What Causes Concrete Buildings to Collapse?

In the aftermath of the Champlain Towers collapse in Miami, Roger takes a look at why concrete fails and what can be done to prevent future disasters.
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[@memyself7413]

Roger explaines things very clearly, so even the “untrained” can grasp the situation. Brilliant videos that I watch with enthusiasm. “Thank you, sir.”

[@SkillBuilder]

Many thanks

[@Me-zo8yc]

@@SkillBuilder Really watchable Roger. I don't mean just the info, just in general. Great vid cheers

[@Kpopzoom]

@@SkillBuilder 9/11 was a 4th gen nuclear event.

[@comment6864]

Yes much better than some other builder videos which take way too long to get a single thought out, as if purposefully stretching the video time. This guy talks smoothly with no stuttering or empty space or excessive repetition. Very interesting. I've always wondered how on earth horizontal concrete is possible. That the thin metal wires can make that much difference in keeping the whole glob stuck together indefinitely doesn't seem intuitive. Concrete buildings also get strange vibrations sometimes. I don't trust them.

[@Kpopzoom]

@@comment6864 But - Mr Construction Engineering & Failure Analysis - really does know his stuff. He just bangs away analyzing it for months on end.

[@dank2265]

You know what is sad my uncle who passed on was a civil engineer in south Florida from 79 to 90 his specialty was concrete and I know for a fact he saw so much bad concrete go in to these condos When he tried to reject it he was threatened with death. He had a few concrete blocks dropped next to him To send a massage. it got so bad he had to go hide out camping in the Fl woods because he could not be bought the man had integrity But the payoffs went all the way up Ps he worked up and down the west coast of Florida he saw concrete plants mixing beach sand into the concrete just think about that He worked inspecting for condos,bridges ect there are bridge abutments in Sarasota county that are made with beach sand So you have salt and other impurities in that He had his tires slashed his windows broken vehicles wrecked then he had enough and left the state

[@phulanadethal]

I'm originally from Surfside Florida. I know exactly what you're saying. By the way, are you referring to the high bridge in Sarasota that connects to the mainland? Gosh it's been ages since I've been there. If you want to know more about the history of Champlain towers and the corruption that took place. Here's a link to the Miami Herald's article about that. It's a very good account of what happened. Other newspapers sugarcoated the story. I won't say anything else because I would be acused of anti this or anti that 🙄 www.miamiherald.com/news/local/community/miami-dade/miami-beach/article252467273.html

[@dank2265]

@@phulanadethal thank you that was a good article

[@dianecelento4974]

Unimaginable. I believe God is taking great care of your uncle.

[@jimarcher5255]

I worked in Florida in the early eighties and can verify everything you wrote.

[@dank2265]

@@jimarcher5255 thank you Jim

[@biffjohnson2001]

I would recommend that someone look closely at how the City of Port St. Lucie has been passing inspections without any due process. I was a structural inspector at the time and had several of my inspections overturned and changed in the computer by William (Bill) Abbot, Vinny (Vincent M.) and approved by Joel the Chief building official. I know for a fact that many of the foundations to the thousands of new homes constructed should have failed, but since the City of Port St. Lucie hadn't seen a boom like this, the only thing they cared about was getting as many permits into the building department as they could. If you've recently purchased a new home in PSL and your foundation is cracking, the blame should fall on those I've mentioned.

[@tutttutt9558]

What was wrong with the foundations?

[@davidschwartz5127]

Wow, you named names.

[@margaretaericsson4795]

I'm laughing now🤣😂 looking around and releasing that LOCKDOWN did that 90% office building dare EMPTY. EMPLOYEES are working at HOME🏡🤣😂 GREEDY make a our Mother Earth very, very ANGRY 🌎😠😡and it will be the end of you BLADY greedy BASTARD. Tornadoes, Vulcan erosion, tsunami is coming. TIME TO THINK ABOUT FUTURE. IF YOU DESTROY our planet you comes to relise that MONEY IS NOT A GOOD THING TO Eat, 😂🤣🌎💸🤑

[@dwanseicheine7409]

@@davidschwartz5127 Those who are culpable SHOULD be named

[@jamessang5027]

Thank you for the explanation and the names of the officials responsible!

[@hannahpumpkins4359]

I lived in Key West and was going to buy this one condo in a mid-rise building, but all the locals told me not to because when they were mixing the concrete they used sea water. Pieces of onrete were falling off of the building...

[@faithlesshound5621]

There's a lot still to discover about making concrete that lasts. It's a pity we don't know much about how the Romans did it. They had plenty of high-rise building failures in their time, but they also made some high-quality structures that have stood for 2000 years.

[@williamhaynes7089]

@@faithlesshound5621 - used STONE, and lots of it.. when we build a building we want to maximize the floor space and also make it higher than the romans did

[@DamoSuzuki66]

Very interesting and amazing how much information you managed to squeeze to such a short video. Well done that man!

