There is a driver, but he was placed there by fraudulent methods and is suffering dementia. His handlers believe their feelings and political rhetoric above science and engineering.. a formula for absolute failure and destruction.
@@jenniferwhitewolf3784 I was referring not only to political, but to health wellness and medical, financial, local gov't, you name it the train is off the track!
As an old structural Concrete Contractor, I've wondered how come the rebar did not start rusting right away since we had to pour or pump it in a liquid state. Now I know, Thanks
@@jwenting A little light rust is good because it gives some roughness and adhesion but thick brown rust with a thickness you can brush off is bad. There should not be loose material. That is just one of a hundred defects in construction reality, like less rebar than spec, insufficient lapping, not properly tied, insufficient coverage ( too near surface ) etc. etc.
@@tuberroot1112 concrete does not adhere to rebar ever. Watch the video one more time and note when he says “mechanical bonding” it doesn’t mean “glued” together.
Don't know when I'll ever get to use the education you're providing but I hope to earn an honorary degree in engineering by continued viewing. Thanks Professor Josh, I find your content fascinating!
This is only a small piece of engineering. You are not getting any of the mathematical modeling. Engineering is about applying mathemetics, physics and chemistry and making a simple model to explain what is happening. We test the model to see how well it explains what is happening and then work to improve it and reduce error. Because we know we have errors, we assign a safety factor to ensure there is enough strength.
@@scottkelley1558 I think the intention of my comment may have been lost in translation. It was an attempt to deliver a sincere compliment in a humorous manner. Clearly I failed. I understand that the field of engineering requires many years of study spanning a deep dive into subjects I failed miserably in, especially math. That being said, as a lay person I'm grateful to this channel for a better understanding, albeit simplistic, of why the building I'm living in manages to keep itself upright.
When you see someone talking so fluently about such specialized stuff without any „err‘s“ „hmm‘s“ or other flaws, you easily can see, that this person is a person of outstanding ability and knows, what he is talking about. Found this channel via the Champlain disaster - great vid Josh, as always, thanks and best regards from Germany.
Josh... YOU Sir are THE authority on the Champlain Tower tragedy. That "Other Guy" couldn't explain his way out of a wet paper bag! Thank You for the expertise you share with us!
Years ago, my aunt and uncle were going to retire next to the ocean in Northern California. They rented a house near the beach before purchasing land. After seeing the damage that sea air does, they decided to move inland a bit.
Amazing that I seriously watch each episode and am learning. All because of the Florida structure collapse. Now I see better as to why my two contractor buddies take their jobs seriously.
No kidding , the Florida collapse sure awakened me to learn all about concrete structures . I live in Central America and concrete is all over structures . The instructor in this video should talk about what has happened in Cuba over time ( buildings just topple unexpectedly ), and now we know why .
This isnt what really happened... It was not salt water or oxygen ... It was much more than that...They arent tell you the whole story... Unless you can figured this out... You have to observe why it happen or how it happened...No one has mention anything about Chlorine or Shock water ... WHY ??? Coney Island Buildings has ever failed ? We have Frost and Rust also .... Explain that ... and we are talking over 75 years with no issue.
@@supernova8962 I guess you missed the part about the original contractor and his shenanigans huh? There is a whole other issue related to this and is damn near criminal.
@@ianchandley Yes!! I've just retired from teaching 5th grade science for 20 years! ( Not anywhere on the same level, but those kiddos have got to start somewhere lol)
All my aptitude tests in high school said I would be really good in engineering. I thought that sounded really boring. ( although I was the only female in the mechanic drawing class ) Now I can't get enough of watching these videos. What have I missed 😳. A little too late as now I'm 75! 😥
You know I’m not an engineer, contractor or have any building experience at all, but I find your videos fascinating. I found you by your Champlain videos but I’m here to stay just to keep learning. 😊
Many people mention that. maybe he still feels he's more helpful being out working in the field. with each decade priorities and desires change. I know he would be a natural for instructor. I also know first hand about going out every day and solving problems. don't be surprised if he and his firm are still doing this 40 years from now.
@@BuildingIntegrity Along those lines, I was curious if you've ever considered packaging continuing education units/professional development hour lessons that people can buy. Honestly most of what's out there is trash, and your style and presentation are very good, in my opinion.
This engineer seems to explain the issues pertaining to the recent structural failure on everyone’s mind much more straightforward than the other channels -& without a lot of hullabaloo + pets thrown in for no good reason. Thank you.
ngl this stuff is fascinating and the pH explanation was easy to understand. thanks for the quality videos! much respect to the hardworking engineers and contractors out there!
I’ve learned a lot from a select few channels like this. They’d make great teachers or lecturers. I can’t even build Lego, but the way it’s explained I understand it, but I don’t feel like I’m being patronised. I was talking to a friend about this & he asked where I got the information from 😀 I tried ‘I’m just a genius’ it didn’t work. So I showed him this channel and a couple others 😀
Richard Feynman was known as "the great explainer". Not only was he a knowledgeable person, but had a special talent for sharing that expertise with us laypersons - and making it interesting. Josh, I'd put you in that camp of great explainers. Top notch work on these videos, you have a real talent for sharing your knowledge in an understandable and interesting way. "Dumbing down" without being condescending or pretending to be the holder of all knowledge. In particular with the Surfside series, I particularly like how you distinguish between definite facts, probability, possibility, and indications. All without sensationalism too. I have a couple of engineers in the family. I'm not sure if they just lack that ability to translate into non-engineer info as well, or they think that I'm smarter than I really am. But you sir, absolutely nail it. Thank you.
@@katdistefano8551, yes. Love it. From now on I fully expect Josh to personally play any intro or background music on bongos. I'll be one happy chappy. I'm guessing being in construction engineering, he already knows how to break into houses and knows how to spot weak points in security devices. Possibly not as good at gleaning information to guess safe combos though (or cracking them), unless he also has a practical joker side to him.
Excellent presentation especially for lay-people. I’m a CE by academia, and this was easy for anyone to follow. Unless they don’t understand why steel rebar is in R/C to begin with. But you’ve explained that to novices well enough in other videos.
I learned a lot about chloride ion penetration into steel reinforced concrete structures during my first internship. I left the military to pursue civil engineering after being a draftsmen from an early age (although through my time in the service I was IT). That internship was rough. My PM, within my first week at this giant bridge project, handed me a post-it note with something along the lines of, “research coatings to knock down the chloride ion permeability of concrete.” It was basically gibberish but he stuck it on my forehead and I went on my way. His intentions were to provide me real-world experience in researching field applicable problems in civil engineering, the kind of stuff which isn’t taught in school-the kind of situations which formal engineering education doesn’t begin prepare you for-where you need to think fast and solve a problem in the field QUICKLY. I’m about to finish my degree soon, at one of the best civil programs in your state, although as a UCF grad I’m sure you’d disagree (haha). While I certainly didn’t enjoy being in the field 6 days a week, working 12-14 hours a day, it has been the foundation for my engineering knowledge. Your videos have been awesome too, Josh. Thanks man, keep up the good work. I hope we meet some day since the CivE field in FL is so close-knit. I won’t disclose my personals here on UA-cam, but hey, if you read this comment and we do in fact cross paths (hopefully not you investigating one of my projects!) I’ll let you know. Keep on keepin’ on brotha.
Yeah, I agree. That's the main issue with college. They never teach you stuff you actually WANT and NEED to know. Or it's the exact opposite of the real world.
In London there’s a condition known as ‘Regent’s Street disease’ due to the fact the first reinforced concrete used in construction was to the lintels of the buildings constructed around 1910 down Regent’s Street (it was mostly rebuilt at this time). Within a few short years they had to be replaced (including cracked stone cladding) due to the corrosion.
@@anna-lisagirling7424 I stayed in a condo hotel on Waikiki Beach. The lanais on a number of units were undergoing the first repair described in this video.
@@johnhaller5851 How long ago was that? Crazy amount of high rises in that neighborhood, eh? In the 70's when I was first there, there were still single family houses scattered beneath just a few high rises but they were disappearing fast! I'm glad i saw it all before it statred to look like Hong Kong. But that whole area was entirely swamp land and the Alaw Wai canal was dredge out to drain that swamp to allow for development. The "land" is coral. After our tutorial here with Building Integrity, my heart beat faster thinking of the entire Waikiki Beach tourist district and the possible nightmares awaiting.
