Blacktop vs. Concrete

[US71]

I ponder the question, why the northeast states repaved most of their interstates with blacktop when concrete seems to last longer?

Short answer: asphalt is cheaper.

--
About 20 years ago, Fayetteville, AR was expanding their street system at a rapid pace. One street, Township Road was scheduled to be extended east. There were 2 bids: one contractor offered to pave it in asphalt, the other in concrete. The concrete contractor won the contract and the asphalt contractor sued the city because his bid was much lower. The city explained why they chose concrete (uneven terrain, lots of hills) and won. Then again, the concrete contractor is an 800lb gorilla, but I'm sure that had nothing to do with it

[Coelacanth]

A couple of other things to consider:

There are often political factors involved. Do not underestimate the power of the asphalt (or PCC) lobby in a particular region. Not that engineering decisions would ever be made for political reasons...

There is also some volatility in the prices of raw materials. In particular, in periods of construction booms, PCC becomes more expensive because concrete is used for building footings, etc.

[myosh_tino]

My Point:
CONCRETE > ANY ASPHALT
YESTERDAYS ASPHALT > TODAYS ASPHALT
TODAYS ASPHALT IS PURE GARBAGE.

I agree with "concrete is better than asphalt" up to a point and I disagree with the other two points.

While concrete lasts longer (much, much longer) than asphalt, when it rains, the spray kicked up by the vehicles can just about blind a driver.  Over the past 4-6 years, Caltrans has used a new type of asphalt on some Bay Area freeways (most notably US 101 between San Jose and S.F. and I-880 from San Jose to Hayward) that contains ground up tires mixed in with the asphalt.  This surface provides a nice smooth, quiet ride and when it rains, there is very minimal spray because the rubberized asphalt allows the rain water to drain through the pavement.  IIRC, I-880 was repaved about 5 years ago and the rubberized asphalt is still in very good condition.

Obviously, this type of pavement works in California due to our mild climate but I suspect it's not really an option in harsher climates (freezing cold or blistering heat).

[HighwayMaster]

There's still several concrete overpasses in Connecticut. Here are the two I know:

• Route 8 NB after Exit 39, Thomaston
• I-84 Exit 39 ramp to Route 4, Farmington

And in Massachusetts:

• The I-91/I-90/US-5 connector, overpass over US-5, Holyoke

[roadfro]

Sorry, but pretty scenery doesn't make I-80 through the sierras look or feel any less $hitty.

Caltrans had been doing multiple projects over the last several years repaving PCC pavements along I-80. Much of the PCC pavement near Donner Pass appears to be of original Interstate construction--it's held up well but is horribly rutted due to trucks and chain controls. Caltrans is currently working on a couple sections in this area, completely reconstructing the old concrete with new.

[roadfro]

While concrete lasts longer (much, much longer) than asphalt, when it rains, the spray kicked up by the vehicles can just about blind a driver.  Over the past 4-6 years, Caltrans has used a new type of asphalt on some Bay Area freeways (most notably US 101 between San Jose and S.F. and I-880 from San Jose to Hayward) that contains ground up tires mixed in with the asphalt.  This surface provides a nice smooth, quiet ride and when it rains, there is very minimal spray because the rubberized asphalt allows the rain water to drain through the pavement.  IIRC, I-880 was repaved about 5 years ago and the rubberized asphalt is still in very good condition.

Obviously, this type of pavement works in California due to our mild climate but I suspect it's not really an option in harsher climates (freezing cold or blistering heat).

It's not necessarily the rubber in the asphalt that allows the rain water to drain through the pavement. With asphalt pavements, the top layer or "lift" is often designed as open graded layer ("open grade" being rock material containing very small fines or pebbles and bigger rocks or crushed aggregate pieces). The open grade material bonds together with asphalt binder, but since there's no small stone material in the mix, the result is a top layer (typically about 2" thick for major roads) that is porous. This allows rainwater to drain down slightly from the pavement surface and travel between asphalt lifts off to the side of the road or gutter due to the natural cross slope of the roadway.

[shadyjay]

Just found this thread and although it was already said, I will reiterate:

The concrete sections of roadway throughout Connecticut are 100x smoother and have held up much better than asphalt.  The concrete sections are:

I-84 in Waterbury, from the Naugatuck River crossing to the Hamilton Avenue (CT 69) overpass
I-84 in Manchester from Exit 59 to Exit 63
I-95 in New London, from Vauxhall Street overpass to the start of the Gold Star Bridge in New London
I-691 from the Route 10 overpass in Cheshire to the Route 322 overpass in Southington
CT 9 from Exit 25 (Ellis Street) to Exit 29 (Route 175) in New Britain
CT 25 north of the Merritt Parkway, to its northern terminus

I too never understood why they repaved the concrete sections with asphalt.  I remember when I-91, I-95, CT 9, and others were concrete.  Seems like a simple milling every now and then would be cheaper and last longer than repaving - which seems to be anything from a mill-and-pave job to just a new top layer.