[@ΣπυροςΓιαννας]

"we basically haven't figured out yet how to prevent rust in the long term, we need to however" That sounds so reassuring. As a physicist I thought engineers had everything in control and clicked to learn more about structures and this answer surprised me. However, I guess if proper inspection is done you can 99.9% predict it and evacuate the building before a Miami disaster happens

[@ΣπυροςΓιαννας]

@The Mutt with no Butt lmao, either way we will die so who cares

[@northernpatriotmanchester675]

My structural engineer said its a problem waiting to happen .poor vibration when it's being poured will let air in and that in turn will rot the rebar

[@chihuahuadachshund4264]

Massive shame to hear of the loss of life. Rip people

[@businesslp3027]

Nothing new..

[@Hitngan]

There was a sheetpiled cofferdam excavated on the adjacent plot. Dewatering was carried out. Reducing the groundwater level increases the effective stress on the foundations which can over stress the bored piles.

[@vinm300]

Oh, interesting. You're well informed.

[@abhaynatoo]

quite a good technical reply. seems to be a science person .

[@billgateskilledmyuncle23]

There was also issues of standing water in the downstairs parking lot next to some of the most vital piers and the standing water has happened for years.

[@99ryanlee]

I watched an amazing video once of a concrete pour for offshore drilling rig piers. All done in one continuous pour to create the enormous hollow piers. Simple stuff concrete but sometimes you need a genius at the helm to get it all done right!

[@rashidtayidi1423]

Excellent info! Thank you for so nicely clarifying the concrete construction process and pitfalls.

[@pandahugger3095]

The more I learn, the scarier life feels

[@SkillBuilder]

The world is a lot safer than it was a hundred years ago. Relax a bit, worry is a killer.

[@comment6864]

stick with wood and steel and don't build too high. 'Keep it simple stupid'

[@davep6977]

don't buy a condo and leave your fate in somebody else hands

[@pastelskies8466]

The past 5 years have been like a bad dream we have yet to wake up from. We must pull together.

[@pastelskies8466]

@@SkillBuilder that's not even remotely true. Violent crime and corruption is worse than ever.

[@edwardleigh-wood1540]

Terrifying really when you think about the implications of concrete collapse.

[@jonesconrad1]

I love the way you sneaked a history lesson in Roger.

[@Teukka72]

Read about galvanizing the rebar for reinforcement concrete a while back. As I've understood, the galvanization adds significant cost, as does the post treatment (galved rebar apparently needs to be baked to prevent the galvanization delaminating during handling or working life). Here's hoping that they come up with a good way around this, either some special surface treatment or a new surface patterning which maximizes "grab".

[@goedelite]

Government officials who allowed the construction of high-rise buildings on a foundation of sand and in a salt water environment were irresponsible.

[@freegedankenzurbaukunst5613]

Sheikh Mohammed bin Rashid al-Maktoum " 'Build it and they will come"

[@alankaufman385]

All of the barrier island, from South Beach to Sunny Isles, has the same substrate. There are high rise structures, hotels and condos, on the beach that are more than twice as old as Champlain Towers that are still in good condition. We know how to build structures on such substrate. My conclusion is that there was human error or human indifference involved.

[@Angel-tw3ko]

@@alankaufman385 Champlain was built by a conman from Canada

[@pastelskies8466]

In a state known for sandy muddy sinkholes. Florida is the sinkhole capitol of the US, yet they build.

[@adorabasilwinterpock6035]

ONE building has collapsed. All others are still standing

[@jonathanlanglois2742]

There's a bridge in my town that has a visible downward bow. Fortunately, it's getting torn down. Trucks have been forbidden from driving on the bridge for a few years already, but still, the problems had gotten severe enough that they built steel umbrella above an underpass to prevent debris from falling on traffic. I'm glad to see the thing go.

[@MatSmithLondon]

One thing I feel you missed - one of the most important things when casting suspended concrete slabs or indeed any kind of concrete - is “cover”! It’s one of the most overlooked details especially by people who don’t understand concrete. There’s a whole British Standard dedicated to the types of spacer you must use in different applications (pretty sure I have seen and played with most of them from cementious lateral spacers to the magic plastic A-type of spacer, chairs, etc), and it is all related to ensuring that bar doesn’t move during the pour, to ensure that there is the specified (eg 40mm) amount of concrete cover over every surface of reinforcement bar. Once you see failed concrete, you can’t unsee it, and the most common form - by far - of concrete failure comes from inadequate cover. (This I am told by the guy who wrote the British Standard - Chris Shaw of the British Concrete Society!)

