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Q. |
What is "Tracking" ? |
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A. |
Tracking is when
tires come in contact with uncured emulsion and it sticks to the
tires and then is transferred to the tops of the aggregate in
the wheel paths. Tracking will always polish off (wear
off) in time. |
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Q. |
What is "Bleeding" ? |
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A. |
Bleeding is quite
possibly the most misused term in all of asphalt surface
treatment. Bleeding is different from "Tracking", but
tracking may occur due to "Bleeding". Bleeding is when the
level of the asphalt is very near or above the top of the
aggregate. Bleeding can be a result of: too much
asphalt, too much aggregate, breakdown or crushing of aggregate, or aggregate being pushed into a
soft surface below. The latter may occur at any point in
time even long after application. |
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Q. |
Which state has the best
specifications for Asphalt Surface Treatment? |
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A. |
My personal
favorite is Texas with a little bit of Oklahoma sprinkled in.
Texas is second only to California in the volume of Asphaltic
Surface Treatment used, but we have not worked in CA.
Although there are often more ways than one to accomplish
something, there is always only one best way. So it is a
mystery that there are differences. An example would be:
If Louisiana would adopt Oklahoma's allowance of applying
emulsion on wet pavement, it would create more work days each
season which would spread depreciation over more work days and
in turn yield lower costs. Also Louisiana has their own
recipe for "Hot" AC, while Texas already has very successful
"Hot" ACs that are being produced daily and are readily
available in large quantities - why would LA not just use those?
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Q. |
I accidentally drove through your work area
and got tar on my vehicle, how can I get it off? |
|
A. |
The black substance on your
vehicle is probably Liquid Asphalt which is a product made from
crude oil. It will not harm your car or the paint.
But the sooner you get it off the easier it is to get it off.
For a quick fix use WD40 and a rag. Most commercial
cleaners from an automotive store that claim to remove tar
should also work. There is no reason to remove it from the
underside of the vehicle, as we have been told it is similar to commercially
applied asphalt based undercoating. |
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Q. |
What is Chip Seal/Asphaltic
Surface Treatment? |
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A. |
Asphaltic
Surface Treatment, also known as Chip Seal, is a process where
pure Liquid Asphalt is distributed over an existing pavement
(left side top picture) and then Aggregate is spread over the
asphalt (left side second picture) before it cures. The
surface is then
rolled to seat the aggregate. once the asphalt has cured,
any loose aggregate may then
be swept away leaving a new driving surface that seals out all
moisture. The asphalt seals out water and the aggregate
carries the traffic and prevents tires from coming in contact with
the asphalt. Asphalt surface treatments are an important
step the most successful pavement preservation programs where a
hot-mixed asphalt surface gets a life-lengthening asphaltic surface
treatment to renew and extend its life for several years. |
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Q. |
Why has the asphalt on my parking lot {driveway
or street} deteriorated and failed? |
|
A. |
Most people do not
understand what causes pavement failures. The chief cause
of pavement cracking, rutting, and potholes is moisture that
seeps into the base and sub-grade through cracks in the surface. When hot-mixed asphalt
ages to the extent that it becomes brittle, cracks develop
and then moisture sneaks in. The base and sub-grade below
the pavement surface are what supports the weight of traffic
(not the pavement surface) and it must not yield. Moisture acts as a lubricant
between gravel, soil and other earthen particles in the base and
sub-grade which promotes
movement when traffic rolls over. The typical process
occurs first by the development of very small cracks which allow
moisture in, then once
the material below the surface starts to move, the surface
begins to break showing larger cracks (allowing even more water
in), then alligator cracking
occurs, then potholes and rutting, then all is lost. All
because of moisture. |
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Q. |
Can I save my parking lot {driveway or
street} with an asphaltic surface treatment? |
|
A. |
If your pavement
structure has not yet failed, an asphalt surface treatment will
certainly extend the life of your pavement structure by preventing the
dangerous infiltration of moisture below the surface while at
the same time provide a new uniform driving surface. But
if your pavement has already started to fail in isolated areas, those failures
will require repair and patching prior to the application. |
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Q. |
Can I save money by resurfacing my
asphalt pavement with an asphalt surface treatment? |
|
A. |
Absolutely.
