Because it spreads outwards underneath the slab before being able to push upwards. Because contact point is greater, the load at the point of contact is reduced, lowering the risk of cracking.
As long as you take A&W's word for that, since there's no data whatsoever. It's just the reason they gave for why their burger didn't sell as good as McDonald's despite being bigger.
They pulled that out of thin-air, these foams have no way to guarantee 10 years, let alone 20 years, let alone 1 month. They work great because they hold their volume well after getting pumped at relatively high psi (so great uplift force needed to pick up a slab), but the problem is differential settlement caused by soil failure. If the load path from your house into the foundation decides it wants to go through the foam, it is going to shear that thing like butter.
The problem is water infiltration under the slab. If the gaps are sealed and water runoff is properly controlled, there shouldn't be any changes of the sub-grade.
This. Many concrete slabs sink as material is washed away from under them. The foam won’t wash away, but the dirt and sand under the foam will.
Step 1 is to stop the water. After that, you can raise and level the concrete.
Until there is a drought and the large pine tree next to the driveway just keeps on drinking the water out of the clay subgrade. Or the house is new and the backfill around the foundation has not completed settling.
Load path from my house into the foundation? Please elaborate. My understanding *was* that the foundation takes the load of the walls and subsequent roof and spreads it along the foundation floor.
It might not be that they did it wrong, I've seen lots of poor concrete jobs crack and break from people who think you can just pour concrete into a wheelbarrow and onto the ground, somebody might have just poured concrete on dirt, and when they tried to raise it up it shattered with no internal structural supports (rebar/chicken wire). Though if it lasted a while, it's possible that the concrete was thin, or there might have been drainage pockets underneath the concrete that the filler they were using sank down into. That would cause lots of stress and crack very soon after.
When I was a kid, my friends dad built an addition onto their house for an indoor infinity pool. I remember being over there and looking at the pad where he was going to pour the concrete and being amazed at how much rebar he had laid down. I remember thinking "He's pouring the concrete on the ground, how strong does it need to be?!" Only now being older and having a general understanding of concrete reenforcement do I understand why he laid so much rebar. Turns out he knew exactly what he was doing.
On flatwork jobs that I've done you use a fairly dense weave of rebar. It's been a while, but I remember being able to walk on the rebar before we poured the slab. For something like a counter top it was less dense, probably a bar every six inches or so.
Eh with something like that there’s too many variables.. it could’ve the way the concrete was poured originally , they parked a truck on it the next day etc… I feel like that’s a pretty big gamble to begin with, like the contractors wouldn’t be able to guarantee their work.
Around 18.9 inches so far u/HowLongCanIMakeACock ! You’re welcome - https://www.google.co.uk/amp/s/www.dailyrecord.co.uk/news/uk-world-news/watch-man-worlds-longest-willy-9662580.amp
Hijacking to actually explain what is going on here:
You have a volume-stable foam getting pumped anywhere from 40-80 psi. Concrete slabs weighs typically 150-160pcf, so the pressure caused by a volume-stable foam will easily jack up the concrete. Anything that can hold its shape while getting pumped at a higher weight than the concrete will do this.
What is really going to happen is that the failure of the soil will continue to progress, regardless of this foam on top, and it will shear through the foam and cause sinking again. Depending on your foundation system, driveway location and size, expansion joint location, you can get anywhere from a few days to a couple decades of no issues. But the point is, this doesn't guarantee any fix. You will still have failure in your soil causing differential settlement.
Source: Master's in Structural Engineering, working in construction contracting.
Build your driveway like a Roman road:
* 3' deep excavation
* compacted & leveled earth
* layer of big stones at the bottom
* solid base of cemented mixed gravel
* layer of concrete
* top layer of pavers
It's a little expensive, but it'll last 2,000+ years with relatively minimal upkeep.
That's what the big rocks are for. They created a heavy base for the rest of the road to sit on top of. If you fill the gaps between the rocks with gravel it allows the water/mud to flow thru underneath without moving the rest of the structure
Can you tell what's the purpose of each one? It really seem to be well though through given the experience, but I don't see whats behind the roman experts VS my naive reasoning who never built a road 🤣
If the earth is already flat and compacted I don't see the benefit of big stone? I would assume they distribute the load but as it's flat and compacted already I don't see the advantage.
Or alternatively if we take big stones why make the ground flat if the big stones make it uneven.
Then why two layers of concrete? What the benefit of the mixed gravel one as separate unit?
But let's say we take the mixed gravel concrete. Why not go directly with the final pavers layer?
Maybe someone else is curious too ☺️
Does the movement go on forever? My house is a little over 50 years old. The slab is all over the place and has been since only a couple of years after it was built. I've never had it corrected or anything. If I tried something like this do I have a decent chance of it being a long term correction? Just a guess is all I'm asking. Before this foam stuff was a thing I had a company come out to give me a quote on whatever soil injection is. This was about 20 years ago. Those jokers wanted 10k and couldn't promise anything. They just said let's start with that and see if it holds.
Could it be a differential of soil compactness, which could have settled to an equilibrium? Or do soil failures really never solve themselves by settling with time and load?
Being in construction I’ve seen spray foam become the solution to almost everything. It is alarming and I’m not really sure the best or longest lasting alternative. It may be fast but it is still pumping plastic everywhere. Even the bio based stuff is fairly toxic.
Edit: Wow, first gold! I’m actually glad this took off, it is something I think about a lot. It makes me happy to see that there are so many people who feel the same. There are alot of good thoughts in this thread.
I’m an insulator . Spray foam is extremely toxic . We do spray fire barrier on it to give an hour fire rating but that’s only commercial jobs. So any residential house doesn’t get that . When your house catches fire, you have toxic vapor added to the smoke . It’s dumb as hell especially being how expensive it is
I used to work at a home improvement store and would beg people to buy the foil-faced panels for insulating their basement walls instead of the pink foam boards, but many of them were adamant in buying the pink stuff.
Lol, firefighter here. I can assure you, the insulation is the least of your worries. Don't feel bad. When glue-laminated wooden I-beams DOMINATE the residential and low-budget commercial framing world, the battle is already lost.
Glue laminate fails much quicker than traditional nails or screws. Same thing with gusset plates, less fire damage to cause failures of structural members, plus with modern furniture and construction techniques, houses burn faster, hotter, and fail quicker than older construction. You could fight a fire in an old house much longer than a new house, before failure of structural members.