@@anna-lisagirling7424 I think where we stayed was 2500 Kalakaua, Foster Tower. Most of the lanais are now enclosed, they were all open when we were there. I'm guessing a bit more than 10 years ago, my son was still in college. It was sort of an air-bnb place, where there was an office which rented out the condos when the owners weren't there.
@@johnhaller5851 Wow. Just close the lanais. Imagine such a thing. That speaks volumes, doesn't it? I wonder if the Champlain Towers collapse set off a bit of a panic in Hawaii re: their old re-enforced concrete high-rised building inventory? Maybe I'll do some snooping in my "spare" time. . . Thanks for this!
I've spent most of my career evaluating public works contractors' financial condition and experience to guarantee their performance of their jobs and payment of their bills. I have learned and understood more in the last couple weeks since finding these videos than in decades previously. Josh Porter is a wonderful instructor, able to make these concepts easy to grasp and entertaining as well.
Great explanation, well done! Having lived in a coastal environments most of my life I have seen concrete and repairs continually fail over time. Also happens with brickwork where the mortar and certain kinds of brick seem to go through a similar process of degradation.
How I have become so interested in concrete is due solely to your fascinating and educational videos on the subject. You really are an amazing teacher. Can you explain how is it that there is Roman concrete that has been under water for >2000 years that is still structurally sound?
I found this on the Internet regarding Roman concrete: Roman concrete was based on a hydraulic-setting cement. It is durable due to its incorporation of pozzolanic ash, which prevents cracks from spreading. When seawater gets into its cracks, it causes a chemical reaction that actually strengthens the concrete. Minerals called Al-tobermorite and phillipsite form as the material leaches mineral-rich fluid that then solidifies, reinforcing the concrete and making the structures even stronger.
@@markvasiloff2217 any idea where these minerals are located in abundance? Looks to be a smart move to mine and export to contractors bent on creating strong structures. A niche to be considered.
I've understood for many years that at least some Roman concrete was accidental. Bricks were mixed with aluminium rich ore. The bodies of dead slaves were thrown into the mix, and the resulting reaction of bone calcium with aluminium ore created a cement. I was told this by a university lecturer. I don't have a reference to cite.
@@markvasiloff2217 so interesting. TY. I wonder how much of the chemistry they understood or if it was just a lucky use of locally available materials?
Join the paranoid about parking garages club, lol. I have nightmares about someone WALKING in there around the corner or at the top of the slope where you can't POSSIBLY see them, and are DEFINITELY NOT expecting them! I could see someone walking around there on purpose to get hit and sue. Plus, I refuse to pay for parking, so there's that. Especially in like a hospital. They have nerve even asking for more $$. Lol
My thirst for knowledge brought me to your channel but it is the clear straightforward explainations and relaxed conversational pacing that keeps me coming back. Bravo
I live in Chicago and the arches in many of the viaducts for the red line trains are massively spalled from top to bottom. It never looked safe, and thanks to you I know what to call it! Your subject matter, which I never gave a thought to before the Surfside condo collapse, is totally enthralling! (Enspalling?!) Thanks for all you do and your peaceful demeanor while teaching us.
Me too! But it's a non-issue since the virus. I'm not on the tuberculosis express any more. I do know an arch is the most solid design, if I recall right...I wonder if those are something that covers something else, because those train lines are well over 100 years old (no rebar then)
Thanks very much for this tutorial. I am a formulation chemist,designing impermeable acid/caustic/chemical resistant coatings for concrete structures. Novalac epoxies are typically used to coat concrete in large chemical plants. Problems arise because there are only two types of concrete...concrete that has cracked or concrete that will crack. Epoxies are unfortunately nearly as crack prone as the concrete,so when concrete cracks,the epoxy coating that`s supposed to protect the concrete cracks as well. This new coating,soon to be released,will solve those issues. Understanding the deterioration functionality of concrete is extremely important to the design of industrial coatings. I need to say in touch with your channel. Best regards.
Thank you for this video! It’s so informative! I’m reminded of Roman Harbour concrete that’s been getting stronger over the centuries in the ocean instead of breaking apart. I went and looked up the article I read a while back on it and it makes me wonder if something like that might be better for coastal structures than standard concrete… my understanding from the article was that the special minerals in it react with seawater make the concrete’s pH higher, which sounds like a good thing for preventing the rebar from rusting! The article is from 2017 in Nature and it sounds like at the time companies were still playing around with recipes to find one that can work with modern manufacturing.
I now understand that sealing my concrete is more about preserving the concrete rather than esthetics. You don't know what you didn't know. Till you know what you didn't. Thanks for this valuable information.
I imagine that once there is cracks and such, that even more water, oxygen, etc. can penetrate creating positive feedback leading to rapid deterioration.
My father in law and almost every one of my friends are all engineers. I’m learning so much from your presentations. I’ve never trusted beach front condos. Everyone wants to be on a high floor. Not me. I want to be on the ground floor. Why? The pool and beach are right outside and you don’t have to worry about a deck rail failing causes your loved one to fall to their death. Now, because of you, I will only rent a beach front condo that is less than a decade old.
So let me get this straight, when a guy in shorts and a polo shirt can rip apart your concrete building with his bare hands, that's a bad thing, right?
That’s almost exactly what he said as we were filming that segment! I think he said, when you can pull chunks of your building off with your bare hands, you know it’s pretty bad. It was moments after the clip in this video.
While I have no background in Building Engineering, such a beautiful explanation in an easy to understand manner! Look forward to more. I do have one question that got me thinking. How does the concrete aging compare to like glass skyscrapers where the concrete is embedded in the building with glass facades? Does the concrete last longer since it's not directly exposed to the weather elements?
Our three story condo in SWFL was built in the mid 1970’s and was retrofitted with an electric cathodic protection system about 20 years ago. That was a costly upgrade but the system greatly minimizes spalling.
Don't ever forget to have the regular maintenance done on that system. I saw a condo in FL with cathodic protection and they didn't change the anodes one year and almost all the balconies spalled completely apart within a year.
@@BuildingIntegrity does that indicate that the system was holding off the effects of serious water/salt intrusion? Or can a system like that exacerbated the problem when it stops working? I ask because one year seems (to uneducated me) like quite a short period for significant spalling to appear.
@@langdons2848 The anode sacrifices itself as a material which corrodes more readily than steel. It's like a galvanized nail, once the zinc corrodes, the steel will go quickly.
@@johnhaller5851 I understand what you are saying John, but it still seems very fast unless there was already a *very* acidic environment waiting to attack the steel. I was wondering if there were any other effects that could come from a failed cathodic protection system.
@@langdons2848 Cathodic protection cannot prevent the intrusion of corrosive elements, it just delays the process and hides the severity of the underlying problem. Most likely the waterproofing failed years previously.
I'm seeing major cracks all over the place now, mostly older retail store fronts. One was so bad the other day I called an employee out to show him. Not sure if he took me seriously.
Employees are not paid enough to care , if he reported to his manager he would have been told, to go back to his job , if you are really concerned you should call for the manager directly.
Hah! This reminds me last week I went into my usual Thai place to get takeout and the place stank of leaking gas. I told the lady at the register (who speaks English fine) and she just said “Gas?” with a bland smile on her face, same as if I’d commented on the weather. There was only her and the cook in there. I just grabbed my food and left. I guess I would have heard by now if it had exploded…
If you only care now what do you expect from an employee (not his building or enterprise) who has no education (would he work there in the first place) nor the knowledge that you have now. Better call the local government and make a complaint.
I worked on alcatraz island for 24 years, with the sea air on the island I have seen rebar 1/8 in diameter in the concrete went doing my repairs! Thanks
Thank you for your informative video. I retired in coastal Mexico. I have been living in a rented house that has a history of roof issues. Like most Mexican construction, it is made of reinforced concrete. The owner of the house is a wonderful lady doctor who lives in a city an hour away. She tried to sell the house until I rented it 6 years ago. She wants me to buy the house, but the foundation is cracked and the roof still leaks. Actually, part of it just blew off during Hurricane Nora recently. The lower floor becomes a shallow lake during tropical storms. Thanks to your video, I now understand the deep gouges in the first floor walls at ankle level. The superficial repairs and paint of the past haven't worked. Now I understand why. I wish you were local, and could help la doctora.
They don't teach anything about concrete when studying Mechanical Engineering, but I've learned more about it in a few of your videos than I'd ever thought I wanted to know about it.
Thanks for taking your time too explain this detailed process. Your videos are extremely helpful, and filled with in depth information. Look forward to the next one. Extremely interesting materials and presentation.
