its kinda addictive. from internet :"The reason that concrete doesn't dry out and then reabsorb water later is because water isn't leaving the concrete at all. It's reacting with it and becoming part of the concrete form." im still trying to figure this out. i've broke some concrete and didnt see any water. maybe i should see some of his chemistry videos, but english is not my first language :(
Dr. Ley, as one of your former students, I think these videos are an awesome tool to keep current on design and stand as a foundation on the fundamentals!
Nice video. Great explanation of why rebar has revolutionized concrete in terms of tensile strength. Maybe a small bit on long term weakness of reinforced concrete in areas with any kind of humidity could be helpful though. I like the idea of exploring arches more in bridges. Rebar eventually causes concrete to fail due to flaking. Short term gain for long term guaranteed failure. I wish engineers would discuss how we can avoid rebar as well, so that we don't have all this bridge repair work to do. Just seems like lots of wasted money.
Now cause of You Tyler Concrete is getting Concrete...(planning diy stuff in concrete) and your the best Teacher eaver...Thanks for all much appericiated...
It is amazing how quickly a crew can build wire cages with a simple spring tool. The more steel the better. Many times concrete has less steel because of cost. This is part of design stage. As the GC on some projects, I would go back to engineering and request more steel in some ares, because I could tell it was not enough. And it was very important that is be deep in pour and not move otherwise the design strength goes to hell. Remember the steel is an interconnected cage to move stress around what could be a very complex form and it use to connect different pours. It is also important to allow concrete to crack in certain places. So having pre-designed cracks is also important. When we would build walls over 100 feet in length, we would have expansion joints with floating stainless rebar pegs every 100 feet to take the expansion and contraction forces.
Another fantastic video, thank you very much professor. OK, what about self-healing concrete as a new technology in concrete? If you don't mind, could you tell us about it? Thanks a lot.
Welded wire mesh is for sidewalks. It's relatively cheap, easier to break up a slab and adds less steel to deal with while recycling. The concrete actually bonds to it very well. The square size is decent for holding standard sidewalks together. Something slightly thicker would be better but on average it lasts forever without completely rusting out.
Check your diagram of the arch to the picture. The photo of the Coliseum clearly shows the Roman arch as a half circle. The diagram or cartoon you use is much lower-flatter than a half circle. What you will also find with the remaining original Roman arches is that they were not cast concrete. They were mortared stone.
The last roll of 9gauge welded wire the I bought had deformations. (I was actually looking for smooth wire because it was for a garden trellis.) It seems like you might get to a point with so much re-enforcing that you might as well skip the concrete and just design with steel.
To increase life time of a concrete structure I think a good idea would be to use stainless rebar on the rebar layer closest to the surface of the concrete. That way you should buy yourself some extra life time in terms of rebar corrosion initiation at a fairly low overall cost increase for the home building project. I've also heard that keeping your vct at about 0,4 is a good idea if possible in order to get a concrete as impermeable as possible. I would appreciate some comments on these suggestions.
I would like your opinion on wellding rebar vs tiying them with a wire I keep hearing mixed info, Wellding rebar is good in cold weather concrete beam doesn't flex a lot VS tying rebar in warm places were concrete beam tend to flex .
I need a lightweight 8 inch concrete cap over an 8 foot diameter buried cylindrical plastic tank with load bearing 2 foot wide perimeter. I'm doing a mix design using pumice gravel, portland, 3 micron pumice pozzolan, steel fibers, and rebar. I have waterglass (sodium silicate) available also. Do you have any recommendations or cautions for the mix design? I'm going to be pouring some preliminary test cylinders before the job, along with sample cylinders during the pour, but I want the preliminary work to be as successful as possible. I have a series of these tanks going in a tank farm.
I've watched some the videos and subscribed as trying to learn about concrete is hard. Would you please do a video about sonotubes and whether or not to use them. I am planning on pouring a concrete pad and new fence posts. As you have PhD after your name whatever conclusion you arrive at could be taken as gospel. Out of curiosity, what was your thesis about? What do you think of air-crete?
Don't let the PhD blind you. Make sure things make sense. I like sonotubes. I have had good luck with them and I would encourage you to try them. My PhD was on air entrained concrete. I like air crete for certain applications but I wouldn't use it for anything that you want to be long lasting.