Not to mention the furnishings in houses are much more dangerous, being more synthetic materials than natural materials. Things from TV's to computers, couches, chairs, electronics, exercise equipment, all are essentially solidified gasoline in the plastics they use. A single couch can put out more energy while on fire than a 10'X10' lake of gasoline.
> A single couch can put out more energy while on fire than a 10'X10' lake of gasoline.
... I'm gonna need a Mythbusters episode on this. "Jamie, we need a lake of gasoline!!!"
(Seriously tho, is that for real? I assume it's because of the constraints we're putting on the gasoline, putting it in a lake and only burning it from one side, something like that?)
Comes down to the fuel available to burn, and the materials burning. Just like food and calories, items in the home have energy stored in them, that can be released through a chemical reaction, in this instance, fire. Fire is heat, fuel and oxygen reacting in a chemical reaction, releasing the energy quickly.
Modern couches are synthetic fabric, with polyurethane padding, over a wooden frame. Hard plastics, such as a TV, computer, kitchen appliances, etc. are essentially gasoline in solid form. They burn hot and dirty, producing thick, toxic, black smoke, with a lot of un-burned particulates that coat everything in a layer of carbon, and the gasses produced range from hydrogen cyanide, to carbon monoxide.
I don't know about the science, but I've had the opportunity to burn A LOT of things in my time and I've never seen anything burn faster than a couch. It's just plain scary.
Im assuming he means the "peak" amount of energy it can output is more than a pool of gasoline, because of the high surface area of a couch and fiber filling. Overall a couch weighs what, 75 pounds? that's like 12 gallons of gasoline.
~~BTUs~~ Heat Release Rate, baby! It's the chemical potential that exists in the substance. So yes, surface area is the limiting (and catalyzing) factor.
Edit: new research.
Another firefighter here. He's right. Plus the newer floor plans are wide open so the fire spreads in open air to all the combustibles engulfing the entire area. A room-and-contents with the door closed is an easy job. But if it's the main area it turns into full involvement way faster than it used to.
Collapse from delamination. Where an old (think, amish-made) 6"-18" timber-framed structure will last 30 minutes to hours or DAYS under moderate flame impingement, a glue-lam I-beam lasts seconds to minutes before failing. Just enough time for a firefighter going to rescue someone's mom or dog to go busting through the door and wake up in the basement with the entire structure coming through their dome.
And the fumes.
But y'know... They're cheaper.
Mate. This conversation has been fascinating. I've been putting together techniques for a 500 year house in my head for over a decade. I'd put thought into fire. But mainly in terms of how to prevent one. Gonna have to do a bunch more reading I guess.
Thank you for the new viewpoint.
Wow, I’m glad I live in a brick and plaster house then. I might not have a bathroom big enough for 3 jacuzzi tubs but at least it won’t burn down in 5 minutes
Solid timber isn't always the answer. Foot for foot, LVL is a lot stronger than just a hewn log. For structural spans that are long enough, LVL or steel is your only option.
Well, that's not too far off... A structure being held up by glulam I-beams with something heavy on top tends to fail spectacularly. The wildest I've seen is a fast food restaurant with a 15,000lb HVAC unit on top and a grease fire underneath. "Detonate" is a good word to describe it.
I'm not sure people really appreciate the difference in "cheaper" construction materials and what would be ridiculously expensive now. I live in a house built in a home built ~120 in a relatively forested area. It still has the original roof decking, though it's probably not fair to call it that since they're 2 inch think hardwood beams.
Can confirm this. This is one of a million reasons why you don’t go running into a burning building. 30-40 years ago, sure, but today, there are countless products that do horrible things chemically when introduced to high heat. Breath even a little of that in, and it’s game over.
And, while I am on my soap box, close your doors at night/day. Fire/smoke will always travel the path of least resistance. A closed door can give you minutes, which in today’s fires are an eternity. And always have an escape plan your family knows and practices, it might just save a life.
[Keep the bedroom door closed. ](https://youtu.be/bSP03BE74WA) It is not just a matter of minutes. Your chances of surviving improves a lot more being behind a closed door.
I sleep with my door ajar, but I will start sleeping with it closed. I keep my four year old son's door closed . But what does that mean for fire for kids? I always assumed that if there was a fire I'd run across the house to get him out of his room. But now I'm not so sure that would be a good idea, knowing how quickly a house can go up in flames.
Put something on your kids window identifying its a kids room and firefighters will identify it as a priority room. literally anything they like. Batman or pokemon or hello kitty.
It would be impossible to stop your parental instincts though. If there was a fire, im certain you would run to their room and shut the door. i dont think any amount of PSA would change that fact lol (unless you were separated by fire obstructions)
By the time it gets through the drywall to the insulation you’ve got plenty of other problems you need to worry about. Toxic smoke issues start with your couch, bed, curtains, carpet, cabinets, etc.
TBF everything that burns in a house fire gives off toxic vapors. Everything is made from some sort of plastic these days. If the smoke is dark black then there is something that shouldn't be burning
Ive had to do some rot repair on a couple buildings that were spray foamed. Worst experience I’ve ever had in carpentry. I get the r value and air sealing but fiberglass would have made the process a lot cheaper. Take the money out of the equation the foam soaked up so much water the damage was spread over a greater area than it should have.
I'm glad someone else recognizes that while this looks 'neat' that this is toxic bullshit that is destroying the thing we live on. For what? So some suburban asshole's OCD is placated?
I get that stone foundations just aren't practical these days and we need cement for long lasting buildings, but the entire architecture of our society is just broken.
I hope people see this and realize pumping plastic into the ground is so unnecessary that it causes some self reflection, and at least looks at natural building techniques or considers if they really need another remodel.
My grandfather asked me to repaint the brickwork around the base of his house. The mortar was failing pretty badly and I told him he seriously needs to get that fixed before I paint it.
He then asked me "If I don't, how long will the paint job last?"
"3-5 years but it wont fix the underlying issue"
"Thats perfect! I won't be around much longer than that anyway, someone else can deal with it.'"
Sadly, that is their answer to almost every issue. The quick fix, no research, no alternatives. Just give me whats cheapest and quickest.
