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Here is a small article from twitter on "real world" applications that we do here.

 

  • Researchers from ORNL and the University of Tennessee collaborated to perform lab-scale evaluations on the high early strength fiber-reinforced self-compacting concrete mix. Credit: University of Tennessee
  • ORNL researchers used fiber reinforcements made of steel, glass and carbon to develop a concrete mix that demonstrated high early strength within six hours of production, which is needed for the precast concrete industry. Credit: ORNL/U.S. Dept. of Energy
     
  • Researchers from ORNL and the University of Tennessee collaborated to perform lab-scale evaluations on the high early strength fiber-reinforced self-compacting concrete mix. Credit: University of Tennessee
     
Topic: Clean Energy
April 5, 2021

A team of researchers at Oak Ridge National Laboratory and the University of Tennessee have developed a concrete mix that demonstrated high early strength within six hours of mixing, potentially doubling the production capacity for the precast industry.

Quick performing concrete shortens manufacturing time for prefabricated assemblies such as walls, beams and floor slabs. However, early-strength mixes have short setting times and require specific curing methods.

In a study, researchers evaluated commercially available components including steel, glass and carbon fibers. The result was a self-compacting mix that not only showed early strength but also maintained its workability for 30 minutes.

“We followed a practical, cost-effective process easily implemented with typical mixing procedures,” ORNL’s Diana Hun said. “This could enable precast plants to cast twice per day.”

Future research includes decreasing the amount of carbon embodied in the mix. The study was conducted in collaboration with the Precast/Prestressed Concrete Institute

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Interesting. You work at ORNL or the university. I have had some dealings with other national labs but not Oak Ridge. I started as a structural engineer in aerospace (not much concrete used but still interesting).

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Good video and very interesting info.  I was in the construction industry in both heavy highway and building all my life. I work with GPS 3D guidance of heavy equipment which included slip form pavers and. These are the machines they use to build concrete roads, curb and gutter and barrier walls.  I know that the DOT's and concrete companies were constantly trying different concrete mixes to try to improve strength, cure time, flexibility and overall longevity.  You see and take for granted the building materials that things are made out of without every considering how the material itself is made.

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4 hours ago, cwalker509 said:

Interesting. You work at ORNL or the university. I have had some dealings with other national labs but not Oak Ridge. I started as a structural engineer in aerospace (not much concrete used but still interesting).

I'm a lab employee. But I actually work at the Spallation Neutron Source.

 

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Roy is the dude in jeans and the jackets lost...looks like he is about to tell them they are pouring the mash into the tank to fast 

 

Interesting stuff, my son in law works for a company in FL that makes all kinds of pre-cast products

 

 

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I once sat in on a thesis defense where the candidate explained how he was adding crushed used tires to add to asphalt to not only recycle tires but to make the road more durable.

Question: does the new concrete still work well for creating shoes for undesirable personnel?  Curious minds want to know.

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Let me check your shorts!

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They're adding fly ash to concrete, now, should make the concrete overshoes last longer in salt water. :cool:

 

 

“If you can't explain it simply, you don't understand it well enough.”

--Albert Einstein

 

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Over the other side of the pond where 1sostatic hangs out, they still use "Cement Galoshes" to take care of people who refuse to pay for protection.

