5/14/2024: I set my shop on fire. 4k sq ft, 50x80. The spray foam insulation got to combustion temp and *every* square inch inside the building burned. The fire lasted maybe an hour. The fire department, rural volunteers, showed up 20+ min after I called 911 and put a little water on/in one end. After cleanup, the slab looks like a German airstrip in 1944. Some spots were maybe 1/8", some over an inch. I tried patching the spots but there were too many and I gave up, pushed the "Easy" button, and had 6" poured on top. "Easy" except paying for it. I never thought about the rebar getting hot enough to yield, but I'm sure it did. The slab ponded badly, one large area left of center on the 80' direction, one on the right. It had bellies. It didn't when it was poured. I learned good stuff in this video. I feel more confident in my choice to cap the slab. The original slab was 4", something I'll never do again unless it's for an air compressor or similar. The rebar was #3, I don't recall the spacing. "Chairs" are something people sit in, not to hold rebar in place...🤬 They didn't use chairs for crap, something I'll never let happen again. Towards one end of the 80' direction, there were several places where rebar was exposed, sometimes within 1/4" of the finished surface. For a slab with no expectation of load bias, that's ineffective and amateurish. If you don't already have a video on the subject, a video on rebar supports, especially the spacing, would be most interesting. The 6" slab had chairs under #4 on 16" centers...but they did maybe 25% of the intersections. After they left, I put dozens more in. The workers on all the slabs I've watched get poured run over the rebar like drunk buffalo. They don't care, it gets a glass finish, they get paid, and it's not their problem. FWIW. Thanks for your videos, I've learned a lot about getting and pouring better concrete. I wet-cured my new slab and I'll be ready, when the time comes, to properly finish it (sealer or maybe densifier and sealer). The burned slab was boom pumped but still looked like soup which may have affected it's ability to withstand the fire. We're in a rural area...most of these yahoos couldn't spell "admixture": the only way they make concrete easier to place and consolidate is to have the driver add water. Even specifying a slump isn't very effective because the drivers rinse down their truck funnel w piles of water. The guy who did the 6" cap slab is *the guy* to get around here...his concrete showed up looking like it had a "slump" instead of soup. He had told them, per the driver I know through having orderer concrete before, was, "If you send me a wet load, I'll send it back." Words of caution to anyone thinking of ordering concrete from a plant.
I think, first make the water content very high, you can submerge it in water for few days after casting. Then also prepare it with high water to binder ratio. Add silica fume to make it less porous and consider the size. I had some crazy spalling with cylinders 300x150 mm. Heated 5 C/min or faster will also help you do that as the water has less time to escape the pore structure of the concrete.
Tyler, thanks for another great video. It was a pleasure to meet you at World of Concrete this year. Would you be able to provide a reference for the graphs you have included in your presentation here? Would love to do some more reading on this. Thanks!
The best explanation ever why concrete spalls in concrete. You proposed the use of low-melting fibers in plain matrix of concrete. But this is not enough to retain high residual strength. The better approach is to use hybrid fibers (use steel fibers with synthetic fibers). Plastic fibers melt and the steel fibers can minimize the strength degredation. 😉
Great video. Sometimes people want to use discarded manhole sections as a fire pit. I allways tell them it's not a good idea. But might make a good raised garden bed. And when cutting rebar with a torch. Don't get close to the concrete floor. Get one of these hot concrete pieces in your work boot when it pops. You'll be hopping around for a little bit.
- would you please make a video to inspect and evaluate the foundation of a fuel tank that burnt for hours when it was full. - is the result of Schmidt hammer enough to redesign the member depending on the reduced compressive strength of concrete or we should go for more tests? - should we test the tensile strength of the rebars to update the strength of the steel in the redesign? many thanks for your valuable videos'.
Thanks Tyler, good subject and video... Also, never weld on concrete, it can be a deadly projectile! PS I think it is ''steam'' that causes the explosive forces... Like a boiler- exploding...
Thanks for the comment! There is a lot of debate about this. It seems to be caused by a combination of the steam and the liquid water. Steam can move through concrete pretty easily and so the pressure build up is not that large and so it is not just the steam. However, liquids take much longer and there is often liquid water present right at the surface of the spall after it happens. Once the liquid forms then the vapor between the liquid and the surface may increase in pressure and cause the spall. I agree with you that I should have done a better job of explaining it!
I greatly appreciate you,yet one thing is not clear for me ,when you say the water will evaporate when heated .which water ,i thought there is no water ,once the concrete is hard ,i mean the water and cement underwent chemical reaction and formed a cement paste ,which i think is a chemicaly created new material .if we can evaporate water from the concrete ,doesnt that mean we can obtain water from old concrete constructions.please clarify thank you so much from ethiopia.
humidity and air inside the concrete becomes vapor trapped within the pores and when pressure increases, concrete explodes, from inside out!.. high pressure vapor seeks the path of least resistance, so it tries to migrate to the surface but concrete does not allow it. Vapor is trapped until pressures builds up and breaks the concrete suddenly.