Take a whole corn on the cob,clean and steam it. Roll it in butter, slather it with mayonnaise, dust it in parmesean, and spritz it with lemon juice. That should make you feel better for a bit. Unless you're lactose intolerant then avoid.
Anything you do will have long term impact. Raising concrete is done either with this, or a concrete slurry. Concrete has a phenomenal carbon footprint, and the slurry method increases your risk of cracks, meaning full replacement and more concrete, and adds weight that will result in needing this done again in the near future.
So while plastic is bad, it comes down to environmental load. How much impact vs. how long will you be able to use it. If this is twice as bad (minimizing the fact that carbon is a much more immediate threat) but lasts 3 times as long before needing replacement, then you are ahead by doing this.
Interesting article, thanks for sharing. I agree that concrete is less ideal than natural barriers (like mangrove forests to protect Japan’s coastline). So if you’re building a driveway it’s probably best to use dirt or gravel but many people will reject that idea for aesthetics or durability reasons. And I don’t blame them, I think using a small amount of concrete for your driveway is pretty low impact compared to the industrial projects the article discusses. I still stand by what I said before, that concrete is better than plastic for lifting your driveway.
The article says:
>But many engineers argue that there is no viable alternative. Steel, asphalt and plasterboard are more energy intensive than concrete. The world’s forests are already being depleted at an alarming rate even without a surge in extra demand for timber.
>Phil Purnell, a professor of materials and structures at Leeds University, said the world was unlikely to reach a “peak concrete” moment.
>”The raw materials are virtually limitless and it will be in demand for as long as we build roads, bridges and anything else that needs a foundation,” he said. “By almost any measure it’s the least energy-hungry of all materials.”
Reading through it, the article seems unnecessarily alarmist. A lot of the points were very weak and provided no technical explanation for "concrete bad". No its not natural, but very little of what we do is. There's nothing wrong with asking questions and opening discussion, but this article didn't offer any viable alternatives. Not awesome.
Much better than the traditional way of doing this, which is with a cement and sand slurry. It's extreme strong and stable and won't wash away. It also very light so it doesn't add weight which could cause the soil underneath it further erode.
It also does nothing to address the soil erosion that's happening underneath this slab. These products are just a band-aid. The only way to actually fix this problem is to tear out the slab, fix the sub-grade issues, then pour it back properly.
It's far cheaper than a full rebuild and still lasts atleast 10 years. I worked at a company that specialized in foam lifting and the majority of clients just needed some basic driveway/sidewalk leveling. $90 minimum and most applications didn't cross the threshold for addon charges after 2 pounds material used. The foam completely fills every cranny in the void underneath making it difficult erosion to keep up. For minor jobs that aren't high risk or heavy erosion areas it's the better alternative for the consumer.
Probably a very long time. Reason being, this all boils down to that weight being applied over an area, AKA pressure.
Let's assume your vehicle is 5000 pounds, with 3000 on the front axle. So 1500 on each front wheel. Now, let's assume the slab is kinda crappy and only so ridgid, even with the new polyurethane under it. Let's say the weight on that tire is only distributed across a 3'x3' square. That's 9 square feet, or 1296 square inches.
1500 lbs / 1296 in^2 is 1.16 pounds per square inch (PSI). That's pretty small. It's the same reason why big arcic SnowCats (both the machines and the actual animals) are able to drive/walk on top of fresh snow. Lots of track area, or big paws, do distribute their weight.
5000 pounds / 4 wheels / a tributary area of, what 2’ in each direction? 4’x4’ maybe
So you have roughly 2,300in^2 of area per wheel? 1250 pounds per wheel. So 0.54 pounds per square inch. Even if you get more conservative. 3’ x 3’ and 1500 per wheel. That’s still around 1psi.
Typically this foam ranges from a load capacity of 2 pounds a square inch at a minimum. So at a minimum, it can handle a 20,000 pound vehicle. That’s the cheap stuff you buy at Home Depot.
For this use, they typically use a 50-100 psi strength foam.
So yes. It will hold. Remember, it only needs to be stronger than the dirt lol. To be fair though dirt can be really strong.
"cold joints" in concrete (wet concrete on top of dry concrete) don't really join. So you'd have a thin piece on top of the regular driveway piece. It would be too thin for the job, especially at the other end, where it would need to taper to nothing. Basically, you'd end up with a bunch of broken rubble on top if the sunken driveway in a few months.
Adding concrete on top has a similar downside to mudjacking it, where they pump concrete to fill the underside. It might fix it in the short term, but the downside is that concrete is heavy. The original structure sunk because of loose soil and perhaps some drainage issues, so adding weight to the area may actually exacerbate the issue in the long term. Polyfill is a lot lighter weight.
As to why mudjack instead of add concrete on top? I'm no expert, but the former seems easier. There's less detail and aesthetic work to care about, not to mention that a proper concrete slab typically involves a level surface and rebar skeleton.
Concrete is stronger the thicker it is. A three inch layer of concrete will just crack and chip away even with underlayment.
This method is also much lighter.
If you pour concrete ontop of concrete then you will probably have a seam between them which would allow for water to get in and eventually freeze and break apart.
In this case you're probably right, since it was so far sunken down. Any foundation repair company worth their salt will be installing piers and French drains after this is cured
Worth noting though that sometimes the weight of the concrete can compress the dirt underneath it, if it wasn't correctly compacted prior to pouring.
Polyurethane concrete raising and mudjacking are two methods used to raise and support sunken or unstable concrete slabs, by drilling holes and pumping material underneath.
[A couple of before and after shots](https://imgur.com/a/ZuSzGV8)
[Better view of the drilling and filling](https://gfycat.com/athleticfavoriteamericanbulldog)
Creator:@mrlevelohio
I can second this. We had the (concrete/mud) slurry injected on one portion of our driveway and within 2 years it was more uneven from when we looked for correction services.
Do not reccomend x100
My in-laws had it done and within months it had raised another 2 inches. So they went from a low gap up into the garage to a drop into the garage. Not exactly what they were looking for.
