Cement vs. Asphalt on roads?

[AlvinofDiaspar]

I think 407 is. Another reason behind the use of asphalt is for noise attenuation (esp. on highways) I believe.

AoD

 

[nfitz]

You can always put a layer of asphalt on a concrete base.

 

[MisterF]

Parts of the 115 are paved in concrete as well.

http://maps.google.ca/maps?hl=en&ie=UTF8&ll=44.216674,-78.414681&spn=0.002268,0.005386&t=k&z=18

 

[Transportfan]

Asphalt is a much darker colour, and therefore absorbs a lot more heat. From an environmentalist's standpoint, concrete would be a better choice due to less heat absorption.

Generally only when new. After a number of years they both turn the same dull grey.

 

[nstuch]

wasn't the 401 concrete at one point?

i remember some sections were in Scarborough years ago

 

[vegeta_skyline]

Anyone who has stood at a popular TTC bus stop would see the waves that are created in the asphalt over time due to the weight of the vehicles in the same location... concrete prevents this.

Good point, and that's why new bus stop inlets are all paved with concrete. Also remembered that Southdown road in the Clarkson area in Mississauga is concrete. The area is heavily industrial what with an oil refinery, concrete plant, sewage treatment facility and numerous other industrial warehouses and facilities.

 

[valkoholic]

I could be wrong but wasn't one of the reasons the 407 was built with a concrete surface because Dufferin Construction (owned by a concrete company) was part of the design-build consortium and wanted to show off the benefits of concrete-surfaced roads? Could be a really dull conspiracy theory, but I do know the composition of roads is subject to lobbying by both asphalt and concrete companies.

Anyway, most of downtown Toronto's streets, most of the arterial road in Toronto, and most 400 series highways are concrete base with an asphalt topping. It makes for easier maintenance (you can drive on the concrete base while the road is being resurfaced).

 

[kEiThZ]

In Texas this week. Concrete roads everywhere. The noise is annoying as hell. Can't say I'd want to see more of this in TO. But I can see the point about maintenance....its perfectly suited for Houston's car mad culture.

 

[Swamp Thing]

FYI, cement is merely the binding agent in the building material known as concrete. Cement is to concrete as flour is to cake. The proper way to refer to it in construction is "concrete roads" or "concrete structures".

Yes, this bugs me too. BUT, technically, asphalt is also merely the binding agent for aggregate in the construction of surfaces more accurately described as tarmac. (Tarmac = tar+macadam.).

So, asking "Cement vs. asphalt?" can be considered a legitimate question as it asks for a comparison of one binding material to another.

(Of course, insisting on using these terms this way will get you laughed off any North American construction site, so be warned.)

 

[Prometheus The Supremo]

actually, it's asphalt concrete: http://en.wikipedia.org/wiki/Asphalt_concrete

but in reality, alot of people refer to cement concrete as cement and asphalt concrete as asphalt, referring to the binding agent.

 

[nfitz]

I could be wrong but wasn't one of the reasons the 407 was built with a concrete surface because Dufferin Construction (owned by a concrete company) was part of the design-build consortium and wanted to show off the benefits of concrete-surfaced roads?

Dufferin Construction was owned by St. Lawrence Cement, which was then partly owned by Holcim, and the other part was publicly traded - the aggregate and concrete company; since then it's now fully-owned by Holcim.

Back when 407 was constructed, it was owned by a consortium of a Spanish construction company (Grupo Ferrovial), SNC-Lavalin, and the Caisse de Depot et Placement du Quebec.

I'm not aware of there ever having been any links between St. Lawrence Cement, and Holicm with the 407 ownership.

I'd have simply assumed that concerete was used, because in the long-run it would be cheaper. And I'd think that governments tend to not use concrete, because in the short-term (which is what governments tend to think about), it is cheaper.

 

[MisterF]

I'd have simply assumed that concerete was used, because in the long-run it would be cheaper. And I'd think that governments tend to not use concrete, because in the short-term (which is what governments tend to think about), it is cheaper.

I've been told the opposite by civil engineers who do MTO work. While concrete lasts longer, the initial costs are so high that the maintenance savings don't make up the difference.

 

[nfitz]

I've been told the opposite by civil engineers who do MTO work. While concrete lasts longer, the initial costs are so high that the maintenance savings don't make up the difference.

Surely it all depends on what interest rate you use in your calculations. Perhaps the opportunity cost for a government is higher than that for private businesses? Perhaps MTO interest rates haven't received as much scrutiny as they do in the private sector, and they are wrong. Perhaps the actuaries at 407-ETR dropped the decimal place wrong. I don't know anything, but I'm just guessing ...

What interest rate does the MTO use these days?

 

[W. K. Lis]

Bendable Concrete Heals Itself -- Just Add Water

From National Geographic News:

Bendable Concrete Heals Itself -- Just Add Water
Anne Minard
for National Geographic News
May 5, 2009

Its not quite as advanced as Terminator technology. But a new concrete that can heal its own wounds may soon bring futuristic protection to bridges and roads.

Traditional concrete is brittle and is easily fractured during an earthquake or by overuse.

By contrast, the new concrete composite can bend into a U-shape without breaking. When strained, the material forms hairline cracks, which auto-seal after a few days of light rain.

Dry material exposed by the cracks reacts with rainwater and carbon dioxide in the air to form "scars" of calcium carbonate, a strong compound found naturally in seashells, said study co-author Victor Li of the University of Michigan in Ann Arbor.

The flexible material is just as strong after it heals, the study authors report.

Quiet Concrete

For the past 15 years Li, along with colleagues such as study leader and visiting scholar Yingzi Yang, has been developing next-generation concrete for various applications.

Similar self-healing concrete has already been used inside the core of Osaka, Japan's tallest residential building, a 60-story structure, Li noted.

The material was also used in a bridge built in 2006 over Interstate 94 in Michigan, where it eliminated the need for traditional expansion joints. These "toothed" metal slats allow normal concrete to expand and contract without bending, but they can create significant road noise as vehicles rattle over them.

"One of the big attractions, apart from reducing maintenance requirements, is the fact that [the new concrete] is very quiet" without expansion joints, Li said.

Self-healing concrete is now being considered for use in irrigation channels in Montana.

Although it costs three times as much as traditional concrete, the material is a cost-saver in the long run, due to its reduced maintenance needs and energy demands, Li said.

Builders using the bendable concrete, for example, don't need to buy and install devices that counter seismic activity.

"The initial building cost actually becomes lower," Li said.

Findings published online March 4 in the journal Cement and Concrete Research.

I wonder if the TTC knows about this.

 

[Prometheus The Supremo]

there's even a wiki article for it:

http://en.wikipedia.org/wiki/Bendable_concrete