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Author Topic: Downstate Illinois Notes  (Read 2710 times)

edwaleni

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Re: Downstate Illinois Notes
« Reply #50 on: November 22, 2022, 08:35:27 PM »

It's from the North junction of 135 south about 5 miles. The remaining 6 starts next Spring. They are behind right now but as you point out that was a dangerously substandard stretch of road and they had to completely dig down and replace some sections.

Thanks, I found it.

Adding extended shoulders, sealing the cracks and then a fresh new layer of asphalt.

The base was already 30+ years old and not being replaced, so essentially this is a 10-12 year stop gap until more US-67 funding can be had.

Guaranteed the rip-rap will start cracking back through by 2030.

But its definitely an improvement over what was there before!
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3467

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Re: Downstate Illinois Notes
« Reply #51 on: November 23, 2022, 09:09:55 AM »

It's strange you see the cracks sealed. But after they cold milled the road.And they appear to be putting at least one extra layer on.
They are doing the same South of Monmouth . The original 4 lane there has lasted since 1992.
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edwaleni

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Re: Downstate Illinois Notes
« Reply #52 on: November 23, 2022, 11:25:35 PM »

It's strange you see the cracks sealed. But after they cold milled the road.And they appear to be putting at least one extra layer on.
They are doing the same South of Monmouth . The original 4 lane there has lasted since 1992.

I didn't see it in the pictures, typically after the joints are replaced and the rebar fixed and the concrete is poured over them, they perform a cold mill and prior to actual paving they put down a polymer (usually called "liquid road") based sealer that spreads and looks like asphalt, but due to its increased liquidity and ability to drop down into cracks, it provides a moisture wall.  This maybe the "extra" layer you see.

My issue is that while the polymer layer is effective, the old base is still subject to movement from traffic. The vibration and load isn't pushed out throughout the original pour segment, it is much smaller. Eventually the movement will rise upward, break the polymer and move up to the surface asphalt which is way more pliable than the original concrete.

I remember IDOT did something similar on I-55 where clearly there was a construction defect on a section built in the 1970's where the contractor did not work the rebar correctly. Over and over and over each pour segment had the same form of crack appear. Finally when they came through to repave it, they did the same thing, milled it, sealed it and put a new asphalt layer.  Sure enough, about 5 or 6 years later, I could see that same crack starting to appear on the surface. The movement around that crack was already starting to push its way up to the top.  Shortly after IDOT did a tar seal on the sections where the crack was worse. I haven't driven it lately to see if they finally replaced the whole thing, or simply did one of those scrape and replace jobs.

Concrete highways are very expensive, but they last a long time. Asphalt is just not as durable, but it is significantly much cheaper to apply. So what to do, once every 30-40 years? Or mill and resurface every 12-15 years?

I have had several discussions with road engineers about the choices made between cost, budgets and time extensions to highways. It's seems to always be on the agenda at engineering conferences.

Perhaps @Rick Powell can weigh in here as he did this at IDOT and is a consultant now.
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Rick Powell

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Re: Downstate Illinois Notes
« Reply #53 on: November 24, 2022, 09:58:11 PM »

Perhaps @Rick Powell can weigh in here as he did this at IDOT and is a consultant now.

The choice between asphalt and concrete for reconstruction or new construction at IDOT comes down to a life cycle cost analysis using current material prices and estimated maintenance cycles. Heavy truck traffic and heavy overall traffic will usually tilt the analysis more toward concrete. If both options are reasonably close, it goes to a committee who will discuss the pros and cons and make a choice. Constructability factors are sometimes a consideration in the close calls.
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