Asphalt
surface treatment is the very best way to seal your existing
asphalt pavement while providing a beautiful and durable new
surface. We believe that every dollar spent on
pavement preservation now will save approximately ten dollars in
pavement rehabilitation in the future. TXDOT (Texas Dept of
Transportation) seems to have a goal of applying a new asphaltic surface
treatment to many of their roads approximately every five years. |
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Q. |
What is a Fog Seal? |
|
A. |
A fog seal is a
light application of emulsified asphalt to renew an old
pavement surface. Fog Seals are used to seal small cracks,
increase aggregate retention, rejuvenate and add a uniform dark
new color to old pavement. A slow setting emulsion is distributed
over the pavement surface and left to "break" and cure. Once the water
and asphalt separate, and depending on temperature, wind and
humidity, the surface is usually ready for traffic within one or two
hours with a beautiful new water-tight surface. Fog Seals
are used as an additional step in more sophisticated pavement
preservation programs where hot-mixed surfaces get a
life-lengthening asphalt surface treatment, and then the surface treatment gets
a fog seal after a while to extend its life as well. Fog
seals are also applied directly over less aged hot-mixed asphalt
surfaces in some cases prior to the inevitable development of
noticeable cracks. |
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Q. |
My asphalt pavement has many small
cracks - is it too late for a fog seal or an asphalt surface
treatment? |
|
A. |
Tiny cracks often
begin to appear in hot-mixed asphalt surfaces as early as six
months after installation. And some agencies will apply a
fog seal when these are first detected. Usually a Fog Seal
will handle cracks smaller that one sixteenth of an inch in
width. A one course asphalt surface treatment will usually
handle cracks that are no wider than one eighth of an inch.
And a second course of asphalt surface treatment may
be required if cracks are still visible after the first course.
We have successfully sealed pavements with cracks of
approximately one quarter inch in width with two courses.
It is best to seal cracks of one quarter inch or more prior to
resurfacing. |
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Q. |
How do you know when to adjust the
asphalt rate on an asphaltic surface treatment? |
|
A. |
The easiest way to consider an asphalt surface treatment is to
think of a
saucer partially filled with water and some marbles. If
the saucer starts out with 1/2 inch of water in it and then one
marble with a diameter of one inch is dropped in, the water will
come up about 1/2 inch on the marble. But if you continue
to add marbles, the water level will rise nearer and nearer to
the top of the marbles with each additional marble. Just
as the water rises on the marbles, so will the liquid asphalt
rise nearer the top of the aggregate of an asphaltic surface treatment. If
the asphalt rises
high enough, the tires of vehicles may reach down and touch it. When this happens, the asphalt will stick to the
tires and "tracking" will occur - and possibly something worse.
So if you desire to have more rock, the asphalt rate must be
reduced. So it is usually considered good
practice to start out light with
the asphalt and aggregate and slowly increase the aggregate rate until the
desired rock appearance is reached, then tweak up the asphalt
rate to match. If the rock rate is increased - the asphalt
rate must be decreased, but remember the chief purpose
of the rock is to prevent tires from coming in contact with
the asphalt
which is there to seal out water. So be sure there is
plenty of space between the aggregate. A wise old TXDOT
inspector once said, " a quarter should easily fit between
the rocks when laying flat on the asphalt." |
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|
Q. |
What is the lowest temperature
that emulsion may be applied? |
|
A. |
Almost every state
department of transportation has specific seasonal requirements
restricting the application of asphalt surface treatments, and most also
have specific temperature ranges that override any calendar date
restrictions. With so many different rules, P. R. Parker
Company decided to experiment and find out what the real limits
are for CRS-2P emulsion. We started at 55° and rising, and
worked our way down in 5° increments. We had success at 45° and rising,
with a low temperature of 38° the following night. The
morning of the application, the temperature rose to 45° at 10:20 a.m. at which time we
began the application which we completed by 12:00 noon. The
temperature continued to rise following the application to a high of
61° for the day, and then fell again that night to a low of 38°. We waited
until 10:00 a.m. the next morning to sweep the area, and all was good.
