PVA fibers are extremely abrasion and fatigue resistant. 20 years in concrete roof shakes showed essentially no breakdown in the alkali environment. The are also resistant to UV. They are 40 microns and 3microns is the danger zone for the lungs. Even if they got there, they are organic and will break down and be absorbed. If you want to worry about something, the silica sand dust is highly carcinogenic and can be small enough to get into the scilia. Strictly OSHA carbon masks for that stuff.
PVA fibers have been used for 20 years as a safe alternative to asbestos. Many (most?) of the old plants have been converted to PVA.
Also it is totally organic and the 40 micron size is well over the 3 micron respirable limit. These fibers are highly abrasion resistant and will not break up like asbestos. PVA is even FDA approved for use with food. (We make a food covering, and hundreds of other products.)
Check out the web site: www.kuraray-am.com/pvaf/
Rick McCabe
Better coefficient of friction than normal concrete. 40 -44 lbs per yard of concrete is a lot of fiber. It is naturally textured unless you pour it into a mold. Then it can come out like glass.
Rick McCabe
www.kuraray-am.com/pvaf/
There is a natural fibery texture to PVA-ECC because we use 40 lbs/yard of 40 micron fibers. You can pour it in a mold and have it come out glass smooth, but generally we use texture rollers to move it around. (The standard recipe is nearly self-levelling.) A good finisher can make it very smooth (no hairs, 1.3 density) but you would probably then want to go back and put a brush finish on it for driveways and sidewalks. I don't know how they are texturing the road work, if at all.
Over time the concrete will probably break down and not the fibers. (But with a very high fly ash content, the pozzlanic characteristics will help with aging.) The fibers are enormously abrasion resistant. Where a client had a one inch bump for his heavy forklifts to go over, I put down some PVA-ECC and feathered it down to paper thickness. After months, there were no cracks or damage in the main section. At the paper thin area, the mortar was gone but the fibers were still intact in their molecularly bonded grid. Strange stuff but it works.
Rick McCabe
That is correct. They are PVA (polyvinyl alcohol) and the company site is www.kuraray-am.com/pvaf/
There is a good third-party site at www.engineeredcomposites.com
Rick McCabe
They are building a runway in Zurich with only PVA fibers as reinforcement so that they can embed instruments to measure the weight, speed whatever of the incoming planes.
The material, polyvinyl alcohol is entire organic and even has FDA approval for use with food. (We make gas tanks and food wrapping and thousands of other products.)
Rick McCabe
I work for the company that makes the fibers mentioned in this story. This mix is called PVA-ECC and our site is www.kuraray-am.com/pvaf/ . The third party site with all the research is www.engineered composites.com
The way it works is that the fibers have low stretch and a free hydrogen molecule that creates a chemical bond with the cement during hydration. So what you get, as concrete shrinks over time, is millions of microcracks generally too small for water to penetrate. Those cracks can heal by themselves from the free, unhydrated lime in the mix. But using a crystal-generating product like Xypex, Kryton or Tegraproof will certainly assist in the healing of the microcracks. These cracks are so small that usually--even without control joints--you have to wet the surface to see them.
Because of the molecular bond between the fibers and the cement, and because at 40 microns, 8mm long, you have many millions of fibers at 40lbs/yard dosage, this material is also highly fatigue resistant. Hence the bridge angle. Yeah, that's a lot of fiber, but you can cut your concrete cover way down, cancelling out fiber costs. For many applications you can eliminate most or all of the steel reinforcement.
But because of these features, plus chemical, alkali, UV and abrasion resistance, there are a myriad of uses for PVA fibers. Even just a pound per yard cuts long term cracks by 50% in regular old ready mix. Just toss it in the truck.
Rick McCabe
Slashdot Mirror
Yep. People are. About to start a movie set. Spray it over EPS foam with super thin layers on both sides. Very cool stuff.
PVA fibers are extremely abrasion and fatigue resistant. 20 years in concrete roof shakes showed essentially no breakdown in the alkali environment. The are also resistant to UV. They are 40 microns and 3microns is the danger zone for the lungs. Even if they got there, they are organic and will break down and be absorbed. If you want to worry about something, the silica sand dust is highly carcinogenic and can be small enough to get into the scilia. Strictly OSHA carbon masks for that stuff.
PVA fibers have been used for 20 years as a safe alternative to asbestos. Many (most?) of the old plants have been converted to PVA. Also it is totally organic and the 40 micron size is well over the 3 micron respirable limit. These fibers are highly abrasion resistant and will not break up like asbestos. PVA is even FDA approved for use with food. (We make a food covering, and hundreds of other products.) Check out the web site: www.kuraray-am.com/pvaf/ Rick McCabe
Better coefficient of friction than normal concrete. 40 -44 lbs per yard of concrete is a lot of fiber. It is naturally textured unless you pour it into a mold. Then it can come out like glass. Rick McCabe www.kuraray-am.com/pvaf/
There is a natural fibery texture to PVA-ECC because we use 40 lbs/yard of 40 micron fibers. You can pour it in a mold and have it come out glass smooth, but generally we use texture rollers to move it around. (The standard recipe is nearly self-levelling.) A good finisher can make it very smooth (no hairs, 1.3 density) but you would probably then want to go back and put a brush finish on it for driveways and sidewalks. I don't know how they are texturing the road work, if at all. Over time the concrete will probably break down and not the fibers. (But with a very high fly ash content, the pozzlanic characteristics will help with aging.) The fibers are enormously abrasion resistant. Where a client had a one inch bump for his heavy forklifts to go over, I put down some PVA-ECC and feathered it down to paper thickness. After months, there were no cracks or damage in the main section. At the paper thin area, the mortar was gone but the fibers were still intact in their molecularly bonded grid. Strange stuff but it works. Rick McCabe
That is correct. They are PVA (polyvinyl alcohol) and the company site is www.kuraray-am.com/pvaf/ There is a good third-party site at www.engineeredcomposites.com Rick McCabe
They are building a runway in Zurich with only PVA fibers as reinforcement so that they can embed instruments to measure the weight, speed whatever of the incoming planes. The material, polyvinyl alcohol is entire organic and even has FDA approval for use with food. (We make gas tanks and food wrapping and thousands of other products.) Rick McCabe
I work for the company that makes the fibers mentioned in this story. This mix is called PVA-ECC and our site is www.kuraray-am.com/pvaf/ . The third party site with all the research is www.engineered composites.com The way it works is that the fibers have low stretch and a free hydrogen molecule that creates a chemical bond with the cement during hydration. So what you get, as concrete shrinks over time, is millions of microcracks generally too small for water to penetrate. Those cracks can heal by themselves from the free, unhydrated lime in the mix. But using a crystal-generating product like Xypex, Kryton or Tegraproof will certainly assist in the healing of the microcracks. These cracks are so small that usually--even without control joints--you have to wet the surface to see them. Because of the molecular bond between the fibers and the cement, and because at 40 microns, 8mm long, you have many millions of fibers at 40lbs/yard dosage, this material is also highly fatigue resistant. Hence the bridge angle. Yeah, that's a lot of fiber, but you can cut your concrete cover way down, cancelling out fiber costs. For many applications you can eliminate most or all of the steel reinforcement. But because of these features, plus chemical, alkali, UV and abrasion resistance, there are a myriad of uses for PVA fibers. Even just a pound per yard cuts long term cracks by 50% in regular old ready mix. Just toss it in the truck. Rick McCabe