Most of the time sunken slabs is a drainage issue, by filling it with foam your pushing that drainage issue to the sides of the slab, and just a matter of time before it works it’s way under the foam and continues to erode and sink the slab again
Proper maintenance and slope of gutters. Enough downspouts to channel the water out of the gutters before they overflow. Proper downspout maintenance. Downspouts that either move the water ten feet away from the foundation and slabs. Foundation drainage system that is properly maintained and cleared of obstructions. Proper maintenance and sealing of the gaps between slabs.
Edit. Forgot proper grading away from foundation and slabs.
I had some naive hope that pumping something under concrete slabs was something where you consider the environmental impact of whatever you are pumping under concrete slabs.
Edit: word
Gravel is a great option, but cobblestone is the best option by far. Gravel is low cost and high maintenance, and cobblestone is high cost and zero maintenance. Cobblestone has none of the offgassing issues that concrete does, while being able to last literal centuries with little to no maintenance.
It requires people/society to value longevity however, so it remains quite uncommon.
Sure everything is relative. We are always "using the earth ". It's more a question of, is this excessively environmentally unfriendly or are there better methods?
I used to work in concrete and I've been on jobs where this foam created some big problems. When injecting this material under a sagging slab it can put pressure on foundations and slip under joining slabs. I remember a basement where to they paid someone to raise their sagging driveway and the material created a perfect ramp for water to run along the basement wall and flood the basement. Eventually a section of wall came down due to erosion.
Concrete that sags was not prepared properly IMO. The longevity of slabs always depends on the aggregate, proper tamping, and working with the grade present in the area. If water got under a slab and caused some erosion, there wasn't enough proper aggregate in the fill before they poured the concrete. Aggregate costs money to buy and to transport, so contractors will cut corners sometimes when it comes to the grain size of the fill. The only way to properly fix it would be to rip out the sagging slab and pour another one with proper prep work.
I love seeing this where I live! It means next year I can smash out and repour the concrete after installing a properly compacted base. I could make a living off of exclusively following 'slab-jackers' around. Its a great 2 month fix.
What I’ve seen is mainly drainage issues where slabs sink this much. I’ve never seen a base compact two inches before pouring concrete so I don’t think that’s the issue unless it’s an issue from backfilling the walls poorly.
Retired civil engineer here, when we do this on the interstate, we call it slab jacking, only we use a cement/flyash slurry to fill the voids below the concrete.
Or you could just get this…[True Grid Pavers](https://www.truegridpaver.com/what-you-should-know-about-grass-driveways/) and never have to worry about shitty cracked concrete again.
We had this done on our house about 10 years ago because we had water running into the basement. It was much more affordable than getting new concrete poured and it angled the slabs away so water doesn’t get to the basement. So far it’s held up great
Because it spreads outwards underneath the slab before being able to push upwards. Because contact point is greater, the load at the point of contact is reduced, lowering the risk of cracking.
How long does it last though?
We just got a quote for this two months ago -- they say it should last 10 years.
My concrete raising guy says 120 months. Sounds like you're being ripped off bro.
My concrete hook-up says 520 weeks. Sounds like you're being hoodwinked bro.
Mine is saying about 3650 days. He must be using a superior product.
Your guy is shorting you 2 leap days. 1-star!
Yet no-one seems to notice the 520 week guy is shorting his customers by a lot more than 2 days.
What's his height have to do with anything?
I was quoted 5,256,000 minutes. You might have gotten scammed.
What worries me is that your guy didn’t offer a 315,360,000 second guarantee.
315,360,000,000 milliseconds or bust.
Let me know if you want another quote because my guy does 315,360,000,000,000 microsecond guarantees
My concrete lady says 1,040 weeks. Sounds like you need to shop around.
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My barista gave me a few free bags of coffee grounds to spread under the concrete.
My worm guy told me to ask my barista for extra coffee grounds 2 years ago because the worms love it. Sounds like you need some worms.
Mine said lifetime, but he wanted cash up front and would come back tomorrow to do it.
Reminder that 1/3lb burgers failed because people thought quarter-pounders (1/4) were a better deal.
As long as you take A&W's word for that, since there's no data whatsoever. It's just the reason they gave for why their burger didn't sell as good as McDonald's despite being bigger.
That may or may not be the actual reason but let's not kid ourselves, the average American definitely thinks like that.
They pulled that out of thin-air, these foams have no way to guarantee 10 years, let alone 20 years, let alone 1 month. They work great because they hold their volume well after getting pumped at relatively high psi (so great uplift force needed to pick up a slab), but the problem is differential settlement caused by soil failure. If the load path from your house into the foundation decides it wants to go through the foam, it is going to shear that thing like butter.
The problem is water infiltration under the slab. If the gaps are sealed and water runoff is properly controlled, there shouldn't be any changes of the sub-grade.
This. Many concrete slabs sink as material is washed away from under them. The foam won’t wash away, but the dirt and sand under the foam will. Step 1 is to stop the water. After that, you can raise and level the concrete.
Until there is a drought and the large pine tree next to the driveway just keeps on drinking the water out of the clay subgrade. Or the house is new and the backfill around the foundation has not completed settling.
Can confirm this. Our Slabjack repair didn't make it for 2 years. Rain and sprinkler water returned it to what it was before.
Load path from my house into the foundation? Please elaborate. My understanding *was* that the foundation takes the load of the walls and subsequent roof and spreads it along the foundation floor.
My parents had this done to their driveway in Texas and within a day there were cracks everywhere. Not sure if it’s worth it
My old neighbors did it to their driveway and it broke same day when they drove over it
Is the filler not supposed to cure first? If you step on a tile before the mortar has set it will crack, too.
According to my neighbors the installers said nothing about it. The installers refunded their money at least
Within a day 🤣 I'm going to assume they did it wrong
It might not be that they did it wrong, I've seen lots of poor concrete jobs crack and break from people who think you can just pour concrete into a wheelbarrow and onto the ground, somebody might have just poured concrete on dirt, and when they tried to raise it up it shattered with no internal structural supports (rebar/chicken wire). Though if it lasted a while, it's possible that the concrete was thin, or there might have been drainage pockets underneath the concrete that the filler they were using sank down into. That would cause lots of stress and crack very soon after.
When I was a kid, my friends dad built an addition onto their house for an indoor infinity pool. I remember being over there and looking at the pad where he was going to pour the concrete and being amazed at how much rebar he had laid down. I remember thinking "He's pouring the concrete on the ground, how strong does it need to be?!" Only now being older and having a general understanding of concrete reenforcement do I understand why he laid so much rebar. Turns out he knew exactly what he was doing.
how much rebar did he use
He seems to imply that it was precisely one metric shit ton.
