fletch_961 wrote:Let me help you w/ the math:
One foot thick asphalt road, 5280 ft per mile, 12 ft wide = 63,360 cu ft
~100pounds per cubic ft = 6,336,000 pounds
2000 pounds per ton = 3,168 tons
$60/ton = $190,080.
Let me help you help me (The result I used was in ton per lanemile per year, but I didn't notice the year part, doh!) with the math. Asphalt tends to be
~150pcf. We've already pointed out that using the construction/reconstruction costs for brand new roads isn't accurate when looking at road costs as a whole, and I've never heard of putting down a solid foot of HMA even on a new road.
Most overlays tends to be ~1.5-3" thick, maybe up to 4", depending on the road and type of asphalt used. RAC for instance tends to be thinner all things being equal. 2" of RAC
can replace 4" of conventional asphalt. Anyhoo, odds are, for most work (~2" of HMA), the math goes like...
1/6th of a foot deep, 5280ft long, and 12 ft wide = 10560 ft^3/lanemile
(10560ft^3/lanemile)*(~150lbs/ft^3) =~1584000lbs/lanemile
(~1584000lbs/lanemile)/(2000lbs/ton) = ~792 tons/lanemile
($60/ton)*(~792 tons/lanemile) = ~$47520/lanemile
fletch_961 wrote:Now what is the price of this yet to be invented glass per ton delivered? Add what $50 per ton to that just to heat it. How thick will it have to be?
Whatever it ends up at, hopefully it'll be cheaper than asphalt roads where the HMA thickness is measured in feet!
fletch_961 wrote:Really?
Show me the math. What does an asphalt paving crew cost per mile? What does a glass paving crew cost per mile (hypothetically speaking, of course)? Links to the cost of the guys who drive around and patch potholes all day is not exactly a fair gauge of labor costs per square foot, wouldn't you agree?
From the above link, resurfacing is ~$1.50-2/ft^2. A lane mile has 5280ft*12ft=63360ft^2/lanemile, so asphalt at $47520/lanemile is
($47520/lanemile)/(63360ft^2/lanemile) = $.75/ft^2. There isn't much besides asphalt used for materials, so all we have left are labor/machinery at $.75-1+/ft^2. The hot-in-place project I linked to earlier saved about $38000 via less new HMA, and up to $38000 via reduced labor/machinery costs. Assuming the materials/application work out (<-Disclaimer), do you think it's going to take more money with fewer machines/labor or less money w/ fewer machines/labor? $600/hour isn't exactly cheap, even when a crew isn't sitting idle.
fletch_961 wrote:Really? I ask where you are going to find the guys to work in high temperature conditions and all you can show me is a puny little blow-torch that puts off a measly 1MMbtu/hour?
Do I really need to explain the difference between temperature and energy? You could compare it to something at 100MMbtu/hour, but if the temperature of that substance is only 200F, then it's still not going to be high temperature. Something that can heat asphalt to 1000+F is quite hot.
fletch_961 wrote:I've already posted a link for you that shows that it takes up to 7.5x that just to heat one ton of glass (in a controlled facility-designed to minimize input) and you want to lay thousands of tons per mile? I would be worried about trees catching fire, wouldn't you. Imagine molten glass cooling right next a forest.
First, wood is dried as water is vaporized at a temperature of 100 °C (212 °F). Next, the pyrolysis of wood at 230 °C (450 °F) releases flammable gases. Finally, wood can smolder at 380 °C (720 °F) or, when heated sufficiently, ignite at 590 °C (1,100 °F).
First off, lava doesn't even ignite trees and we're looking at way more energy, probably with a higher temperature, rolling right on the poor things. Don't get me wrong, I don't think pouring molten glass, or even hot asphalt, on trees or brush of any sort is a good idea, but you should look to similar phenomenon before jumping to any conclusions.
Adventurers poking around the Big Island will find the spirit of trees past in the form of lava trees and tree molds. These volcanic features are created when fluid lava surrounds a tree and a coating of solid lava forms around the trunk. It might seem that 2,000°F lava would cause a tree to burst into flame and burn away. But when hot lava touches the moist, cool tree, the layer of lava next to the trunk chills and solidifies, insulating the tree from the heat of the oncoming flow. Eventually, the tree does burn to ash or, if the temperature and airflow are right, "bakes" into charcoal. But if the lava flow that encased the tree drains away through a nearby crack or to a lower area, a pillar of lava, or lava tree, remains, rising above the ground's surface where the tree once stood.
If you really want to figure out how much the glass would raise the temperature of the surrounding air, just take the energy needed to heat however much asphalt is needed for a 12x12x2 patch of road, multiply that by ~5-10, depending on what the specific heat/temperature of the glass is, to get the rough amount of energy used to heat whatever glass, then determine how much that energy would heat up the air in a half-sphere with a 10ft radius, keeping in mind the proportion of heat transmitted between the Earth/base (thermal conductivity of 1.5W/mK or similar) and the air (thermal conductivity of .024W/mK), and then calculate how much that half-sphere of air at whatever temperature would heat up stuff in it given the specific heat of the stuff, assuming we can somehow instantaneously dump out all the heat from the glass into the air/ground, then keep the air in a half-sphere.
fletch_961 wrote:I worked w/ the stuff for one summer, hence the reason why I find it ridiculou to try and do the same thing w/ molten glass.
What kinda base did you lay a foot of HMA on? For that matter, why would you even work with it in the same way? It's not like you'll have a lute person out behind the glass. If the application by machine doesn't cut it then the idea won't fly and that's that.
if it (application/materials) managed to pan out (hint- It needs lower labor/machine costs to offset the (likely) higher materials costs, except if they can get away with using a lot less material ala RAC), then the application process would be very different.