribute to climate change problems due to the burning of fossil fuels during the creation of asphalt. In contrast, producing recycled asphalt does not require any form of fossil fuel to be burnt, thereby preserving on our natural resources while also decreasing air pollution.

Roads paved with virgin asphalt have also been blamed for the urban heat island effect, which is a phenomenon where heat from the sun is absorbed into the ground, thereby heating the paved area even after the sun has set. On the other hand, recycled asphalt is lighter coloured, thereby making it less susceptible to heat absorption from solar radiation and hence, contributes less to the urban heat island effect.

At the same time, the introduction of recycled asphalt into the market can not only meet the USD100 billion asphalt demand but can also help create job opportunities as more recycling asphalt plants are created. As Asian countries in particular began to increase the amount of roadwork constructions, the recycled asphalt industry becomes a blue ocean choice in a red sea filled with expensive virgin asphalt suppliers whose prices are closely dependent on the price of oil at that point of time.

How to Fill Gaps with Recycled Asphalt

Homeowners can also contribute to a greener environment by applying recycled asphalt along their driveways as well. The first thing you need to do is thoroughly clean the surface of your pavement. It is best to do this with a high powered air blower first followed by a high power washer. You might also want to do this on a sunny day as it is important to allow the surface of your pavement time to completely dry before proceeding to the next step.

While waiting for the surface to dry, carefully mix hot or cold crack fillers. You can then fill up the holes in your driveway with the crack fillers, followed by a generous shovelling of recycled asphalt. To achieve a smooth finish, do run an asphalt rake over the surface area. To further condense the gap and prevent further cracks, you might also want to run a vibrating plate (or hand tamper) over the filled surface as well.

Next, carefully corner off the area to allow the filled gaps to completely dry for at least 24 hours before proceeding to apply commercial-grade asphalt seal coat to the surface. The purpose of the seal coat is to protect and extend the lifespan of the newly applied recycled asphalt, so do not skip this step.

How to Create Pavements with Recycled Asphalt

If you’re creating a new pavement, you might want to consider surfacing your pathway with recycled asphalt as well. A depth of at least 3 inches should first be created virgin aggregate is added, followed by recycled asphalt. Although recycled asphalt tends to leave tracks due to the higher content of oil, line paint and rubber, an extra layering of asphalt sealant can easily protect the rest of your flooring from asphalt contamination. Generally, we recommend that the sealant should at least be 1 inch thick to protect the integrity of the newly installed asphalt pavement.

If you’re going to fly this one solo, then you’ll run the risk of never having enough time to get the job done. What many people don’t know is that asphalt paving takes quite a bit of time, and if you already have a busy schedule, then you may never find the time to get started. Or you may be off to a good start, but then something comes up and you’re not able to finish, leaving the job half done and looking rather foolish. People would wonder why someone started a project and was never able to finish it! Even if you do have a little bit of time to dedicate to such a project, it may take you so long to finally complete it, that it wouldn’t really be worth it. Would you really want to spend an entire summer doing a paving job yourself? It would take forever! Save yourself the time and let one of the many professional Georgia paving companies take care of it for you.

In addition to being a huge time-sink, doing a paving job yourself it disadvantageous because you may not possess the necessary skills or ability to do it yourself. While we don’t doubt your ability, the truth of the matter is that some over-zealous do-it-yourselfers end up with worse results than they would have if they had just hired a company to take care of it for them. If you decide to do the asphalt paving job yourself, then you may be disappointed by a poor outcome and an unprofessional appearance. And it’s not like you can go back and fix it without ripping up what you just spent all that time and money on!

Not only are you unlikely to have the time or know-how to do the paving yourself, but you also won’t have any type of guarantee on the work. When you hire Georgia paving companies to do the project for you, you’ll be getting that company’s guarantee that you will be satisfied with the work, so if something isn’t quite to your liking, the company will take care of it, usually for free. If you tackle the project yourself and make a mistake, then you’ll have to shell out even more money and time to fix it. Why not hire a professional company and have them take care of any problems, and save yourself the headaches?

The bitter cold temperatures of winter can definitely do a number on an asphalt parking lot. Cracks spread easier, painted lines fade, and the overall stark black color, turns an ugly gray. If you’re up to your neck in dealing with other spring cleaning property issues, it’s easy to understand why giving your parking lot a “clean slate,” might not be something you’re jumping at the chance to have done. Nevertheless, in order to extend it’s lifespan, a parking lot restoration is highly recommended.

