Define "okay". To walk on? To strike formwork? What recipe? What is the strength supposed to be? You can never generally say that concrete is or isn't strong enough, it all depends what the situation and purpose is.
I'm a structural engineer- that looks like lots of fun. (We did similar tests in college.) Concrete has been studied and tested for a long time, people tend to do that sometimes. There are pretty well understood curves for concrete strength over time, in construction typically we specify concrete according to its strength at 28 days and beyond that it may gain another 15% or 25%. At 7 days it should be around 70% of its design strength at 28 days. There are variables that will affect this a little bit- how much cement, how much water, how is it cured, what other chemical admixtures does it contain, etc. Some types of modern concrete with special curing conditions has very high strength at 2 days for instance. You can't compare concrete you mixed with ancient concrete because you don't know what is in it. If you want to know what is strongest then modern concrete will win that comparison, concrete has been made that achieves compressive strength almost equal to mild steel. Your beams without reinforcing failed as expected. Your beams with reinforcing actually failed in shear not in bending due to the ratio of length vs. height that you had. With more length you could have gotten them to fail in bending.
Good demonstration of how concrete continues to cure and gain strength over time. This has been a good chunk of my career. But those samples were not cast or tested according to proper testing methods.
Question: if we were to leave one of those ‘new’ samples for 130 years, would they be as strong as the fortress sample, or did they make concrete differently then? TIA
@@AndrewJillings No. The samples in the video were not correctly made and had visible air holes and the curing conditions are unknown. Also, the concrete in the video appeared to be from a bag and hand mixed, which shouldn't be used for structural purposes - every wheelbarrow mixed would be different. That stuff is okay for anchoring fenceposts, a small patio floor on the ground, or maybe a sidewalk on private property, but you wouldn't want to drive over a bridge made out of it. It's all about the "recipe" used to make the concrete, which would make the compressive strength vary wildly. Concrete does strengthen with time, but after 28 days or so it's pretty much at it's max - for small pieces like those used in the video.
The one major thing you did wrong when you originally made the blocks was you didn't vibrate all the air out. That is very critical to the strength of concrete.
I agree totally i used my wifes vibrator took ages but it worked ,for when i made foundations for a shed. However she was hopping mad ,as the sand made the device rough.
Pro Tip- If you find yourself bidding on coring holes in 50+ year old concrete, double or triple what you usually charge- or put a cost adjustment charge in the contract. A client converted a 70 year old parking garage into apartments and the first coring company pulled out and the next one had an escalation charge of $48K over what was originally bid. Making holes in old concrete is "hard" (pun intended). : )
This is excellent content. Made some sidewalks and patio sections last summer, and now i see why i used mesh and rebar and kept the slabs covered and wet for several days. Thanks!
That's an indication that the concrete he made was fairly low strength. Concrete used in normal construction should have allowed the plywood to squash pretty flat before failing the concrete.
The last two failures are concrete strut failures meaning the tension rebars didn't fail. If the section had vertical shear links, it would have increased the capacity. Also the aggregate size for the last two specimens were a bit too large.
Mi sembra di ricordare che progettare, impastare, Vibrare, tensionare i ferri nel cemento sia un'arte che richiede molta perizia, esperienza ed il rispetto di moltissimi parametri. Solo così può dare il meglio di se. Hai fatto del tuo meglio, bravo. Ma si possono ottenere valori di molto più elevati rispettando le procedure opportune.
the fact that you had your ancestors to prepare the block of concrete for this video way back from 134 years ago is amazing... that,... or you're a vampire or something.
My understanding is that keeping wetted for the entire 28 day cure time can improve strength by up to 50%. Can you maybe qualify this "myth"/statement and maybe demonstrate differing aggregate mixes and admixtures utilizing lime. More mileage in concrete for you yet, including testing ancient Roman samples?
That's a myth. When cement comes into contact with water the curing process starts. you keep it wet to ensure all of the cement has a chance to react. It will never increase strength by 50%. And you don't keep concrete wet for 28 days . A week is fine. The reason why we use the 28 day because the mix design says the concrete has to reach a certain strength by the 28th day so on the 28th we crush a sample to see if we reached the designated strength. If you don't and it's structural concrete there's a problem
@@stevenferro The Portland Cement Association states that concrete must be kept wet during the entire curing period. 21 days is optimal, after that point the rate of strength increase drops off. But, the strength will increase for years. When I was in school, I took a concrete class, and the data proved this.
