Asphalt Overlay

[civengPE]

I am looking for some advice on a particular issue we are having.

We have a 30 year old concrete curb & gutter street here that was deeded to the City about 15 years ago. This road was originally constructed by a group of doctors that this road services. The concrete thickness is about 3 to 4 inches in most places. We are now having an issue with the pavement unraveling in places. It does not appear to be a sub base failure, as there are no depressions in the area, the concrete is just breaking up.

As far as I can see, We have 4 options:

1. Do Nothing

2. Full pavement replacement along with the storm sewer under the road ($1.7M)

3. Replacement of only those panels that are failing ($700K)

4. 2" Asphalt overlay the entire roadway. ($100K)

In a perfect world, I would remove and replace, but this is a lot of money for a City our size. I am leaning toward the asphalt overlay, but am concerned with the longevity of the asphalt.

Any suggestions / advice?

 

[Hill William]

If you have a good compacted base which is not settling the overlay would be okay. Its not going to last as long and will have to be replaced every so often for maintainence. But here, on our approach slabs we pour them 2" shorter than the top of the backwall and cover with wearing and it seems to work out fine.

 

[ctiedt]

You forgot about option 5..... Whitetopping. It would probably cost almost double the asphalt overlay, but would last at least 3 times as long. It costs a little more, but is much more durable than asphalt! We have had pretty good luck with white-topping here for projects with a poor subbase and over existing streets. It is something to think about! Just my $0.02

 

[cement]

would that be a bonded or unbonded design?

 

[civengPE]

From what I have read, white topping is for asphalt and not for concrete. This is not something that is utilized very much in our area, so I am not familiar with it.

 

[Road Guy]

I would recommend the panel replacement if you dont have the $$ for the full depth.

the asphalt overlay will look pretty for about 6 months to a year at best. If the panels below it are failing, then the asphalt will just mimick the cracks in the concrete slabs.

Are you pretty sure the subgrade is okay?

 

[civengPE]

I am pretty sure the subgrade is ok. The failures I am seeing are not due to a weak subgrade. The existing concrete is over 30 years old and only around 3 to 4 inches thick.

I am really hesitant to replace just failing panels, because I am going to have to go back and replace other panels very often. Then at some point in time, I will have an entire relatively new road with a 40 year old storm sewer system below it.

My Plan is to do the asphalt overlay and come back in a few years for the full replacement.

Is there any way to mitigate the reflection cracking?

 

[cement]

have you looked at rubblizing in place? old conc busts up for great road base. esp if you know there is a good base under the conc so it will take the pounding. if no rubblizer, a mill would do the trick. then grade it, compact it and top w/ 4" hot in 2 lifts.

 

[ktulu]

Is there any way to mitigate the reflection cracking?

You can use a cold pour type emulsion crack filler in the cracks/joints. Then perform a simple overlay. I would recommend using a PG grade binder tack coat to make sure you have the bond between concrete & asphalt. I would not use a typical emulsion tack coat - not enough strength...

 

[ctiedt]

We have actually placed White-topping over asphalt and concrete surfaces and it has held up great in both cases....