The
2002 construction season is winding down as Thanksgiving day
approaches. Other than the two week period of rain in the last
part of October, our fall season has been pretty good for
pushing the completion of projects. With the late spring
starts in several divisions, the good fall weather has
provided for some opportunity to fill up the season.
As
of November 22nd, both crews are up in Grundy County working
on the new Highway 20 paving projects. Virg and his crew have
been laying shoulder stone and doing some subdrain work on the
Manatt portion of this construction project. Bob and his crew
are finishing up on Carlson's east portion of Highway 20. This
project will then tie into Irving Jensen's 6 mile stretch of
new pavement. They will have installed over 71,000 feet on
Carlson's section and will have approximately 74,000 feet
available to install on Jensen's. This project does not have
to be completed this year. Once the weather starts closing in,
they will shut down for the year. As of today, this will bring
the approximate total installed to 660,000 feet.
At
the start of the year I wasn't expecting to even have 500,000
feet the way the lettings were going! This crew also laid
several thousand tons of shoulder stone to fill in between
subdrain projects. We have approximately 200,000 feet on the
books for next year and will be hitting every letting hard to
fill another season.
Sealcoating
finished a strong season by combining several stabilization
projects. It was a season mainly comprised of city, county and
a very small portion of state work.
One
state project that we were awarded in the August letting
launched Manatt's down another avenue in providing recycling
and stabilization options. The project was 20 lane miles of
full depth shoulder recycling and stabilization using foamed
asphalt. This process has been used in several western states
and is slowly working its way east. This was a test project
for the Iowa DOT and they were very impressed with the
results.
Foamed
asphalt is a controlled process in which hot asphalt cement
(350 degrees) comes in contact with a small amount of water.
The asphalt cement explodes into millions of bubbles. In this
form the volume of asphalt expands as much as 15 times,
drastically reducing viscosity. While in this state, the
asphalt is mixed with a cold moist aggregate. The bubbles
formed burst when they come into contact with the aggregate,
uniformly dispersing amongst the fine particles to form a
stable mortar. The reaction time lasts for only 10 to 20
seconds for mixing as the asphalt returns to its normal liquid
state. This process allows for the use of smaller amounts of
asphalt cement per square yard because it has far better
particle coverage.
The
Wirtgen WR2500, that we have just recently purchased, is
equipped with the foamed asphalt system. It has a
thermostatically controlled heating system for the asphalt
lines and spray bar. The spray bar is made up of 16 expansion
chambers where the asphalt cement is introduced to the water
and air mixture. This spray bar directs the foamed asphalt
into the cutting head chamber and is then mixed with the
recycled (pulverized) material. The recycler machine is
coupled to, and pushes an asphalt tanker, plus, pulls a truck
with a water tank. (See pictures above.) Compaction is done
directly behind the machine starting with a 12 ton vibratory
pad foot roller (see picture #2 below). Blading of material is
done as the material is moist and then rolled again with a
rubber tire roller (see picture #3 below). The final surface
is rolled with a smooth drum roller (see picture #4 below).
|
Picture
#2:
Vibratory Pad, Foot Roller,
& Motor Grader
|
Picture
#3:
Rubber Tire Roller
|
Picture
#4:
Smooth Drum Roller
The
original contract was bid with one mix design for
construction. As test results came back, it became evident
that some changes were going to have to be made to achieve
finished minimum construction densities. The biggest change
was the addition of Portland cement to the design, which was
later changed to fly-ash. Other mix design changes involved
different percentages of asphalt cement being added for
foaming in addition to crushed shoulder stone for added
stability.
This
project was a learning experience for all involved. For our
first week of operation we had the knowledge and help from
some international engineers to educate ourselves with the
process. Marcus Stockhausen from Windhagen, Germany with the
Wirtgen group worked directly with Kurt in the operation of
the foamed asphalt system on the machine. Eric Uppink from
Kloof, South Africa who is a civil engineer technician with
Louden International worked with Virg, Jeremy and myself in
the construction process of this project. Their expertise was
greatly appreciated!
This
project is going to open the door for several more
opportunities to utilize this process at the State and County
levels!
I
want to thank Kurt, Virg, Jeremy and the whole sealcoat crew
for the professional attitude and quality-minded completion of
this project. Everyone and every piece of equipment had a
direct effect on the outcome of the final product. Several
times, on the go, ingenuity was used which shows what this
crew can really do when put to the challenge.
I
also would like to thank Mark Olson and Dave Sanders for
putting up with the added challenges of spreading the fly-ash
and cement. Carmen and the weld shop went the extra mile to
fit us in for our equipment modifications, hats off to them!
Brett
Strong dropped in for a couple of days showing his
versatility! Also, Phil Maddison and his milling crew along
with thanks to the Ames Division for the water truck and
trucking needs. I'm sure I missed someone, but it was not
intentional!
My
last "att-a-boys" go out to Bob and the subdrain
crew. The last few years the competition has been tough and
the volume of work has declined. We managed another
respectable year and that is due to your superior work ethic
and determination.
The
projects have changed and involve a lot more, stop and go
construction, plus a higher level of labor. I try my best to
schedule projects in a logical order, but when you are the
sub-contractor, you go as the prime contractor fills his
schedule.
I
don't get out to the jobs like I used to as 3 divisions are a
true handful when running a full schedule, but I still realize
the added efforts you put in for these "not so easy
projects." Bob's crew, along with the group of trucks
that follow him around, make this crew the best subdrain crew
in the state! Thanks for the extra efforts you put in as well
as your safe driving.
With
this, I close wishing you all a Happy Holidays and Happy New
Year! Take time to enjoy your families and time off! Continue
to practice safe habits even at home and I look forward to a
safe and productive 2003 season!
