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.

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

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

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...

"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

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

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?!

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

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

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

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

The more I learn, the scarier life feels

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

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!

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

that was excellent Roger, really informative!

Fascinsting insight and clarity as usual Roger.

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

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

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.

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.

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.

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.

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

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

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

Great video and very interesting. Thanks

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

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.

EXCELLENT presentation and so enjoyable! Thank you!

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

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.

Another great lesson ! Cheers Rog 🙂

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

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

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".

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

A man of many talents. Thank you.

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.

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

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

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!)

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.

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

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 .

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 ?” 😏😆🧱👍🏼

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

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

Very informative video

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

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.

Fascinating stuff. So well explained. Thanks, Roger

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

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.

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'.

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

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.

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?

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.

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.

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

This was really interesting 🧐

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.

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 🙏

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?

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?

KZfaq 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

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

Really enjoyed that Rog do more of them👍

Interesting stuff, good vid

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

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 😁👍🏻

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

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

Good explanation easy to understand for the simple mind

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

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

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.

No matter how sophisticated sprinkler and suppression systems may be, ALL high rise apartments, condos and business towers are fire traps. Stairwells are no guarantee of getting out of any building alive.

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.

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

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.

Great explanation, thank you.

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.

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

This is the construction pandemic

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.

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

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

As a boy I remember seeing concrete flats with spaling and being told it was concrete cancer . These flats were later demolished .

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

Great explanation. Thanks

Some people spend their entire life just rejuvenating the concrete of THE SAME underground parking lot. The maintenance is labour intensive, dangerous, and expensive. Great vid.

A very informative and educational blog. Thankyou.

thanks for your time to make this info!

Absolutely brilliant video and explanation thanks👍

High Strenght / Low Water 💧Concrete like you find with bridge 🌉foundations in water is the best. The up-front cost is the problem!!!!!!!

Sad that these peoples lives were sacrificed. This is happening throughout the country with the collapse of infrastructure and this is going to cost more people to lose their lives if the something is not done immediately.

Real nice explanation, in layman's language of how concrete buildings can collapse.

Enjoyed that, really informative and interesting. Cheers lads