The videos of this channel should be required viewing for all property owners, property management boards and councils, building contractors, real estate agents. I'm sure insurance companies will use 'lack of maintenance' as an excuse for limiting or avoiding many building failures or issues.
Total layman here, but SO appreciate your clear and concise explanations. If nothing else, hundreds or thousands of us will now have at least a modicum of knowledge as we enter into, and spend time in, the concrete buildings around us. Who knows, maybe one day that knowledge will save lives!
Maintenance is key. The condo or building also needs someone with a good eye. Once the condo shows blatant problems it's probably already too late for minor repairs. The expense of major repairs may also be at fault. Once the condo board has to come up with 15 million dollars, the repairs might not happen.
No one gives you a maintenance manual with a building like you get with your car. And buildings conceal issues much better/longer than your car before you know there's any problem. This information is invaluable to substitute for that missing owner's manual to help HOAs get and stay on top of maintenance so there is never another Champlain Towers-type tragedy.
@@1556cm That's why it's so stupid that people are bidding tens of thousands of dollars (in some cases, hundreds of thousands of dollars) over the asking price for houses _in addition to_ waiving all inspections in this insanely hot housing market. They are basically signing themselves up for a financial deathtrap if there is anything wrong with the property by foregoing inspections.
I got a new concrete driveway about 5 years ago - don't remember how many thousands it cost because a city grant loaned me the money interest free, and the loan is now half forgiven, having lived here 5 years - that was the deal. The concrete used was very high quality, according to the company putting it down, and I believe it, given the nice finish. Anyway, just last week I finished pressure washing and putting down a light coat of Thompson's water seal - the 2nd time I've done this. Watching your video makes me feel good about putting in the work.
I always thought, if you HAVE to buy a condo, buy one that used to be a heavy duty factory. It'll be tremendously overbuilt for residential (tho you'll have odd design things, like a short top floor or MAJOR beams sticking out of the ceiling), but you'll ALSO probably get a free sprinkler system, too. As they were made in the late 1800s in their modern form. Assuming it works. It makes sense that it would or they'd have pulled it all out. Also, it would probably be near perfect in fires, assuming doors and new walls were as solid that way. Open spaces being not good for that at all. You'd have sold brick or stone walls, most likely. Miss the old days in that, MAN, those building were made to last HUNDREDS of years!
A few years ago, can't remember exactly how many, I watched the video on a comparison between waterproof concrete made by the Romans and waterproof concrete made nowadays. I have often wondered why waterproof concrete isn't a standard when it comes to building buildings that are going to be subjected to water. Also, I'm wondering if you can provide an opinion as to why buildings being constructed use rebar that has a layer of surface rust on it. I've seen this in so many construction sites that I have observed. The rebar sits there for days and gets a layer of rust on it, some of which gets knocked off when they start actually building the rebar portion prior to the pour of concrete. Then it sits there for days waiting for the concrete to be poured and gets a renewed layer of rust on the rebar. Then the concrete gets poured and that layer of rust gets sealed into the concrete. Is there a reason why this is done? And is this surface rust as dangerous as the rust you referred to in this video?
The only alternative would be to epoxy all the rebar prior to sending it to the job. The cost of that would be astronomical. As he was saying rust needs water. The best defense is a good offense. Keep the concrete dry through coating any exposed areas and staying on top of caulking joints. These new buildings are such pieces of crap and will need extensive maintenance early and often. Next time you're in a building that's about five years old look around the windows and I guarantee you will find some that are already leaking and that's all it takes.
Very good question. There are many variables, including if the concrete is not properly mixed, poorly compacted, of low quality ingredients, (including using water that has a higher than acceptable saline component). The concrete needs to bond to the rebar obviously the main purpose of the rebar. If the rebar is already rusting when concrete added should theoretically be detrimental to the process. Ultimately depends how much moisture exposure the concrete then gets in its lifetime. In most exterior applications - a lot.
Concrete can be easily protected from water and chloride intrusion using specialty admixtures which significantly lower the porosity of concrete. In fact concrete can be designed to have a permeability reaching that of granite which is ultra low. Unfortunately code officials, general contractors and owners won't spend the relatively small amount of money to make highly durable concrete. Per your examples, not all of the concrete in the building needs this level of protection. It's only needed in areas directly exposed to these corrosive environments. I've made concrete that's completely impervious to gases like is required in mining applications. It only added about $12 per yard on top of $115 per yard concrete. It's unfortunate that it takes a tragedy to even start a conversation about this. You're doing get work on this channel and keep it up.
Yeah, XC3 XD3 XF4 concrete is just 10~15% more expensive than XC1! (environmental factors per Eurocode, sorry, have no idea how it is called in other codes)
@@georgescotsdale361 Low water/cement ratio (a lot of cement, low water), special cements (inc., e.g with Silica Fume and such), special sand, special aggregates (granite), generally these concretes are always high-strength, C35/45 and up (that's 45MPa crushing pressure on cube specimen), special additives, etc.
Research silica fume and metakaolin in terms of low permeability concrete. Also silicates which provide both surface hardening and permeability reduction.
EXCELLENT VIDEO. REALLY FASCINATING AND EDUCATIONAL. EVERY COMMENTOR SHARES A DEEP RESPECT FOR YOUR COMMUNICATION SKILL IN MAKING ENGINEERING UNDERSTANDABLE TO US. OUTSTANDING.
Watching from the Philippines. Since I came upon your videos, I've been more aware of cracks in our office building and my home. Even my architect brother loves your videos. Keep educating us, Sir!
So in the images where the soundings were done, even though we see the oxidation going on in the rebar, it does still appear they are getting to this particular example before that bar deteriorated any more. the first rebar you showed on that house was just crumbling apart. time really is the most valuable thing we have.
I've watched quite a few of your videos, and they've simply convinced me that I don't want to live in a concrete/rebar building. It looks like they're destined to fail. I've mostly lived in brick or stone-built houses, some 100 - 200 years old, there might be (usually were) timber faults that needed fixing, but not the stone work. Even the house I lived in, built on the cheap by miners, primarily using mine-waste - built 1905, it lacked modern facilities, but was structurally sound.
There are ways to test the concrete, but they all involve drilling, coring, or other semi-destructive testing techniques which are not usually economical. There is a less-destructive method which measures the electrical equipotential in the steel iirc but it doesn't tell the pH and thus can't tell the whole story.
If I was an association or individual that owned buildings, I'd hire your firm. For sure. Edit: can you explain "Green Bar" ? The process of how its made and applications is used in?
Appreciate your explanation and illustration Josh. I once lived in a building where the concrete in hanging plant box are disintegrating and falling, exposing the corroded steel bars inside them.
Can you do a video on galvanized rebar and how often is it and would it reduce the need for sealing? Also I have heard there are issues with epoxy coated rebar. How much has that been used in Florida?
Someone's going to have to pay for that repair now!!! Seriously, thank you for the channel, and the work you do. I've gained alot of insight into engineering failures, such as failing concrete. Love your work, thank you.
One of the reasons I hate slab on ground construction. When the slab goes bad in 30 years, well, you can't repair it like a traditional floor on joists and piers. But it's cheap and quick and developers can increase profits from both those things...
Foundation slabs are supposed to have a layer of waterproofing and gravel underneath. Foundation walls are usually covered with a liquid waterproof coating before the soil around the walls is backfilled. Both are required by building codes, but a building inspector has to make sure it was done. After the Surfside collapse, both contractors and inspectors will probably be a little more vigilant that this is done correctly. Unfortunately, over time, many will become complacent again.
So new structural concrete in/near a salt environment would benefit from a layer or two of thick rubbery paint BEFORE the ph drops below 13 but after the crete dries through and through. Then the coating/s must be diligently maintained forever to keep ph at 13. Does that make sense? LOL, it does to me but I'm no expert.
@@windsofmarchjourneyperrytr2823 - Every couple of years you strip off the paint and apply a new coat. It's an inconvenient expense, and you could probably get away with not doing it for 15-20 years, but if you want to still have a building in 30 years it might be good to go ahead and redo the protective paint layer.
The Pantheon in Rome is 2000 years old and is solid concrete ….How did they manage to make it last .. Roman concrete is a different mix… so is it chemically different…?