Hey Tyler thanks for the great videos. Maybe some day you get a sample from the Bosnian Pyramids and run some tests on it. I have read it is some of the strongest ever. Cheers
[Student of the concrete game] Without much information and knowledge about reinforcement of concrete, I wonder there are other options like slag or silica fume that can not only reinforce the strength but also UTILIZE pre-existing material. Since those metals aren't unlimited supply... Just a thought. Great lesson as always!
Hello Dr. Ley, can you please post a video regarding the inverse analysis of Ultra high performance concrete? I am struggling in finding a good reference for that method. The inverse analysis will basically inverse the load deflection curve obtained from 4 or 3 points bending test to an equivalent tensile stress strain curve. Thanks for your time.
I look at rebar as future cancer for concrete. It rusts and expands causing cracks and spalling. GFRC or “ Fiberglass” rebar solves this problem. It’s lighter and easy to cut and is corrosion resistant.
You said you want to place the rebar mat in the middel whenit comes to concrete floor, what if it is a double mat? Is a double mat with smaller diameter size bars beter than a single mat with larger diameter size? The double mat uses more steel and the cost is more, but i take it that the cost out ways the benefits if the double mat is stronger.
5:35 'do not let your rebar fall to the bottom ', I would think (for creating a kitchen counter) that would be ideal to have rebar on the bottom? what's your thought on that?
Great video Tyler. What about post tensioning some small non critical project like a bench? I’d assume the practical way to do this is place tubing like PEX centered in the slab, and the run threaded rod in after it’s pulled from the forms. I’d assume more compression, more better? Is it best to pull something from a form ASAP and then put it underwater for a month or so, or keep it in the form and flood it on one side? What about temperature. If we have control over temperature, is it better to pour and cure at lower temperatures?
Post tensioning on anything less than 15' is not really worth it because the shortening and losses will cause you to lose your prestressing. I would leave things in the form as long as possible. You can pond the exposed surface. Lower temperatures are better but you don't want it to freeze. Good luck on your projects!
Given that concrete is weak in tension, why don't modern RCC beams incorporate a slight arch in their design? Wouldn't even just a slight arch increase the strength of the beam?
Hey Tyler, I’ve been obsessed with gothic cathedral architecture lately. I visited the Guadalajara Cathedral in Mexico. And obviously the Notre Dame Cathedral has been in the news lately. I was wondering, would it be possible to make a gothic style Cathedral, with all the complex ornamentation and decorative elements, completely with reinforced concrete? Using forms and 3d printed chamfer strips and what not?
Most of the columns use high strength concrete to try and shrink the column size and to reduce the creep. The slabs and beams are pretty typical concrete mixtures.
I have a question on how to design long lasting concrete. I'm going to build a forever home and want the house to last for centuries. This house will be built in MO where footings and foundations are the standard design. The house will be 100% ICF and I want to know how to protect or waterproof my concrete footings? I want all 4 sides of the footing to be protected. If you just pour the footing on dirt, the bottom part of the footing will soak up water over time and the reinforcement in the concrete will deteriorate. You have one time to protect your footing until it will be buried forever. I would like your opinion on how to protect a concrete footing for the elements and to protect an ICF foundation / house from the elements. This is such an important subject that no one goes into great detail on how to achieve this. I'm not worried about cost since the footing will be a very small part of the entire project. As far as protecting the ICF's, cost is a little bit more of a factor since it will be a very large area of the house. The more detail you can provide about what type of concrete and when and how to protect these areas the better. Thanks Eric Wehmueller
Hello Tyler Ley Phd.; I really need you to recommend a book for me on concrete cantliever beams/slabs of about 2 meters and above. This was the main reason I started a second degree in civil and industrial engineering, My first was in Architecture.
Hint about free (hated by the industry) additives that would make concrete durable, economical and safer: volcanic ash, organic ash (yeah! ashes from burnt leaves and wood pieces from your back yard), salts, and CLAY. Clay in small amounts is awesome for the mixture because it expands with humidity. Imagine a concrete that seals itself with the presence of water.. Also imagine a concrete that repairs itself by leaching minerals when water is present. There are sooo many cheap and free ways to make concrete better but, it is not good for the business of never ending spending.