The walk-through

The first thing you ought to do before you have the actual paving done, is to do a simple walk-through of the parking lot. Generally, you may notice that your parking lot may need some repairs, but take the time to cracking patterns, spalling etc. Take a few notes, so you can explain some of the problems to the paving contractors before they come by. Your local commercial paving contractors will do there own walk-through of course, but it’s always good to give them a heads up on what they’re going to be dealing with.

Calling the paving contractor

Your paving contractors won’t only find a way to deal with the “here-and-now” problems of your asphalt parking lot, they will create a long-term plan of attack, so that your parking will continue to be in good shape for years to come. Many paving companies will work with you to create a maintenance program, prioritizing what needs to be addressed right now, versus a few months down the line.

Starting the parking lot restoration

Patching

With a long-term plan in place, the current repairs are ready to commence. One of the most common jobs in a parking lot restoration is a “cut-and-patch.” This techique helps target specific problem areas, like a pothole, for instance. The paving contractors jackhammer the damaged areas, before putting in new processed stone, and covering it with a thick layer of asphalt.

Overlaying

Although many people think that overlaying is a quick, effective fix to asphalt deterioration, it can sometimes be a big waste of money. If your parking lot is generally in good shape, then, overlaying might be a good solution for getting it in better shape, but if the pavement is already faced with serious problems, overlaying can actually create reflexive cracking - making things worse. If you’re looking for a temporary fix, and an aesthetic make-over for the time being, a simple “overlay,” might be appropriate.

Seal-coating

Seal-coating basically reduces the ultraviolet effects on pavement. Seal coating prevents the pavement from turning gray, and it also helps it maintain its oils and elasticity. The procedures is usually done for preventative maintenance, and when the parking lot is around a year old. Each seal coating procedure should be designed specifically for the parking lot. It’s definitely not a one-size-fits-all type of procedure.

Crack Filling

Crack filling is another very common type of parking lot repair. This type of procedure is done to  prevent water from entering into the cracks, and penetrating into the subgrade of your pavement, which will cause further damage. If you have a pavement that is in decent condition but you have a few visible cracks, filling those cracks to prevent water infiltration is key to extending its lifespan.

Taking care of problems before they’re problems

Overall, just an annual pavement maintenance is the secret to a healthy and long lasting parking lot. If you have any questions about this, your local commercial paving contractors would certainly be able to help you.

If you are in need of a parking lot rehabilitation, don’t hesitate to contact Dykes Paving, your number one commercial paving contractors in Atlanta.

More Effective

Believe it or not, “green asphalt pavement” or recycled asphalt is actually higher quality, and  more durable than brand new, virgin asphalt.

Requires Less Energy, and it’s Easy to Make

Recycled asphalt paving requires about 20 percent less energy than other pavements. Plus, the time it takes to create recycled asphalt paving is much less than other pavements, so roads can be created and repaired in a snap.

Highly Repairable

Unlike other pavements, asphalt can be easily fixed using crackfilling and various other products to increase its lifespan.

Saves Money While it Saves the Planet

Recycled asphalt or “green asphalt paving”  saves U.S. taxpayers almost $2 billion, annually, and it obviously saves acres upon acres of landfill space.

Helps Recycle Other Materials

Pure asphalt doesn’t just become pure asphalt again, once it’s recycled. Chances are, various other materials have been added into the recycled asphalt mix, as a means for recycling those materials. These recycled asphalt mixes may include things like asphalt roofing shingles, rubber from old tires, metal casting, etc.

Reduces Emissions

Since 1970, the asphalt industry has managed to decrease emission by almost 100 percent, while managing to increase production by 250 percent! One of the best things about recycled asphalt is that virtually no harmful emissions are created in the process - what is emitted however, is almost all steam. This is from heating rock, gravel, and sand to the required 300 degrees to mix with the asphalt oil, which is the “binder” or glue that holds the other natural materials together, and which gives asphalt its black color.

It Doesn’t Have a Negative Aspect, to Date

Recycled asphalt pavement only seems to carry positive weight, and it’s downsides seem virtually non-existent. Still, this wasn’t the case about 20 years ago. As early back as the early 90’s, the asphalt industry did not produce their product very efficiently, billions were spent on creating it, and they had very little concern for their environment or the future of the planet. Thankfully, this has all changed, and today’s asphalt paving contractors are extremely environmentally sensitive, and are proud to be working with an innovative product that’s just as efficient as it is cost-effective.