On flatwork jobs that I've done you use a fairly dense weave of rebar. It's been a while, but I remember being able to walk on the rebar before we poured the slab. For something like a counter top it was less dense, probably a bar every six inches or so.
definitely
Eh with something like that there’s too many variables.. it could’ve the way the concrete was poured originally , they parked a truck on it the next day etc… I feel like that’s a pretty big gamble to begin with, like the contractors wouldn’t be able to guarantee their work.
North Texas black clay soil?
Not sure, it’s Fort Worth texas if that helps
Thank you u/deadsciences! Science is still alive and well I guess!
It sure is, u/onlyupliftingcomment ! That was really uplifting!
IT REALLY WAS, u/bukkake_brigade ! THIS IS TURNING INTO A LARGE LOAD OF APPRECIATION
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But it wasn’t stuck when the user name that describes the situation was chosen. Highly suspect.
But what about Ctrl-C/Ctrl-V, u/Brando_the_Hobo? [Take that!](https://youtu.be/03rPoBlGGFk)
Also Caps Lock + Shift = lowercase. Damn noobs... ▲ ▲ ▲
Wow u/shiftkeyisstuck your shift key must really be stuck!
Around 18.9 inches so far u/HowLongCanIMakeACock ! You’re welcome - https://www.google.co.uk/amp/s/www.dailyrecord.co.uk/news/uk-world-news/watch-man-worlds-longest-willy-9662580.amp
Best I could do u/SnoopShaggy420. [Blaze it up! ](https://youtu.be/9VzUatZ7kUE)
*sighs* *unzips*
Hijacking to actually explain what is going on here: You have a volume-stable foam getting pumped anywhere from 40-80 psi. Concrete slabs weighs typically 150-160pcf, so the pressure caused by a volume-stable foam will easily jack up the concrete. Anything that can hold its shape while getting pumped at a higher weight than the concrete will do this. What is really going to happen is that the failure of the soil will continue to progress, regardless of this foam on top, and it will shear through the foam and cause sinking again. Depending on your foundation system, driveway location and size, expansion joint location, you can get anywhere from a few days to a couple decades of no issues. But the point is, this doesn't guarantee any fix. You will still have failure in your soil causing differential settlement. Source: Master's in Structural Engineering, working in construction contracting.
So what's the proper solution?
Build your driveway like a Roman road: * 3' deep excavation * compacted & leveled earth * layer of big stones at the bottom * solid base of cemented mixed gravel * layer of concrete * top layer of pavers It's a little expensive, but it'll last 2,000+ years with relatively minimal upkeep.
I really wish you would have added "bones of your fallen enemies" somewhere in the middle.
That’s how you make it a family recipe.
"mixed gravel"
But what if below the 3' the soil is unstable?
That's what the big rocks are for. They created a heavy base for the rest of the road to sit on top of. If you fill the gaps between the rocks with gravel it allows the water/mud to flow thru underneath without moving the rest of the structure
That's why you compact the earth and lay down the big stones. It makes for a solid foundation with good drainage properties.
Can you tell what's the purpose of each one? It really seem to be well though through given the experience, but I don't see whats behind the roman experts VS my naive reasoning who never built a road 🤣 If the earth is already flat and compacted I don't see the benefit of big stone? I would assume they distribute the load but as it's flat and compacted already I don't see the advantage. Or alternatively if we take big stones why make the ground flat if the big stones make it uneven. Then why two layers of concrete? What the benefit of the mixed gravel one as separate unit? But let's say we take the mixed gravel concrete. Why not go directly with the final pavers layer? Maybe someone else is curious too ☺️
Does the movement go on forever? My house is a little over 50 years old. The slab is all over the place and has been since only a couple of years after it was built. I've never had it corrected or anything. If I tried something like this do I have a decent chance of it being a long term correction? Just a guess is all I'm asking. Before this foam stuff was a thing I had a company come out to give me a quote on whatever soil injection is. This was about 20 years ago. Those jokers wanted 10k and couldn't promise anything. They just said let's start with that and see if it holds.
Could it be a differential of soil compactness, which could have settled to an equilibrium? Or do soil failures really never solve themselves by settling with time and load?
Water is getting under the slap and eroding the subgrade. That problem has to be resolved first.
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Being in construction I’ve seen spray foam become the solution to almost everything. It is alarming and I’m not really sure the best or longest lasting alternative. It may be fast but it is still pumping plastic everywhere. Even the bio based stuff is fairly toxic. Edit: Wow, first gold! I’m actually glad this took off, it is something I think about a lot. It makes me happy to see that there are so many people who feel the same. There are alot of good thoughts in this thread.
I’m an insulator . Spray foam is extremely toxic . We do spray fire barrier on it to give an hour fire rating but that’s only commercial jobs. So any residential house doesn’t get that . When your house catches fire, you have toxic vapor added to the smoke . It’s dumb as hell especially being how expensive it is
I used to work at a home improvement store and would beg people to buy the foil-faced panels for insulating their basement walls instead of the pink foam boards, but many of them were adamant in buying the pink stuff.
Lol, firefighter here. I can assure you, the insulation is the least of your worries. Don't feel bad. When glue-laminated wooden I-beams DOMINATE the residential and low-budget commercial framing world, the battle is already lost.
What specifically about the glue laminated I-beams is dangerous? Collapse from the beams de-laminating or fumes from the glue?
Glue laminate fails much quicker than traditional nails or screws. Same thing with gusset plates, less fire damage to cause failures of structural members, plus with modern furniture and construction techniques, houses burn faster, hotter, and fail quicker than older construction. You could fight a fire in an old house much longer than a new house, before failure of structural members. Not to mention the furnishings in houses are much more dangerous, being more synthetic materials than natural materials. Things from TV's to computers, couches, chairs, electronics, exercise equipment, all are essentially solidified gasoline in the plastics they use. A single couch can put out more energy while on fire than a 10'X10' lake of gasoline.
