Dear Sir, I'm 62 years old and living in Belgium. My father was a small entrepreneur. He made all kinds of things in concrete: walls, drinking troughs, barriers, crosses for tombs. He was unschooled, but together with my mother, he succeeded in making a living for themselves and their five children. My father knew concrete, he could smell if it was the right quality. I and my two brothers worked, during weekends and holidays, with him. I never liked the hard work and went on studying mathematics (I am a Math Ph.D). But now, being much older and much wiser, I discover a new interest in the art of building. Thank you for your videos: they deepened the respect for my parents even more!
I'm a young structural civil engineer from Brazil, and lately I started to study how things work in other countries. Your content is extremely helpful to me, Tyler! Thank you, and keep up with the excellent educational work, it really makes a difference for people like me.
Thank you so much for adding the metric measurements! Also, thank you for everything else, these videos are pure gold. I liked concrete before, armed with more knowledge I love it. You rock!
Great overview. In the oilfield everything we pump is paste whether for cement plugs or for cementing the casing inside the hole. We use silica sand or silica flour to prevent strength retrogression when well static temperatures are above 235F. We use various chemicals depending on the application to control free water and fluid loss, to provide desirable pumping characteristics (dispersants), and to provide viscosity when cement fallback to the formation after placement is a concern. These are just some examples. Typically we use fibres to either prevent losses of cement to the formation or to impart good mechanical properties like elasticity and resilience. In the oilfield we don’t use the term “paste”, instead we call the cement/water mixture “slurry” with or without other additives.
Dean - We call dispersants - water reducers We also use a viscosity modifying agent or VMA to give concrete more cohesion and avoid segregation. This is made of a gum. One example is wellan gum - although I don't think this is used anymore. The slump test is the most widely used test to measure viscosity. You should check it out. You will think it is funny. Some researchers use rheometers to measure the viscosity of concrete but it is not common in the field. Silica fume is widely used in concrete as an SCM (supplementary cementitious material). It is a coarser silica flour. We use it because it acts as a nucleation site and a great filler to help with packing. Out concrete doesn't go to 235F during placement, at least not on purpose. Fibers are somewhat common in construction cements. Most people don't use them because of the added cost but I think they are a great tool.
Tyler Ley thanks for sharing this info. We use silica fume/compacted silicalite commonly in oilfield cement often as a compressive strength enhancer for low temperature, lightweight cements. It also imparts some thixotropy which is good for preventing slurry fallback to the formation after placement. Silica fume also helps with strength retrogression at high temperatures. Another thing we frequently test is fluid loss. Well cements are often pumped under high pressures so if fluid loss is not controlled then you can have filtrate leak to the formation which increases the viscosity of your fluid and could create pumping issues. Fluid loss after placement can create issues with gas influx into the cement. When static fluid loss happens after placement the slurry begins to gel at which point full hydrostatic pressure is not transmitted to the bottom of the well. If you have a deep gas zone in the well then this becomes undesirable as your bottom hole formation pressure becomes greater than the hydrostatic pressure of the cement slurry column at which point gas can influx into the cement percolating through it creating channels that affect zonal isolation, not good as you want full hydrostatic pressure until the cement sets. Also the transition time on the cement is a key consideration too. Transition time is the time it takes for the cement to go from 100lb/100ft2 to 500lb/100ft2 when static. If gas migration into the cement from high pressured zones is a concern then you want that time to be fast, 30 mins or less. I had a customer who used to request 10 mins and I often design for 15-20mins. At 100lb/100ft2 the cement is gelling and losing its ability to transmit full hydrostatic pressure. At 500lbs/100ft2 the cement is gelled so much that gas can no longer infiltrate it. If the transition time is quick you shorten the time span that the gas can percolate into the cement. If it’s long then that is an issue as you risk having gas cut cement and cement that does not provide full zonal isolation.
Excellent video, Tyler. Might be worth pointing out that for metric the stated relationships between the compressive and flexural/shear strengths are only valid for imperial units. As 1 psi = 0.0069MPa, *Flexural strength* 7.5*sqrt(Fc_psi) -> 7.5*sqrt(0.0069*Fc_MPa) = 0.62*sqrt(Fc_MPa). *Shear strength* 4*sqrt(Fc_psi) -> 4*sqrt(0.0069*Fc_MPa) = 0.33*sqrt(Fc_Mpa)
These are great lessons! You made so many things clear in this single one. Hey Tyler, could you do one on aircrete? Could you adress the question of the ratio of water to cement in aircrete, and whether it has to be computed as with regular concrete, or does it follow other rules? I've watched many of your vids already, I'm learning a lot of the stuff I wanted but until now I only got small bits from different places... Thanks!
Thanks for the comment. I will make an aircrete video. Keep watching. Can you send me a reference to the w/c not applying to aircrete? I have never heard that one before.