It's also a structure designed and built around concrete alone. Concrete is very, very strong in compression, but weak in tension. The Pantheon is an unreinforced structure almost totally in compression. With no steel inside to rust and produce spalling, and no part of the structure in a shape in which concrete is weak, as well as being overbuilt, it'll stand for another 1000 years easy. Modern structures have slabs and such where there's tension on the slab, so the steel is there to take the tension loads to prevent the concrete just giving up.
the romans used no steel reinforcement so they do not degrade and spall. also, the walls are 5=10x the thickness of modern walls. modern rc construction allows cheap airy contstruction while sacrificing durability. roman concrete is different in that it used volcanic ash as a big component in the mix. fly ash from coal plants is used as a modern substitute.
@@dealsfromvirginia1773 cement is made by burning calciferous rocks in a kiln. the romans used volcanic ash that had been burned in volcanoes and spewed out. similar product, different processes.
Your educational videos have me obsessed with learning about construction and engineering. What a wonderful way to pass the days/months in quarantine. Thank you Josh.
No they don't. The main reason is that it just doesn't need it. But the second reason is that sometimes if those coatings are left to fully cure, they can create a bond breaker between the steel and concrete... so not worth the risk in new construction.
Great presentation with very simple and clear diagrams (I mean this as a compliment) accompanied by equally clear commentary 🤔 ..... 👍 My youngest son has just taken himself off to University to study chemistry and earth sciences .... so I will forward this to him as a practical example of chemistry at work in the real world! Hopefully this will inspire him to continue to work hard and realise the benefits off a couple more years of study! 😋
I would assume so as long as the paint forms a complete seal, is hydrophobic, and is renewed/refreshed as needed. If not, it seems like it can actually make things worse by trapping in water more efficiently.
There are products that if applied to bare concrete regularly can inhibit the loss of pH in the concrete. Some products even claim to restore it but I am a bit skeptical of those for various reasons.
There are products that if applied to bare concrete regularly can inhibit the loss of pH in the concrete. Some products even claim to restore it but I am a bit skeptical of those for various reasons.
@@peetky8645 that’s probably more to reflect heat and light than protect any rebar. Plus it’s cheap and locally available. Steel bars were not used to reinforce concrete until the mid-19th century in France. There are modern alternatives available such as rebar made from carbon fibers or basalt, but as relatively new technology, have not caught on.
Another great video thanks for all of your efforts in producing these educational videos. I appreciate your systematic presentation of the contributing factors in the building collapse.
thanks, well said. I was looking through the comments. Composite reinforcements such as fiberglass and resin reinforcement bars. The fibers can be glass, or basalt. This eliminates the corrosion of steel problem. How ever don't forget that the water percolating through the concrete structure selectively leaches out the concrete minerals. I would say the best way to protect concrete structures is to protect them from water. Just like we put a water proof roof on our wood frame houses.
How about anti-rust coating the rebar? How much time does that buy you? How much does it cost? Another youtube engineer I watched didn't like epoxy coated rebar (it gets damaged too easily during installation, and even though you can spray over the damage, bits always get missed) but did quite like galvanized rebar. Would stainless steel rebar ever be worth the cost?
I've seen a lot of epoxy rebar in Florida and I quite agree, it's not a great option. I haven't seen much galvanized rebar so I can't comment on that. Stainless steel properties would not be good for reinforced concrete unless special detailing requirements exist which I'm not aware of.
Galvanised rebar is an interesting question. Galvanised posts and the like last well inland in my experience. But after 20 years all of the galvanised steel foot bridges in the park near where I live (over salt water estuaries) are having to be replaced because of massive corrosion problems. So perhaps gal rebar might just buy you a bit of extra time?
I think galvanisation has roughly the same effect on the steel as the alkaline passivation layer that forms due to the high pH. The question is, will those effects together or the galvanisation alone, make it last longer? I don't know.
@@mjouwbuis I think the the biggest weakness for gal rebar would be the ends when lengths are cut. It becomes a point of failure/low protection, especially if the bar is cut with a grinder rather than bolt cutters. So that might negate much of the benefit of the galvanisation.
@@langdons2848 IMHO on building sites the quality of work is very low. All things get dinged and scratched. So construction material needs to be robust and be useable even in less than pristine condition. If one wanted to change that to the standards of other trades the whole industry would get very expensive.
In this time when many feel there is no driver driving the bus..it is most comforting to know there are competent experts in the Engineering field.
There is a driver, but he was placed there by fraudulent methods and is suffering dementia. His handlers believe their feelings and political rhetoric above science and engineering.. a formula for absolute failure and destruction.
@@jenniferwhitewolf3784 I was referring not only to political, but to health wellness and medical, financial, local gov't, you name it the train is off the track!
@@jenniferwhitewolf3784 Right on Jen!
@@jenniferwhitewolf3784 same story last President. It doesn’t matter which you vote for, all you get is crap.
@@ironmagma thanks people to trust God not those in office the will all fail you at some point and that's no fake news FACTS
As an old structural Concrete Contractor, I've wondered how come the rebar did not start rusting right away since we had to pour or pump it in a liquid state. Now I know, Thanks
and makes me even more worried seeing the amount of rusting rebar on construction site after construction site...
@@jwenting A little light rust is good because it gives some roughness and adhesion but thick brown rust with a thickness you can brush off is bad. There should not be loose material. That is just one of a hundred defects in construction reality, like less rebar than spec, insufficient lapping, not properly tied, insufficient coverage ( too near surface ) etc. etc.
@@tuberroot1112 Exactly.
@@tuberroot1112 Bingo!
@@tuberroot1112 concrete does not adhere to rebar ever. Watch the video one more time and note when he says “mechanical bonding” it doesn’t mean “glued” together.
Don't know when I'll ever get to use the education you're providing but I hope to earn an honorary degree in engineering by continued viewing. Thanks Professor Josh, I find your content fascinating!
This is only a small piece of engineering. You are not getting any of the mathematical modeling. Engineering is about applying mathemetics, physics and chemistry and making a simple model to explain what is happening. We test the model to see how well it explains what is happening and then work to improve it and reduce error. Because we know we have errors, we assign a safety factor to ensure there is enough strength.
@@scottkelley1558 I think the intention of my comment may have been lost in translation. It was an attempt to deliver a sincere compliment in a humorous manner. Clearly I failed. I understand that the field of engineering requires many years of study spanning a deep dive into subjects I failed miserably in, especially math. That being said, as a lay person I'm grateful to this channel for a better understanding, albeit simplistic, of why the building I'm living in manages to keep itself upright.
@@scottkelley1558 , Do engineers monitor builders at building sites so that they don’t take shortcuts to save $$$ ?
🤣🤣🤣🤣 an honorary degree? 🤣🤣🤣🤣🤣🤣🤣🤣
@@dp26385 I was wondering the exact same thing.
When you see someone talking so fluently about such specialized stuff without any „err‘s“ „hmm‘s“ or other flaws, you easily can see, that this person is a person of outstanding ability and knows, what he is talking about.
Found this channel via the Champlain disaster - great vid Josh, as always, thanks and best regards from Germany.
Josh... YOU Sir are THE authority on the Champlain Tower tragedy. That "Other Guy" couldn't explain his way out of a wet paper bag! Thank You for the expertise you share with us!
Years ago, my aunt and uncle were going to retire next to the ocean in Northern California. They rented a house near the beach before purchasing land. After seeing the damage that sea air does, they decided to move inland a bit.
Amazing that I seriously watch each episode and am learning. All because of the Florida structure collapse.
Now I see better as to why my two contractor buddies take their jobs seriously.
No kidding , the Florida collapse sure awakened me to learn all about concrete structures . I live in Central America and concrete is all over structures . The instructor in this video should talk about what has happened in Cuba over time ( buildings just topple unexpectedly ), and now we know why .
This isnt what really happened... It was not salt water or oxygen ... It was much more than that...They arent tell you the whole story... Unless you can figured this out... You have to observe why it happen or how it happened...No one has mention anything about Chlorine or Shock water ... WHY ??? Coney Island Buildings has ever failed ? We have Frost and Rust also .... Explain that ... and we are talking over 75 years with no issue.
@@supernova8962
I guess you missed the part about the original contractor and his shenanigans huh? There is a whole other issue related to this and is damn near criminal.
My husband wanted to know why I was subscribed to an engineering video-- he just wouldn't understand! lol :) :) I've learned so much!
Glad you're learning!
Good for you! More women in STEM!!!
Mine does too!! I am utterly fascinated with this subject and the teacher is outstanding.