When we performed the application at 40° and
rising, we experienced some rock loss in isolated patches. |
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Q. |
Your staff said the dark color of
the wheel paths (Tracking) was due to not enough emulsion.
How can this be? |
|
A. |
When there is not
enough asphalt to hold larger aggregate firmly in place during
curing, it can get rolled over by traffic which causes the
individual rocks
to become coated. This coating of the rock robs even more
asphalt away from the road surface where it is needed to seal
the road and hold the rock. You indicated that you were an
LADOTD Engineer (you are the 4th to ask this), so with all due
respect, the general mindset of the day within LADOTD seems to
be, "what is the least amount of asphalt required to hold
the rock", while the practice in Texas and other states with
long histories in asphaltic surface treatment is, "we are
here to seal the road so we want as much asphalt as possible".
If your road is perfect with no cracks, it can easily take 0.41
gallons of CRS-2P per square yard with a Size-2 aggregate - if
there is any cracking at all then the asphalt rate must be increased. |
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Q. |
Can No. 7 Stone be
substituted for LADOTD Size 2 for asphaltic surface
treatment? |
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A. |
Absolutely not!
Although the gradations are identical on the No. 8 sieve and
above, the stone must be washed. Any amount of material
passing the No. 8 sieve is not useful for the intended purpose
of the aggregate, and anything smaller than the No. 16 sieve is
detrimental to a successful application. Only washed stone should be used for chip
seal aggregate. We have found that any dirt, dust, silt or clay can form a
film (much like flour in the kitchen) around the aggregate that works to prevent the rock
from adhering to the asphalt. |
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|
Q. |
Did your company work in Nebraska? |
|
A. |
Yes we went to
Nebraska in 2008 to apply a fog seal on I-80 and I-880 near
Lincoln, NE. The NDOR (Nebraska Department of Roads)
project consisted of 328,900 gallons of slow setting emulsion,
some of it applied at night, and we where
there for four weeks performing the work. The NDOR
specifications are very clear and reasonable, and we intend to do more
work in Nebraska in the future. |
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|
Q. |
What are the Asphalt Surface
treatment Sections/Items for other State DOT Specifications |
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A. |
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Q. |
Why does your company let people
drive so fast in your work zones? |
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A. |
That is an
interesting question. We have requested various law
enforcement agencies to please come and spend some time in our
work zones hoping their presence might influence motorists
to slow down. But not once have any agreed, so we
eventually gave up and stopped asking. We are not permitted to
change the speed limits. We are only allowed to post
construction signs that are shown in the plans. Several
years back, Louisiana DOT allowed us to use a pilot car as had
been the practice in Texas for many years, and now pilot cars are
required on most Louisiana projects. This has been a great
help in reducing speeds and windshield damage. It seems
that law enforcement does not consider our work zones as open-public-roadway. Much of our construction equipment and
vehicles operating within our work zones are "unlicensed" and
are typically hauled to the project on trailers. This may
be one reason law enforcement stays clear of our work zones.
All we can really do is post flaggers at each end of the work
zone, run a pilot car, and say, "please slow down for your,
and
everyone's safety".