Wow these are great news Tyler!! There are many vids about aircrete but you have deep knowledge of concrete, and also it feels "exhausitve", as if you new the important stuff in all areas of the subject. I can't send any references, but any aircrete vid will show you the following : -they rarely use superplastifier and go as high as 0.5 w/cement -then they add foam that is anywhere from 57 grams/Liter to 110 grams/ Liter, and often, 3 to 5 times the volume of foam for 1 volume of cement... So I let you guess all the water that gets incorporated into the final product... I don't know all the mechanics of concrete (though I'm an avid watcher of your vids, that I watch each several times while taking written notes as in class). I suppose a lot of this water evaporates during curing, but still it must have a negative impact on strength, as some water probably gets trapped, or even, there can be so much that the concrete crystals can't reach each other... Anyway, I look forward to all your vids, and to anything you would upload concerning aircrete especially... Btw I'm pouring some monday and a second time at the end of the week, but with my own mix!
Mr. Ley, Have very much enjoyed several of your videos although some of the information is a little deep for me. Do you have any videos on resurfacing concrete? I have some walks and slabs that are in great shape (as far as cracks go) but are 55 years old in need of having the surface freshened up a bit. I know there are many products out there but would rather hear from a professional like yourself before reinventing the wheel and making some unnecessary mistakes.
That is a good one! We usually use a different cement if we want the concrete to resist high heat. For example, calcium aluminate cements are good for high heat.
This is a good question. Most fibers used in concrete are pretty long. Maybe 1.5" or so. They need to be this big to intercept cracks. Look for a video over fibers soon!
Dear Sir, I'm 62 years old and living in Belgium.
My father was a small entrepreneur. He made all kinds of things in concrete: walls, drinking troughs, barriers, crosses for tombs. He was unschooled, but together with my mother, he succeeded in making a living for themselves and their five children. My father knew concrete, he could smell if it was the right quality.
I and my two brothers worked, during weekends and holidays, with him. I never liked the hard work and went on studying mathematics (I am a Math Ph.D). But now, being much older and much wiser, I discover a new interest in the art of building.
Thank you for your videos: they deepened the respect for my parents even more!
I'm a young structural civil engineer from Brazil, and lately I started to study how things work in other countries. Your content is extremely helpful to me, Tyler! Thank you, and keep up with the excellent educational work, it really makes a difference for people like me.
Seeing this man so exicited about concrete has made my day. Thanks for the great video!
Thank you so much for adding the metric measurements! Also, thank you for everything else, these videos are pure gold. I liked concrete before, armed with more knowledge I love it. You rock!
Great overview. In the oilfield everything we pump is paste whether for cement plugs or for cementing the casing inside the hole. We use silica sand or silica flour to prevent strength retrogression when well static temperatures are above 235F. We use various chemicals depending on the application to control free water and fluid loss, to provide desirable pumping characteristics (dispersants), and to provide viscosity when cement fallback to the formation after placement is a concern. These are just some examples. Typically we use fibres to either prevent losses of cement to the formation or to impart good mechanical properties like elasticity and resilience. In the oilfield we don’t use the term “paste”, instead we call the cement/water mixture “slurry” with or without other additives.
Dean -
We call dispersants - water reducers
We also use a viscosity modifying agent or VMA to give concrete more cohesion and avoid segregation. This is made of a gum. One example is wellan gum - although I don't think this is used anymore.
The slump test is the most widely used test to measure viscosity. You should check it out. You will think it is funny.
Some researchers use rheometers to measure the viscosity of concrete but it is not common in the field.
Silica fume is widely used in concrete as an SCM (supplementary cementitious material). It is a coarser silica flour. We use it because it acts as a nucleation site and a great filler to help with packing. Out concrete doesn't go to 235F during placement, at least not on purpose.
Fibers are somewhat common in construction cements. Most people don't use them because of the added cost but I think they are a great tool.
Tyler Ley thanks for sharing this info. We use silica fume/compacted silicalite commonly in oilfield cement often as a compressive strength enhancer for low temperature, lightweight cements. It also imparts some thixotropy which is good for preventing slurry fallback to the formation after placement. Silica fume also helps with strength retrogression at high temperatures. Another thing we frequently test is fluid loss. Well cements are often pumped under high pressures so if fluid loss is not controlled then you can have filtrate leak to the formation which increases the viscosity of your fluid and could create pumping issues. Fluid loss after placement can create issues with gas influx into the cement. When static fluid loss happens after placement the slurry begins to gel at which point full hydrostatic pressure is not transmitted to the bottom of the well. If you have a deep gas zone in the well then this becomes undesirable as your bottom hole formation pressure becomes greater than the hydrostatic pressure of the cement slurry column at which point gas can influx into the cement percolating through it creating channels that affect zonal isolation, not good as you want full hydrostatic pressure until the cement sets. Also the transition time on the cement is a key consideration too. Transition time is the time it takes for the cement to go from 100lb/100ft2 to 500lb/100ft2 when static. If gas migration into the cement from high pressured zones is a concern then you want that time to be fast, 30 mins or less. I had a customer who used to request 10 mins and I often design for 15-20mins. At 100lb/100ft2 the cement is gelling and losing its ability to transmit full hydrostatic pressure. At 500lbs/100ft2 the cement is gelled so much that gas can no longer infiltrate it. If the transition time is quick you shorten the time span that the gas can percolate into the cement. If it’s long then that is an issue as you risk having gas cut cement and cement that does not provide full zonal isolation.
