Is sandstone the solution to cheaper roads?

[scalziand]

Is sandstone the solution to cheaper roads?
Korky Koroluk, Daily Commercial News and Construction Record
November 29, 2010
http://www.dcnonl.com/article/id41858

Tight municipal and provincial budgets are making it tough to find the money for new roads and for proper maintenance and revitalization of existing roads.

That’s not news to anyone in the roadbuilding industry. One gets an uneasy feeling watching the inexorable upward trend in oil prices, knowing that the price of liquid asphalt cement can’t help but follow.

So, some people are thinking, instead of paving with asphalt, why not use stone — sandstone to be exact, sandstone that is manufactured in place using a biological process. ...

[M II A II R II K]

Will Roads of the Future Be Paved With Sandstone?


http://www.next100.com/2010/11/sandstone-highway.php

Two ingenious American designers, Thomas Kosbau and Andrew Wetzler, won the grand prize at the Incheon International Design Awards competition in Korea this year for their path-breaking proposal to replace asphalt with stone. But not just any stone—in their words, “a biologically treated and processed paving material that uses a common microbe to alter the properties and behavior of loose grains of sand into stabilized sandstone.”

The environmental and economic impetus for their work is easy to see. Asphalt requires tremendous amounts of crude oil to produce and energy to heat; the two designers estimate that South Korea’s roads alone required 28 million barrels of oil. Application of hot asphalt releases toxic vapors and greenhouse gases. The dark surface absorbs sunlight, creating an urban heat island effect that drives up air conditioning demand.

Their solution: road-building trucks would carry hoppers of sand along with tanks of common Bacillus Pasteurii bacteria in solution. Sprayed on the road, the bacteria go to work chemically on the sand and turn it into a hard, tough cement. Once the bacteria do their work of binding the sand together, they conveniently die off, leaving their structures for people to enjoy.

U.C. Davis engineer Jason DeJong, one of the principal investigators, tells me the sandstone surface probably won't hold up under the punishment of traffic on highways and other major thoroughfares, but "it is a great idea for low volume roads." In other words, it could be ideal for the rural roads that local governments are now abandoning to dirt and gravel in such large numbers.

[hammersklavier]

Cool. I like stone roads. I wish Belgian blocks and bricks would make a resurgence in urban areas...

[Colin Giersberg]

Originally Posted by hammersklavier

Cool. I like stone roads. I wish Belgian blocks and bricks would make a resurgence in urban areas...

I can't reply in regards to the above mentioned process, but we don't use limestone on chip seal roads anymore, unless it will have an asphalt surface on top of it. If it is a chip seal surface only, then we require slag for the aggregate. It doesn't wear down as fast. Limestone rounds off too quickly, and your skid resistance is reduced because of it.

Regards, Colin

[Rizzo]

Road building is incredibly far ahead with technologies available to our disposal. From permeable surfaces to flexible concrete with lifespans in the hundreds of years. We can use them at any time, but likely never will.

[vid]

We don't use them because the upfront cost is too high. Instead of spending twice as much and not having to repair the road for three times longer, we'd rather spend half as much every few years to constantly rebuild the road. Doing otherwise would be considered "waste" which is ironic because everyone seems to want the entire municipal budget spent on roads.

This could be very practical though. Just clear some trees, flatten the path, apply the treatment, and you've got an instant road.

[SHOFEAR]

Originally Posted by vid

This could be very practical though. Just clear some trees,rough grade, trench for watermain, install watermain, backfill and compact above watermain, trench for sanitary, install sanitary, backfill and compact above sanitary, trench for storm, install storm maine, install catchbasins, backfill and compact above storm, fine grading of subgrade and whatever subgrade prep is required, fine grade and install gravel base course, string curb line, pour curbs, let concrete sit for a week to harden flatten the path, apply the treatment, and you've got an instant road. install gas, cable, power, backfill, install separate sidewalks or pathways.

fixed it for you.

[hammersklavier]

Originally Posted by SHOFEAR

fixed it for you.

In rural areas mainly served with wells and septic systems there is no need to install water or sewer mains--or, when permeable pavement is applied--storm sewers. Also in such places, most roads are quiet enough that they're essentially naked streets.

Originally Posted by Colin Giersberg

I can't reply in regards to the above mentioned process, but we don't use limestone on chip seal roads anymore, unless it will have an asphalt surface on top of it. If it is a chip seal surface only, then we require slag for the aggregate. It doesn't wear down as fast. Limestone rounds off too quickly, and your skid resistance is reduced because of it.

Regards, Colin

But how does that apply on stone roads? The chip-seal treatment, as I understand it, is a fixer for gravel roads, which mainly occur in rural areas...there are some remnant Belgian-block roads in Philly, most notably the crowded Germantown Avenue, and I don't think they're as maintenance-intensive as asphalt or concrete roads.

[Colin Giersberg]

Usually, chip seal is used on secondary roads, due to tight budgets, and the sheer number of roads that need repair. Secondary roads are, in my opinion, never built to handle large amounts of traffic. They don't have the multiple layers of crushed aggregate base, black base, binder layers, and wearing surface, which allows roads to handle heavier traffic volumes than the secondary roads do. Secondary roads are built with a finished dirt base, then chip sealed to prevent erosion and provide a somewhat decent surface to ride on, albeit noisy. This light construction is quick, but not durable, requiring regular maintenance to keep them drivable.
Primary roads, with their multi-layer build ups, only require the surface (when it is worn out) to be milled off and replaced. Chip seal may be used on these as a protective layer late in the year and the wearing surface cannot be placed due to cool or cold temperatures. The Superpave mixes used now are a bear to work with when the air temperatures get below 70 degrees or colder. In fact, 80 degrees should be the lowest air temperature allowed for working with Superpave mixes. You get a much better road surface when the temperatures are above 80 degrees.
In short, chip seal is a stopgap fix when the wearing surface cannot be placed due to cold temps, and it is a quick and inexpensive repair to a secondary road that already has this surface.

Regards, Colin

[vid]

Originally Posted by SHOFEAR

fixed it for you.

No, you misunderstood what I meant. I was thinking of this road, not this one. People in the sticks complain about their roads not being paved all the time. This would give us a cheap way to provide a better surface for them.

[SHOFEAR]

Originally Posted by vid

No, you misunderstood what I meant. I was thinking of this road, not this one. People in the sticks complain about their roads not being paved all the time. This would give us a cheap way to provide a better surface for them.

I see. I wasn't thinking rehab, just building new roads.....and it's not like we build many country roads anymore.

[vid]

It could also be used for driveways, which are built regularly and in suburban estates are often quite long and not paved. And logging operations build new roads all the time, though the permanence of this technology might be a detriment. There are logging operations from the 60s that still have pretty navigable roads, since trees can't grow well on the compacted soil.

[photoLith]

Sandstone is highly influenced by weatheing if I'm not mistaken. I'm sure that these roads wont be just your average run of the mill sandstone you find in nature because if it were, just a few years of use would wear down the roads, with traffic and rain.