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|
Q. |
How do you know the computers in
your distributors are correct? |
|
A. |
The tank of each P. R. Parker Company, Inc
distributor is calibrated in accordance with Texas Department of
Transportation (TXDOT) testing procedure (TEX-922-K) which is certified and
stamped by a Licensed Professional Engineer. Each
distributor is then
periodically verified throughout the life of the distributor. This
certification guarantees the owners of our projects that they are receiving the
quantity of asphalt product for which they are paying. The data collected while
performing the TXDOT procedure has also been suitable for preparation
of all other tank certifications we have encountered to date. |
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|
Q. |
Did your company apply an asphalt surface
treatment at night? |
|
A. |
Yes we applied an asphalt
surface treatment during a nighttime operation on I-49 between
Opelousas and Lafayette, Louisiana. It was decided that it
would be safest to perform the work at night due to high
traffic volumes. During the hours of 7:00 p.m. and 6:00 a.m. traffic
was channeled into
one lane northbound and one lane southbound while we applied the
one-course surface treatment within
the lane closures. According to LADOTD personnel,
this was the first time an asphalt surface treatment had been
applied at night in Louisiana.
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|
Q. |
Did your company apply a chip seal out of season in
December? |
|
A. |
Yes we applied an asphalt
surface treatment during December on an experimental LADOTD (LA
Dept of Transportation & Development) project on LA 490 near
Chopin, Louisiana. LADOTD was experimenting with the use
of reclaimed asphaltic pavement mixed with a rejuvenating agent
as a paving surface course over an asphaltic surface treatment over a
milled surface. |
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|
Q. |
How can a subcontractor get established
with
P. R. Parker Company? |
|
A. |
The first step to is to be
properly insured, which means having coverage and limits equal
to what we are required to have as a prime contractor by the owners of
our projects.
The next step is to bid on our work. We take great pride in the
fact that we award to the subcontractor who was low
bidder on bid day.
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Q. |
My windshield was broken on one of your
projects, what is the procedure for having it replaced or
repaired? |
|
A. |
We do not replace
or repair damaged
windshields on vehicles that we do not own. We are
required by the Department of Transportation to place "loose
gravel" signs in our work zone and we are not allowed to begin work until
State representatives have confirmed their placement. We
are not at liberty to do any more than that, such as change the speed limit, although
irresponsible speeds are the cause of
windshield damage. Most windshield damage occurs
when one vehicle passes another traveling in the opposite
direction while one or both are traveling at speeds greater than
25 mph. Speeds of 25 mph and less, no matter what the
posted speed may be, are usually adequate to prevent debris from
being throw up that
might damage your vehicle or those of others. Your own
insurance provider is the best avenue for road hazards of
this type. |
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|
Q. |
Why doesn't P. R. Parker Company
mark up subcontractor's prices? |
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A. |
When we turn in
our bid to the owner we will typically bid the exact unit prices
quoted to us by the subcontractor whose prices we used.
This allows all subcontractors to immediately know whether or
not we used their price, and to have confidence of complete
confidentiality when they give us a quote. |
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|
Q. |
How do you know how much rock is
in a stockpile? |
|
A. |
The key is
consistency of stockpile housekeeping. All stockpiles
should be constructed neatly and then reshaped at the end of each shift back to its original
configuration (i.e. conical if it was originally conical).
A simple "T" made from two pieces of 2
x 4 lumber of known lengths can then be used with a camera to quite
accurately estimate the volume of the pile. Stand the "T"
at the base of the pile and take a picture of a new stockpile.
Print the picture and use the known lengths of the "T" to
prorate the dimensions of the pile. Then use these
dimensions with the original know tonnage as a ratio with later
dimensions to estimate the volume. |
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|
Q. |
Does P. R. Parker Company build
bridges? |
|
A. |
No, we have never
built a bridge, but we have installed or constructed box culverts that may
resemble a bridge. These projects are often called
"bridge replacements" by the owning agency, but in the case of the projects we have
done, the old bridges were replaced with new box culverts. |
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|
Q |
Can an asphalt surface treatment
be applied directly onto base or does it have to first be
primed? |
|
A. |
We have
successfully applied asphalt surface treatments directly onto
completed sub-base without a primed surface. The base
must be kept moist, and the first course must be emulsion.
