What We Do Best

Asphalt-Rubber Chip Seal &
Asphalt-Rubber Cape Seal

What Are Asphalt-Rubber Chip Seals and Asphalt-Rubber Cape Seals?
Asphalt-Rubber Chip Seals and Asphalt-Rubber Cape Seals fall under the category of Road Surface Treatments.  They are a cost-effective solution for roads that have alligator cracks in the 3/8” to 1/2″ range.  In the hierarchy of road maintenance products, it is above a slurry seal, above Micro Surfacing, above conventional emulsion chip seals, but before an overlay.
How Does An Asphalt-Rubber Chip Seal Differ From An Asphalt-Rubber Cape Seal?
In an Asphalt-Rubber Chip Seal, hot, viscous, Asphalt-Rubber binder is applied to the road.  Then preheated aggregate chips are dropped into the binder.  The chips are rolled into the binder with pneumatic rubber-tired rollers.  Then any excess chips get swept up and disposed of.  A fog seal of diluted emulsion is applied to the Asphalt-Rubber Chip Seal to further lock in the chips and to give the road a nice black appearance as a contrast for striping.  Asphalt-Rubber Chip Seals are primarily used on County “farm to market” roads and on highways. An Asphalt-Rubber Cape Seal takes an Asphalt-Rubber Chip Seal, and instead of a fog seal of diluted emulsion being used to finish it off, uses a Type II Slurry Seal as “The Cape” over the Asphalt-Rubber Chip Seal.  The Type II Slurry Seal fills in all the roughness in the Asphalt-Rubber Chip Seal, making it more “neighborhood friendly” for residents to recreate with their skateboards, rollerblades, and scooters.  Asphalt-Rubber Cape Seals are primarily used in residential applications.
How Do Asphalt-Rubber Chip and Cape Seals Differ From Emulsion Chip and Cape Seals?
There are a couple of main differences between Asphalt-Rubber Chip and Cape Seals and Conventional Emulsion Chip and Cape Seals:
  1. Three times more binder goes down on the road with Asphalt-Rubber vs. Conventional Emulsions. Asphalt-Rubber Binder can be shot at a much higher rate because it is so viscous and gooey.  It is “honey-like” in viscosity compared to Emulsion Chip Seals that are more “water-like.”
  2. Because Asphalt-Rubber Chip and Cape Seal binder is so thick and viscous, and you are applying so much more material to the road than in a Conventional Emulsion Chip Seal, you can be successful on much larger cracks. Convention Emulsion Chip and Cape Seals work best on alligator cracks that are in the 1/8” to 1/4″ range.  Asphalt-Rubber Chip and Cape Seals of course work well on 1/8” to 1/4″ cracks, but they also excel at holding back 3/8” to 1/2″ reflective alligator cracks, cracks that are much too wide for a Conventional Emulsion Chip Seal.

    Why is this?  Because with a shot rate of 0.55 to 0.65 gallons of binder per square yard, a lot of material is being applied with an Asphalt-Rubber Chip or Cape Seal.  Enough to fill larger cracks, bridge larger cracks, and still have enough binder on the road to hold the aggregate.  Conversely, Conventional Chip and Cape Seals are routinely shot at 0.25 to 0.40 gallons of emulsion per square yard.  But 1/3 of the emulsion is water.  So, the actual amount of residual asphalt left on the road after the emulsion “breaks” and the water evaporates is 67% of the shot rate, or 0.17 to 0.27 gallons per square yard, about 1/3 of the amount of binder that is on the road with an Asphalt-Rubber Chip or Cape Seal.  It’s a magnitude issue.  You have more binders, a thicker membrane, and a binder that is flexible and elastic.  This all leads to success with bigger cracks.
  3. Conventional Emulsion Chip Seals cost about $1.00 to $1.25 less per square yard than an Asphalt-Rubber Chip Seal. Conventional Emulsion Cape Seals cost about $1.00 to $1.25 less per square yard than an Asphalt-Rubber Cape Seal.  Conventional Emulsion Chip and Cape Seals last about 6 to 8 years on roads with 1/8” to 1/4″ alligator cracks.  Asphalt-Rubber Chip and Cape Seals last about 12 to 15 years on roads with 3/8” to 1/2″ alligator cracks.  So, for a little more money per square yard, you get a lot longer life expectancy.
What Types Of Roads Are Good Candidates For Asphalt-Rubber Chip and Cape Seals?
This question has been partially answered already in the paragraphs above.  The type of roads where Asphalt-Rubber Chip and Cape Seals work the best overtime is on roads with alligator cracks in the 3/8” to 1/2″ range and show no signs of base failure, which is indicated by concave depressions in the pavement.  Because the Asphalt-Rubber Chip and Cape Seal binder is applied at such a high rate, 0.55 to 0.65 gallons a square yard, there is plenty of material to get down in the large alligator cracks, bridge the cracks, and have enough left on the road’s surface to grab onto and hold the chip.  Very rarely do you hear of issues of “chip loss” with Asphalt-Rubber Chip and Cape Seal jobs because there is so much more binder on the road’s surface and because the binder is so sticky and gooey.
Asphalt-Rubber Chip Seals and Cape Seals vs. Overlays – $aving Money By Picking The Right Roads.

Sadly, many agencies jump from slurry seals and Micro Surfacing directly to asphalt concrete overlays (hot mix) without looking at two cost-saving options that lie between these two bookends.  When the cracks move into the 1/8” range, it is beyond a slurry seal.  Slurry seals are meant as a first line of defense on newer roads. But 1/8” to 1/4″ alligator cracks are in the range where Conventional Chip Seals are effective.  When the cracks move into the 3/8” to 1/2″ range, Asphalt-Rubber Chip and Cape Seals become a very good choice.