JR - In my opinion the industry is very interested in producing long lasting concrete. It is horrible publicity when a structure fails too early. I have studied volcanic ash, organic ash, and clays in my lab and while they can be helpful they are also quite variable. This means that one sample may be helpful and the next will do nothing. This is why these materials are not widely used. If someone could find a way to rapidly evaluate these materials or purify them then I think they would be used in much higher volumes. Thanks again for the comment.
I never thought i would be spending my lunches at work watching videos on concrete everyday.
its kinda addictive.
from internet :"The reason that concrete doesn't dry out and then reabsorb water later is because water isn't leaving the concrete at all. It's reacting with it and becoming part of the concrete form." im still trying to figure this out. i've broke some concrete and didnt see any water. maybe i should see some of his chemistry videos, but english is not my first language :(
Thanks for watching!!!
So glad you like them!
haha. true. the channel rocks
You're one of the most underrated engineering channels I have seen and one of the best professors I've ever heard.
agreed... 100%
This video answered so many of my questions. Greatly appreciate you for sharing.
Dr. Ley, as one of your former students, I think these videos are an awesome tool to keep current on design and stand as a foundation on the fundamentals!
Thanks so much! Stay in touch!
I am neither civil engineer, architect, builder nor I am gonna construct my house but I dont know why I like these videos :D
Thanks so much for watching!!! I really appreciate the nice comment.
Great scholar,thanks from ethiopia
I like the way you show your enthusiasm ...your videos are very helpful to me, I wish you successful life.
Thanks so much!
Nice video. Great explanation of why rebar has revolutionized concrete in terms of tensile strength. Maybe a small bit on long term weakness of reinforced concrete in areas with any kind of humidity could be helpful though. I like the idea of exploring arches more in bridges. Rebar eventually causes concrete to fail due to flaking. Short term gain for long term guaranteed failure. I wish engineers would discuss how we can avoid rebar as well, so that we don't have all this bridge repair work to do. Just seems like lots of wasted money.
Now cause of You Tyler Concrete is getting Concrete...(planning diy stuff in concrete) and your the best Teacher eaver...Thanks for all much appericiated...
dont forget that concrete is the best fire protection in a building. thats why concrete stairwells are good fire escapes.
Love your videos! Nice, referencing past videos because I can open a tab on ones I find interesting
Thanks a bunch for the comment and encouragement!
It is amazing how quickly a crew can build wire cages with a simple spring tool. The more steel the better. Many times concrete has less steel because of cost. This is part of design stage. As the GC on some projects, I would go back to engineering and request more steel in some ares, because I could tell it was not enough. And it was very important that is be deep in pour and not move otherwise the design strength goes to hell. Remember the steel is an interconnected cage to move stress around what could be a very complex form and it use to connect different pours. It is also important to allow concrete to crack in certain places. So having pre-designed cracks is also important. When we would build walls over 100 feet in length, we would have expansion joints with floating stainless rebar pegs every 100 feet to take the expansion and contraction forces.
Excellent, wonderful advice.
Another fantastic video, thank you very much professor.
OK, what about self-healing concrete as a new technology in concrete? If you don't mind, could you tell us about it?
Thanks a lot.
Welded wire mesh is for sidewalks. It's relatively cheap, easier to break up a slab and adds less steel to deal with while recycling. The concrete actually bonds to it very well. The square size is decent for holding standard sidewalks together. Something slightly thicker would be better but on average it lasts forever without completely rusting out.
What types of fiber do you recommend? I am doing a 4” thick, 8x20 cement slab for a plastic ached. Love your channel; thank you!!! ⭐️⭐️⭐️⭐️⭐️⭐️
Always great videos - as welded wire mesh is used on many if not most residential driveways and patios - what are the reasons for not being a fan.
Check your diagram of the arch to the picture. The photo of the Coliseum clearly shows the Roman arch as a half circle. The diagram or cartoon you use is much lower-flatter than a half circle. What you will also find with the remaining original Roman arches is that they were not cast concrete. They were mortared stone.
You make concrete sounds so cool that I want to eat some
The last roll of 9gauge welded wire the I bought had deformations. (I was actually looking for smooth wire because it was for a garden trellis.)
It seems like you might get to a point with so much re-enforcing that you might as well skip the concrete and just design with steel.
Thank you for knowledge!
I thought rebar was supposed to be in the bottom 3rd of the concrete on the ground, what about wire mesh
Good video sir...
Thanks Kiran
Cracks also form due to shrinkage during the curing process, not just when the tensile strength has been exceeded.