Emulsion is well suited to wet conditions, and bases/sub-grades
must be kept moist to prevent unraveling, so the two go
hand-in-hand. It is certainly better to prime a base prior
to application, but when it is unpractical or unfeasible, it is
possible to skip the prime and still achieve success. The
first examples of this process in which we were involved,
occurred in north Louisiana when new cement-treated base needed
to be cured under traffic. Since prime courses do not
stand up for long periods under traffic, LADOTD decided to
attempt an asphalt surface treatment directly and immediately
over a cement-treated base to provide a curing membrane and
driving surface at the same time. It worked great.
Those first applications where later covered with a hot-mixed
asphalt surface, but now second courses of asphalt surface
treatment with both hot asphalts and emulsions are successfully
being used as the final surface.
|
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|
Q. |
What is the difference between
Emulsion and Hot AC? |
|
A. |
There are
basically two types of liquid asphaltic materials that we
regularly apply: Emulsions and Hot AC (Asphaltic Cement).
Although both types do an excellent job at sealing, each has
different characteristics when it comes to application.
Emulsions such as
CRS-2P are generally considered to be excellentat at
aggregate retention once they properly cure and set up, but it
can take several hours to properly cure. Emulsions are
therefore excellent for new construction, city and county
streets, parking lots or other situations where traffic
can be minimized until properly cured, only after which sweeping
can take place. But when traffic (especially higher speed)
must be allowed on a surface on the same day of application,
things quite often get messy with emulsions, and this is
aggravated increasingly as daytime temperatures rise.
Perhaps emulsions best characteristics are its good performance
with lower surface temperatures and they may be applied over wet
surfaces, and with wet aggregate, so this means more application
opportunities. {good with: low temp, damp surfaces} {not
so good with: high temp, immediate high traffic}
Hot AC such as
PAC-15, AC-15P, AC-20-5TR, and many others set up very quickly
and can usually be rolled, completely swept and open to traffic
almost immediately. This makes ACs a favorite among
contractors and engineers for resurfacing higher traffic and/or
higher speed roads. Hot AC with its fast setup is a very
high production and much less messy material, and all but
eliminates motorist complaints. AC may not be applied on
wet surfaces and it is more limited by cooler surface
temperatures than emulsions, so this means more limited
application opportunities. {good with: high temp, immediate high
traffic} (bad with: low temp, wet surfaces} |
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|
Q. |
What is a distributor calibration? |
|
A. |
A distributor tank
calibration is a test to insure that the computerized onboard metering
equipment is working correctly. As described in TXDOT
TEX-922-K, we have an Asphalt Distributor Tank Calibration Test (Section 2, Part I)
performed on each of our new distributors with the resulting metal strap mounted
onto the driver's side of the tank. Then periodically we employee
a Licensed Professional Engineer to oversee an Asphalt
Distributor Tank Verification Test (Section 3, Part II) to insure that the strap
remains correct. A typical Tank
Verification Test usually consists of a few check points near the
bottom, a few near the midpoint, and some near the top. This will
verify or construct data arranged in either 25 or 50 gallon increments within
allowable tolerances. The testing procedure leaves the actual
number of check points up to the attending Engineer.
Engineers representing our customers may request a copy of the
calibration by clicking Ask a Question. |
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|
Q. |
What is a spray bar test on a
distributor? |
|
A. |
A spray bar test
is a test to insure that the rate of asphalt metered out by a
distributor's onboard computer, is being evenly distributed
across the surface. As described in TXDOT TEX-922-K, we
periodically Employee a Licensed Professional Engineer to
perform an Asphalt Distributor Spray Bar Test (Section 4, Part III) on each of the
Company's distributors with a written and stamped report. Our
personnel performs the same procedure several times each season
using volume instead of weight. We use containers
manufactured by TUPPERWARE each having the exact same dimensions.