@@ianchandley Yes!! I've just retired from teaching 5th grade science for 20 years! ( Not anywhere on the same level, but those kiddos have got to start somewhere lol)
All my aptitude tests in high school said I would be really good in engineering. I thought that sounded really boring. ( although I was the only female in the mechanic drawing class ) Now I can't get enough of watching these videos. What have I missed 😳. A little too late as now I'm 75! 😥
You know I’m not an engineer, contractor or have any building experience at all, but I find your videos fascinating. I found you by your Champlain videos but I’m here to stay just to keep learning. 😊
Glad to have you!
Same here
LOVE learning this about concrete and how it gets damaged with time. I’m loving all this info
I really hope you're a teacher, in you field. Our young people really need competent educators.
Thanks that means a lot!
Many people mention that. maybe he still feels he's more helpful being out working in the field. with each decade priorities and desires change. I know he would be a natural for instructor. I also know first hand about going out every day and solving problems. don't be surprised if he and his firm are still doing this 40 years from now.
He is, right here.
@@BuildingIntegrity Along those lines, I was curious if you've ever considered packaging continuing education units/professional development hour lessons that people can buy. Honestly most of what's out there is trash, and your style and presentation are very good, in my opinion.
Amen!
I live about 2 km from the Andaman Sea in Phuket Thailand. I now have an appreciation for the cracks I see in the buildings here.
This engineer seems to explain the issues pertaining to the recent structural failure on everyone’s mind much more straightforward than the other channels -& without a lot of hullabaloo + pets thrown in for no good reason. Thank you.
Real engineers are allergic to bullshit. This channel really exemplifies that.
ngl this stuff is fascinating and the pH explanation was easy to understand. thanks for the quality videos! much respect to the hardworking engineers and contractors out there!
Thanks for watching!
I also learned lots from this as well as your other videos. You do a great job explaining things and use handy visuals. Keep up the great work!
I’ve learned a lot from a select few channels like this. They’d make great teachers or lecturers. I can’t even build Lego, but the way it’s explained I understand it, but I don’t feel like I’m being patronised. I was talking to a friend about this & he asked where I got the information from 😀 I tried ‘I’m just a genius’ it didn’t work. So I showed him this channel and a couple others 😀
@@lilacscentedfushias1852
Sure you are a genius, you just don't know it yet. ;)
Let’s build buildings out of thin strips of iron that rusts and make the building fail. People that design these buildings have high IQ?
Excellent teaching for ordinary people. Keep it coming
More people need to realize that cutting corners is NOT the way to go.
The guy who's construction company it was has been dead since 2014. So...he just cashed his check and moved on, I guess.
Unless you have spalling, then cutting corners is a good idea, as in the video.
How about Spalling corners?
Sure , what if your spalling is in your corners ? Then you would need to cut those corners out ?
Cutting corners = corruption in modern times ,it's always the cause of all causes of failures .
Richard Feynman was known as "the great explainer". Not only was he a knowledgeable person, but had a special talent for sharing that expertise with us laypersons - and making it interesting. Josh, I'd put you in that camp of great explainers. Top notch work on these videos, you have a real talent for sharing your knowledge in an understandable and interesting way. "Dumbing down" without being condescending or pretending to be the holder of all knowledge. In particular with the Surfside series, I particularly like how you distinguish between definite facts, probability, possibility, and indications. All without sensationalism too. I have a couple of engineers in the family. I'm not sure if they just lack that ability to translate into non-engineer info as well, or they think that I'm smarter than I really am. But you sir, absolutely nail it. Thank you.
Now if Josh takes up playing bongos . . .
@@katdistefano8551, yes. Love it. From now on I fully expect Josh to personally play any intro or background music on bongos. I'll be one happy chappy. I'm guessing being in construction engineering, he already knows how to break into houses and knows how to spot weak points in security devices. Possibly not as good at gleaning information to guess safe combos though (or cracking them), unless he also has a practical joker side to him.
Excellent presentation especially for lay-people. I’m a CE by academia, and this was easy for anyone to follow. Unless they don’t understand why steel rebar is in R/C to begin with. But you’ve explained that to novices well enough in other videos.
I learned a lot about chloride ion penetration into steel reinforced concrete structures during my first internship. I left the military to pursue civil engineering after being a draftsmen from an early age (although through my time in the service I was IT).
That internship was rough. My PM, within my first week at this giant bridge project, handed me a post-it note with something along the lines of, “research coatings to knock down the chloride ion permeability of concrete.” It was basically gibberish but he stuck it on my forehead and I went on my way.
His intentions were to provide me real-world experience in researching field applicable problems in civil engineering, the kind of stuff which isn’t taught in school-the kind of situations which formal engineering education doesn’t begin prepare you for-where you need to think fast and solve a problem in the field QUICKLY. I’m about to finish my degree soon, at one of the best civil programs in your state, although as a UCF grad I’m sure you’d disagree (haha).
While I certainly didn’t enjoy being in the field 6 days a week, working 12-14 hours a day, it has been the foundation for my engineering knowledge. Your videos have been awesome too, Josh. Thanks man, keep up the good work. I hope we meet some day since the CivE field in FL is so close-knit. I won’t disclose my personals here on UA-cam, but hey, if you read this comment and we do in fact cross paths (hopefully not you investigating one of my projects!) I’ll let you know.
Keep on keepin’ on brotha.
Yeah, I agree. That's the main issue with college. They never teach you stuff you actually WANT and NEED to know. Or it's the exact opposite of the real world.
I’m just going to go live in a tent. Thank you, Sir for always explaining everything so clearly.
Hollow logs work well, too. Just get one from a really big tree.
@ jerome, so much for that, I guess, haha!
Sure, you’ll love living in your nice safe tent, until a bear comes along. Then you’ll miss having those reinforced concrete walls around you!
My tent didnt survive from last windy season. Those tent just flies away like paper!
Any suggestion for tent alternative?
@Sergei Torockov You really shouldn't be using insects and snakes as foreplay.
As always you did a great job of explaining and illustrating the problem. Josh the illustrator !!! EVERY Visual learner should love you !!! THANKS !!!
💯
Thanks!
Your explanations are so good I could watch this for hours.
You make the engineering and science more interesting than the way I learned in university. Thanks so much for your videos.
In London there’s a condition known as ‘Regent’s Street disease’ due to the fact the first reinforced concrete used in construction was to the lintels of the buildings constructed around 1910 down Regent’s Street (it was mostly rebuilt at this time). Within a few short years they had to be replaced (including cracked stone cladding) due to the corrosion.
Wow, the rebar in the opening clip was totally disintegrated. That was eye opening! How many buildings worldwide are in danger of collapse?
I don’t think we wanna know...... 🤦🏼♂️
@@anna-lisagirling7424 I stayed in a condo hotel on Waikiki Beach. The lanais on a number of units were undergoing the first repair described in this video.
@@johnhaller5851 How long ago was that? Crazy amount of high rises in that neighborhood, eh? In the 70's when I was first there, there were still single family houses scattered beneath just a few high rises but they were disappearing fast! I'm glad i saw it all before it statred to look like Hong Kong. But that whole area was entirely swamp land and the Alaw Wai canal was dredge out to drain that swamp to allow for development. The "land" is coral. After our tutorial here with Building Integrity, my heart beat faster thinking of the entire Waikiki Beach tourist district and the possible nightmares awaiting.
@@anna-lisagirling7424 I think where we stayed was 2500 Kalakaua, Foster Tower. Most of the lanais are now enclosed, they were all open when we were there. I'm guessing a bit more than 10 years ago, my son was still in college. It was sort of an air-bnb place, where there was an office which rented out the condos when the owners weren't there.
@@johnhaller5851 Wow. Just close the lanais. Imagine such a thing. That speaks volumes, doesn't it? I wonder if the Champlain Towers collapse set off a bit of a panic in Hawaii re: their old re-enforced concrete high-rised building inventory? Maybe I'll do some snooping in my "spare" time. . . Thanks for this!
I've spent most of my career evaluating public works contractors' financial condition and experience to guarantee their performance of their jobs and payment of their bills. I have learned and understood more in the last couple weeks since finding these videos than in decades previously. Josh Porter is a wonderful instructor, able to make these concepts easy to grasp and entertaining as well.
Great explanation, well done! Having lived in a coastal environments most of my life I have seen concrete and repairs continually fail over time. Also happens with brickwork where the mortar and certain kinds of brick seem to go through a similar process of degradation.
How I have become so interested in concrete is due solely to your fascinating and educational videos on the subject. You really are an amazing teacher. Can you explain how is it that there is Roman concrete that has been under water for >2000 years that is still structurally sound?