Conventional Chip Seals and Cape Seals are about 4-5 times less expensive than a 2” AC overlay.  Asphalt-Rubber Chip and Cape Seals are about 3-4 times less expensive than a 2” AC overlay.  So, if you pick the right roads, roads with the right sized cracks, you can get to a lot more roads each year than with an AC focus, and in that process, eliminate a lot more cracks each year, driving up your PCI scores, all with the same budget.

How Is The Asphalt-Rubber Spray Applied Binder Made?

The same binder goes into Asphalt-Rubber Chip Seals and Asphalt-Rubber Cape Seals.  It is “Field Blended”, meaning that it is blended in the field on the day of the job.  It is so viscous that it cannot be stored at a terminal or depot because you would have to keep it at 375° F – 400° F 24/7 in order to be able to pump it out, and that would be cost-prohibitive.

The contractor sets up the blending equipment early in the morning on the day of the job and starts the heating/blending process.  The Performance Graded asphalt (PG 64 -10, PG 64 -16, PG 70 -10) which is chosen based upon the climate conditions where the job is to be performed is heated to 425° F.  The car tire rubber and high natural rubber are loaded into their appropriate bins.  When the asphalt reaches temperature, the asphalt and rubber are introduced to each other in a high-sheer blender, and then are sent to a large reaction vessel.  The asphalt and rubber are reacted with constant agitation at high temperature (425° F) for 45 minutes per spec.  Then a sample is drawn.  A hand-held Haake Viscometer (torque meter) is inserted into the center of the sample can.  A temperature probe is put in the can.  When the mixture cools to 375° F, the operator takes a measurement of viscosity on the Haake Viscometer.  The mix site operator is looking for a viscosity of 1,500 to 2,500 centipoises at 375° F.  That is the range where the binder will fan out correctly when applied from a distributor truck.  If the viscosity is too low (too watery), more rubber is added and reacted, and then another sample is pulled and tested.  If the binder’s viscosity is too high (too thick), more asphalt is added and reacted further, and then a sample is pulled, and the viscosity is checked again.

How Are Asphalt-Rubber Chip & Cape Seals Constructed?

Once the binder reaches the proper viscosity of 1,500 to 2,500 centipoises, a spreader truck is loaded with Asphalt-Rubber binder and it is delivered to the job site for application.  The spreader truck leads the Asphalt-Rubber train, putting down binder in the range between 0.55 to 0.65 gallons per square yard.  Right behind the binder spreader truck is the aggregate spreader truck.

Aggregate is placed into the binder at the rate of 28 to 32 pounds per square yard. The aggregate comes delivered from a hot plant preheated to 325° F and lightly coated with asphalt at 1/2% by weight. The preheating is a quality control measure for cooler climates. If you have a binder that has started to cool and the chip spreader has fallen farther than ideal behind the spreader truck, the hot aggregate will melt itself into a cooling binder. The salt and peppering of a light application of asphalt on the aggregate at the hot plant also aids in maximum rock retention by making the aggregate sticky.

Right behind the chip spreader are 3 rubber-tired pneumatic rollers to roll the aggregate into the binder. Pick up sweepers follow the rollers to sweep up any loose aggregate.

If it is an Asphalt-Rubber Chip Seal, it is finished off with a fog seal of CSS1 or CSS1h Emulsion, diluted 50% with water, and shot at 0.10 gallons per square yard to lock in the chips and give them a nice black color.

If it is an Asphalt-Rubber Cape Seal, a Type II Slurry Seal goes down over the top as “frosting” to smooth out the surface and get rid of the Chip Seal’s roughness to make it rollerblade, scooter, and skateboard “friendly”.

Why Do Asphalt-Rubber Chip and Cape Seals Do Such A Good Job Of Holding Back Alligator Cracks Over Time?

1. In the blending process at high temperatures, some of the car tire rubber digests into a very viscous gel. This gel changes the properties of the base PG graded asphalt, making it more flexible and more elastic.  Flexible and elastic are good words to use when you are talking about inhibiting cracks.  If a pavement is rigid and unforgiving, cracks have an easier time breaking through.  But if the binder is flexible and elastic, it is harder to break when forces are exerted on it.

Think of the Asphalt-Rubber binder as a trampoline.  How hard is it to break through something that is moving, is flexible, is elastic?  The car tire rubber, blended at high temperatures, modifies the asphalt in a very positive way, making it less susceptible to reflective cracking.

2. A second benefit of adding car tire rubber at high temperature to the base PG graded asphalt is that the chemicals that originally went into the manufacturer of the car tire to resist aging from UV and ozone leach out into and become part of the new Asphalt-Rubber binder.  This is another reason why Asphalt-Rubber Chip and Cape Seals last as long as they do (12 to 15 years).  The car tire rubber, at high temperatures, modifies the asphalt and S-L-O-W-S its normal aging process, which then slows the rate at which the modified Asphalt-Rubber binder cracks from aging.

In the 1930s and 1940s, car tire sidewalls routinely rotted out before the tread on the tire was gone. To overcome this problem, car tire manufacturers added anti-ozonates, carbon black, and antioxidants to the car tire rubber to combat these “aging” problems.  Now car tires resist decay so well that they just sit in landfills, impervious to the elements.

Before & After

Scoter Way, Suisun
Before: September 2008 | After: August 2019 (11 YEARS LATER)

Lugo Park, Lynwood.
Before: May 2013 | After: August 2019 (6 YEARS LATER)

Why are we your best choice

We Will Help You Every Step Of The road


pavement maintenance


road and parking


pavement solutions

Manchester, West Sacramento
Before: Oct. 2005
After: Oct. 2019 (14 YEARS LATER)

When it comes to pavement maintenance, APS can do it all

Let us show you