If you’re interested in having recycled asphalt pavement in your commercial setting, don’t hesitate to contact Dykes Paving, your “green commercial paving contractors in Atlanta!

The certain demise of asphalt pavement

No matter how good of a job the asphalt paving contractor does at installing the pavement, and no matter how much the pavement is maintained, deterioration is inevitable, to a degree.

Asphalt deterioration begins immediately. Even in standard conditions, significant deterioration can begin to take place after the first couple years. Around this time, asphalt starts to turn gray and begins cracking. Water seeps into the cracks, freezes, and thaws during the yearly cycle, causing larger cracks. The liquid asphalt binder starts to lose it’s water-resistance properties, and this is how water is able to penetrate the asphalt, causing it a great deal of wear and tear.

When asphalt pavement is properly maintained, it wears out slowly but can last more than 25 years. Water is not the only element that kills asphalt though. Sunlight dries out flexible liquid asphalt that holds the rocks together, causing cracking. Chemical exposure is another asphalt killer - gas and oil can soften asphalt causing it to deteriorate more quickly.

Asphalt pavement deterioration due to paving contractor errors

Although the deterioration of asphalt pavement will happen eventually, errors in construction can certainly speed up this process. There are a number of things that paving contractors can do wrong that might cause an asphalt paving project to fail. These errors include over or under compaction of the asphalt, improperly compacted base, improper asphalt temperature, poor drainage, amoung other things.

Other causes of asphalt pavement deterioration

landscaping irrigation around the asphalt can cause water run-off which can eventually lead to erosion. Heavy stationary and heavy slow-moving vehicles can also lead to a great deal of stress on asphalt paving.

Types of asphalt deterioration

Distortion - This is often caused by improper pavement construction, and it includes corrugations and shoving, channels or ruts, and grade depressions.

Disintegration - Types of asphalt deterioration includes potholes and gas and oil spills.

Cracking - The most common type of asphalt deterioration, cracking comes in many forms, and takes on many names: shrinkage, reflection, edge joint, alligatoring, etc.

Proper asphalt maintenance

As we laid the ground work earlier, proper asphalt pavement maintenance is key to giving it a long and healthy lifespan. Asphalt paving ought to be treated with a coal tar-based sealant within 2-3 months from the day of application.

As you can see, there are many causes or asphalt deterioration. Most of the time, weathering is primarily to blame, but as we have seen, human error and vehicle stress can cause wear and tear to asphalt, as well. Understanding the type of deterioration your asphalt is experiencing is critical in getting at the cause, so that it can be properly treated. All in all though, a periodic application of asphalt sealant is the best way to keep it strong and healthy.

If you’re interested in having your facility equipped with asphalt paving, don’t hesitate to contact Dykes Paving. We also specialize in Asphalt paving overlay - we invented Perma Flex paving. Call today to discuss!

As we just stated, recycled asphalt is obviously good for the environment. Asphalt is made from oil, which is a non-renewable resource and it can also be quite dangerous to extract.  Recycling used asphalt reduces the amount of new oil byproduct needed, and it also might reduce dependence on foreign oil. Recycling asphalt also cuts down on transportation costs needed to bring in new materials.

Recycled asphalt can be mixed into “hot mix” and “cold mix” paving applications, which is certainly a great benefit for paving contractors. The reuse of asphalt for fill, base or embankment asphalt paving projects can definitely save paving contractors money and materials, allowing for better roads, parking lots, etc.

Since asphalt is derived from petroleum, its cost is relative to the constantly changing prices of the market. Old asphalt is readily available to be pulled up or processed on site. Up to 25 percent of asphalt material in some states is made up of recycled asphalt. And, the Federal Highway Administration has research projects testing mixes of up to 50 percent. All in all, recycled asphalt saves money. Did you know that about 90 million tons of asphalt are recycled annually? This saves taxpayers hundreds of million of dollars each year. When asphalt is recycled, everyone wins: paving contractors, tax payers, and the planet as a whole.

Now that you’re aware of all of the amazing benefits of recycled asphalt, here’s some basic instructions for laying it (in case you ever get your hands on some, and want to do it yourself). Still, for the best results, it’s highly recommended that you contact your local paving contractors.

