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IAN
The surface area (milled out or hammered), should be cleaned of all debris using shovels, vacumn, brooms etc. A tack coat of emulsified asphalt or CSS-1/CSS-1h should be then applied uniformly in required amounts. Hot asphalt mix similiar to that specified for the surface annd dispensed covering the overlay. The asphalt is then compacted using rollers or vibrators.RUSS
We make every attempt to keep runway shutdowns to a minimum to do repair work. Asphalt patches are a common practice we use. We also seal every patch with tar sealant to keep as much moisture out of the subgrade as possible.SOWHAT
DOING SOME SLURRY SEALING ON SOME TAXIWAYS. SEEING A LITTLE TOO MUCH TRACKING IN AIRCRAFT LANDING GEAR. I DON’T NEED ANOTHER FOD CREATOR. IS THERE A SEALANT OVERLAY AVAILABLE?
LASSE
I would like to start a discussion of what requirements (i.e. type of asfalt, stability, voids etc.) airport operators set when paving/repaving their runways. And also, are these criteria met by the contractors?
Denard
Lasse–Runway pavement surface irregularities may cause vibrations in the cockpit that make controls difficult to manipulate. Pavement profile irregularities can also cause increased stress and premature failure of critical airplane components. Uneven pavement can reduce braking capacity as the airplane responds to vertical acceleration.The finished surfaces of each course of the pavement, except the finished surface of the final surface course, shall not vary more than 3/8 inch when evaluated with a 16 foot straightedge. The finished surface of the final surface course shall not vary more than 1/4 inch when evaluated with a 16 foot straightedge”.
we fill they up to 3/8″ from the surface. We use two silicone products.
Dow Corning 888 for joints wider than 1 1/2″ and Dow Corning 890SL for the the smaller ones.
Our process is
1. Saw cut joint
2. Power wash joint
3. Sand blast joint
4. Blow out
5. Backer rod placement
6. Seal
This process is working well for us so far.Craig —we basically use the same procedures for our crack sealing efforts. This year we tried SILKASIL 728 SL SILICONE because of the many deviations in pavement joint width. I purchased this product as an attempt to address our budget restraints but found that it was a thinner product that sometimes took 2-3 applications because it drained throw the backer rod (we use several sizes) to best match up with the width’s. Previously, I had been using Craftco’s ROADSAVER, both self-leveling. I found that the application process was far less labor intensive with the Craftco product. I will look into the DOW CORNING PRODUCTS. Do you have a contact person with DOW? What were the costs attached to the 52 gallon drums? JM
We contracted out the work. Cracks under 1 1/2″ we paid $4.39 LF. I do not have a contact at Dow. I priced out a barrle a few years ago, all I remember now is it was not cheap.
Craig—we got our SILKASIL 728 SL SILICONE for around $1,500.00 a barrel. Craftco’s ROADSAVER was around $2,000.00 a barrel. We invested in a pump/dispenser unit handling 52 gallon drums and have kept alot of the work internal. I will follow-up with DOW to get some pricing availabilities for next spring.
SAND MAN
Over time, a strict diet of pavement sealing must come into play. 6 to 8 years may be your cost effective target for silicone longevity, but realistically and unmanaged, a great deal of moisture is getting into your sub-base each year. Crack sealing must be constant. Once you have a breakdown on the adhering joints, time is not on your side.HUGH
Obviously, joint sealing is a major factor in keeping moisture from entering into the subgrade, to a minimum. Is there a self-leveling silicone that stands up to heat/freeze/thaw conditions?rich
Anthing other than good clean pavement will prevent the sealant from bonding correctly. When sealing does become necessary, plan on throwing the “toolbox” at the task to assure longevity. We have used concrete saws, high pressure water/bead and steel rotating high speed brushes to get the edges as clean as possible. High priced contracting outfits are not an option for us so we look to intense labor and creativity. How long the sealant lasts is determined by many things but we know that premature failure is not the fault or lack of our efforts.
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