Another unbelievably stretch of smooth concrete is I-95 (New England Thruway) north of NYC.  In one spot, near I-287, the concrete surface has been patched and looks bumpy but is unusually smooth.

[Crazy Volvo Guy]

84 in Waterbury isn't what I'd call smooth; not all of it anyway, but I doubt it's anything a diamond grind couldn't fix or at least help.

[Crazy Volvo Guy]

I agree with "concrete is better than asphalt" up to a point and I disagree with the other two points.

While concrete lasts longer (much, much longer) than asphalt, when it rains, the spray kicked up by the vehicles can just about blind a driver.  Over the past 4-6 years, Caltrans has used a new type of asphalt on some Bay Area freeways (most notably US 101 between San Jose and S.F. and I-880 from San Jose to Hayward) that contains ground up tires mixed in with the asphalt.  This surface provides a nice smooth, quiet ride and when it rains, there is very minimal spray because the rubberized asphalt allows the rain water to drain through the pavement.  IIRC, I-880 was repaved about 5 years ago and the rubberized asphalt is still in very good condition.

Obviously, this type of pavement works in California due to our mild climate but I suspect it's not really an option in harsher climates (freezing cold or blistering heat).

California's never done transverse grooved concrete, it's always been longitudinal, which seems to spray much worse than transverse in all of my experiences.  I'm sure depends on the cement formulation as well.  Diamond ground concrete sprays horribly.

[myosh_tino]

California's never done transverse grooved concrete, it's always been longitudinal, which seems to spray much worse than transverse in all of my experiences.  I'm sure depends on the cement formulation as well.  Diamond ground concrete sprays horribly.

Does transverse grooved concrete produce that annoying whine that I hear on concrete sections of I-5 in Oregon and on I-15 in Nevada?  If that's the case, then I'm glad Caltrans does not groove their concrete that way.

[Crazy Volvo Guy]

Does transverse grooved concrete produce that annoying whine that I hear on concrete sections of I-5 in Oregon and on I-15 in Nevada?  If that's the case, then I'm glad Caltrans does not groove their concrete that way.

No, it doesn't.

And unless they do the transverse grooves completely wrong (i.e. try to "randomize" them to make it not whine - result is usually a polar extreme opposite of what they're going for - see Indiana concrete from the 1980s and 1990s, for instance) the whine is not annoying.  NY and PA did it right, with the grooves more or less evenly spaced.  I always found that noise more pleasant than the toneless growl of asphalt - cheap coarse asphalt especially

[vdeane]

There's some stuff in NY with no sound, which is actually disappointing, though if you drive 40 mph instead of 65 on it you'll hear the whine.

[Crazy Volvo Guy]

Case in point - "did" it right.  It's the 80s/90s stuff that whines, much newer than that, it doesn't.

[Mergingtraffic]

Just found this thread and although it was already said, I will reiterate:

The concrete sections of roadway throughout Connecticut are 100x smoother and have held up much better than asphalt.  The concrete sections are:

I-84 in Waterbury, from the Naugatuck River crossing to the Hamilton Avenue (CT 69) overpass
I-84 in Manchester from Exit 59 to Exit 63
I-95 in New London, from Vauxhall Street overpass to the start of the Gold Star Bridge in New London
I-691 from the Route 10 overpass in Cheshire to the Route 322 overpass in Southington
CT 9 from Exit 25 (Ellis Street) to Exit 29 (Route 175) in New Britain
CT 25 north of the Merritt Parkway, to its northern terminus

I too never understood why they repaved the concrete sections with asphalt.  I remember when I-91, I-95, CT 9, and others were concrete.  Seems like a simple milling every now and then would be cheaper and last longer than repaving - which seems to be anything from a mill-and-pave job to just a new top layer.


Another unbelievably stretch of smooth concrete is I-95 (New England Thruway) north of NYC.  In one spot, near I-287, the concrete surface has been patched and looks bumpy but is unusually smooth.

Here is a press release from CTDOT:  Does this mean they are ripping up asphalt for concrete?

Pavement Preservation Project on Interstate 84 in the Towns of New Britain and Farmington is Scheduled To Start Sunday, July 24, 2011


The Connecticut Department of Transportation is announcing that a pavement preservation project that includes the milling and resurfacing of I-84 in both directions is scheduled to begin Sunday July 24, 2011, weather permitting.  The project starts in the vicinity of the Route 72 interchange (exits 35/36) and extends easterly to the Route 6 Interchange (exits 38/39) in the towns of New Britain and Farmington.

The project consists of the removal of the existing deteriorated pavement surface and resurfacing with a new layer of bituminous concrete followed by the installation of new pavement markings and rumble strips.  Only the travel lanes are being resurfaced under this project.

