Posted on 05/28/2016 11:29:45 PM PDT by 2ndDivisionVet
You have nailed it twice and for me the word “sustainable” and the sentence below was all I needed to know. BEE ESS!!!
These guys are just hunting for Grant money, their ideas are impractical.
Slogging through through the buzz words, I came to the same conclusion,
I don't see this as BS.
I worked a few biomedical research studies as project statistician (of course), and they put in an AIDS reference whenever they could. If you deleted those references, which were true in the sense that the work applied to many conditions including some associated with AIDS, what you had left were excellent research proposals. I think the sustainability nonsense is there for the same reason, purely to make scientifically-illiterate liberals happy. What they are really looking at is the structure of concrete as an organized rather than randomly mixed composite material - whether it can be made stronger either along specified axes or overall by controlling that structure. "Sustainability" is just a buzz word that adds to their odds of funding without detracting from the quality of the science.
“with the structure and properties of natural materials such as bones”
Made by Yoyodyne?
Wow! “Buyukozturk” is my middle name!
Excellent point...PC buzzwords to give real science a chance!
Do you assess this research as valid, or just having the potential to be valid?
Even so, I’m not sure that is the goal. I think they are referring to them by analogy. Seashells are much stronger and more durable than the same materials are used by humans to build. It is the microstructures and controls that need to be learned. If we can figure out ways to improve control and create these ultra strong microstructures within the materials, the product can be much stronger, durable, and lighter.
lastly, the term “a random assemblage” is used by the authors when in truth Portland cement concrete for engineering structures is a carefully engineered
It is a ‘random assemblage’ in the sense that it is not a consistent crystalline, lattice, or even colloid form - or assemblage of such. On the micro scale it varies in constituency and molecular arrangement from point to point.
Exactly.
Remember when cinder blocks were promoted as a great advance because of their lighter weight and superior strength?
Concrete mix is like the male member, the stiffer it is the better it works.
I am not a materials scientist, but I see the potential for a lot of value in the ideas behind parts of approach. To a large extent, the paper seems theoretical "let's start thinking about concrete again" rather than a report of results. It also has multiple points.
In terms of materials, concrete has several recipes, depending on the intended application, and the nod in the direction of more variation and tracking the properties of those variations seems like a good idea that could eventually provide a small to moderate benefit.
In terms of mesoscale structure, I expect a much bigger payoff, potentially. Current concrete is a precise and nearly uniform mixture on that scale. The real challenge will be to build with a controlled mesoscale structure (different from rebar, but for similar purposes) at an affordable price. I'm not sure how easy that will be compared with pouring a truckload of concrete and counting on the standard strength of the isotropic mixture. I'm not sure how far we will get in treating concrete like our more sophisticated composite materials, not when the whole point of concrete as it is used today is that it is low-cost and durable. We might find that there is a way of building in that anisotropic structure at an affordable price, and it may even be worthwhile to get high strength concrete at a much lower weight.
All of the above is a wordy way of saying: "Valid? No. Potential? Maybe."
I always thought different levels of stiffness were best for different purposes. Some concrete needs to be as hard as possible. Other times, for example in earthquake zones, a little flex is good.
Re bar handles the flex part. Stiff is always the best.
I now await the screams of horror.
Then why so many types of concrete? I was under the impression that we gave up both strength and stiffness to save weight with the lightweight concretes. I thought you would get better thermal and shock durability but less stiffness with extra air in either the aggregate or the mortar for the lightweight mixes. The same for polymer concretes. I assumed that polymers would change (probably reduce) the stiffness. Why add it if stiff is always best, and why only sometimes?
I'm not disagreeing - this is well outside my area. I'm just confused because I've been on the edge of projects where engineers argued over the selection of particular concrete mixes.
The water molecules do not evaporate like drying paint. Concrete cures and does not dry. The water molecules form bonds with the cement. The more water molecules the weaker the concrete.
SUSTAINABLE
The Agenda 21 code word
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