Step 1: Clear Area of Debris

Clear the soon-to-be-paved area of any pebbles, branches, or leaves that might be in the way.

Step 2: Make a Smooth Surface

Break up any large clumps of earth with your shovel, and subsequently, smooth out the surface with the rake, until your left with a smooth surface - ready to be paved.

Step 3: Lay the Recycled Asphalt

Lay the recycled asphalt across the area you wish to pave, so that you’re left with an even layer of around an inch.

Step 4: Tamp down the Recycled Asphalt

Do this with a hand tamper - hitting every square inch with a great deal of force to compact the layer of asphalt the best you can.

Step 5: Steam Roll

After your tamping is complete, use a steam roller to roll over, and further compress the recycled asphalt. This will help it in melting together so it can harden into a durable recycled asphalt surface.

Step 6: Curing

Allow at least 24 hours for your asphalt surface to cure.

If you’re interested in having your facility paved with eco-friendly recycled asphalt, don’t hesitate to contact Dykes Paving. We’re a premier paving company in Atlanta!

“Reclaiming/Recycling: The Kings Gesture

Road construction is a more than $80 billion annual industry in the U.S. Over the last decade, the industry has been driving toward greener and more sustainable design, construction, use and maintenance.

New technologies, new materials and new practices all play an important role in reducing the environmental impacts and maximizing economic and social benefits of our nation’s roadways.

The use of recycled materials in hot-mix asphalt (HMA) in road construction has long been an important green strategy of the asphalt-paving industry. Reclaimed asphalt pavement (RAP) is one of the most widely recycled materials in the U.S., with much of this material going into the construction of new roadways.

Recently, the use of recycled asphalt shingles (RAS) in paving has gained significant momentum. RAS can be derived from tear-off shingles from re-roofing projects or from manufacturers’ scrap. Currently 21 states and two Canadian provinces have specifications or procedures in place for using RAS in HMA (all allow manufacturers’ scrap and 11 states allow tear-off roofing shingles).

Using RAS in HMA has the potential to reduce the costs of paving due to the high quantity of oil in the shingles. By capturing the oil from the shingles, less virgin oil is needed in the HMA. However, for widespread use of RAS in HMA, engineers demand data to confirm that the use of RAS in HMA has no negative impact on roadway performance. A rigorous paving demonstration in King County, Wash., is showing the potential for widespread use of this recycled material.

Certainty is high

In fall 2009, a 2-mile-long stretch of roadway in south King County was overlaid with a 2-in.-thick layer of HMA, incorporating both RAP and RAS derived from tear-off roofing shingles in designated test sections. Road engineers have been closely monitoring the roadway’s performance and are seeing good results. The project is a collaboration of King County Solid Waste Division’s LinkUp program, the King County Road Services Division (KCRSD), the Washington State Department of Transportation (WSDOT) and Seattle Public Utilities. An advisory group of representatives from across the industry was brought together to provide input and help guide the project.

The goal of King County’s paving demonstration is to show—with a high degree of certainty—that the addition of RAS to HMA has no significant negative impact on pavement performance. The paving demonstration was the first in the state to use RAS in HMA to pave a public roadway in a controlled experiment.

“We are pleased to report that, one year later, the pavement is performing as good as a traditional roadway,” said Paulette Norman, KCRSD acting director. “This is an innovative approach that can help cut paving costs for taxpayers while keeping a valuable resource out of landfills. We are thrilled to see it performing well.”

The positive results from a road-paving demonstration bodes well for the future recycling of some 40,000 tons of tear-off roofing shingles generated in King County annually.

“This is exciting because it creates a new use for a material that has traditionally gone to landfills,” said Kevin Kiernan, division director of the King County Solid Waste Division. “Recycling asphalt shingles not only benefits the environment, but can have a positive economic impact as well.”

The most recent development is that WSDOT—which was closely involved in King County’s paving demonstration—is now working with the paving industry to outline requirements and next steps for a permissive specification to allow increased RAP and RAS in the design, production and acceptance of HMA in Washington state, with a goal to allow RAS in the 2011 paving season.

“This project is important to the paving industry in our state,” said Tom Gaetz with the Washington Asphalt Paving Association. “Our members are excited and ready to provide HMA with shingles to private- and public-sector customers.”