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I spent 17 months living in China. They are concrete addicts for sure. Never seen so much concrete used in my life. The apartment buildings got up over 40 stories and they are all concrete. Interior walls even concrete. The speed that they build things is also amazing can be a canal, park, high speed train rails they do it many times faster than in U.S.. I need to go find some pics of them bringing the high speed train to Wuhu where I lived for 12 months. They pre cast the long beds for the rails. They go through first and pour the T shaped columns. They have this machine that runs on the just laid last bed and has hundreds of wheels under it. The next section is brought in from behind and is pushed through the monster machine and then the machine extends it out to the next column and sits it in place. They probably go a mile a week would have to research. When on the high speed train it is smooth as glass no bumps no noise no shake. Do well over 100 mph and all rails are elevated so not going to hit a car or cow. They are on time to seconds for arrive and depart.
They did a new park in Wuhu just started when I got there and about six months in finished and the trees were 2' in diameter transplanted without huge root balls and they live.
When I stayed in Shanghai it was incredible the amount of building going on. You see hundreds of cranes any direction you look. They have to spend all the money we send over buying their stuff.
They will build and have sitting empty entire industrial complexes. So if you want to start a business just go pick out a building and buy in.
On the apartments when you buy it is a 99 year lease the government owns everything. But seems to work lots of millionaires there for sure. My friend that went over about 10 years ago is well into his second million and he is an American. He bought into business start ups and does not even go into the shop and makes six figures each year off his investment of $100,000. His wife is Chinese and she retired in her 40's a millionaire. Took forever to get her visa to come visit the U.S. China was afraid she would leave and not come back. They made her put her money in special account that could not be pulled out if outside of China. China has large crews around the world doing construction for other countries. When I got there in 2014 my last trip they had to raise the retirement age from 60 to 65 they ran out of workers. When you retire it costs about $300 USD a month for apartment, utilities and food, here $300 won't pay the electric bill.
Everyone needs to go to China to see how it really is. There are brand new entire cities with nobody there just waiting for people to move in from the country. Instant growth no waiting years to built it is already there.
BTW I told them when I went over that I did not want to be in one of the 40 + story apartment buildings. I was in 5 story on the second floor with trees and grass out front and in back.
I just do not know why concrete is so much I think my neighbor said $120 a yard here now. My concrete slab for my shop was almost as much as the building was.
When I lived in Orangeburg, S.C. there is a cement producer there Little Giant I think it is. They had one time a year they let people come in and search for fossils in the quarry. I have seen huge mastodon tusks and teeth that were found. They just go through and mine it and grind it up every day fossil or not. Some day we are going to run out of everything it looks like.

When a man is in the woods and talks and no women are there is he still wrong??:P

David

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On 4/6/2021 at 5:52 AM, Tnfastbk said:

Here is a small article from twitter on "real world" applications that we do here.

 

  • Researchers from ORNL and the University of Tennessee collaborated to perform lab-scale evaluations on the high early strength fiber-reinforced self-compacting concrete mix. Credit: University of Tennessee
  • ORNL researchers used fiber reinforcements made of steel, glass and carbon to develop a concrete mix that demonstrated high early strength within six hours of production, which is needed for the precast concrete industry. Credit: ORNL/U.S. Dept. of Energy
     
  • Researchers from ORNL and the University of Tennessee collaborated to perform lab-scale evaluations on the high early strength fiber-reinforced self-compacting concrete mix. Credit: University of Tennessee
     
Topic: Clean Energy
April 5, 2021

A team of researchers at Oak Ridge National Laboratory and the University of Tennessee have developed a concrete mix that demonstrated high early strength within six hours of mixing, potentially doubling the production capacity for the precast industry.

Quick performing concrete shortens manufacturing time for prefabricated assemblies such as walls, beams and floor slabs. However, early-strength mixes have short setting times and require specific curing methods.

In a study, researchers evaluated commercially available components including steel, glass and carbon fibers. The result was a self-compacting mix that not only showed early strength but also maintained its workability for 30 minutes.

“We followed a practical, cost-effective process easily implemented with typical mixing procedures,” ORNL’s Diana Hun said. “This could enable precast plants to cast twice per day.”

Future research includes decreasing the amount of carbon embodied in the mix. The study was conducted in collaboration with the Precast/Prestressed Concrete Institute

How are they/you dealing with the surface finish caused by the fibers? We have concrete here in my office that was mixed with fibers. What happens is that the fibers that stay at the top eventually "separate" or come off the concrete leaving cracks behind. I can only assume that the fibers let moisture wick through, which eventually leads to separation and cracking. So after a few years the top surface becomes rough due to the the cracks left behind by the fibers that separate from the concrete.

20160929_171923_edit2_small.jpg

 

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I've used fiber reinforcement for many years for my own home projects, driveways, sidewalks, etc., and never had a problem with the fibers showing through the surface, even after several years of wear. I also use air entraining where subject to freezing.

I had them use fiber for reinforcing in my new work shop floor, the finished surface looks good. One advantage of fiber reinforcing in wet climates, like Oregon, is that water getting into expansion joints doesn't have steel reinforcing to follow along and rust, causing spalling.

I would say they either added too much fiber or didn't get it consolidated in the mix.

 

 

“If you can't explain it simply, you don't understand it well enough.”

--Albert Einstein

 

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