[@SkillBuilder]

Good point Mat I know that problem with inadequate cover. There are videos on KZbin of people pouring reinforced foundation strips where the rebar is sitting on the soil (dirt as they call it) and it will rust for sure. I think a lot of the problems we see are poor workmanship but if the design of something is dependent upon a critical level of application then the design needs changing. I say this because it is rare to see the level of supervision that is required.

[@harveysmith100]

Point well made Mat, I am only a humble bricklayer but we did cover this subject during my apprenticeship.

[@MatSmithLondon]

@@harveysmith100 Glad to hear :) Seems like a lot of people know it but then when they get onsite and someone else tells them they don't need to be so anal about it, peer pressure and all that... people lower standards. I really do think this is one of the most important /overlooked things in building that go wrong, maybe not on larger sites but certainly smaller residential stuff like basements etc...

[@harveysmith100]

@@MatSmithLondon I couldn't agree more, I started my apprenticeship in 1981 so it was a proper one. We had to learn about everything that touched brickwork. Concrete was a big subject for us. There is no one supervising that builders are doing it correctly, that is half the problem.

[@harveysmith100]

@Senior Housing Analyst Could you explain more?

[@craigfourie3485]

Roger - Brilliant presentation. One additional piece of information that may be significant to this specific collapse. With some of the coastal builds, the type of sand can also be a factor. From time to time, there have been companies that obtain sand from nearby ocean locations and may not complete the proper analytics. This sand may have a higher salt content that could result in accelerated oxidation of the rebar.

[@SkillBuilder]

Craig. You are so right, beach sand was just too tempting to leave there and though it was washed it is still salt laden.

[@jimarcher5255]

I remember reading engineering articles about Florida in the late 50’s where beach sand was used in the concrete

[@SteveAndAlexBuild]

Very interesting Roger 👌🏼. Rust is a very powerful thing , a lot more than people think . I’ve seen a 1940 house with flat bar used as lintels . The rust gets in then the expansion starts . It lifts , the crack gets bigger more water gets in and so it goes on , unfortunately there isn’t a quick cure . This particular house the lintels lifted the face work up so much it pushed up against the rafter ends and kept going ! When We were removing the plaster inside the wallplate had gone with it leaving a good 30 mm gap . Most people see the initial crack and just fill it and think that’s cured it but it’s just a matter of time . We do so many lintel replacements all the time . You see the same on the concrete posts and panels when the rust blows them apart . Nice one Roger , by the way “ where’s James ?” 😏😆🧱👍🏼

[@SkillBuilder]

Hi Guys. I replaced the concrete lintels in my daughters house for that reason. 1950's council built with concrete boot lintels. The ones next door we worse and in the end the face blew off with a loud bang and the lintel crashed down smashing the lean to roof. All good work for you guys but not much fun to do.

[@SteveAndAlexBuild]

@@SkillBuilder . We will always be busy with them as not many brickies will do them . I’ve also seen some shocking attempts at it too 😳🤯🧱👍🏽

[@RobMancusoJr]

Just found your channel - I didn’t want this video to end! Very interesting insight for a construction novice. Thank you Roger!

[@DrAlexVasquezICHNFM]

That was a better explanation than any lecture I ever received in medical school

[@jethrobo3581]

Wow! Fantastic video! Wish all profs were this clear and concise!

[@habsom1406]

Fascinating and informative video, beautifully well explained and presented. Never realised there was so much to it. Scary at the same time.

[@tomjackson4374]

This building was originally designed to be a post tension slab and got changed to rebar. Then they used #4 in the slab with #5 in the columns. But the real culprit seems to be a leaking swimming pool that leaked continuously and contaminated the parking garage on the bottom. We call your day joints a cold joint and all slabs are continuous pores, never stop in the middle.

[@MsMedford]

The swimming pool survived the collapse wit no damage. Seems like it was built better than the building. The lady who was on a 4th floor balcony talking to her husband. Said that the pool deck collapsed. The pool deck was on top of the garage. The same garage that was always inundated with flooding. Se tourists filmed major flooding in the garage 7 minutes before the collapse. The flooding didn't come from the pool. The building is built on a sandbar. Rising sea levels and salt corrosion played a part in it.

[@guyemmott4009]

Fascinsting insight and clarity as usual Roger.

[@kasualskeptik2584]

First time I've ever heard a discussion on the ins and outs of concrete in buildings.... Thanks...!

[@plummetplum]

Enjoyed that. Got a high rise going up near me, day joints every storey. Apart from the rebar will they apply an epoxy glue before each pour?

[@hadrianaugustus5712]

They should apply a bonding agent

[@jimarcher5255]

While vacationing in Cozumel, I watched a crew building an add on to our hotel, They were pouring concrete columns by climbing a ramp carrying a 5 gal. bucket and pouring it into the form. When quitting time came that was where the column ended for that day. Next day they would start pouring the column again a bucket at a time. Of course it did occur to me that they had built my room the same way.

