Blacktop Drive #448 -vs- ???

I have requested three quotes from contractors to replace our asphalt driveway. All three are to remove the old completely, add new gravel, compact and install new asphalt. Two of the quotes state #448 grade. The third is a hand written quote from a contractor I met who stated he uses a better grade of asphalt, of which I cannot remember if or what that was. His quote was the highest.

All the quotes are recommended from the message board "Next Door". A Facebook type board where your neighbors, based on zip code and street discuss yard sales, baby sitting, lost dog etc. I also checked them on the BBB before requesting the quotes.

Given the steepness of our driveway, are there any questions I should be asking?

The old drive has lasted our 23 years here so far and has two to three layers which we did not do. We just did seal coat every two to three years.

Thanks

Wouldn't it be much cheaper to just go over the existing asphalt with new?

Nope, the op is right in tearing out the existing as it definitely needs better rock, drainage. Plus the weak substrate of his present asphalt would just give under a new layer ....and crack probably. jmo

Maybe this is what the contractors are referring to with the 448 grade ?



http://www.flexiblepavements.org/sites/www.flexiblepavements.org/files/events/conferences/448density.pdf

I have met with two of the three contractors. I did not tell them what I wanted them to do, I suggested that they were the professional's and what would they suggest. Both that I met suggested that they tear out the existing since it was at least two layers and delaminating in several spots. There is a large crack that goes all the way across the drive about 3/4's the way up. I feel that by the time you remove enough and make sure the gravel base is good there, you would have taken out most of the drive.

I know very little about asphalt mix, but what I would guess they are talking about is the coarseness of the aggregate. A highway mix is very coarse to allow for a bit of drainage so as to avoid heavy spray in the rain. For a driveway, I would want as fine as mix as you can get by with.

448 is the ODOT standard it is much coarser that your existing drive. Some of the smaller producers may make you something different. If it were mine I would stay with the 448 type 1 mix.

Thanks Brad, that is what I appreciate hearing. I plan to check out the neighbor who recommended the low bidder's driveway to see the quality.

I would be comparing the price of 20 year lifespan of asphalt with 3 year servicing vs concrete...

JonnyMac said:

I would be comparing the price of 20 year lifespan of asphalt with 3 year servicing vs concrete...

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I agree with the above. Personally I prefer concrete over asphalt anyday. Here's an article comparing the two
http://www.greatdayimprovements.com/asphalt-vs-concrete-driveways.aspx

cheers
Steve

I am a paving contractor. We have different names for our surface mixes.

So its a grey issue sort of...a coarse surface mix which has appearance in 9 mm rock and less fine aggregate and sand is a superpave highway type mix. It is tougher and stronger than a sandy "driveway" private mix. I would want a DOT type superpave mix.

The only rub is that these mixes are more difficult to install well for some small driveway asphalt contractors. Most little driveway guys like a Sandy or mix because it's easier to lute and creates a smoother finer surface.

When we did driveway work we used to like the private mix 4 above reasons when we got really good at installing asphalt and did more commercial work we realized the superpave State type mix was harder to install but did not produce the Shadows that you get in a finer Sandy mix.

Out of the 10 or so plants in our metro area most have a comprable surface mix however two plants have a private mix the driveway guys like to use.

As far as removing the layers of asphalt that are on your driveway now that also is a debatable topic. I could certainly argue that your existing two or three layers of asphalt and the existing Stone under your new layer of asphalt provides a more solid sub-bass for the new asphalt. I could also argue that it is better to remove the existing asphalt.

All this sounds contradictory however the reality of it is if you remove the existing asphalt you may have poor soil and with all the movement on top of the subgrade and stone that is in your driveway you can loosen the soil and create areas that bring moisture to the surface and will want to "pump". My analogy to this would be to drive a dump truck through a field once and it gets through by the time you drive through it 10 times the dirt is soft and has rutted and you've basically floated moisture to the surface and made your subgrade soft.

So it depends on how the asphalt will be removed. I would not want to see a wheel Bobcat removing the asphalt Because by the time he is done he will have done a pretty good job of loosening your subgrade if it is not dry well compacted, compatible High CBR dirt underneath your stone. This will not allow for a solid new lift.if asphalt to be compacted well not be.installed at an even depth as. The truck will fit the subgrade as the paver screed is about to go over it. This will caise high and low spots in subgrade and thus in your lift of asphalt.

I would certainly want to see a track bobcat which has much lower ground pressure removing the existing asphalt.

If the asphalt has been built up to be higher than the tie-in to the garage and has more cracks whether they be alligator or like the larger crack that you have shown I would remove the asphalt. There is a product called petro mat that is a liquid asphalt impregnated Geo textile. It can be placed over cracks and creates a moisture barrier as well as a bridge so that the existing crack doesn't reflect to the surface of your new asphalt. It works extremely well. This can be done over ramdom cracks.

You may need a combination of the two remove the portion in front of the garage maybe that covers the larger cracked areas and overlay the rest. If your driveway is much higher than the ground and grade around it then remove a layer or two to pull that grade down install petromat where needed over cracks and pave over existing lower "base" coats.

You need to remember it is only a driveway and it will not see hi axle load counts.

The other thing to consider is that on a steep driveway that has been seal coated several times that the asphalt you might overlay on that Hill may want to slide particularly if it is a finer Sandy mix. We used to run the mill head on the bobcat up and down driveways with steep portions so that the new asphalt overlay would have Mill teeth marks or grooves to lock into and at the same time it would remove the Slick seal coat that was placed on the existing driveway.

There is no easy button answer however for a driveway I don't think you could go wrong with either approach unless a wheel Bobcat was being used to remove the existing driveway or if your grade of your driveway was much higher than the surrounding grade of grass. This can lead to the edges cracking because they do not have a supporting Edge to hold them in place and any wheel that goes off the side of the driveway what's a heavy load on The weakened edge of asphalt.

Check references and ask to see a drive way they've done. If it looks good it most likely is good.


Hope this helps a little.

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Machsnell, you are why I love this board! Your answer is simple enough for a layman to understand and will benefit all who read it. I am meeting with contractor #3 as he came out to evaluate and write his estimate while no one was home. I will be asking him about his Bobcat!
My existing drive is higher than the grass and is level with the concrete pad inside the garage, so it would need to at least be brought down a few inches if a recoat was decided upon.
Now I feel confident I understand the difference between the 448 DOT superpave and the finer grade blacktop. Consider me and all the GJ members schooled!

Thanks again! Awesome!

As an additional note, your GJ member name machsnell brings back lots of great memories of my dad Lothar who immigrated here from Germany after the war. He and my mom owned a bakery and as a lad I went to work as a baker's helper. I heard "machsnell" many mornings ( we baked at night) when I wasn't moving fast enough. Nobody likes burned bread!

gahrajmahal said:

As an additional note, your GJ member name machsnell brings back lots of great memories of my dad Lothar who immigrated here from Germany after the war. He and my mom owned a bakery and as a lad I went to work as a baker's helper. I heard "machsnell" many mornings ( we baked at night) when I wasn't moving fast enough. Nobody likes burned bread!

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Gahranmahal
No worries we all have our areas and this was mine. I get much more than I can comtribute in all the areas.I dont know so I am glad to lend advice for whatever it's worth.

On your note about your parents I had to do a double-take. My nickname in college was lothar and when I read your post I couldn't believe that I'd seen that name as it is extremely rare. My father was German and they spoke German in their household growing up so I heard machsnell (not spelled correctly) pretty much daily also! Too funny.



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