Does a fire with alcohol or gel fuel get hot enough to cause this type dangerous situation? I’m looking into making a tabletop fire pit with the standard concrete at hardware stores such cement all ( rapid set) .
I agree with every point. However, these things are only true of Portland cement based concrete. Cement is a binder Portland cement is one type of binder. It is by far not the only binder ( cement ) and is not the best choice in some applications OPC creates a pore and capillary structure Ceramic cements, Geopolymer cements and our Algae derived binder make concrete which eliminates the problems you point out
Tyler Ley yes, I agree Other countries are way, way ahead of us in the area of utilization of what I call “ appropriate binders”. I have built concrete structures all over the world for 33 years and now, for the last 14 years, I have devoted my efforts to research a development in appropriate binders. Sometimes even OPC is the correct choice 😀.
Man I know this is a bucket-O’crazy buuut… makes me think of 9/11. This in the right scenario could be the “explosives” to cause a free fall scenario. Most likely they used high performance mix, don’t think they were using plastic strands at that point. Know it’s morbid but something to consider. Still doesn’t explain 7, but might.
![CAMPปลิ้น | รวม Highlight 2024! PART [1/2]](http://i.ytimg.com/vi/6hnvNnvYloU/mqdefault.jpg)
GREAT LEARNING EXPERIENCE. THANK YOU SO MUCH FOR THE SPLENDID INFORMATION AND EFFORTS TO PREPARE THESE PRESENTATIONS.
You have good explanation about concrete. Thank you .
Love your concrete lectures. Keep up the good work.
5/14/2024: I set my shop on fire. 4k sq ft, 50x80. The spray foam insulation got to combustion temp and *every* square inch inside the building burned. The fire lasted maybe an hour. The fire department, rural volunteers, showed up 20+ min after I called 911 and put a little water on/in one end.
After cleanup, the slab looks like a German airstrip in 1944. Some spots were maybe 1/8", some over an inch. I tried patching the spots but there were too many and I gave up, pushed the "Easy" button, and had 6" poured on top. "Easy" except paying for it.
I never thought about the rebar getting hot enough to yield, but I'm sure it did. The slab ponded badly, one large area left of center on the 80' direction, one on the right. It had bellies. It didn't when it was poured.
I learned good stuff in this video. I feel more confident in my choice to cap the slab.
The original slab was 4", something I'll never do again unless it's for an air compressor or similar. The rebar was #3, I don't recall the spacing. "Chairs" are something people sit in, not to hold rebar in place...🤬 They didn't use chairs for crap, something I'll never let happen again.
Towards one end of the 80' direction, there were several places where rebar was exposed, sometimes within 1/4" of the finished surface. For a slab with no expectation of load bias, that's ineffective and amateurish. If you don't already have a video on the subject, a video on rebar supports, especially the spacing, would be most interesting. The 6" slab had chairs under #4 on 16" centers...but they did maybe 25% of the intersections. After they left, I put dozens more in. The workers on all the slabs I've watched get poured run over the rebar like drunk buffalo. They don't care, it gets a glass finish, they get paid, and it's not their problem.
FWIW. Thanks for your videos, I've learned a lot about getting and pouring better concrete. I wet-cured my new slab and I'll be ready, when the time comes, to properly finish it (sealer or maybe densifier and sealer).
The burned slab was boom pumped but still looked like soup which may have affected it's ability to withstand the fire. We're in a rural area...most of these yahoos couldn't spell "admixture": the only way they make concrete easier to place and consolidate is to have the driver add water. Even specifying a slump isn't very effective because the drivers rinse down their truck funnel w piles of water. The guy who did the 6" cap slab is *the guy* to get around here...his concrete showed up looking like it had a "slump" instead of soup. He had told them, per the driver I know through having orderer concrete before, was, "If you send me a wet load, I'll send it back." Words of caution to anyone thinking of ordering concrete from a plant.
If you wanted to make cement that spalls dramatically for demonstration purposes, how would you do it?
I think, first make the water content very high, you can submerge it in water for few days after casting. Then also prepare it with high water to binder ratio. Add silica fume to make it less porous and consider the size. I had some crazy spalling with cylinders 300x150 mm. Heated 5 C/min or faster will also help you do that as the water has less time to escape the pore structure of the concrete.
@@andresarce5514 Thats pretty much what i did, you can see the results here th-cam.com/video/-v-II1FPFSU/w-d-xo.html
Tyler, thanks for another great video. It was a pleasure to meet you at World of Concrete this year. Would you be able to provide a reference for the graphs you have included in your presentation here? Would love to do some more reading on this. Thanks!
Dr, very good knowledge sharing, thanks so much. One suggestion is please show the source of your graphs.