[@petergambier]

Good talk thanks Roger. A very interesting and topical subject that has far reaching consequences for people living in high rise concrete structures by the sea Everything you said about drying times, the longer something takes to dry the stronger it becomes, or adding too much water (common practice with dodgy builders) or having too little cement, adding rebar or fibres, also applies to my preferred mortar, haired lime putty. The mortar can take anything up to 6 years to fully carbonate. Besides arches the Romans used roof tiles to strengthen area's above windows, doors & edges. Their lime blocks were left to soak in sea water because this caused a mineral to form called Phillipsite, a plate like mineral that bends rather than shatters when put under stress. But before you rush around soaking your blocks of lime in sea water, the Phillipsite takes about a decade to form It was quite surprising to hear you talk about not leaving day-joints on a concrete pour and astounded that some builders do. You can't half finish a floor pour and go home but if there's money in it you are bound to find some bad apples. Fun facts: * The Hoover Dam used 4,360,000 cubic yards of concrete, imagine a 4 foot wide concrete pavement wrapped once around the world. * 1 tonne of cement produces 3/4's of a tonne of carbon dioxide and globally we produce 4 billion tons of the stuff. I specialise in lime putty mortars and plasters and also carve in stone as well as use lime and coloured sands or stone dust to make mortar repairs in old properties around the SW of England, mostly doing whole house lime rendering, 1st & 2nd coats by myself but hire in a friend and his labrador for a final finish coat, the last job we spread on a ton of lime mortar around the 6 inch recessed, 5 sash-window reveals and a doorway. I also make quoins, cob & strawbale man-caves and do pargetting (designs in mortar) which I think can add a bit of value and makes it look nice, especially a simple bull-nosed line around a doorway or a window If you stop for the day half-way through a finish coat (3rd coat) that is also called a day-joint, I always try to complete a whole side in a day for that reason and just recently found my rendering limit at the young age of 62 which is 18 square metres that I put on and floated without labrador support in a day, I'd also like to add that it was a very hot day and I was in the full sunlit heat trap for the 2 hours it took to spread it on, no doors or windows to go around. Currently doing some patch repairs to 16th century, Grade 1 listed, lath and haired plaster ceiling in a Somerset church and all the first coat lime mortar under the top coat lime skim has about 80% hair in it which gives it such amazing tensile strength and longevity, (the modern day equivalent is polypropylene fibres which you can buy in any builder merchants) and rather than hair I prefer to use hessian or sisal (rocking horse hair) mixed into the mortar, In actual fact when fibres are added, instead of 4 kilo's of hair per tonne it should perhaps be double or even triple that amount, perhaps we should mix in old plastic (shredded) waste which will make it stronger and save the planet a bit. However Champlain Towers just like many other concrete built high rise towers is by the sea which has a much higher salt content in the air which will (like you said) accelerate any rusting in the rebar. An engineering report was done 3 years before because of the spalling and cracking found in the basement of the building. This means that Roman harbour sea walls are stronger today than they were when they were first made.

[@mathometer]

that was excellent Roger, really informative!

[@danielbuckner2167]

Oh and also there are methods like cathodic protection where you run a current through the system of rebar to prevent oxidation and I see that as a retroactive methodology employed on older buildings like the one that fell in Miami. It is already currently being used and helps keep the oxidation and therefore the spalling at Bay but of course if it was put on buildings we knew it would keep that from happening and would not have to be used as a remediation tool.

[@johnreese3943]

Regarding the Florida building collapse: I suspect the concrete was made using beach sand. The salt was IN the concrete when it was placed.

[@Nostradamus_Order33]

Oh my

[@badgastein2]

When we built the Falklands Airport it was not economically viable to import sand to make the concrete so we used local sand which was put through a washer to remove the salt.

[@jimarcher5255]

I remember reading in engineering magazines about Florida in the late 50’s where the had to condemn several buildings and roads where they had used beach sand in the concrete. Apparently it was common.

[@seedplanter7173]

kzbin.info/www/bejne/rHO4hHywlrhjrdU

[@jmyers9853]

beach sand tends to be very round, sharp sand is irregular and holds the concrete together, just put the two in your hands and you will see the difference

[@ypaulbrown]

really great information, thank you so much for making....cheers from Florida, Paul

[@johna6327]

Can see your passion for history coming through here Roger. V enjoyable video.

[@SkillBuilder]

Glad you enjoyed it, to be honest I just find a lot of stuff interesting, it is one of the joys of life.

[@02markcal]

Yeah John, between the history and the technical information, it kept my attention all the way through.

[@williesnyder2899]

Just here, in a late 1880’s dwelling, for the field stone and mortar foundations! Very good overview from the channel presenter!