When the concrete shrinks the movement is restrained by the internal aggregates and this exceeds the tensile strength and causes the cracks.
To increase life time of a concrete structure I think a good idea would be to use stainless rebar on the rebar layer closest to the surface of the concrete. That way you should buy yourself some extra life time in terms of rebar corrosion initiation at a fairly low overall cost increase for the home building project. I've also heard that keeping your vct at about 0,4 is a good idea if possible in order to get a concrete as impermeable as possible. I would appreciate some comments on these suggestions.
carpenter here! love your vids
You should do a video on Saint Augustine. Large parts of this city are a literally a monument to poured concrete.
Hello Professor. Why Column footing and Columns and beams were not welded but tie instead??
Appreciate your explanation, sir. Thank you.
I would like your opinion on wellding rebar vs tiying them with a wire
I keep hearing mixed info,
Wellding rebar is good in cold weather
concrete beam doesn't flex a lot VS tying rebar in warm places were concrete beam tend to flex .
Nice!!!!( so much to learn!!! Thanks!!)
I need a lightweight 8 inch concrete cap over an 8 foot diameter buried cylindrical plastic tank with load bearing 2 foot wide perimeter. I'm doing a mix design using pumice gravel, portland, 3 micron pumice pozzolan, steel fibers, and rebar. I have waterglass (sodium silicate) available also. Do you have any recommendations or cautions for the mix design? I'm going to be pouring some preliminary test cylinders before the job, along with sample cylinders during the pour, but I want the preliminary work to be as successful as possible. I have a series of these tanks going in a tank farm.
Awesome
I've watched some the videos and subscribed as trying to learn about concrete is hard. Would you please do a video about sonotubes and whether or not to use them. I am planning on pouring a concrete pad and new fence posts. As you have PhD after your name whatever conclusion you arrive at could be taken as gospel. Out of curiosity, what was your thesis about? What do you think of air-crete?
Don't let the PhD blind you. Make sure things make sense.
I like sonotubes. I have had good luck with them and I would encourage you to try them. My PhD was on air entrained concrete. I like air crete for certain applications but I wouldn't use it for anything that you want to be long lasting.
What concrete mix is suitable for a big underground water tank slab . Tank measurement : length 13 meters, width 5 meters, depth 8 metres.
Hey Tyler thanks for the great videos. Maybe some day you get a sample from the Bosnian Pyramids and run some tests on it. I have read it is some of the strongest ever. Cheers
That would be cool to test!!! Thanks
[Student of the concrete game] Without much information and knowledge about reinforcement of concrete, I wonder there are other options like slag or silica fume that can not only reinforce the strength but also UTILIZE pre-existing material. Since those metals aren't unlimited supply... Just a thought. Great lesson as always!
Our planet is made up out of mostly iron.
Might as well be an endless supply
@@UmaROMC thank you!! Another lesson learned!
Thankyou thankyou thankyou
Great awesome video like always, can you unweave thin nylon rope cut 1in. strands of the nylon rope and mix in with the concrete for reinforcement?
What about a clad coating to get rid of the hairs?
Hello Dr. Ley, can you please post a video regarding the inverse analysis of Ultra high performance concrete? I am struggling in finding a good reference for that method. The inverse analysis will basically inverse the load deflection curve obtained from 4 or 3 points bending test to an equivalent tensile stress strain curve. Thanks for your time.
I look at rebar as future cancer for concrete. It rusts and expands causing cracks and spalling. GFRC or “ Fiberglass” rebar solves this problem. It’s lighter and easy to cut and is corrosion resistant.
You said you want to place the rebar mat in the middel whenit comes to concrete floor, what if it is a double mat? Is a double mat with smaller diameter size bars beter than a single mat with larger diameter size? The double mat uses more steel and the cost is more, but i take it that the cost out ways the benefits if the double mat is stronger.
5:35 'do not let your rebar fall to the bottom ', I would think (for creating a kitchen counter) that would be ideal to have rebar on the bottom? what's your thought on that?
Did I miss it in another video or did you not yet discuss the benefits of BASALTIC REBAR?
Not yet.
I asked about that earlier, can't wait either. Tyler, great video again!
I'd like to see this too!