I’m a Building Inspector and have enjoyed and learned a ton...thank you...Gypsy
Thanks - that video just saved my next project
The best explanation ever why concrete spalls in concrete. You proposed the use of low-melting fibers in plain matrix of concrete. But this is not enough to retain high residual strength. The better approach is to use hybrid fibers (use steel fibers with synthetic fibers). Plastic fibers melt and the steel fibers can minimize the strength degredation. 😉
Thanks for the detailed information.
The background "music" is pure torture and nearly made me spalling
Tyler, this is AMAZING!! Thanks 👍
مقارنه قيمه وجديره بالاهتمام بين الباطون المسلح والباطون مسبق الاجهاد ، شكرا جزيلا المعلومات.
Great video. Sometimes people want to use discarded manhole sections as a fire pit. I allways tell them it's not a good idea. But might make a good raised garden bed.
And when cutting rebar with a torch. Don't get close to the concrete floor. Get one of these hot concrete pieces in your work boot when it pops. You'll be hopping around for a little bit.
Thanks Patrick! Good call on the torch.
- would you please make a video to inspect and evaluate the foundation of a fuel tank that burnt for hours when it was full.
- is the result of Schmidt hammer enough to redesign the member depending on the reduced compressive strength of concrete or we should go for more tests?
- should we test the tensile strength of the rebars to update the strength of the steel in the redesign?
many thanks for your valuable videos'.
What type of concrete is used to make the fire pits at the beach?
These are so helpful!!!! Thank u
Please upload video about compressive strength of columns under fire how to analyse
All your videos are so useful, thank you Dr. Tyler 🙏
Thanks so much.
Thanks dr tyler !!
Thank you!
Thank you very much sir,
Thanks Tyler, good subject and video... Also, never weld on concrete, it can be a deadly projectile! PS I think it is ''steam'' that causes the explosive forces... Like a boiler- exploding...
Thanks for the comment!
There is a lot of debate about this. It seems to be caused by a combination of the steam and the liquid water. Steam can move through concrete pretty easily and so the pressure build up is not that large and so it is not just the steam. However, liquids take much longer and there is often liquid water present right at the surface of the spall after it happens. Once the liquid forms then the vapor between the liquid and the surface may increase in pressure and cause the spall. I agree with you that I should have done a better job of explaining it!
@@TylerLey , I think you did a great job of sharing... I was not attacking on that point... Keep the videos coming. Thank you.
I didn't think you were! Thanks so much for the support.
How hot do "usual"building fires get?
I greatly appreciate you,yet one thing is not clear for me ,when you say the water will evaporate when heated .which water ,i thought there is no water ,once the concrete is hard ,i mean the water and cement underwent chemical reaction and formed a cement paste ,which i think is a chemicaly created new material .if we can evaporate water from the concrete ,doesnt that mean we can obtain water from old concrete constructions.please clarify thank you so much from ethiopia.
humidity and air inside the concrete becomes vapor trapped within the pores and when pressure increases, concrete explodes, from inside out!.. high pressure vapor seeks the path of least resistance, so it tries to migrate to the surface but concrete does not allow it. Vapor is trapped until pressures builds up and breaks the concrete suddenly.
Nice!!!
Some rocks will also explode when put into fires. Steam expands roughly 1300 times its liquid water volume.
Does a fire with alcohol or gel fuel get hot enough to cause this type dangerous situation? I’m looking into making a tabletop fire pit with the standard concrete at hardware stores such cement all ( rapid set) .
I understand how concrete is damaged by fire pits. can someone tell me how to prevent this?
I learned the hard way - as boy, we built a fire on a concrete surface - my clothes were shredded but I only had bruises.
Thanks for sharing!!
I agree with every point.
However, these things are only true of Portland cement based concrete.
Cement is a binder Portland cement is one type of binder. It is by far not the only binder ( cement ) and is not the best choice in some applications
OPC creates a pore and capillary structure
Ceramic cements, Geopolymer cements and our Algae derived binder make concrete which eliminates the problems you point out
Thanks Jonathan! You are right that this only applies to OPC. We need more research on these alternate binders to give insights into how they perform.
Tyler Ley yes, I agree
Other countries are way, way ahead of us in the area of utilization of what I call “ appropriate binders”. I have built concrete structures all over the world for 33 years and now, for the last 14 years, I have devoted my efforts to research a development in appropriate binders. Sometimes even OPC is the correct choice 😀.
Did anyone else notice he used the original Legend of Zelda's flame graphic in this video to represent the burning concrete? 😂
I spalled my concrete member the other day. Ouch.
Man I know this is a bucket-O’crazy buuut… makes me think of 9/11. This in the right scenario could be the “explosives” to cause a free fall scenario. Most likely they used high performance mix, don’t think they were using plastic strands at that point. Know it’s morbid but something to consider. Still doesn’t explain 7, but might.
Your green screening is kind of creepy. Look up hiith. He did this too and moved away from it.