[@highdownmartin]

2018the Miami building had a report highlighting large cracks in the fabric of the building. So it wasn’t out of the blue

[@philoso377]

Thanks for the informative episode. That leads me to think of an alternative cement on concrete mix. Special blend of concrete involving hydraulic cement which is impermeable to moisture. There may be a need to rework structural design to compensate properties differential.

[@144Donn]

EXCELLENT presentation and so enjoyable! Thank you!

[@roysammons2445]

I work in a four storey building built from reinforced concrete. I have screen this kind of thing occurring. We had ther windows replaced ar the front of the building and we found several of the concrete beams needed repair. Great explanation Roger 😁👍🏻

[@twmd]

at that scale 'brittle failure' is a damn scary thing.

[@chaspitt7061]

Very interesting, the UK building industry is well aware of these rusting problems, some cements are more susceptible to rust than others. 40 plus years ago I was involved in constructing a huge safe for a bank. The shuttering was Acropan units (steel plates) The main reinforcing was 4 inch x 3/8 mesh, interspersed with 3/4 inch Barley Sugar (twisted) Stainless Steel bar, which of course would not rust.

[@sevenodonata]

A man of many talents. Thank you.

[@kyoxilbuzz]

I knew all this already, but that was really well explained and narrated. Thks

[@paul756uk2]

"It can snap very very easily" as Roger casts his mind back to that shower tray.

[@SkillBuilder]

You are so right Paul.

[@gdfggggg]

Roger snapped the shower tray on purpose to provide useful content for the viewers. Cmon man.

[@thesunreport]

@@SkillBuilder There is another issue that I saw recently, about poorly made concrete blocks in Ireland that are contaminated with a material called Muscovite Mica. You guys should do a video on that as it also looked interesting. :)

[@Dave5843-d9m]

The reinforcing steel has to be properly tied in. When it’s not done properly you get a very handy fracture point. However painted or galvanised bars cannot be 100% covered. Those bare spots rust much faster and the localised corrosion fails catastrophically.

[@maxmerton]

@@Dave5843-d9m Why do the bare spots rust much faster?

[@AB-nu5we]

In US flyover country, I worked for a municipality in a division that worked on all the city construction sites (not an engineer). The city had a very large (very nice) parking ramp built with pre-stressed cables in the build to support the flooring for the ramp and business suites on the front side. I remember the city architect telling me 'if you need a floor piercing, it has to go in _before_ the concrete pour. There is absolutely no drilling allowed after. If you hit one of those cables 'Sprong!' and the whole thing explodes outward.' We made sure we had all our floor piercings planned before the pour. I actually had a 'save' on that build too, preventing a contractor from following an error on a blue print that involved drilling in the floor. Glad they asked 'the city guy' who just happened to be inspecting my area of responsibility before proceeding. Of course I said 'stop right now' and called the architect. Was told that would have been a disaster. Not the contractors fault, but the designers'.

[@krakenwoodfloorservicemcma5975]

That soup coming out the chute was like a 54” slump..

[@GoogleAccount-xe8bx]

We have building failures in Ireland due to pyrite and mica used in building blocks during the building boom. The percentage of pyrite and mica used in block manufacture exceeded recommended levels and houses are starting to show cracks and subsidence. Some of these homes are only 16 years old.

[@Wonkabar007]

When it comes to good concrete, in Ivan Locke we trust.

[@mrlotusmic]

Great concrete, he’s not so good with relationships.

[@comment6864]

who's that?

[@tjsap]

@@comment6864 Its a movie with Tom Hardy named Locke.

[@polygamous1]

Very interesting mate I really appreciate this as with Most of your videos, this explains it 100% why when I was working in Nottingham on Ratcliff n Soar power station for KIER on the chimney breast it was a 24 our job 12 hours day time 12 hours night time n we didn't come down at the end of our shift till the other crew came up first ( amazing money in 1965 I wasted it ALL) n when my mate build a ferro cement boat a 41 footer in the boat yard I had my little boat he was there day n night watering the boat to stop it cracking Many thanks mate Brilliant explanation, ops n many thanks on how to clean silicone with Bleached It worked better than I was even hopping cheers

[@stevendouglas3860]

Very interesting SB loved your video on shower back boards. And how plasterboard "rots away " behind your tiles ...a must watch by all ppl getting a new shower .

[@danielbuckner2167]

I dont know any new showers being permitted like that nowadays.

[@cholman57]

thanks for your time to make this info!

[@steveriley1952]

Another great lesson ! Cheers Rog 🙂

[@rickibrown9233]

Great video and very interesting. Thanks

[@TB-zf7we]

You forgot to mention Self-Healing Concrete, which looks to be the future of concrete material use where water ingress can bring a total failure.