My wife asked me "Why would I watch this channel and Why would this guy do all this stuff to compare"... Why Not? If I had that press equipment I would test everything too....
Yeah, I've had to drill into old buildings many times. One project required over 2,000 six inch rebar embedment. Let's just say 100 year old concrete is no joke.
Nice. I bet the bigger stones in the bunker concrete are helpful bc they interrupt internal cracks similar to what happens to metal grainstructures after heattreatment
Nice demo. If you really want to get it strong with the re-bar in it, pulling a tension on the re-bar while the concrete sets will do that. Basically you can see that the concrete failure starts at the bottom of the beam where the concrete is being asked to work in tension. Pulling on the bar makes it some that that part is under compression up to a heavier weight. BTW: There are also additives you can mix into concrete. Some of them slow the hardening but also tend to make concrete that is tougher in that cracks don't start as easily
The hand-mixed concrete from a bag is great if you want to make a walkway in your back yard, but that stuff would never be allowed for structural concrete in a building or bridge for many reasons. You should contact a concrete plant near you, they keep sample cylinders of their concrete in water and after a while they throw them out - maybe they would give you a few.
Spent 25 years as an ACI 1 ACI Advanced & ICCI Concrete Inspector..Know all of what you show. Did all in NYC 1998 to 2020 . 1000ft Down (Water Tunnel #3) to last high rise (86 stories)...8=)
I would have to agree with you, I retired from our local irrigation district and when we closed the canals to put in pipelines, all the structures came out that were poured in the 30's and if you broke one up, the concrete had a light blue tint to it. And if you drilled into one, you could tell they were way harder than any of the newer concrete that was poured in later years.
Oh yea. I work in the demolition industry, and we recycle the rubble ourselves. Everything goes into a big rotary rock crusher, and small 0-40mm stones and sand come out the other end. The thing makes a lot of banging noise from breaking the rocks, but nothing is as violent as dropping in blue concrete. Sometimes I feel like the machine is about to "dismantle" itself after a big chunk
I would have radius'ed the edges in contact with the concrete blocks as sharp edges magnify stress. It appeared to me that the blocks fractured at or near the points of contact so radius'ing them would have given higher numbers.
Shame you didn't include the most common reenforced concrete in the UK that's with fibers added to the mix as well as steel rebars but a good video anyway thanks
Fibers added to the mix is to help control cracking. Rebar is added for tensile strength. Neither has any appreciable effect in a compression test. The test of the rectangular piece includes rebar and is a test of tensile failure. The one thing not defined is the mix design. Can make a huge difference...
modern concrete is a mixture of portland cement, water, sand, and aggregate (stones). Your mixture looks to be missing the aggregate, which will result in a much weaker end product.
How does yoir machone in kg relate to your standard concrete cured that is rated for 3500 psi or 4000 psi or 6000psi . Your naching is in kgs so times 2.2 your way over any normal psi driveway or foundation strenght.. so i am confused.
I can't say that I was impressed by the testing method. Firstly, the cubes were not what I would call concrete as they did not appear to include any coarse aggregate in the mix. Secondly, the cement content and water ratio between the recent and historic samples was not considered, so the two could not be regarded as comparable. Thirdly, the recent sample failure points were shown in metric Kilograms , the historic sample in imperial Tons. Finally, the units were given as pressure applied by the press but without the pressure being described as pressure per unit area and the readings are therefore meaningless. That is why the strength of concrete, in the metric system, is described in Newtons per square millimetre. Having said that; for the DIYer with no real knowledge of the nature of concrete; it was a reasonable illustration of how the material hardens over time.
What makes you think they were imperial tons? When he measured 18,000 kg they put up "18 tons". Those were metric tons. And I think you're missing the entire point here. This is a comparison between materials. The absolute pressure is irrelevant. We're looking at the difference.
@@stargazer7644 It's a matter of spelling. Imperial TON (2240lb), as opposed to metric TONNE (1000kg). The units were not specified on the press display. Sadly, after nearly 60 years of using the SI system, most Brit's still aren't educated enough to know the difference. Concerning testing the material; as an Architectural Technologist; I can say that you are mistaken. Because without knowing the load per square unit, the different results are useless for accurately calculating the strength of the material.