Great video Tyler. What about post tensioning some small non critical project like a bench? I’d assume the practical way to do this is place tubing like PEX centered in the slab, and the run threaded rod in after it’s pulled from the forms. I’d assume more compression, more better? Is it best to pull something from a form ASAP and then put it underwater for a month or so, or keep it in the form and flood it on one side? What about temperature. If we have control over temperature, is it better to pour and cure at lower temperatures?
Post tensioning on anything less than 15' is not really worth it because the shortening and losses will cause you to lose your prestressing.
I would leave things in the form as long as possible. You can pond the exposed surface. Lower temperatures are better but you don't want it to freeze. Good luck on your projects!
Given that concrete is weak in tension, why don't modern RCC beams incorporate a slight arch in their design? Wouldn't even just a slight arch increase the strength of the beam?
What are your thoughts on Epoxy coated rebar?
Why don’t you like welded rebar mesh?
What is the 10000 Psi cylinder concrete mix design Strength
Hey Tyler, I’ve been obsessed with gothic cathedral architecture lately. I visited the Guadalajara Cathedral in Mexico. And obviously the Notre Dame Cathedral has been in the news lately. I was wondering, would it be possible to make a gothic style Cathedral, with all the complex ornamentation and decorative elements, completely with reinforced concrete? Using forms and 3d printed chamfer strips and what not?
I don't see why not.
what kind of concrete is used in the new super tall buildings?
Most of the columns use high strength concrete to try and shrink the column size and to reduce the creep. The slabs and beams are pretty typical concrete mixtures.
I have a question on how to design long lasting concrete. I'm going to build a forever home and want the house to last for centuries. This house will be built in MO where footings and foundations are the standard design. The house will be 100% ICF and I want to know how to protect or waterproof my concrete footings? I want all 4 sides of the footing to be protected. If you just pour the footing on dirt, the bottom part of the footing will soak up water over time and the reinforcement in the concrete will deteriorate. You have one time to protect your footing until it will be buried forever. I would like your opinion on how to protect a concrete footing for the elements and to protect an ICF foundation / house from the elements. This is such an important subject that no one goes into great detail on how to achieve this. I'm not worried about cost since the footing will be a very small part of the entire project. As far as protecting the ICF's, cost is a little bit more of a factor since it will be a very large area of the house. The more detail you can provide about what type of concrete and when and how to protect these areas the better. Thanks Eric Wehmueller
I know this was posted 10 months ago, but this would do the trick (this guy is in Springfield, MO too BTW): ruclips.net/video/HBfwIhSLppE/видео.html
What kind of concrete chemistry is best for long life?
Is it worth it to use reinforcement mesh and fibre on same slab?
Would fibers help the structure of a monolithic dome and could fibers be projected (sprayed) with shotcrete?
Welding and wire tie, which 1 is recommended
Hello Tyler Ley Phd.; I really need you to recommend a book for me on concrete cantliever beams/slabs of about 2 meters and above.
This was the main reason I started a second degree in civil and industrial engineering, My first was in Architecture.
steel fibers get corroded easily? should not steel (vulnerable to corrosion) be away from the surface?
i make cement wood stoves.....they always crack under fire 😟😟....help me pls
Chemical crystalline or bio crystalline is better???
I want to study concrete under Professor Ley.
how about pour a driveway with a flat top but arched bottom?
I am not sure that would help.
Hint about free (hated by the industry) additives that would make concrete durable, economical and safer: volcanic ash, organic ash (yeah! ashes from burnt leaves and wood pieces from your back yard), salts, and CLAY. Clay in small amounts is awesome for the mixture because it expands with humidity. Imagine a concrete that seals itself with the presence of water.. Also imagine a concrete that repairs itself by leaching minerals when water is present. There are sooo many cheap and free ways to make concrete better but, it is not good for the business of never ending spending.
JR - In my opinion the industry is very interested in producing long lasting concrete. It is horrible publicity when a structure fails too early. I have studied volcanic ash, organic ash, and clays in my lab and while they can be helpful they are also quite variable. This means that one sample may be helpful and the next will do nothing. This is why these materials are not widely used. If someone could find a way to rapidly evaluate these materials or purify them then I think they would be used in much higher volumes. Thanks again for the comment.
Can anyone here help me to design a ground concrete slab for my house?
nice content
want to be friend?
Concrete is pretty handy. Can even be used to cool a gaming PC.
ruclips.net/video/VeT1LFVdUV0/видео.html
Awesome! Thanks for sharing.