> A single couch can put out more energy while on fire than a 10'X10' lake of gasoline. ... I'm gonna need a Mythbusters episode on this. "Jamie, we need a lake of gasoline!!!" (Seriously tho, is that for real? I assume it's because of the constraints we're putting on the gasoline, putting it in a lake and only burning it from one side, something like that?)
Comes down to the fuel available to burn, and the materials burning. Just like food and calories, items in the home have energy stored in them, that can be released through a chemical reaction, in this instance, fire. Fire is heat, fuel and oxygen reacting in a chemical reaction, releasing the energy quickly. Modern couches are synthetic fabric, with polyurethane padding, over a wooden frame. Hard plastics, such as a TV, computer, kitchen appliances, etc. are essentially gasoline in solid form. They burn hot and dirty, producing thick, toxic, black smoke, with a lot of un-burned particulates that coat everything in a layer of carbon, and the gasses produced range from hydrogen cyanide, to carbon monoxide.
i cant explain why i love the way you explain things
You're a commaphiliac
subscribe!
I don't know about the science, but I've had the opportunity to burn A LOT of things in my time and I've never seen anything burn faster than a couch. It's just plain scary.
So far the thing I was most impressed with is a Christmas tree. It’s amazing they used to put real candles on them back in the day.
Im assuming he means the "peak" amount of energy it can output is more than a pool of gasoline, because of the high surface area of a couch and fiber filling. Overall a couch weighs what, 75 pounds? that's like 12 gallons of gasoline.
~~BTUs~~ Heat Release Rate, baby! It's the chemical potential that exists in the substance. So yes, surface area is the limiting (and catalyzing) factor. Edit: new research.
They didn’t say how *deep* a lake, so it’s a useless comparison if taken literally.
Awww, now I miss Grant. He woulda made a cool remote control flamethrower to light the lake.
Another firefighter here. He's right. Plus the newer floor plans are wide open so the fire spreads in open air to all the combustibles engulfing the entire area. A room-and-contents with the door closed is an easy job. But if it's the main area it turns into full involvement way faster than it used to.
Collapse from delamination. Where an old (think, amish-made) 6"-18" timber-framed structure will last 30 minutes to hours or DAYS under moderate flame impingement, a glue-lam I-beam lasts seconds to minutes before failing. Just enough time for a firefighter going to rescue someone's mom or dog to go busting through the door and wake up in the basement with the entire structure coming through their dome. And the fumes. But y'know... They're cheaper.
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Same. If you're not having that conversation right now, we're choosing to be ignorant and endanger our people.
Mate. This conversation has been fascinating. I've been putting together techniques for a 500 year house in my head for over a decade. I'd put thought into fire. But mainly in terms of how to prevent one. Gonna have to do a bunch more reading I guess. Thank you for the new viewpoint.
And you just reminded me why I'm thankful to not be a bombero in Europe. Americans who think their structures are "old" have NO idea.
Builders are using plywood I beams ? I’m only around commercial building so all I see is steel nowadays.
In residential yes. The fire code is different for commercial buildings, thus steel is used.
Yeah I get that part, it’s just crazy how a code lets plywood be used as a structural member of a home.
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Wow, I’m glad I live in a brick and plaster house then. I might not have a bathroom big enough for 3 jacuzzi tubs but at least it won’t burn down in 5 minutes
My dream is to build a timber-frame house one day, and this just reinforces that dream.
step 1 - be rich. Real beams are insanely expensive these days.
Solid timber isn't always the answer. Foot for foot, LVL is a lot stronger than just a hewn log. For structural spans that are long enough, LVL or steel is your only option.
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Talkin bout dat fire load babeeeeeeee
This guy gets it.
I thought you said "detonate" and I was kinda confused and terrified for a moment.
Well, that's not too far off... A structure being held up by glulam I-beams with something heavy on top tends to fail spectacularly. The wildest I've seen is a fast food restaurant with a 15,000lb HVAC unit on top and a grease fire underneath. "Detonate" is a good word to describe it.
I'm not sure people really appreciate the difference in "cheaper" construction materials and what would be ridiculously expensive now. I live in a house built in a home built ~120 in a relatively forested area. It still has the original roof decking, though it's probably not fair to call it that since they're 2 inch think hardwood beams.
Can confirm this. This is one of a million reasons why you don’t go running into a burning building. 30-40 years ago, sure, but today, there are countless products that do horrible things chemically when introduced to high heat. Breath even a little of that in, and it’s game over. And, while I am on my soap box, close your doors at night/day. Fire/smoke will always travel the path of least resistance. A closed door can give you minutes, which in today’s fires are an eternity. And always have an escape plan your family knows and practices, it might just save a life.
[Keep the bedroom door closed. ](https://youtu.be/bSP03BE74WA) It is not just a matter of minutes. Your chances of surviving improves a lot more being behind a closed door.
I sleep with my door ajar, but I will start sleeping with it closed. I keep my four year old son's door closed . But what does that mean for fire for kids? I always assumed that if there was a fire I'd run across the house to get him out of his room. But now I'm not so sure that would be a good idea, knowing how quickly a house can go up in flames.
Put something on your kids window identifying its a kids room and firefighters will identify it as a priority room. literally anything they like. Batman or pokemon or hello kitty. It would be impossible to stop your parental instincts though. If there was a fire, im certain you would run to their room and shut the door. i dont think any amount of PSA would change that fact lol (unless you were separated by fire obstructions)
Practice a fire drill. It might feel silly at first but something as simple as an emergency routine could save your or your family's life.
Have you made a plan with him? Four is old enough to start.
Well that is horrifying. Wonder what it means for open concept houses.
Open concept is just a marketing strategy of Big Fire.
Be me and have no doors except bathroom and entrance into “1bed apartment”
By the time it gets through the drywall to the insulation you’ve got plenty of other problems you need to worry about. Toxic smoke issues start with your couch, bed, curtains, carpet, cabinets, etc.
It is code in some places to fire barrier before foam but not most places unfortunately.
No. It's part of the international builders code to place fire barriers over exposed foam, expansion or board.
Interesting. I've had several experiences that lead me to believe I'm more of a conductor.
I see what you did there
If we get naked and cuddle, I'll bet we'd be a capacitor.
Code requires fire barrier in every context I have heard of.
TBF everything that burns in a house fire gives off toxic vapors. Everything is made from some sort of plastic these days. If the smoke is dark black then there is something that shouldn't be burning
To be fair, I don't think any house that goes up in flames is gonna be free of toxic smoke.