A touch of shingle

To implement the paving demonstration, LinkUp and its project partners worked with a team of stakeholders to address the interests of key market players, ground the study in reality and provide technical and other resource contributions. An advisory group was assembled to provide technical input and to ensure that the demonstration captured objective engineering data needed to gain wide acceptance of results. KCRSD played a leadership role by dedicating a roadway in King County for the demonstration, conducting pre- and post-construction testing and managing the paving contract. WSDOT provided valuable expertise and laboratory services related to the development of specifications and led the HMA mix design and testing. Advisory group members included regulatory agencies, HMA producers, recyclers, roofing contractors and local transportation agencies.

Selecting the right roadway helped lay a foundation for a successful demonstration. KCRSD selected a 2-mile stretch of roadway to be paved with 4,000 tons of 2-in.-thick overlay, offering the right mix of HMA tonnage requirements and traffic volumes, as well as manageable surface and subsurface conditions. Based on extensive evaluation of pre-construction roadway conditions, KCRSD designed the study with four HMA test sections: two experimental sections containing 3% RAS and 15% RAP, and two control sections containing only 15% RAP, as illustrated in Table 1.

Designing the technical standards involved developing specifications for the RAS product and the RAS-modified HMA mix.

The RAS specification included requirements for allowable materials, gradation, extraneous materials, moisture and asbestos-containing materials (ACM), as well as health, safety and other environmental requirements associated with handling asphalt shingles. The shingles recycler was required to inspect incoming loads of shingles, sort and remove all nonshingle materials and sample and test the shingles stockpile to verify that the material was free from ACM. While the risk of finding asbestos in asphalt shingles is low to none, other roofing products such as built-up roofing and mastics are known to contain asbestos, so they were not allowed.

The HMA mix design specified the amounts of RAS and RAP, as well as the estimated amount of virgin binder replacement from the RAS. The inclusion of RAP was not initially part of the study but because King County roads are traditionally paved with an average of 15% RAP, stakeholders strongly recommended that the experimental mix design include RAP to best reflect typical asphalt mixes in production today.

Through a competitive bidding process, KCRSD awarded the paving demonstration contract to Woodworth & Co. in July 2009. Woodworth is an HMA producer and paving contractor.

More stock in the pile

Woodworth proposed using an existing RAS stockpile (ground product) for the demonstration. While the RAS specification called for specific quality assurance and quality control procedures for incoming whole shingles, King County agreed to consider the proposed stockpile provided that the material met asbestos and material engineering standards. Initial testing of 20 samples of the ground stockpile using the standard polarized light microscopy test for ACM came back nondetect for all 20 samples.

King County also tested five additional samples using transmission electron microscopy, a more sensitive test for asbestos, which detected ACM in low levels. King County worked closely with its asbestos-accredited laboratory and a consultant with extensive experience as a roofer and accredited asbestos inspector to understand the test findings. Given the low level of ACM by weight in the samples, the expert consensus was that the ACM most likely came from non­shingle material.

The team decided that more aggressive inspection and sorting of incoming material was needed to identify and remove any potential ACM. Using a revised protocol and on-site training, the crew at Woodworth’s facility hand-sorted and rejected any potential ACM roofing materials from new incoming roofing material. Of the few nonshingle items sorted out of the whole shingle stockpile, two types of ACM roofing materials were identified through testing: builtup roofing with an aluminum coating and a patching material found on a few of the shingles. Within several days, a new RAS stockpile was produced, tested and accepted for processing.

Looking at fines

Materials engineering testing of the RAS product after processing indicated that the RAS product met the extraneous materials limit of the RAS specification, but did not meet the gradation and moisture content requirements by relatively small margins. Table 2 summarizes key engineering properties of the finished RAS product. Even though the materials exceeded the gradation and moisture limits, the KCRSD determined that the RAS product substantially met the engineering intent for the paving demonstration. This decision was in part based on the facts that Woodworth’s process included further reducing the material in size when blended with RAP and that excessive moisture content was manageable given consistent readings.

Additional testing was conducted on the HMA mix during production and pavement construction. Testing verified that all but one of the four test sections substantially met project specifications and materials standards. The test section in question was the first RAS-modified HMA mix, where higher oil and fines content led to significantly low air voids in the job mix. In-place density tests further verified air void loss. These results were below the WSDOT acceptance tolerance for air voids for field-produced HMA. However, the pavement looked perfect at lay down and initially performed as expected.