@@farrier2708 Perhaps that's how the spelling works in your country, but it isn't universally done that way. We generally use ton in the US, and metric ton for 1000kg. Tonnes is more of a UK thing. I am not mistaken. You don't need to know calibrated absolute values for making relative comparisons. If I say this material's measurement is twice the value of that one (for whatever you're measuring), that tells you something. These folks aren't "accurately calculating the strength of the material". They're making qualitative comparative measurements. You might want to consider that your way isn't the only way.
Not correct, modern concrete is capable of very high strength when required. Concrete in tests has achieved compressive strength almost equal to strength of mild steel.
First test is bogus. Those are mortar mixes, not concrete mixes. There's no coarse aggregate. Then you're comparing it to an old sample that is a concrete mix (you can see the coarse aggregate). Comparing apples and oranges.
Concrete made from modern raw materials, if it has been in normal operating conditions, begins to decompose after 20-25 years. This is determined by physical and biological factors.And... this one: composite material armature does'nt good works when the bending stresses are predominant... :)
Pointless to compare to over 100 years old concrete. Different mix completely.. Different method.. Most likely not same size.. This was carved, not cast.
Looking at all the point loading on those cubes, I wouldn’t stand by those breaks. They did not consolidate the original cubes correctly and voids were obvious as well. This demonstration is pretty useless. Spent half my life involved in concrete design and testing. I know one or two things about proper AND improper testing.
What a load of rubbish, the first lot wasn't concrete at all, couldn't see no stones only sharp sand, anyway what do you inspect in 2 days drying out solid rock thumbs down for me
Excellent demonstration. Especially as a quick reminder for someone who will keep telling you that it is okay after two days.
Way too green after 2 days, they should do a water bath vs spray and see the huge differences there
Define "okay".
To walk on? To strike formwork? What recipe? What is the strength supposed to be?
You can never generally say that concrete is or isn't strong enough, it all depends what the situation and purpose is.
@@MyDogIsGoth for your mom to step on needs more than 2 days :P
Congratulations for having waiting for 130 years before running this experiment !
I'm a structural engineer- that looks like lots of fun. (We did similar tests in college.)
Concrete has been studied and tested for a long time, people tend to do that sometimes. There are pretty well understood curves for concrete strength over time, in construction typically we specify concrete according to its strength at 28 days and beyond that it may gain another 15% or 25%. At 7 days it should be around 70% of its design strength at 28 days. There are variables that will affect this a little bit- how much cement, how much water, how is it cured, what other chemical admixtures does it contain, etc. Some types of modern concrete with special curing conditions has very high strength at 2 days for instance. You can't compare concrete you mixed with ancient concrete because you don't know what is in it. If you want to know what is strongest then modern concrete will win that comparison, concrete has been made that achieves compressive strength almost equal to mild steel.
Your beams without reinforcing failed as expected. Your beams with reinforcing actually failed in shear not in bending due to the ratio of length vs. height that you had. With more length you could have gotten them to fail in bending.
Good demonstration of how concrete continues to cure and gain strength over time. This has been a good chunk of my career. But those samples were not cast or tested according to proper testing methods.
I think you still get the idea
Question: if we were to leave one of those ‘new’ samples for 130 years, would they be as strong as the fortress sample, or did they make concrete differently then? TIA
@@AndrewJillings No. The samples in the video were not correctly made and had visible air holes and the curing conditions are unknown. Also, the concrete in the video appeared to be from a bag and hand mixed, which shouldn't be used for structural purposes - every wheelbarrow mixed would be different. That stuff is okay for anchoring fenceposts, a small patio floor on the ground, or maybe a sidewalk on private property, but you wouldn't want to drive over a bridge made out of it. It's all about the "recipe" used to make the concrete, which would make the compressive strength vary wildly. Concrete does strengthen with time, but after 28 days or so it's pretty much at it's max - for small pieces like those used in the video.
The one major thing you did wrong when you originally made the blocks was you didn't vibrate all the air out. That is very critical to the strength of concrete.
That’s what I was thinking. Way too many air pockets
True, but for me was best not to as no one vibrates driveways.