I found this on the Internet regarding Roman concrete:
Roman concrete was based on a hydraulic-setting cement. It is durable due to its incorporation of pozzolanic ash, which prevents cracks from spreading.
When seawater gets into its cracks, it causes a chemical reaction that actually strengthens the concrete. Minerals called Al-tobermorite and phillipsite form as the material leaches mineral-rich fluid that then solidifies, reinforcing the concrete and making the structures even stronger.
@@markvasiloff2217 any idea where these minerals are located in abundance? Looks to be a smart move to mine and export to contractors bent on creating strong structures. A niche to be considered.
@@bill.angelus It comes from volcanic ash and was (or is) found in areas of Italy. I don’t know how abundant it is.
I've understood for many years that at least some Roman concrete was accidental. Bricks were mixed with aluminium rich ore. The bodies of dead slaves were thrown into the mix, and the resulting reaction of bone calcium with aluminium ore created a cement. I was told this by a university lecturer. I don't have a reference to cite.
@@markvasiloff2217 so interesting. TY. I wonder how much of the chemistry they understood or if it was just a lucky use of locally available materials?
This is brilliant thank you, it all makes sense now.
Thank you so much!
Really interesting! We look at concrete every day and never know the science that goes into it!
Thank you Josh. This was very educational and informative. I will look at concrete buildings differently.
Building Tegrity Farms is quickly becoming my new favorite channel
This guy is the best educator
Every time I go by a large garage I am looking for spalling. I think I might need help. ..... And thanks for another insightful video.
Join the paranoid about parking garages club, lol.
I have nightmares about someone WALKING in there around the corner or at the top of the slope where you can't POSSIBLY see them, and are DEFINITELY NOT expecting them!
I could see someone walking around there on purpose to get hit and sue.
Plus, I refuse to pay for parking, so there's that. Especially in like a hospital. They have nerve even asking for more $$. Lol
A trained eye is a terrible thing.
My thirst for knowledge brought me to your channel but it is the clear straightforward explainations and relaxed conversational pacing that keeps me coming back. Bravo
I live in Chicago and the arches in many of the viaducts for the red line trains are massively spalled from top to bottom. It never looked safe, and thanks to you I know what to call it! Your subject matter, which I never gave a thought to before the Surfside condo collapse, is totally enthralling! (Enspalling?!) Thanks for all you do and your peaceful demeanor while teaching us.
Me too! But it's a non-issue since the virus. I'm not on the tuberculosis express any more.
I do know an arch is the most solid design, if I recall right...I wonder if those are something that covers something else, because those train lines are well over 100 years old (no rebar then)
Thanks very much for this tutorial.
I am a formulation chemist,designing impermeable acid/caustic/chemical resistant coatings for concrete structures.
Novalac epoxies are typically used to coat concrete in large chemical plants.
Problems arise because there are only two types of concrete...concrete that has cracked or concrete that will crack.
Epoxies are unfortunately nearly as crack prone as the concrete,so when concrete cracks,the epoxy coating that`s supposed to protect the concrete cracks as well.
This new coating,soon to be released,will solve those issues.
Understanding the deterioration functionality of concrete is extremely important to the design of industrial coatings.
I need to say in touch with your channel.
Best regards.
Thank you Josh from SW Va. Protect the concrete and you will protect the steel.
Thanks for watching!
Very interesting, excellent explanation, WOW, maintenance is very a serious and necessary business.
Yes it is!
Thank you for this video! It’s so informative!
I’m reminded of Roman Harbour concrete that’s been getting stronger over the centuries in the ocean instead of breaking apart. I went and looked up the article I read a while back on it and it makes me wonder if something like that might be better for coastal structures than standard concrete… my understanding from the article was that the special minerals in it react with seawater make the concrete’s pH higher, which sounds like a good thing for preventing the rebar from rusting! The article is from 2017 in Nature and it sounds like at the time companies were still playing around with recipes to find one that can work with modern manufacturing.
I now understand that sealing my concrete is more about preserving the concrete rather than esthetics. You don't know what you didn't know. Till you know what you didn't. Thanks for this valuable information.
I imagine that once there is cracks and such, that even more water, oxygen, etc. can penetrate creating positive feedback leading to rapid deterioration.
You're correct! He's mentioned that in some of his other videos...
My father in law and almost every one of my friends are all engineers. I’m learning so much from your presentations. I’ve never trusted beach front condos. Everyone wants to be on a high floor. Not me. I want to be on the ground floor. Why? The pool and beach are right outside and you don’t have to worry about a deck rail failing causes your loved one to fall to their death. Now, because of you, I will only rent a beach front condo that is less than a decade old.
So let me get this straight, when a guy in shorts and a polo shirt can rip apart your concrete building with his bare hands, that's a bad thing, right?
Bingo!
🤣🤣😪
Thanks for the laugh!
That’s almost exactly what he said as we were filming that segment! I think he said, when you can pull chunks of your building off with your bare hands, you know it’s pretty bad. It was moments after the clip in this video.
It's bad when those bits of concrete fall under gravity onto parked cars and pedestrians.
While I have no background in Building Engineering, such a beautiful explanation in an easy to understand manner! Look forward to more. I do have one question that got me thinking. How does the concrete aging compare to like glass skyscrapers where the concrete is embedded in the building with glass facades? Does the concrete last longer since it's not directly exposed to the weather elements?
Our three story condo in SWFL was built in the mid 1970’s and was retrofitted with an electric cathodic protection system about 20 years ago. That was a costly upgrade but the system greatly minimizes spalling.
Don't ever forget to have the regular maintenance done on that system. I saw a condo in FL with cathodic protection and they didn't change the anodes one year and almost all the balconies spalled completely apart within a year.
@@BuildingIntegrity does that indicate that the system was holding off the effects of serious water/salt intrusion? Or can a system like that exacerbated the problem when it stops working?
I ask because one year seems (to uneducated me) like quite a short period for significant spalling to appear.
@@langdons2848 The anode sacrifices itself as a material which corrodes more readily than steel. It's like a galvanized nail, once the zinc corrodes, the steel will go quickly.
@@johnhaller5851 I understand what you are saying John, but it still seems very fast unless there was already a *very* acidic environment waiting to attack the steel.
I was wondering if there were any other effects that could come from a failed cathodic protection system.
@@langdons2848 Cathodic protection cannot prevent the intrusion of corrosive elements, it just delays the process and hides the severity of the underlying problem. Most likely the waterproofing failed years previously.
Excellent presentation! As a building inspector this is so helpful to me. Thank you greatly.
I'm seeing major cracks all over the place now, mostly older retail store fronts. One was so bad the other day I called an employee out to show him. Not sure if he took me seriously.
Another applicant for the "Not my job award". Here's hoping the building doesn't collapse on him one day.
Employees are not paid enough to care , if he reported to his manager he would have been told, to go back to his job , if you are really concerned you should call for the manager directly.
Hah! This reminds me last week I went into my usual Thai place to get takeout and the place stank of leaking gas. I told the lady at the register (who speaks English fine) and she just said “Gas?” with a bland smile on her face, same as if I’d commented on the weather. There was only her and the cook in there. I just grabbed my food and left. I guess I would have heard by now if it had exploded…
@Sergei Torockov yes I'm sure they do .
If you only care now what do you expect from an employee (not his building or enterprise) who has no education (would he work there in the first place) nor the knowledge that you have now. Better call the local government and make a complaint.
You are very thorough in all your explanations and make things so clear. You’re a pleasure to listen to.
I am so happy that I found your channel a while back! I am very interested in the structure of buildings. And you teach it very well! Thank you!
I worked on alcatraz island for 24 years, with the sea air on the island I have seen rebar 1/8 in diameter in the concrete went doing my repairs! Thanks
I can't stop watching! I literally do not want to buy any structure remotely near saltwater without you Josh! I'm learning so much!
Thank you for your informative video. I retired in coastal Mexico. I have been living in a rented house that has a history of roof issues. Like most Mexican construction, it is made of reinforced concrete. The owner of the house is a wonderful lady doctor who lives in a city an hour away. She tried to sell the house until I rented it 6 years ago. She wants me to buy the house, but the foundation is cracked and the roof still leaks. Actually, part of it just blew off during Hurricane Nora recently. The lower floor becomes a shallow lake during tropical storms. Thanks to your video, I now understand the deep gouges in the first floor walls at ankle level. The superficial repairs and paint of the past haven't worked. Now I understand why. I wish you were local, and could help la doctora.
