Highway pavement foundations

[AU.CASE]

Hi all, a local construction is using Federal money to upgrade a major through road in a hurry.

What do others' reckon on the foundations where part of the original ashphelt is left (1/3 down the centre) and either side is rehabilitated and fill is present over the centre strip when the final and single thin coat is applied.

Is this a standard road rebuilding method?

This is close to final coat application -->

This is a prior section and some of the "centre strip" with road base over same -->

 

[DMiller]

I have not seen this type Asphaltic concrete salvage repair done. The technique does show some merit as to expense savings but I dare say may lack sustainability or survivability over time. Our Highways departments will generally lay small single layer 'patchwork' repairs or pave a half width to the shoulder as a overlay for a temporary fix prior to more sturdy repairs.

In Mid US, Missouri, we are now seeing secondary roads fully trimmered off(pavement ground away to base) with that material added to fresh hot asphaltic mix to be spread and rolled out in 2-3" lifts with two or three dependent on traffic weight/volume for that secondary road across the entire road width in subsequent spreads per lane width.

 

[Scrub Puller]

Yair . . .
Guday AU.CASE. This is just another one of the poor practices I see going on all the time on our highways.

I live on the Bruce Highway the main coastal drag up the coast of Queensland and quite frankly (to me) seems all the old rules have gone out the window.

I constantly see dry gravel tipped onto a dry consolidated lifts as fills are constructed . . . fifty years ago your arse would be kicked proper if you attempted such a caper.

(I believe) the methodology you show will hold up for a while until moisture gets through the new top surface, percolates down on to the old bitumen and causes shear failures at the more impervious layer.

Cheers.

 

[old-iron-habit]

This new "save the planet" asphalt they use here is some real crap. The environmentally friendly stuff does not seal up tight like the old days when they put some real oil in it. The surface is very porous and when the water sets in it and freezes it pops the asphalt. They had to replace the asphalt on the interstate here after only two years after they done a complete makeover. It had huge potholes clean through it all over the place after the first winter. Might work better in a warmer part of the world.
I first seen this about 5 years ago on a hospital project. I had a required certified asphalt inspector on the parking lot when it was paved. I walked out to look when they were near done. I had never seen new asphalt fissured like that. I asked the inspector why he wasn't rejecting it as it had not been rolled enough to seal properly. I thought it was perhaps applied when it had cooled in the trucks to much. He took me to a couple other projects and also to a state road job that had a state inspector on it. They both explained to me that the new asphalt looks like that. Its all I have seen since. Not sure what changed. Less road oil perhaps?

 

[Ronsii]

OIH, you're right about the new stuff being crap!!!


I keep seeing roads around here using the new 'Environmentally friendly stuff' and the second heavy trucks roll over it the stuff turns into a ride at disneyland the stuff lasts about a month or two before they have to rip it out and do it again.

 

[DMiller]

In the US they are adopting porous concrete and porous asphalt for those regions where runoff is excessive. First point that crossed my mind was allows water to infiltrate, will freeze and bust in cold weather. Still selling it here.