Very interesting, Ann. Nice use of waste materials, especially since everything usable has already been squeezed from these materials. I also like that it's non-food materials that are going into the concrete.
Rob, the whole second-generation phase of biofuels is surprisingly unknown to many people, especially here in the US. That second generation is the use of non-food crops, on soil that can't be used for food crops, etc. etc.
You're right, Ann, that second generation of biofuels isn't getting the same coverage as the first generation. It's good to see this new industry is turning to non-food crops grown on non-food-ready soil.
Thanks for presenting a different side about how the refuse from these crops can be reused, Ann. I didn't realize there was this type of research being done, but it's good to see! Anytime natural waste materials can be reused to improve something else, that's a good thing.
Elizabeth, what I really liked about this one was the multi-win-win strategy. Keep a potential pollutant out of landfills, use something that's otherwise thrown away (=trash) to squeeze even more value out if it (aka recycling of a sort), make a better product with it that's also got a better carbon footprint than the previous ingredient, and help farmers make more $$ by selling the cellulosic trash instead of paying to have it hauled away. Now--how do we apply this model elsewhere?
Elizabeth, the model of using waste plant material for making biofuel and bioplastics is already well underway, as we've covered in several posts in DN. One is the DuPont story about biofuel: http://www.designnews.com/author.asp?section_id=1392&doc_id=257126 Another is using cane trash to make bioplastics: http://www.designnews.com/document.asp?doc_id=237554
I would have thought it would be better to turn any such "waste" under to replenish the organic material in the soil. Since it is cellulosic, I would think this would also help keep the soil loose. This should make it a little less important to put synthetic fertilizers on the ground the next spring.
Not all farmers want to recycle this stuff, for several different reasons (one being that cellulosic material doesn't make very good fertilizer, which has very specific chemical requirements, as any gardener knows). Some of them are covered in the story we did on DuPont using corn stover for making biofuel--we gave the link in this story, but here it is again http://www.designnews.com/author.asp?section_id=1392&doc_id=257126
All gardeners know what they buy in a store - the synthetic, or maybe not, fertilizers I mentioned - have specific chemical requirements. Good gardeners also swear by leaf mold: cellulosic material partly consumed by mold that they turn under in the spring to give the soil more tilth. Sounds like what we're taking away from the soil this way.
You're absolutely right about "specific chemical requirements," which is what I said. But there's cellulosic and then there's cellulosic: they're by no means all the same. And the stuff we're writing about here is not leaf mold--which, BTW, can also vary widely in chemical content (for example, high tannin content in oak leaves). Depending on its chemical composition, some cellulosic material adds nitrogen and other nutrients to the soil, some takes those out, and some doesn't do anything nutritionally, but does add bulk and loft, which is not always needed or wanted, BTW. The stuff being recycled here doesn't add much in the way of nutrients and/or can leach it out. It can also cause rot problems. This is a complex subject, which we touched on in the DuPont article. Check it out.
I had read the DuPont article and I re-read it. I have four comments. I own some DuPont stock so I wish them well. I design concrete structures and I like what pozzolans do, so I'm happy to have more sources. They and you talk to farmers other than those I see either making silage from cornstalks or plowing it under - or both, which is the primary similarity - they don't leave much in the field. I don't see any having trouble getting rid of such "waste." I've never talked to any who had any such "waste," either. They will often plant a rye cover crop over the winter for erosion control and to have something green to turn under in the spring, so the corn from last year doesn't "interfere with corn planting." Maybe this is it: they rotate their crops every few years; from the comment that the stover can "house insects and diseases that damage corn plants" it sounds like the Iowa farmers just grow corn. I mentioned this to my 12th-grade daughter who had an immediate and strong reaction: "Anyone who takes AP Environmental Science knows that one wants to use any organic matter they have in their soil." She has that class this year.
Excellent use for recycled materials. Concrete has been reinforced for eons to make it stronger or lighter. From adding straw to mud bricks in thy neighbors hut, steel rebar in just about everything cast concrete, to adding limestone or pumice (lavarock) in the concrete domed cielings of ancient structures such as the Parthenon. A building which has survived earthquakes and other factors for 1900+ years...
When I was in grad school the civil engineers would enter the annual concrete canoe contest where the teams would have to build a canoe entirely out of conrete and then race it against those of other teams. Most broke up or sank before the finish line, but the builders did use unusual fillers to reduce the density. One mix had a specific gravity of just 0.75, about equal to oak, and it had an amazing tensile strength, almost two percent that of oak.
Evidently this ash is much different from "just a filler", used to reduce density. Foam peanuts are a filler that reduces density but does not add strength. The ash somehow enters into the chemical structure, which is totally different.
j-allen, on first reading, your story about concrete canoes sounds like a cross between a Mafia movie and one about college students' jokes. OTOH, I know these things are real, because there's a cement ship on the beach south of the Santa Cruz harbor. According to the local history I've heard, this one was originally built as a supply ship in 1918, and then got towed over here to become an entertainment spot. Here's the history: http://www.santacruzsentinel.com/ci_17234906 and here's a better photo (scroill down a ways): http://www.beachcalifornia.com/cement-ship-seacliff-beach.html
I can back up J-Allen's story. When I was in engineering school, our civil engineering students also had a concrete canoe contest. Either it's a common practice for civil engineering students, or J-Allen and I went to the same school (University of Illinois at Chicago).
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