Thank you for this series. You are doing a wonderful job teaching us
They don't teach anything about concrete when studying Mechanical Engineering, but I've learned more about it in a few of your videos than I'd ever thought I wanted to know about it.
Thank you for your easy to understand explanation. Good graphics and photos.
Very good just glad you explain about how Rebar rust causes Concrete to crack I didn't know it expanded any so much
Brilliant! So helpful! Thank you so much!
I love your videos. Very interesting and informative. I’m a stay at home mom
And never thought I would be interested in a channel like yours.
Thanks for taking your time too explain this detailed process. Your videos are extremely helpful, and filled with in depth information. Look forward to the next one. Extremely interesting materials and presentation.
Clear, consise and professional!
Could you please do a video on “preventive and maintenance measures”. Great videos!!!
The videos of this channel should be required viewing for all property owners, property management boards and councils, building contractors, real estate agents. I'm sure insurance companies will use 'lack of maintenance' as an excuse for limiting or avoiding many building failures or issues.
Wowwwww. When you pulled that off like that I immediately thought about the massive internal damage to south
Total layman here, but SO appreciate your clear and concise explanations. If nothing else, hundreds or thousands of us will now have at least a modicum of knowledge as we enter into, and spend time in, the concrete buildings around us. Who knows, maybe one day that knowledge will save lives!
Maintenance is key. The condo or building also needs someone with a good eye. Once the condo shows blatant problems it's probably already too late for minor repairs. The expense of major repairs may also be at fault. Once the condo board has to come up with 15 million dollars, the repairs might not happen.
This is handy also to know about any building. Just about every building has a concrete base.
No one gives you a maintenance manual with a building like you get with your car. And buildings conceal issues much better/longer than your car before you know there's any problem. This information is invaluable to substitute for that missing owner's manual to help HOAs get and stay on top of maintenance so there is never another Champlain Towers-type tragedy.
@Sergei Torockov not idiots, just people who have no training in that field
@@1556cm That's why it's so stupid that people are bidding tens of thousands of dollars (in some cases, hundreds of thousands of dollars) over the asking price for houses _in addition to_ waiving all inspections in this insanely hot housing market. They are basically signing themselves up for a financial deathtrap if there is anything wrong with the property by foregoing inspections.
@@-._.-KRiS-._.-
Never buy without an inspection
Asking for trouble
I got a new concrete driveway about 5 years ago - don't remember how many thousands it cost because a city grant loaned me the money interest free, and the loan is now half forgiven, having lived here 5 years - that was the deal. The concrete used was very high quality, according to the company putting it down, and I believe it, given the nice finish. Anyway, just last week I finished pressure washing and putting down a light coat of Thompson's water seal - the 2nd time I've done this. Watching your video makes me feel good about putting in the work.
When new concrete buildings are erected, are the exterior walls usually waterproofed? And what is the best waterproofing for concrete?
There was a construction next to my house few years ago and in that buildings foundation, they used some sort of tar-paper like material.
It’s nice to weave through all the UA-cam noise and watch some good content.
I always thought, if you HAVE to buy a condo, buy one that used to be a heavy duty factory. It'll be tremendously overbuilt for residential (tho you'll have odd design things, like a short top floor or MAJOR beams sticking out of the ceiling), but you'll ALSO probably get a free sprinkler system, too. As they were made in the late 1800s in their modern form. Assuming it works. It makes sense that it would or they'd have pulled it all out. Also, it would probably be near perfect in fires, assuming doors and new walls were as solid that way. Open spaces being not good for that at all.
You'd have sold brick or stone walls, most likely.
Miss the old days in that, MAN, those building were made to last HUNDREDS of years!
A few years ago, can't remember exactly how many, I watched the video on a comparison between waterproof concrete made by the Romans and waterproof concrete made nowadays. I have often wondered why waterproof concrete isn't a standard when it comes to building buildings that are going to be subjected to water.
Also, I'm wondering if you can provide an opinion as to why buildings being constructed use rebar that has a layer of surface rust on it. I've seen this in so many construction sites that I have observed. The rebar sits there for days and gets a layer of rust on it, some of which gets knocked off when they start actually building the rebar portion prior to the pour of concrete. Then it sits there for days waiting for the concrete to be poured and gets a renewed layer of rust on the rebar. Then the concrete gets poured and that layer of rust gets sealed into the concrete. Is there a reason why this is done? And is this surface rust as dangerous as the rust you referred to in this video?
The only alternative would be to epoxy all the rebar prior to sending it to the job. The cost of that would be astronomical. As he was saying rust needs water. The best defense is a good offense. Keep the concrete dry through coating any exposed areas and staying on top of caulking joints. These new buildings are such pieces of crap and will need extensive maintenance early and often. Next time you're in a building that's about five years old look around the windows and I guarantee you will find some that are already leaking and that's all it takes.
Very good question. There are many variables, including if the concrete is not properly mixed, poorly compacted, of low quality ingredients, (including using water that has a higher than acceptable saline component). The concrete needs to bond to the rebar obviously the main purpose of the rebar. If the rebar is already rusting when concrete added should theoretically be detrimental to the process. Ultimately depends how much moisture exposure the concrete then gets in its lifetime. In most exterior applications - a lot.
You just got a new subscriber. Am an architect and I must say you are dishing more knowledge than we ever got in school.
Concrete can be easily protected from water and chloride intrusion using specialty admixtures which significantly lower the porosity of concrete. In fact concrete can be designed to have a permeability reaching that of granite which is ultra low. Unfortunately code officials, general contractors and owners won't spend the relatively small amount of money to make highly durable concrete. Per your examples, not all of the concrete in the building needs this level of protection. It's only needed in areas directly exposed to these corrosive environments. I've made concrete that's completely impervious to gases like is required in mining applications. It only added about $12 per yard on top of $115 per yard concrete. It's unfortunate that it takes a tragedy to even start a conversation about this. You're doing get work on this channel and keep it up.
Can you explain how to make the concrete impermeable?
Yeah, XC3 XD3 XF4 concrete is just 10~15% more expensive than XC1! (environmental factors per Eurocode, sorry, have no idea how it is called in other codes)
Hello
Could you provide more information on those impervious/ low permeable concrete? Formulation, code, etc
@@georgescotsdale361 Low water/cement ratio (a lot of cement, low water), special cements (inc., e.g with Silica Fume and such), special sand, special aggregates (granite), generally these concretes are always high-strength, C35/45 and up (that's 45MPa crushing pressure on cube specimen), special additives, etc.
Research silica fume and metakaolin in terms of low permeability concrete. Also silicates which provide both surface hardening and permeability reduction.
EXCELLENT VIDEO. REALLY FASCINATING AND EDUCATIONAL. EVERY COMMENTOR SHARES A DEEP RESPECT FOR YOUR COMMUNICATION SKILL IN MAKING ENGINEERING UNDERSTANDABLE TO US. OUTSTANDING.
Like all concrete structures, the constructing of them is just the beginning. They have to be properly maintained by vigilant owners!
How to maintain rebar which was rusty before they pour concrete on it and after concrete harden?
Watching from the Philippines. Since I came upon your videos, I've been more aware of cracks in our office building and my home. Even my architect brother loves your videos. Keep educating us, Sir!
So in the images where the soundings were done, even though we see the oxidation going on in the rebar, it does still appear they are getting to this particular example before that bar deteriorated any more. the first rebar you showed on that house was just crumbling apart. time really is the most valuable thing we have.
Correct. The second property rusted rebar was salvageable. The first property at the beginning of the video had completely disintegrated rebar.
I've watched quite a few of your videos, and they've simply convinced me that I don't want to live in a concrete/rebar building. It looks like they're destined to fail. I've mostly lived in brick or stone-built houses, some 100 - 200 years old, there might be (usually were) timber faults that needed fixing, but not the stone work. Even the house I lived in, built on the cheap by miners, primarily using mine-waste - built 1905, it lacked modern facilities, but was structurally sound.
Great explanation. Are there testing devices which can identify these hidden concrete cancers?
There are ways to test the concrete, but they all involve drilling, coring, or other semi-destructive testing techniques which are not usually economical. There is a less-destructive method which measures the electrical equipotential in the steel iirc but it doesn't tell the pH and thus can't tell the whole story.
If you seen brown iron oxide rust coming out of the slab, it's too late...
Damn. Feel like I'm getting college classes for free. Thanks so much for sharing your intelligence with us. Nice to be informed.
If I was an association or individual that owned buildings, I'd hire your firm. For sure.
Edit: can you explain "Green Bar" ? The process of how its made and applications is used in?