Thanks for the great reply!
Very interesting !
Excellent video! Thank you for posting it!
Wow this is like the coolest professor ever
Thanks so much!
I like how he explains everything .
Excellent video, Tyler. Might be worth pointing out that for metric the stated relationships between the compressive and flexural/shear strengths are only valid for imperial units. As 1 psi = 0.0069MPa,
*Flexural strength* 7.5*sqrt(Fc_psi) -> 7.5*sqrt(0.0069*Fc_MPa) = 0.62*sqrt(Fc_MPa).
*Shear strength* 4*sqrt(Fc_psi) -> 4*sqrt(0.0069*Fc_MPa) = 0.33*sqrt(Fc_Mpa)
Thank you for this lectures on concrete. It's very interesting, great to watch and it helps me understand things better.
thx for this video, I like concrete so much....one of my favorite subjects on university.....thx for teach me it in English!!!!!
I'm impressed !
Amazing video ❤
thanks for the class
Thanks u for your teaching sir. May god bless u with good health and long life.
I like your teaching way♥️
thank you
Thanks
These are great lessons! You made so many things clear in this single one.
Hey Tyler, could you do one on aircrete? Could you adress the question of the ratio of water to cement in aircrete, and whether it has to be computed as with regular concrete, or does it follow other rules?
I've watched many of your vids already, I'm learning a lot of the stuff I wanted but until now I only got small bits from different places... Thanks!
Thanks for the comment.
I will make an aircrete video. Keep watching. Can you send me a reference to the w/c not applying to aircrete? I have never heard that one before.
Wow these are great news Tyler!!
There are many vids about aircrete but you have deep knowledge of concrete, and also it feels "exhausitve", as if you new the important stuff in all areas of the subject.
I can't send any references, but any aircrete vid will show you the following :
-they rarely use superplastifier and go as high as 0.5 w/cement
-then they add foam that is anywhere from 57 grams/Liter to 110 grams/ Liter, and often, 3 to 5 times the volume of foam for 1 volume of cement... So I let you guess all the water that gets incorporated into the final product...
I don't know all the mechanics of concrete (though I'm an avid watcher of your vids, that I watch each several times while taking written notes as in class). I suppose a lot of this water evaporates during curing, but still it must have a negative impact on strength, as some water probably gets trapped, or even, there can be so much that the concrete crystals can't reach each other...
Anyway, I look forward to all your vids, and to anything you would upload concerning aircrete especially...
Btw I'm pouring some monday and a second time at the end of the week, but with my own mix!
How @ an interlocking aggregate. A fibrous material that has curling reactions the heat
Hello! Where can we apply physics concepts to address failing concrete properties? Your advice will be highly appreciated
HI! I’ve just came across your videos, and love it! Is there a certain order i should watch them to keep track?
Please look at my playlists! I have done my best to organize my videos over different topics.
Mr. Ley,
Have very much enjoyed several of your videos although some of the information is a little deep for me. Do you have any videos on resurfacing concrete? I have some walks and slabs that are in great shape (as far as cracks go) but are 55 years old in need of having the surface freshened up a bit. I know there are many products out there but would rather hear from a professional like yourself before reinventing the wheel and making some unnecessary mistakes.
I noticed concrete bridges and pillars in US are very white compared to our country. Dont know if the composition is different. I am no engineer.
Cement is to concrete as flour is to bread. Brilliant! What's the metaphorical gluten?
Calcium hydroxide! I talk about it in the hydration videos.
What about heat resistance?
That is a good one! We usually use a different cement if we want the concrete to resist high heat. For example, calcium aluminate cements are good for high heat.
How long do the supporting fibers need to be? Could this work on the nano scale? Have carbon nanotubes been explored as an option yet?
This is a good question. Most fibers used in concrete are pretty long. Maybe 1.5" or so. They need to be this big to intercept cracks. Look for a video over fibers soon!
Bi metal?
Yea if you just use pure Portland cement by itself without any gravel or sand it will be extremely brittle
Yes! It will also crack with no loads. =/
الي جاي من طرف استاذ معن لايك
Concrete gets hard, then eventually, it cracks... Seemed so simple.. LMAO til I heard these videos...