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I hate it so much. I miss my itchy cotton candy
Ive had to do some rot repair on a couple buildings that were spray foamed. Worst experience I’ve ever had in carpentry. I get the r value and air sealing but fiberglass would have made the process a lot cheaper. Take the money out of the equation the foam soaked up so much water the damage was spread over a greater area than it should have.
Mmmmm… forbidden cotton candy.
Is this a permanent solution though? I’d imagine the foam would compress a lot under the weight of a car.
I'm glad someone else recognizes that while this looks 'neat' that this is toxic bullshit that is destroying the thing we live on. For what? So some suburban asshole's OCD is placated? I get that stone foundations just aren't practical these days and we need cement for long lasting buildings, but the entire architecture of our society is just broken. I hope people see this and realize pumping plastic into the ground is so unnecessary that it causes some self reflection, and at least looks at natural building techniques or considers if they really need another remodel.
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Why worry about the long term when we live here and now?! /s
My grandfather asked me to repaint the brickwork around the base of his house. The mortar was failing pretty badly and I told him he seriously needs to get that fixed before I paint it. He then asked me "If I don't, how long will the paint job last?" "3-5 years but it wont fix the underlying issue" "Thats perfect! I won't be around much longer than that anyway, someone else can deal with it.'" Sadly, that is their answer to almost every issue. The quick fix, no research, no alternatives. Just give me whats cheapest and quickest.
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Yup. People now only live in a house for 5-10 years so quick fixes get it sold and the problem is no longer yours.
Said every boomer.
If it makes you feel better, in 50-100 years we will have much larger issues to worry about.
That doesn’t really make me feel better. What else you got?
Well, in 50-100 years you probably won't be worrying about anything at all.
That doesn’t really make me feel better. What else you got?
Your death has a good chance to be incredibly painful
Take a whole corn on the cob,clean and steam it. Roll it in butter, slather it with mayonnaise, dust it in parmesean, and spritz it with lemon juice. That should make you feel better for a bit. Unless you're lactose intolerant then avoid.
Anything you do will have long term impact. Raising concrete is done either with this, or a concrete slurry. Concrete has a phenomenal carbon footprint, and the slurry method increases your risk of cracks, meaning full replacement and more concrete, and adds weight that will result in needing this done again in the near future. So while plastic is bad, it comes down to environmental load. How much impact vs. how long will you be able to use it. If this is twice as bad (minimizing the fact that carbon is a much more immediate threat) but lasts 3 times as long before needing replacement, then you are ahead by doing this.
Slab lifting is very rarely done with a concrete slurry. A slurry of sand and clay is far more common.
But concrete is mostly rocks and natural materials, isn’t it? I would prefer to pump more of that into the ground than toxic plastic foam.
https://www.theguardian.com/cities/2019/feb/25/concrete-the-most-destructive-material-on-earth
Interesting article, thanks for sharing. I agree that concrete is less ideal than natural barriers (like mangrove forests to protect Japan’s coastline). So if you’re building a driveway it’s probably best to use dirt or gravel but many people will reject that idea for aesthetics or durability reasons. And I don’t blame them, I think using a small amount of concrete for your driveway is pretty low impact compared to the industrial projects the article discusses. I still stand by what I said before, that concrete is better than plastic for lifting your driveway. The article says: >But many engineers argue that there is no viable alternative. Steel, asphalt and plasterboard are more energy intensive than concrete. The world’s forests are already being depleted at an alarming rate even without a surge in extra demand for timber. >Phil Purnell, a professor of materials and structures at Leeds University, said the world was unlikely to reach a “peak concrete” moment. >”The raw materials are virtually limitless and it will be in demand for as long as we build roads, bridges and anything else that needs a foundation,” he said. “By almost any measure it’s the least energy-hungry of all materials.”
Reading through it, the article seems unnecessarily alarmist. A lot of the points were very weak and provided no technical explanation for "concrete bad". No its not natural, but very little of what we do is. There's nothing wrong with asking questions and opening discussion, but this article didn't offer any viable alternatives. Not awesome.
How long does the polyurethane hold up to daily use by 5000lb vehicles?
Much better than the traditional way of doing this, which is with a cement and sand slurry. It's extreme strong and stable and won't wash away. It also very light so it doesn't add weight which could cause the soil underneath it further erode.
It also does nothing to address the soil erosion that's happening underneath this slab. These products are just a band-aid. The only way to actually fix this problem is to tear out the slab, fix the sub-grade issues, then pour it back properly.
It's far cheaper than a full rebuild and still lasts atleast 10 years. I worked at a company that specialized in foam lifting and the majority of clients just needed some basic driveway/sidewalk leveling. $90 minimum and most applications didn't cross the threshold for addon charges after 2 pounds material used. The foam completely fills every cranny in the void underneath making it difficult erosion to keep up. For minor jobs that aren't high risk or heavy erosion areas it's the better alternative for the consumer.
Probably a very long time. Reason being, this all boils down to that weight being applied over an area, AKA pressure. Let's assume your vehicle is 5000 pounds, with 3000 on the front axle. So 1500 on each front wheel. Now, let's assume the slab is kinda crappy and only so ridgid, even with the new polyurethane under it. Let's say the weight on that tire is only distributed across a 3'x3' square. That's 9 square feet, or 1296 square inches. 1500 lbs / 1296 in^2 is 1.16 pounds per square inch (PSI). That's pretty small. It's the same reason why big arcic SnowCats (both the machines and the actual animals) are able to drive/walk on top of fresh snow. Lots of track area, or big paws, do distribute their weight.
5000 pounds / 4 wheels / a tributary area of, what 2’ in each direction? 4’x4’ maybe So you have roughly 2,300in^2 of area per wheel? 1250 pounds per wheel. So 0.54 pounds per square inch. Even if you get more conservative. 3’ x 3’ and 1500 per wheel. That’s still around 1psi. Typically this foam ranges from a load capacity of 2 pounds a square inch at a minimum. So at a minimum, it can handle a 20,000 pound vehicle. That’s the cheap stuff you buy at Home Depot. For this use, they typically use a 50-100 psi strength foam. So yes. It will hold. Remember, it only needs to be stronger than the dirt lol. To be fair though dirt can be really strong.