Additionally, WSDOT’s HMA mix design was slightly over-engineered in that it was for a roadway with more traffic than what is typical for the demonstration roadway. Thus, the engineering team decided to leave the questionable test section pavement in place but to modify the HMA to reduce the virgin asphalt content and fines for the second RAS-modified test section, which proved successful.

The high oil content in the first RAS-modified HMA mix indicated that the RAS product introduced into the HMA mix contributed a greater amount of asphalt binder to the final HMA product than originally expected. Both Woodworth and WSDOT staff hypothesize that double grinding RAS to meet gradation requirements resulted in smaller particle sizes and may have enabled more of the RAS binder to be released and effectively utilized in the HMA than originally predicted. Future research and analysis is recommended to confirm this hypothesis.

Meeting King’s demands

After paving installation, a series of tests were conducted to evaluate pavement performance. Extensive initial materials-engineering tests on the demonstration pavement indicate that using RAS as a part of the HMA mix has had no negative effect on pavement performance. Initial post-construction testing for deterioration, skid resistance, roughness, structural condition and rutting all indicated that all test sections of the roadway were meeting performance standards. To assess the condition of the roadway, the King County Materials Laboratory performed pavement-condition surveys by walking the site and documenting distressed areas.

Additional pavement condition surveys were conducted by WSDOT using a distress data collection van. The surveys revealed the roadway surface in all test sections continued to appear in excellent condition. The minor amounts of wear and tear shown are consistent with the expected performance of a road paved with traditional HMA. These tests were repeated one year after construction, yielding positive results, and are currently planned to continue annually through 2012.

Just as significant as these empirical engineering test results, the paving demonstration illustrated the critical importance of a multiparty partnership approach to such research and development efforts. Successful implementation of the paving demonstration was a direct result of the productive input and engagement of KCRSD, WSDOT, Woodworth and stakeholders. LinkUp is continuing to coordinate with other regional and national efforts to further the use of RAS in HMA and is planning to incorporate pavement with RAS in its own projects, including the rebuilding of several solid-waste transfer stations. LinkUp also will support WSDOT and the paving industry through the development of a permissive specification in Washington state for using RAS in HMA. Part of this effort will involve closer coordination with regulators, roofing contractors and shingle recyclers on best practices for sourcing and testing of tear-off roofing asphalt shingles for processing.”

If you’re interested in learning more about sustainable asphalt paving solutions, or you’d simply like a paving job completed, don’t hesitate to contact Dykes Paving, your premier paving contractors in Atlanta!

Surveyor Level

Before excavation and paving can begin, a surveyor uses a tool called a level to determine various angles and grades relative to the earth’s horizon. This is to ensure that the paved surface will be as “level” as possible. This level looks a lot like to a small telescope with a tripod.

Shovel

Among all of the high-tech paving tools that modern paving contractors take advantage of, the old fashioned shovel is still used for big and small jobs, alike.

Round-nosed shovel - mainly used for digging areas that could not be reached by machinery.

Square-nosed shovel - usually used for distributing asphalt and dirt into gaps that the machinery could not reach.

Asphalt Lute

An asphalt lute is a device that looks similar to a rake, and it’s used to create a smooth surface across the paved area, by pushing the asphalt forward and backwards. This is done until the area appears flat and even.

Pothole Tamper

A pothole tamper is a mechanism for fixing potholes in parking lots and roadways. The pothole is filled with hot asphalt and then compressed to form a solid, by pressing the tamper down onto the asphalt. The device is usually engine-powered - which vibrates a heavy plate over the asphalt. Sometimes it’s just a rod with a flat end that can be manually struck against the asphalt repair surface.

Crack Bander and Melter

This wheel-like drum is used for pouring crack filler into gaps on the newly asphalted surface. It is stocked with a filling compound, and subsequently, run along the length of a crack, emptying the compound into the crack. Crack banders tend to be used mainly for larger jobs.

Sealcoat Squeegee

Once asphalt is laid and smoothed out, the job is not yet completed. Asphalt ought to be sealed with a protective coating, also called “sealcoat.” Much like the asphalt itself, sealcoat needs to be made even, and a sealcoat squeegee is the appropriate tool to achieve this.

If you’re interested in commercial asphalt paving services, don’t hesitate to contact Dykes Paving, you’re top Atlanta paving contractors!