I agree totally i used my wifes vibrator took ages but it worked ,for when i made foundations for a shed.
However she was hopping mad ,as the sand made the device rough.
@@brucehemmerich9653 i have always vibrated concrete drives or any slab of concrete. {retired now}
👍
The important thing is they were all treated the same so we get a fairly accurate sense of relative strength with time.
Pro Tip- If you find yourself bidding on coring holes in 50+ year old concrete, double or triple what you usually charge- or put a cost adjustment charge in the contract. A client converted a 70 year old parking garage into apartments and the first coring company pulled out and the next one had an escalation charge of $48K over what was originally bid. Making holes in old concrete is "hard" (pun intended). : )
I don’t like you much because of the pun
That's not a pun
How did the pre dynastic Egyptians do it ? Google- core sample 7 can see a spiral shaped cut in it , looks like a thread
@@stestar09 YAWN!
This is excellent content. Made some sidewalks and patio sections last summer, and now i see why i used mesh and rebar and kept the slabs covered and wet for several days.
Thanks!
I was impressed with the plywood holding up..😂
That's an indication that the concrete he made was fairly low strength. Concrete used in normal construction should have allowed the plywood to squash pretty flat before failing the concrete.
The last two failures are concrete strut failures meaning the tension rebars didn't fail. If the section had vertical shear links, it would have increased the capacity. Also the aggregate size for the last two specimens were a bit too large.
Mi sembra di ricordare che progettare, impastare, Vibrare, tensionare i ferri nel cemento sia un'arte che richiede molta perizia, esperienza ed il rispetto di moltissimi parametri. Solo così può dare il meglio di se. Hai fatto del tuo meglio, bravo. Ma si possono ottenere valori di molto più elevati rispettando le procedure opportune.
I would love to see this repeated with hempcrete! Concrete mixed with hemp fibers, it's supposed to be the strongest way to make concrete.
the fact that you had your ancestors to prepare the block of concrete for this video way back from 134 years ago is amazing... that,... or you're a vampire or something.
My understanding is that keeping wetted for the entire 28 day cure time can improve strength by up to 50%. Can you maybe qualify this "myth"/statement and maybe demonstrate differing aggregate mixes and admixtures utilizing lime. More mileage in concrete for you yet, including testing ancient Roman samples?
I thought wetting is only for helping concrete to not develop cracks as it cures.
Ah, I’ll get back to you😄
That's a myth. When cement comes into contact with water the curing process starts. you keep it wet to ensure all of the cement has a chance to react. It will never increase strength by 50%. And you don't keep concrete wet for 28 days . A week is fine. The reason why we use the 28 day because the mix design says the concrete has to reach a certain strength by the 28th day so on the 28th we crush a sample to see if we reached the designated strength. If you don't and it's structural concrete there's a problem
@@stevenferro The Portland Cement Association states that concrete must be kept wet during the entire curing period. 21 days is optimal, after that point the rate of strength increase drops off. But, the strength will increase for years. When I was in school, I took a concrete class, and the data proved this.
@@randallharbour6230 that must have been a 'hard' course😊
My wife asked me "Why would I watch this channel and Why would this guy do all this stuff to compare"... Why Not? If I had that press equipment I would test everything too....
Yeah, I've had to drill into old buildings many times. One project required over 2,000 six inch rebar embedment. Let's just say 100 year old concrete is no joke.
Nice. I bet the bigger stones in the bunker concrete are helpful bc they interrupt internal cracks similar to what happens to metal grainstructures after heattreatment
Nice demo.
If you really want to get it strong with the re-bar in it, pulling a tension on the re-bar while the concrete sets will do that. Basically you can see that the concrete failure starts at the bottom of the beam where the concrete is being asked to work in tension. Pulling on the bar makes it some that that part is under compression up to a heavier weight.
BTW: There are also additives you can mix into concrete. Some of them slow the hardening but also tend to make concrete that is tougher in that cracks don't start as easily
The limiting factor in cured concrete is the strength of the aggregate. If you notice, the last sample has failed aggregate.
Que ótimo vídeo! Parabéns do Brasil!