[jjakucyk]

Something that needs to be asked is why a particular paving material is more or less expensive than another.  Yes, asphalt is more susceptible to rises in the price of oil, because the asphalt emulsion itself an oil byproduct.  On the other hand, concrete requires a very large amount of energy to produce.  To make portland cement requires the raw materials to be crushed and then heated to a very high temperature, which requires a lot of electricity and natural gas.  

There's also things like the type of labor and equipment necessary.  I believe a good part of the cost of a concrete road is in the finishing.  In order to do it properly requires strict timing, quick action, and special equipment, or else you end up with a rough road.  Here in Cincinnati (within the city limits anyway), when a road goes through a major rehab it will be paved first with concrete, then two lifts of asphalt on top (though they raise the concrete up for bus stops).  I figure that by doing this, they get a good solid base of concrete that also holds all the manhole covers and other utilities in place properly, while allowing quick milling and replacement of the asphalt wearing surface.

[Coelacanth]

Here is a press release from CTDOT:  Does this mean they are ripping up asphalt for concrete?

...

The project consists of the removal of the existing deteriorated pavement surface and resurfacing with a new layer of bituminous concrete followed by the installation of new pavement markings and rumble strips.  Only the travel lanes are being resurfaced under this project.

Bituminous = Asphalt, so the answer to your question is 'No'.

[roadfro]

Something that needs to be asked is why a particular paving material is more or less expensive than another.  Yes, asphalt is more susceptible to rises in the price of oil, because the asphalt emulsion itself an oil byproduct.  On the other hand, concrete requires a very large amount of energy to produce.  To make portland cement requires the raw materials to be crushed and then heated to a very high temperature, which requires a lot of electricity and natural gas.  

FYI: PCC requires raw material to be heated to a high temperature to get the basic mix, but can otherwise be applied cold when it is mixed with water. Asphalt, on the other hand, has to be heated to a high temperature during mixing and applied to the roadbed hot in order for it to set properly.

I'd say a major difference in cost is that PCC incorporates structural steel (rebar, often epoxy coated) in order to give the pavement its strength and tie the slabs together. Rebar can be very expensive, and its price also varies based on factors such as the demand for structural steel. It also takes more labor time to prep a PCC pavement due to the placement of the rebar.

[on_wisconsin]

sorry to bump....
What is the point of this:

You see those six grooves/ lines all the time, yet everyone I ask doesn't known why DOT's do it.

[jjakucyk]

They're putting rebar between the slabs which makes them less likely to shift out of place from one another.  Preventing that shifting also reduces the ka-thump ka-thump noise when you drive over the joints.

[vdeane]

But I LOVE the ka-thump ka-thump noise!  Could we get them to stop?  Putting in the rebars defeats the point of having a concrete road (the cool sounds) in the first place!

[Michael]

But I LOVE the ka-thump ka-thump noise!  Could we get them to stop?  Putting in the rebars defeats the point of having a concrete road (the cool sounds) in the first place!

You'll like this video then.  I like the whistling noise, myself.

When I was reading US-43|72's post (reply #8 on the first page) about different pavement types, I did some Googling, and found this page from WSDOT about pavement types.

[Crazy Volvo Guy]

But I LOVE the ka-thump ka-thump noise!  Could we get them to stop?  Putting in the rebars defeats the point of having a concrete road (the cool sounds) in the first place!

It'll still make the noise.  That's caused by the joints themselves, not by the pavement slabs offsetting from each other.  If they stopped doing that, they'd have to pave over the road (which I'd rather them not do) or rebuild it completely (which takes a lot more time) when the slabs begin to offset.

[1995hoo]

But I LOVE the ka-thump ka-thump noise!  Could we get them to stop?  Putting in the rebars defeats the point of having a concrete road (the cool sounds) in the first place!

The big issue is preventing too much of a shift. It doesn't necessarily eliminate the annoying noise, but it reduces it. Consider how it would mess up your suspension or your alignment if the slabs were really uneven with each other and it became like hitting a curb.

[roadman65]

I believe it has to do with now asphalt is recycable where years ago it was not.  Now they mill it over again and re-apply!  I do belive that asphalt is cheaper than concrete as well.

As a child I remember most NJ roads were concrete and still NJ 35 in Monmouth County has some places.  Then slowly from the 70's into the 80's it was changed just like the original white post cable guard rails were over the same period.   That was righ after the oil embargo that it started so that may have to do with it.

[hbelkins]

But I LOVE the ka-thump ka-thump noise!  Could we get them to stop?  Putting in the rebars defeats the point of having a concrete road (the cool sounds) in the first place!

The point of having a concrete road is that concrete lasts longer than asphalt. The noise, both the expansion joints and the whine, is annoying.