[@PaulJersey]

Excellent analysis! The Hover dam has 1’ diameter steel pipes embedded in the pours and they ran ice water through them. They poured 4.4 million cubic yards of concrete. The majority of the pours were in 25’ x 25’ x 5’ sections on the back of the structure and larger pours on the face of the structure. I know that they claim that the concrete is still curing 86 years later. I could never find out how long they had to run the cooling system after a pour for? If the concrete is curing, is it still cooling off as well? Did they use a special joint design between pours? All sorts of questions. I guess I need a time machine, because the book that I read on the Hoover dam did not get into the details so much.

[@tensevo]

People are essentially diseased.... They want to build higher and higher, for cheaper and cheaper, with less and less "ugly" supporting structure between floors, ...with lower and lower quality foundations and materials. What could possibly go wRong?!

[@scottcraig1047]

Fiberglass and basalt fiber rebar has been used quite successfully for years. I think engineers and builders will be paying alot more attention to these alternatives to steel after this tragedy.

[@bowtieguy6870]

I think you’re mistaken about the Hoover dam being poured all at once. It was essentially built by using columns of interlocking blocks poured into forms then used grout to fill voids. They actually wouldn’t pour more than 5 feet at one time in any column then allow it to cool.

[@limbrat5448]

My thoughts exactly.

[@totherarf]

Yes the exothermic reaction from a block of concrete the size of the whole dam would be catastrophic! I believe they poured the adjacent section before the concrete in the first block had cured though. I am not sure if that counts as a monoblock though ;o)

[@craigh8602]

And they did use 600 miles of steel pipe to circulate cooling water---which they later filled in with concrete :)

[@wetrupload9375]

Similar to how the pyramids in Egypt were built.... The most believable theory so far.

[@terencemanthorpe5522]

As a carpenter I did a lot of shuttering and on one occasion I had to replace a 125 mm balcony in Brighton and the structural engineer got us to put in stainless steel high tensile steel , I remember that job as it was an insurance claim I got my money one year later .great channel thank you 🙏

[@danpatch4751]

Very informative video

[@trevorhayes1079]

Roger great video could you do a video on prestressed concrete Trev from down under

[@Santiago_Handle]

I didn't know that Dolph Lundgren had a youtube channel about building!

[@turboconqueringmegaeagle9006]

First time watching your vids, enjoying it cheers.

[@matthewcalder4351]

Really enjoyed that Rog do more of them👍

[@hannahjames3180]

I envy any apprentice who learn with the likes of Roger. His knowledge is immense!

[@hugovanlawick8716]

I believe a relatively economical solution would be a combination of basalt rebar plus twisted or hook end steel fibres. The fibres would help prevent cracking plus add some tensile strength where it's needed most.

[@comment6864]

Concrete always eventually cracks somewhere, and water will get in, so then what is the point of building with these rusting bars that you know in advance have a limited lifespan?

[@kokokaification]

$$

[@comment6864]

@@kokokaification historically it's been money and power. It's harder to control a population that lives in individually owned houses than one that lives in the types of buildings that concrete is used for. Throughout human history the former has been a more natural way to live. Human nature is such that living space is a very individual, personal, and private thing. When people want to commune for some reason they come together to some agreed upon central place, do what they want to together, then retreat to their own completely private space (NOTICE!!! That's exactly how policiticans themselves live!!!). That's why for people to share life the sacrament of marriage is needed. Cramped, mass living quarters of disparate people is not normal or natural for human beings. Anyone who insists otherwise is a wheeler-dealer or a psychopathic power mongerer.

[@colinnewton7291]

What an amazing video. I learned a hell of a lot. Thank you

[@harveysmith100]

Isn't it about time they start to specify stainless steel re-bar? All cavity wall ties have to be stainless now instead of the the old galv, why not re-bar?

[@patrickgarvey146]

Cost$$$$

[@krakenhackenla]

Cost much higher and stainless steel has its own issues in low oxygen environments.

[@alexroge6495]

I’ve thought of that too, but I think that would ruin the entire cost equation for concrete. i.e you might as well just use structural steel

[@denisoriordan6739]

Cavity wall ties are specifically designed to wick water away from a porous concrete block on the outside, and stop the water travelling through to the inner leaf. A completely different construction method to poured concrete. Plastic wall ties were used for years, for cavity walls, but they deteriorated over time, & lost their binding strength. Now we use Stainless wall ties. Stainless steel wouldn’t work in poured concrete, because it wouldn’t chemically interact with the concrete to form the atomic bond necessary to grip the steel to the concrete.

[@godimsofuckingbored]

@@denisoriordan6739 Perhaps you should tell that to the manufacturers of stainless rebar. Why wouldn't stainless rebar interact chemically with concrete in similar fashion to plain steel rebar? What is the crucial difference in chemical reaction? The physical bond between stainless rebar and concrete is identical to that between plain steel rebar and concrete.