The hand-mixed concrete from a bag is great if you want to make a walkway in your back yard, but that stuff would never be allowed for structural concrete in a building or bridge for many reasons. You should contact a concrete plant near you, they keep sample cylinders of their concrete in water and after a while they throw them out - maybe they would give you a few.
Love to see Roman Concrete.
Not allowed to drill a hole into the Pantheon!
Looks like mortar -sand and cement. No aggregate visible
Good
Iam Algerian 🇩🇿🇩🇿🇩🇿
1 2 3
Честно говоря есть такое ощущение что бетон был переувлажнен при изготовлении. Механическую прочность он не набрал должную.
Being a civil engineer it reminds of practical i did in my college days 😁😁
Spent 25 years as an ACI 1 ACI Advanced & ICCI Concrete Inspector..Know all of what you show. Did all in NYC 1998 to 2020 . 1000ft Down (Water Tunnel #3) to last high rise (86 stories)...8=)
Have you tried to make clay bricks; seems like they could be made very hard with the high pressure.
If concrete turns blue, you know it's hard af
I would have to agree with you, I retired from our local irrigation district and when we closed the canals to put in pipelines, all the structures came out that were poured in the 30's and if you broke one up, the concrete had a light blue tint to it. And if you drilled into one, you could tell they were way harder than any of the newer concrete that was poured in later years.
Oh yea. I work in the demolition industry, and we recycle the rubble ourselves. Everything goes into a big rotary rock crusher, and small 0-40mm stones and sand come out the other end. The thing makes a lot of banging noise from breaking the rocks, but nothing is as violent as dropping in blue concrete. Sometimes I feel like the machine is about to "dismantle" itself after a big chunk
Please do some video with wood. What is the possibilities of Vertically placed timber 2 by 4 in house construction. Thank you
Спасибо за ваш труд.
What's the PSI rating? They go by a normal dry way like 5000 PSI all the way to 170,000 used in bunkers.
Проверь пожалуста присадки для П4, пенетрон и вибоирование. Вопрос очень важный, думаю почти для всех строителей. Поддержите ребята.
I would have radius'ed the edges in contact with the concrete blocks as sharp edges magnify stress. It appeared to me that the blocks fractured at or near the points of contact so radius'ing them would have given higher numbers.
the longer concrete failed at the support steel i wonder if the steel had rounded corners would it have prevented that?
motar/concrete takes about 100 years to reach it's highest strengh, Just letting you know.👍
That is some poorly made concrete.
And what about fiber mixed with concrete?
Shame you didn't include the most common reenforced concrete in the UK that's with fibers added to the mix as well as steel rebars but a good video anyway thanks
Fibers added to the mix is to help control cracking. Rebar is added for tensile strength. Neither has any appreciable effect in a compression test. The test of the rectangular piece includes rebar and is a test of tensile failure.
The one thing not defined is the mix design. Can make a huge difference...
modern concrete is a mixture of portland cement, water, sand, and aggregate (stones). Your mixture looks to be missing the aggregate, which will result in a much weaker end product.
How does yoir machone in kg relate to your standard concrete cured that is rated for 3500 psi or 4000 psi or 6000psi . Your naching is in kgs so times 2.2 your way over any normal psi driveway or foundation strenght.. so i am confused.
What mix at what psi? Looks like PostHaste to me.
I can't say that I was impressed by the testing method. Firstly, the cubes were not what I would call concrete as they did not appear to include any coarse aggregate in the mix. Secondly, the cement content and water ratio between the recent and historic samples was not considered, so the two could not be regarded as comparable. Thirdly, the recent sample failure points were shown in metric Kilograms , the historic sample in imperial Tons. Finally, the units were given as pressure applied by the press but without the pressure being described as pressure per unit area and the readings are therefore meaningless. That is why the strength of concrete, in the metric system, is described in Newtons per square millimetre.
Having said that; for the DIYer with no real knowledge of the nature of concrete; it was a reasonable illustration of how the material hardens over time.
What makes you think they were imperial tons? When he measured 18,000 kg they put up "18 tons". Those were metric tons. And I think you're missing the entire point here. This is a comparison between materials. The absolute pressure is irrelevant. We're looking at the difference.
@@stargazer7644 It's a matter of spelling. Imperial TON (2240lb), as opposed to metric TONNE (1000kg). The units were not specified on the press display. Sadly, after nearly 60 years of using the SI system, most Brit's still aren't educated enough to know the difference.