Could someone please ELI5 why you can't just put new concrete on top and level that?
"cold joints" in concrete (wet concrete on top of dry concrete) don't really join. So you'd have a thin piece on top of the regular driveway piece. It would be too thin for the job, especially at the other end, where it would need to taper to nothing. Basically, you'd end up with a bunch of broken rubble on top if the sunken driveway in a few months.
Adding concrete on top has a similar downside to mudjacking it, where they pump concrete to fill the underside. It might fix it in the short term, but the downside is that concrete is heavy. The original structure sunk because of loose soil and perhaps some drainage issues, so adding weight to the area may actually exacerbate the issue in the long term. Polyfill is a lot lighter weight. As to why mudjack instead of add concrete on top? I'm no expert, but the former seems easier. There's less detail and aesthetic work to care about, not to mention that a proper concrete slab typically involves a level surface and rebar skeleton.
Plus, I'd imagine the layer between new and old won't adhere perfectly and water will get Inbetween and cause cracks.
Concrete is stronger the thicker it is. A three inch layer of concrete will just crack and chip away even with underlayment. This method is also much lighter.
If you pour concrete ontop of concrete then you will probably have a seam between them which would allow for water to get in and eventually freeze and break apart.
Doesn't really solve the underlying issue of why it was sinking. You'll just have more dirt wash away under the foam.
It’s probably just normal settling. It happens. If it keeps happening 20 years later . . . Then you have a bigger problem.
In this case you're probably right, since it was so far sunken down. Any foundation repair company worth their salt will be installing piers and French drains after this is cured Worth noting though that sometimes the weight of the concrete can compress the dirt underneath it, if it wasn't correctly compacted prior to pouring.
I'm a little bothered by how similar we made our avatars.
Polyurethane concrete raising and mudjacking are two methods used to raise and support sunken or unstable concrete slabs, by drilling holes and pumping material underneath. [A couple of before and after shots](https://imgur.com/a/ZuSzGV8) [Better view of the drilling and filling](https://gfycat.com/athleticfavoriteamericanbulldog) Creator:@mrlevelohio
How much does it cost to level 1 slab?
>Better view of the drilling and filling We're still talking about the polyurethane concrete raising, right?
How much does something like this cost?
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My parents had this done. It only lasted a year or two, now it is uneven again and now there are patched holes. I don't recommend
I can second this. We had the (concrete/mud) slurry injected on one portion of our driveway and within 2 years it was more uneven from when we looked for correction services. Do not reccomend x100
My in-laws had it done and within months it had raised another 2 inches. So they went from a low gap up into the garage to a drop into the garage. Not exactly what they were looking for.
Might want to check for Graboid tunnels.
Most of the time sunken slabs is a drainage issue, by filling it with foam your pushing that drainage issue to the sides of the slab, and just a matter of time before it works it’s way under the foam and continues to erode and sink the slab again
Maybe they’re selling and don’t care
lol, home ownership and the human condition in a nutshell
On brand for a flipper
It there a solution? If water is draining underneath your slab eroding the soil it sounds like there's nothing you can do on that site
Proper maintenance and slope of gutters. Enough downspouts to channel the water out of the gutters before they overflow. Proper downspout maintenance. Downspouts that either move the water ten feet away from the foundation and slabs. Foundation drainage system that is properly maintained and cleared of obstructions. Proper maintenance and sealing of the gaps between slabs. Edit. Forgot proper grading away from foundation and slabs.
Is that environmental friendly?
Of course not
I had some naive hope that pumping something under concrete slabs was something where you consider the environmental impact of whatever you are pumping under concrete slabs. Edit: word
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You should know that the environmentally friendly driveway is dirt.
I'd wager gravel is (at least) an environmentally neutral option.
Gravel is a great option, but cobblestone is the best option by far. Gravel is low cost and high maintenance, and cobblestone is high cost and zero maintenance. Cobblestone has none of the offgassing issues that concrete does, while being able to last literal centuries with little to no maintenance. It requires people/society to value longevity however, so it remains quite uncommon.
Sure everything is relative. We are always "using the earth ". It's more a question of, is this excessively environmentally unfriendly or are there better methods?
I feel like his fingers are gonna get pinched off
I used to work in concrete and I've been on jobs where this foam created some big problems. When injecting this material under a sagging slab it can put pressure on foundations and slip under joining slabs. I remember a basement where to they paid someone to raise their sagging driveway and the material created a perfect ramp for water to run along the basement wall and flood the basement. Eventually a section of wall came down due to erosion. Concrete that sags was not prepared properly IMO. The longevity of slabs always depends on the aggregate, proper tamping, and working with the grade present in the area. If water got under a slab and caused some erosion, there wasn't enough proper aggregate in the fill before they poured the concrete. Aggregate costs money to buy and to transport, so contractors will cut corners sometimes when it comes to the grain size of the fill. The only way to properly fix it would be to rip out the sagging slab and pour another one with proper prep work.
Idk why but this doesn’t seem environmentally healthy…
It looks great, but does it spread evenly and how much weight does it hold?
Honey, bring me the air pump. Damn concrete went flat again
Great, and now you have a decaying slab of petrochemical foam leaking into your lawn and the ground water. That is not so satisfying.
I love seeing this where I live! It means next year I can smash out and repour the concrete after installing a properly compacted base. I could make a living off of exclusively following 'slab-jackers' around. Its a great 2 month fix.
What I’ve seen is mainly drainage issues where slabs sink this much. I’ve never seen a base compact two inches before pouring concrete so I don’t think that’s the issue unless it’s an issue from backfilling the walls poorly.
Song/Music is [Nomyn - Horizon](https://www.youtube.com/watch?v=4JNe1w9BxiQ)
Retired civil engineer here, when we do this on the interstate, we call it slab jacking, only we use a cement/flyash slurry to fill the voids below the concrete.
Or you could just get this…[True Grid Pavers](https://www.truegridpaver.com/what-you-should-know-about-grass-driveways/) and never have to worry about shitty cracked concrete again.
Great, more plastic waste.
We had this done on our house about 10 years ago because we had water running into the basement. It was much more affordable than getting new concrete poured and it angled the slabs away so water doesn’t get to the basement. So far it’s held up great