General comments/chat, page-17236

Hi Gigachad

I’ve been reading your posts with interest. Whether or not you’re looking to affect the price is irrelevant to me – because, in a way, I’m looking to affect the price with my post. So all’s fair.

I’m interested because you keep posting questions that on the surface are quite reasonable. You’re asking for someone to offer data to support the economic case that Halloysite would make a better substitute than flyash.

I get that. And so far, there has been no answer forthcoming.

But I’m going to have a crack! And I welcome you or anyone else in correcting my (very limited) analysis. Also I will gladly acknowledge third-party (Googled!) sources for all flyash information.

From what I can see, flyash ticks all the boxes in terms of strength, concrete workability and relative abundance. And as you say it’s cheap. (References: https://www.fhwa.dot.gov/pavement/recycling/fach03.cfm; https://assets.ctfassets.net/t0qcl9kymnlu/1Tx57nRsWYYMEC824CkOaI/38239c5e0fb2044af10bc2b1fac38cf8/FlyAsh_WhitePaper.pdf)

On the negative side, the jury is out on whether it’s hazardous. The CO2 argument does not stack up (since you have to produce huge amounts of CO2 to make it in the first place). And perhaps most relevant to the argument here, it’s slower to cure. Indeed addition of flyash results in lowers the strength of concrete in its early drying stages. (Roads Administration, US: “The slower strength gain may require forms to be strengthened to mitigate hydraulic loads. It should be noted that form removal and opening to traffic may be delayed due to the slower strength gains.”)

I also note that not all flyash is equal in terms of quality or strengthening capacities.

So at worst, as early posters have referenced, there is a distinct time factor at play here. And of course time is money.

But how about the economics?

I’ll work off your numbers of $150 for a tonne of flyash (ultrafine is $200 per tonne).

30% of cement is substituted in one tonne of concrete.

There are 13x20kg bags cement in one tonne of concrete = 260kg

30% of that = 78kg

So you’re using 78kg of your 1000kg of flyash at 150/t. Do the costings:

7.8% of $150 = $11.25

The same costings for 1kg/1000kg of Halloysite @ $5,000/t

.1% of $5,000 = $5.

Using my very loose maths, I THINK the numbers speak for themselves.

But really, I think the point is widely missed on nanotech. I stand to be corrected by James Marsh, Prof Vinu and his team at Newcastle Uni, and indeed anyone else – but we’re not comparing like with like.

I believe adding flyash results in a chemical reaction in concrete (though it seems no-one is quite sure), whereas the addition of a kilo of Halloysite is promoting a physical reaction owing to adsorption.

Note the ‘d’, not a b – it’s the business of things adhering to a surface.

The key to understanding Halloysite’s properties seems to be in its structure and its astonishing surface area to volume ratio. (Indeed, I’d wager this is one of the cornerstones of nanotech).

Consider this: a Flyash particle is a ball bearing with a diameter around 0.05mm. A Halloysite tubule is 10nm in diameter – or 0.00001. That’s a ratio of 200:1.

Now put it another way: sit the ball bearing against the tubule and one would be the width of a double-decker bus, one would be the length of a running shoe. Now let’s scale up the relative surface areas by thinking of enough running shoes to fill a double decker bus. Think of all the surface area of all the shoes, all the insides and all the outsides of all those shoes (it is a tube, remember). Think only of the outer surface area of the bus.

Compare.

I don’t have the information as to what Halloysite is actually doing to the tonne of cement, nor do I know how large construction companies will value strength delivered in a reliable and faster manner. But I do know that a kilo of material radically altering the strength of a tonne of cement is a profound thing – and it’s not beyond my imagination (nor my patience) to see what this stuff can do in terms of strengthening concrete, removing waste plastic from the ocean, scrubbing CO2 from the atmosphere or delivering drugs to cancerous cells.

Gigachad, I welcome your feedback on all this. And thanks for getting me to think more carefully on what it is that’s being researched.

Finally, I want to say a huge thankyou to Yagami, Goldhawk, Wombat, bcjk and others for keeping this forum thoughtful and stimulating.

Cheers
max