[@234dilligaf]

The guy in this video really knows his stuff, and explains in a way to keep your attention. Excellent video.

[@tinytonymaloney7832]

Interesting stuff, good vid

[@Kevin-jf4jy]

Interesting video explaining in everyday terms how reinforced concrete works. One thing to mention in terms of the durability though, it's not just cracks and water. New concrete is alkaline. An alkaline environment prevents the reinforcement for rusting. Over time the carbon dioxide in the air causes carbonation of the concrete which reduces its alkalinity and this allows the reinforcement to corrode. This is the real problem. Most concrete structures (in the UK at least) were designed for a 50 year life, some for a 100 year life. Looks very shortsighted now. It will become a huge problem in the future.

[@jasonantigua6825]

Some of the cockney wide boys I worked with called it a joint joint!

[@Roman-nu1om]

I thought you were "just another tool guy" but hell no you could teach at the university, I'm seriously impressed!

[@ygrbooks]

Thanks you for your insights. You know, in the 70 and 80s we were told that it would cost more to demolish a reinforced concrete building than to build it, because its structure would resist any cheap demolition means. Seems that a wee bit of (salt) water will do the trick.

[@mikeharrington5593]

If you have seen any of the collapses of comparatively recently constructed buildings in China the whole lot crumbles like Wensleydale Cheese, pillar/columns and all - which you would expect to retain some reasonable shape even from collapse

[@seedplanter7173]

kzbin.info/www/bejne/rHO4hHywlrhjrdU

[@pedroisaacs6212]

Love your show Roger! Very informative. Is there any form of coated steel rebar support that does resist rust better? I have seen both zinc and plastic polymere coated rebar support steel but apparently rust still gets in through open pits in the rebar coating?

[@SkillBuilder]

Yes it does seem that the coatings are too soft to resist the hard knocks

[@rgs6236]

This was really interesting 🧐

[@donaldcarter4324]

Thankyou for the information as I was about to have a concrete and steel home built in central Florida by Steel X companies. Fire,termite, and wind resistant but cracking and structural fatigue is of great concern.

[@robertbrandywine]

Go with steel I-beams and clad with concrete blocks with brick outside that. I would.

[@richardblaauwgeers4349]

I already knew all of this, but i really like Roger story telling. More please

[@steveflor9942]

Fascinating stuff. So well explained. Thanks, Roger

[@vinnysurti]

I always learn by watching & listening to Roger. A very clever guy. Thank you 🙏🏽

[@SkillBuilder]

Thanks for listening, we enjoy your humour. Maybe there are no jokes in this one.

[@vinnysurti]

@@SkillBuilder you need a build a solid foundation in everything you do before you can afford to joke around.

[@lionrocklr9217]

Terrific primer in concrete and its uses, weakness etc Thanks.

[@richardshort4587]

When I worked in construction I was told concrete keeps on curing and can take up to 50 years to reach maximum strength. Can anyone verify this 🤔 Thanks.

[@johnclements6614]

Most of the curing will take place in the first month or two. Concrete mixes with PFA (coal power station ash) and GGBS (blast furnace slag) take slightly longer to cure and hence gain strength. But no matter what mix there will not be much significant strength gain after a year but there will be some minor gain. Long term concrete can loose strength so after 50 years it may be declining.

[@richardshort4587]

@@johnclements6614 Thank you for the reply. I always considered concrete only a few months old as still green, especially when it’s quite thick. I can see thinner layers drying out quicker but heavier thicker layers taking longer as the moisture has further to travel to escape. With today’s modern mixes and additives I can see perhaps an acceleration in drying times. There are many different recipes of concrete each designed for its purpose and it’s placement if there is ground abnormalities and conditions that can effect its curing and longevity. As for PFA this was collected at the power stations. My father worked in kms in the UK for 40 years. Again I thought this product was only used to make cinder blocks and not concrete.

[@johnclements6614]

@@richardshort4587 You should call it curing rather than drying out as a substantial portion of the water bounds chemically with the cement | (or PFA). An acceleration in early strength gain is not always an advantage as it will be caused by an increase in the speed of the chemical reaction which generates heat. More heat creates early thermal cracks which lowers durability, hence the reference to cooling at the Hoover dam in the vid. Early strength gain is good for multistorey RC frames where you want to load the previous pour in a few days, so then you would not use PFA etc to replace part of the cement. PFA is cheaper than cement, I would not be surprised if the construction industry was given it for free originally. We have stopped burning coal, nearly, in the UK so the chemically suitable PFA will run out. PFA has also been used a fill material. It is lighter than sand and gravel so it produce less load on the ground. Good for building road embankments on marshy ground as there is less settlement.

