New runway help

[karlwatt]

I need your input ASAP. Our club is investigating putting in a new runway. The old one is deteriorating after over twenty years of use with poor maintenance. The other problem is there was no foundation placed under the asphalt. We have bids to tear up the old runway, place a foundation, and then lay asphalt. We are currently having difficulty with how much of a foundation to place. Some say 3 inches is adequate, some 6, and some say we need 12. We will not be driving vehicles over it.

Can you tell me the type of runway you have, how much of a foundation is under it if paved, and how long it has lasted?

[hillmanr2]

I have my own company doing concrete forming so I can offer some advice. The issue is always sub grade or the material and conditions under the surface you are laying and the seasonal conditions. The most important aspect of any sub grade is drainage. If you are putting a surface on clay or material subject to water retention and freezing road crush or pit run should be 12-18" to reduce heaving. Compaction should be in 4" lifts. So every 4" of material placed should be compacted.

Now this not being the land of unlimited money drainage is the most important. Compaction means nothing if water can collect under the asphalt. Remove and replace as much as your club can afford with road crush. Road crush is a sand and gravel mix used in road bedding. Once you place the road crush at 4" max at a time water the crud out of it and compact it with the heaviest vibrating machine you can get. If you are on clay or Glacial till cut trenches in the natural ground across the runway and make sure these trenches will drain. Fill the trenches with road crush and compact.

I hope this helps your situation.
The best Road crush is 70% sand with -3/4 rock but use what you can afford. Pit run works well to.

Vehicles driving over it is not the issue when it comes to lifespan.

[Boulder]

Hi Karl,

I'm assuming you are getting your price from a reputable paving contractor, he will have to test the runway bed, digging up a spot to find out what is actually under the runway, and advise the appropriate sub grade for your area. If the runway is on a sandy base, there will less depth of sub grade necessary.
As hillmanr2 said, if you have a clay ground condition, you will need more sub grade.
Hillmanr2 is 100% correct when he says "drainage is key". No matter what you put under the asphalt, if the water is able to lay there, you will get frost heaving and destroy your finish in one winter.

The asphalt runway will only be as good as the sub grade under it.

[karlwatt]

Wow, thanks a lot guys. Then obviously what has been under the existing runway drains well. The asphalt was laid over dirt as far as anyone knows, no foundation at all, and has lasted over 20 years without any heaves, but with cracking. Here in Boise it is pretty much high desert type conditions outside of town, which is where the field is located. I suspect this is why the runway has heald up as well as it has and this is part of the argument that maybe we can save money with a 3" road mix foundation instead or 6 - 12".

[Disciple]

if it's really drie jsut go with the 3in......but if your in a pretty wet area...go as thick as possible.

[LawnJockey]

Wow Karl,
BARKS is getting a new runway. I might have to join again. If you waive my dues I will bring my divining rods out and help find water. LOL. BTW give me a call.

Bruce

[karlwatt]

	Quote: Originally Posted by LawnJockey
	Wow Karl, BARKS is getting a new runway. I might have to join again. If you waive my dues I will bring my divining rods out and help find water. LOL. BTW give me a call. Bruce

Bruce, I have called and left you several messages with no return call. BTW how much base is under the asphalt in Nampa?

[Boulder]

Hey Karl,

What did you decide to go with for your runway?

[airbusmech]

Hey guys,
We are also looking to improve our rwys at our field.What length,width and thickness of pavemnent do some of your clubs have?

[karlwatt]

Well, after much discussion we have made a decision. The old runway will be dug up and removed. We will lay 3-4 inches of road mix for a foundation then 2 inches of asphalt pavement. Drainage has not been a problem for us in the past, there is no clay to deal with, it is mostly a sandy loam and our winters are relatively mild with little snow. We have been re-assured that as long as we do not drive vehicles over it we will be fine. We believe this will be the case, our current runway was built with no foundation and has lasted twenty years. The new runway will be 50 x 500 feet, a bit longer than the current one of 60 x 400, the giant scale guys are happy about this.

[Boulder]

It sounds like you guys will be having a ball in no time!!

Good news.

[Kiwi]

Whow 600 ft. What giant scale boy wouldnt be happy with that.

Full scale guys in Cubs etc would also be extremely excited at a runway that sort of length.

That is sure one decent place to fly. Jet guys will have a ball with that as well.

Kiwi