We follow the procedure outlined in TEX-922-K, Section 4, Part III,
except that we compare the volume of liquid from each nozzle rather than
its weight. The resulting data has proven to be exactly the same. |
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|
Q |
What is the difference or
relationship between Embedment and Asphalt Rate? |
|
A. |
The asphalt
"Rate" is the exact gallons of asphaltic liquid
distributed/sprayed over a
given area, The "Embedment" is the depth of the
residual asphalt as a
percentage of the average height of a single piece of aggregate.
So, a 40% embedment on a 1/2" aggregate would represent a depth
of 0.20 inches of residual asphalt. Although it may at first seem
like a simple task to calculate the embedment from a given rate,
or vise versa, there are several things you must consider that
will
drastically complicate things.
We know that one
Square Yard (SY) is 36" x 36" or 1,296 Square Inches, and we know
that there are 231 Cubic Inches in one Gallon (Gal). So
mathematically we can determine that a rate of 0.40 Gal/SY yields a
liquid depth of 0.0713 Inches in an area of one SY. And if a single piece of
aggregate is 1/2 inches tall, then we see that this appears to
be an embedment of about 14%. Now we cannot forget
that this depth of 0.0713 Inches is "before" the addition of aggregate:
which will displace some amount of liquid
(reference), which will increase the depth of the liquid,
which will increase the embedment. Now you see why I said it
can get complicated. Aggregate size, shape, gradation, and
amount all effect embedment and rate, as well as asphalt to
water ratios when dealing with emulsions. |
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|
Q. |
What is a box culvert/what is the difference between a
box culvert and a bridge? |
|
A. |
A Box culvert (left bottom
picture) is a concrete drainage structure with a rectangular
section that is constructed from the ground as opposed to bridge
construction which typically requires above-ground operations.
A box culvert may be used to replace a bridge in many
applications. A concrete box culvert is typically
constructed by one of two methods: precast or
cast-in-place concrete. A precast box culvert is constructed by
placing fully completed precast sections on a prepared
sub-grade, much like laying concrete pipe. A cast-in-place
culvert is constructed in up to three phases: (1) floor or
foundation, (2) Walls, (3) Top, with all of this work being done
from the ground. |
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|
Q. |
Should a
county, parish, town or city self-perform asphalt surface
treatment? |
|
A. |
We
have performed work for local government agencies that have
their own asphalt surface treatment equipment. The
reasons we have heard they call us are lack of expertise, lack
of production, cost concerns, and unsatisfactory results. Our
operators apply asphalt surface treatment every day and that is
all they do. A county or town would have to perform
approximately
$10,000,000 of asphalt surface treatment each year for their
employees to equal that much hands-on experience, but most only spend a fraction of that.
Typically county employees perform many different types of work in a year
and only spend a minimal amount of time performing asphalt
surface treatment.
Taxpayers
of any county, parish or town would almost certainly agree that all work should be
performed by contractors if allowed to see the real difference in
cost, and if
for no other reason, there is the guarantee of proper
performance provided by the contractor's bonding:
http://www.sio.org/html/why_bonds_reqd.html
One of the most, successful pavement programs I know of is that
of Bienville Parish, Louisiana. Their own forces have become
experts at patching and base work, while they contract out the
final asphalt surface treatment. Their current Road Superintendent
is one of the most knowledgeable in that state when it comes to asphalt
surface treatment, and could certainly manage the chip seal work.
But he and the Bienville Parish Police Jury stretch their dollars over the most miles
of road by
being experts at a few important operations instead of
attempting to be jacks-of-all-trades. Annually Bienville Parish accepts bids for an
asphalt surface treatment project in the $1,000,000 range.
Their forces then prepare new and existing roads all over the
parish to be surfaced. Then the contractor is released to
apply asphalt surface treatment, and their roads are among the
best in all of Louisiana. |
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|
Q. |
Is your company Union or
Open Shop? |
|
A. |
P. R. Parker
Company is Open Shop, Non-union, and does not support socialism
or
discrimination in any form, and the Company itself is a product of free enterprise, a chief principle on which these United States were
founded. |
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