[@orcaluv]

Owens Corning makes fiberglass rebar. I wonder if it's any good. I don't see any issues with a slab for a residential home but I wonder if it has issues for multi floor buildings.

[@autodidact537]

There's also the more expensive stainless steel rebar & also rebar made from basalt fiber.

[@w2385-i2s]

I'm glad my house is wood, not concrete.

[@lennon28280]

In almost all the world, houses and government buildings are built entirely of concrete, in fact I always ask myself the question of how in the United States they build with materials as flimsy and easy to destroy as wood, I feel much safer living in a house made of bricks and concrete than one made of wood, not to mention apartment buildings. no intention of offending greetings.

[@saintslad5399]

Absolutely brilliant video and explanation thanks👍

[@m4inline]

I reckon if we got a new government where Jeremy Clarkson had the ministry of transport and Roger had Ministry of Everything Else then the UK might just be able to save itself. Anyway, great video as ever. Thanks.

[@SkillBuilder]

I think Clarkson wants the Ministry of Agriculture. He has become a right swede basher.

[@lloyd4011]

@@SkillBuilder Swede basher 🤣

[@Tbevel]

KZbin channel jeffostroff has very good theory on the collapse. He is an engineer. I have been a commercial Carpenter for last 32 years and can see his point. The pool deck was not designed with slope to run off rainwater. The vast layer of pavers trapped and held the water and it eroded the waterproofing , concrete , and thus rebar. The evidence was the water and spalling in the ceiling of parking garage which is also pool deck. The pool deck collapsed, which cased building to give way

[@TheHonestFoodTeller]

If Anthony Hopkins and Malcolm McDowell had a cousin...

[@garrynutter860]

Just had a concrete hard standing built. There is a bit of a dip in it and water collects in that area. What can i use to level up the dip. Thanks

[@SkillBuilder]

self leveller that is suitable for outdoors or make up a slurry of SBR and sand and cement and trowel it in

[@TurinTuramber]

Rest assured that when Humans have had their time on earth, everything they have built will be undone with a bit of time.

[@SkillBuilder]

Geralt I remember an old and very wise guys I worked with who pointed to some trees next to our building site and he said "These are the guvnors. After we have gone they will push their roots into the M25 and tear it up inch by inch, they will wrap around the skyscrapers in all the big cities and turn them to rubble".

[@mikes4163]

Yeah, but Roger's projects will be the last to go 🙂

[@TurinTuramber]

@@mikes4163 PU glue will be the last thing to go. Anyone who ever got it on their hands would agree.

[@MrSmid888]

@@SkillBuilder you only need to look at the Chernobyl site to see FULLY what nature will do. How it THRIVES. Like other species to roam Earth I believe humans will end one day. Already we need drugs to beat nature 🦠💉 Man waterproofs Earth and the waters rise.

[@hannahjames3180]

I worry what all of the deep digging will do to the earth. Homes should be built using the correct and suitable materials to match the weather and elements for that region. For instance, not building shed-like structures in hurricane alley.

[@bobpetty6482]

I poured concrete for over 50 years and was never able to pour concrete that wet. Looked like a 10 inch Slump and and we very rarely poured over a 4 inch slump

[@erictam7014]

I thought he was just washing out his shoot. . . into the prepped rebar

[@zachblundeto7137]

It’s the seismic effect that collapsed the building when the US Navy exploded a bomb off the coast of Florida.

[@earthman6700]

Nuclear Weapons tests over the years must cause seismic activity.

[@bluevireo425]

Thank you so much, appreciate your clear teaching...Wish you were instructing the young civil engineers of today...very serious work!!

[@TYLERCONSTRUCTION]

This is the construction pandemic

[@robertbatters53]

A very informative and educational blog. Thankyou.

[@donniedarko979]

In America everthing is political. We will never know what happened in Miami.

[@Hisloyalservantslistenlove613c]

Miami Beach not Miami

[@Peter-un8no]

The other reason these materials are used together is that they expand and contract at the same rate. Another point is that buildings are not meant to last forever, everything has a design life with maintenance requirements.

[@sproglode]

Roger, an excellent video, and no doubt, a scary one for the millions of people living in coastal areas, and where buildings were constructed on land less stable than, say, rock. I feel sorry for the residents of such buildings since it is quite possible that they, not the designers and constructors, will be faced with massive bills that they may not be able to afford. Finally, many must also now be aware that their investment may be seriously and negatively affected by the tragedy in Miami.

[@jamessang5027]

Excellent video! All these years and we don't know how to build with concrete!

[@andrewsim9180]

Fascinating Roger. I learned a hell of a lot from this pithy video. Thanks!

[@SkillBuilder]

I like that 'pithy'

[@eamonnw]

08:30 just wondering if those rebar could have electrical sensors on each end to test for corrosion