Thank you! That means a lot.
Appreciate your explanation and illustration Josh. I once lived in a building where the concrete in hanging plant box are disintegrating and falling, exposing the corroded steel bars inside them.
Can you do a video on galvanized rebar and how often is it and would it reduce the need for sealing? Also I have heard there are issues with epoxy coated rebar. How much has that been used in Florida?
I was wondering about Epoxy Coated Rebar too! I noticed (courtesy of the Blancolirio channel) that the rebuilt Oroville Dam Spillway used a lot of it!
@@welshbordergirl2476 hahah I just started watching Blancolirio for the aviation related content : D
@@BuzzyStreetOoh, do check out Blancolirio's playlists related to the Oroville Dam for lots more concrete and engineering fun! 😄
@@welshbordergirl2476 Oroville Dam is hundreds of miles away from coastal corrosion effects.
Someone's going to have to pay for that repair now!!!
Seriously, thank you for the channel, and the work you do.
I've gained alot of insight into engineering failures, such as failing concrete.
Love your work, thank you.
How about home foundation slabs which are usually in frequent/continuous contact with water in the soil and from direct rain?
One of the reasons I hate slab on ground construction. When the slab goes bad in 30 years, well, you can't repair it like a traditional floor on joists and piers.
But it's cheap and quick and developers can increase profits from both those things...
Foundation slabs are supposed to have a layer of waterproofing and gravel underneath. Foundation walls are usually covered with a liquid waterproof coating before the soil around the walls is backfilled. Both are required by building codes, but a building inspector has to make sure it was done. After the Surfside collapse, both contractors and inspectors will probably be a little more vigilant that this is done correctly. Unfortunately, over time, many will become complacent again.
Josh, you do a great job. Far better than any other channel. Clear and concise. Thank you!
Has there been any study to determine the conditions of foundations in older costal high rise buildings in the U.S.?
So new structural concrete in/near a salt environment would benefit from a layer or two of thick rubbery paint BEFORE the ph drops below 13 but after the crete dries through and through. Then the coating/s must be diligently maintained forever to keep ph at 13. Does that make sense? LOL, it does to me but I'm no expert.
Pretty darn close!
I could see that working BUT, what happens when it gets older and begins to dry rot? It'll start peeling, I'd think.
@@BuildingIntegrity
Could you touch on what the future has in store for the Hoover Dam?
@@larrybe2900 1. It is a massive pour. No rebar. This is standard for dams. 2. The Hoover Dam is not going anywhere! P)
@@windsofmarchjourneyperrytr2823 - Every couple of years you strip off the paint and apply a new coat. It's an inconvenient expense, and you could probably get away with not doing it for 15-20 years, but if you want to still have a building in 30 years it might be good to go ahead and redo the protective paint layer.
Outstanding video, the best 12 minutes spent today.
The Pantheon in Rome is 2000 years old and is solid concrete ….How did they manage to make it last .. Roman concrete is a different mix… so is it chemically different…?
It's also a structure designed and built around concrete alone. Concrete is very, very strong in compression, but weak in tension. The Pantheon is an unreinforced structure almost totally in compression. With no steel inside to rust and produce spalling, and no part of the structure in a shape in which concrete is weak, as well as being overbuilt, it'll stand for another 1000 years easy.
Modern structures have slabs and such where there's tension on the slab, so the steel is there to take the tension loads to prevent the concrete just giving up.
the romans used no steel reinforcement so they do not degrade and spall. also, the walls are 5=10x the thickness of modern walls. modern rc construction allows cheap airy contstruction while sacrificing durability. roman concrete is different in that it used volcanic ash as a big component in the mix. fly ash from coal plants is used as a modern substitute.
Google says portland cement was invented in 1824, so it must be very different.
@@truckerallikatuk I read they used volcanic ash in the concrete mix as well … there was not much rebar around back in the old days
@@dealsfromvirginia1773 cement is made by burning calciferous rocks in a kiln. the romans used volcanic ash that had been burned in volcanoes and spewed out. similar product, different processes.
Your educational videos have me obsessed with learning about construction and engineering. What a wonderful way to pass the days/months in quarantine. Thank you Josh.
Great info Josh! Do they coat rebar with protective seal on new construction like on the repair you show? If not, why?
No they don't. The main reason is that it just doesn't need it. But the second reason is that sometimes if those coatings are left to fully cure, they can create a bond breaker between the steel and concrete... so not worth the risk in new construction.
Great presentation with very simple and clear diagrams (I mean this as a compliment) accompanied by equally clear commentary 🤔 ..... 👍 My youngest son has just taken himself off to University to study chemistry and earth sciences .... so I will forward this to him as a practical example of chemistry at work in the real world! Hopefully this will inspire him to continue to work hard and realise the benefits off a couple more years of study! 😋
This might seem like a dumb question but, does painted concrete offer more protection against rust as is the case in bare metal?
@Big Leagues lordy what a pathetic ass response. rest assured buddy we all see exactly who you are.
I would assume so as long as the paint forms a complete seal, is hydrophobic, and is renewed/refreshed as needed.
If not, it seems like it can actually make things worse by trapping in water more efficiently.
@Big Leagues apparently you are bitter cuz you never made it to the"big leagues"... But the heck the world needs dishwashers and laborers too.
I'm A builder from Vancouver Canada. Love watching your videos!!! Just want more after each one. Keep up the great work.
I'm curious, is there any way to dope the exterior of aged concrete with an alkaline product that could soak in and neutralise the acidic buildup?
traditional culture in the med in coastal areas would whitewash their masonry structures annually or often with lime.
There are products that if applied to bare concrete regularly can inhibit the loss of pH in the concrete. Some products even claim to restore it but I am a bit skeptical of those for various reasons.
There are products that if applied to bare concrete regularly can inhibit the loss of pH in the concrete. Some products even claim to restore it but I am a bit skeptical of those for various reasons.
@@peetky8645 that’s probably more to reflect heat and light than protect any rebar. Plus it’s cheap and locally available. Steel bars were not used to reinforce concrete until the mid-19th century in France.
There are modern alternatives available such as rebar made from carbon fibers or basalt, but as relatively new technology, have not caught on.
@@ianchandley agree, but it may protect masonry from degradation due to salt, just a guess. no steel involved
Another great video thanks for all of your efforts in producing these educational videos. I appreciate your systematic presentation of the contributing factors in the building collapse.
So if you regularly coat the concrete with water proofing sealant the concrete will never age?
Never say never, but it will last a whole lot longer.
Yes - Sherwin Williams has an excellent product called Loxon
thanks, well said. I was looking through the comments. Composite reinforcements such as fiberglass and resin reinforcement bars. The fibers can be glass, or basalt. This eliminates the corrosion of steel problem. How ever don't forget that the water percolating through the concrete structure selectively leaches out the concrete minerals. I would say the best way to protect concrete structures is to protect them from water. Just like we put a water proof roof on our wood frame houses.
How about anti-rust coating the rebar? How much time does that buy you? How much does it cost?
Another youtube engineer I watched didn't like epoxy coated rebar (it gets damaged too easily during installation, and even though you can spray over the damage, bits always get missed) but did quite like galvanized rebar.
Would stainless steel rebar ever be worth the cost?
I've seen a lot of epoxy rebar in Florida and I quite agree, it's not a great option. I haven't seen much galvanized rebar so I can't comment on that. Stainless steel properties would not be good for reinforced concrete unless special detailing requirements exist which I'm not aware of.
Galvanised rebar is an interesting question. Galvanised posts and the like last well inland in my experience. But after 20 years all of the galvanised steel foot bridges in the park near where I live (over salt water estuaries) are having to be replaced because of massive corrosion problems.
So perhaps gal rebar might just buy you a bit of extra time?
I think galvanisation has roughly the same effect on the steel as the alkaline passivation layer that forms due to the high pH. The question is, will those effects together or the galvanisation alone, make it last longer? I don't know.
@@mjouwbuis I think the the biggest weakness for gal rebar would be the ends when lengths are cut. It becomes a point of failure/low protection, especially if the bar is cut with a grinder rather than bolt cutters. So that might negate much of the benefit of the galvanisation.
@@langdons2848 IMHO on building sites the quality of work is very low. All things get dinged and scratched. So construction material needs to be robust and be useable even in less than pristine condition. If one wanted to change that to the standards of other trades the whole industry would get very expensive.
I thought I knew why rebar rusted until I watched this video,. Thanks for such a great explanation of what is really going on.👍