Concerning testing the material; as an Architectural Technologist; I can say that you are mistaken. Because without knowing the load per square unit, the different results are useless for accurately calculating the strength of the material.
@@farrier2708 Perhaps that's how the spelling works in your country, but it isn't universally done that way. We generally use ton in the US, and metric ton for 1000kg. Tonnes is more of a UK thing.
I am not mistaken. You don't need to know calibrated absolute values for making relative comparisons. If I say this material's measurement is twice the value of that one (for whatever you're measuring), that tells you something. These folks aren't "accurately calculating the strength of the material". They're making qualitative comparative measurements.
You might want to consider that your way isn't the only way.
@@stargazer7644 Ah! You are American! That accounts for your certainty and reluctance to learn.
@@farrier2708 My reluctance to learn? One day you'll hopefully grow up and realize you don't know everything, grasshopper.
Even concrete isn't nowadays what it used to be in good old days.
Not correct, modern concrete is capable of very high strength when required. Concrete in tests has achieved compressive strength almost equal to strength of mild steel.
Oh man...Who knew that concrete got harder over time? I thought it was harder in liquid form... no wander my shoe prints remained...Dang it!!!
I would have felt sorry for the last block
I don’t think I would have given it a 60 tonne final squash having survived for so long 😳
I want you to put things that rumble
Next time pre-tension and post-tension strength test.
And people wonder why Roman concrete lasts so long… 😂
The video was interesting,butt you must vibrate the concrete
First test is bogus. Those are mortar mixes, not concrete mixes. There's no coarse aggregate. Then you're comparing it to an old sample that is a concrete mix (you can see the coarse aggregate).
Comparing apples and oranges.
Anyone who has had to drill holes in 50 year old cinder blocks will tell you this isn't bogus.
Weird - earlier today I cast a concrete hearth. 14 days to wait.
Yeah but what about Spider-Man's webbing? I bet you didn't try that one
Imagine hydraulic press vs Nagarjuna cement 😁
Concrete made from modern raw materials, if it has been in normal operating conditions, begins to decompose after 20-25 years. This is determined by physical and biological factors.And... this one: composite material armature does'nt good works when the bending stresses are predominant... :)
What?
Looks kind of like English, reads more or less like English, and makes about as much sense as Klingon. Absolute fail.
It can take decades for concrete to fully cure.
It cures by absorbing carbon dioxide from the air. It forms calcium carbonate or limestone in the concrete.
@@cpeast Next I'll mix my concrete with dry ice.
@@SiXiam It would freeze solid before it cured...
It never cures completely
that's a myth
Why can’t we make concrete like it was 130 years ago?
We can, but it takes 130 years to cure.
We can, I make concrete that takes 130te to crush after 28 days
He can't but modern concrete batch plants can.
Надо было в бетон стекло фибру добавить.
You obviously did it all wrong. Dry pour would have been an unbelievable result.
Я думаю тут еще много зависит от марки бетона
OK, and now Roman concrete, please.
Pointless to compare to over 100 years old concrete. Different mix completely.. Different method.. Most likely not same size.. This was carved, not cast.
Doesn't look like concrete.
Get a bunch of different hydraulic presses, arrange them horizontally and have them push against each other to see which is stronger.
Looking at all the point loading on those cubes, I wouldn’t stand by those breaks. They did not consolidate the original cubes correctly and voids were obvious as well. This demonstration is pretty useless. Spent half my life involved in concrete design and testing. I know one or two things about proper AND improper testing.
A lot of whining here
And you just added to it. Nice.
Also: Nonsense
Long!!!
I cannot believe you destroyed such a piece of history
Worth a tiny peice for science
It was probably a part that needed to be repaired but regardless people destroy historical stuff all the time and just throw it into the dumpers
It actually happened
Lots of videos do stuff lime this. It was fun to watch tho.
It did not go to waste. It was a good demonstration
1
What a load of rubbish, the first lot wasn't concrete at all, couldn't see no stones only sharp sand, anyway what do you inspect in 2 days drying out solid rock thumbs down for me
Primero
Glad I didn't drive on my new driveway for a whole week
Looks like mortar -sand and cement. No aggregate visible