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Have we ever hit a bump going over a bridge? The first thing that comes to mind is that "ka-thunk" sound from both sets of tyres. Of course we have :)

the background music in your video isn't loud and annoying enough.

Truck driver joke for bridges in Louisiana was we need a step ladder to get on and off.

There's a bridge in Dallas (southbound Greenville Avenue over the DART Blue Line) where there's a significant bump at the end of the bridge. They've patched it at least twice, but it's obvious that the ground just keeps settling.

@@stevenjlovelace a jackable ramp, 3 meters long, would solve the problem. Just send someone out to jack it up every 6 months.

"A catastrophic loss of function" is just the most hilarious and accurate engineer-speak for "the building collapses on you."

significant emotional event

Unfortunate unintended obsolescence

A catastrophic loss of function also applies to condoms.

RUD in rockets - Rapid Unscheduled Disassembly

"Is there a doctor in the building?" "Unfortunately, yes."

Your content just keeps getting better and better! Big fan of EPS and using it more and more in my industry too.

Can we all just pause for a second and reflect on the fact that we've never met a "light weight Phil?" 😁

Thanks for making this video. I live in the Netherlands, where large parts of the western part of the country are basically glorified swamp. In my new neighbourhood, the decline is 2.5 to 4 centimeters a years, and have been declining at this rate for about 30 years now. The locals often refer to the peat ground as "thick water". All houses are build on poles, that reach a layer of sand 7-10 meter deep, and are stable. However, gardens and roads are not. Over time, in particular the roads have subsided (not really settled, as it is still declining) and the common solution was just to add another layer of asphalt on top of the parts that settled too much. Of course, that added a lot to the weight, so it settled even further. They found that by now some parts of the asphalt were 1.5 meter thick. After some heavy rain they decided to tackle this and for the whole village, street-by-street, and replace the heavy roads with low-weight material that basically floats on top of the thick water (also known as "ground"). It's a 10-year project, and interesting to see. Other solutions were tried as well, like excavating the borders of a neighbourhoud up till the sand-layer 7 meter deep, and replacing it with clay. This basically turned the watery ground into a bath tub: all the peat (thick water) in the middle would be contained by sand underneath and impermeable clay on the sides. In theory, this should stop the decline of the ground. In practice, it failed. It just keeps declining about 3 centimeters every year.

A better solution is to treat the large roads the same way as the houses, by building them on concrete plates supported by poles, with an asphalt top layer.

I admire the Dutch engineering, nevertheless, you will need to make everything float because the sea will rise

Hoi Freek Dijkstra. Welk dorp is het? Interesting comment. I think I've seen a Dutch documentary about that but I forgot where. I would like to see if I can find that again. Maybe you can mention where your example happened and when ? Bedankt !

Well yeah about the bathtub idea failing! The clay may be impermeable but it's still perfectly deformable! It'll stretch like sweatpants on thanksgiving!

​@@alexanderpas and where do you get the surety to declare that your idea is better? I'm assuming you're a road engineer, right?

Thanks for making this. Living in Seattle as a member of a family of civil engineers, I was pointing out the use of styrofoam in the construction around the viaduct southern entrance. My mechanical engineer colleagues refused to accept that the styrofoam was used for structure, insisting that it must be temporary packaging waste! I'll happily share this video with them.

That will be so satisfying.

Just remember, civils build targets… mechanicals build weapons… mic drop.

About 60 years ago, I visited Seattle. I was surprised to see empty lots with soil piled up sometimes up to 10' high. When I asked, I was told that they did this to compact the soil. It might take 2 - 3 years to compact the soil, then they hauled the dirt someplace else and started a building project. A learning experience for a farm boy from Wyoming.

A family of civil engineers and a family of beavers are basically the same thing

@@gunner4544 You say that like building weapons is a good thing. When in reality, it just reinforces existing power structures and increases the odds of us all dying. We've had weapons capable of causing human extinction for nearly a century now, how can anyone still think we need to invent even better weapons?

I wish you had discussed the environmental downsides of Styrofoam. It's probably the worst of all plastics. I am curious if roadway engineers have mitigated any of those issues or if they just ignore them for the short term benefit of "completing the project quickly".

I fully agree!

As a Lab Technician for ENGEO I would like to thank you for all your videos. They serve as training aides for our interns, and help us explain what we do and why we do certain testing in a simple and entertaining way. We can show them your videos and then what we use in our lab setting. Keep up the great work.

Have ya'll considered sending him a bit of money?

Gotta love modern YouTube

But this is superficial knowhow. Barely scratches the surface. Maybe 2 pages out of a 600 page book.

@@madistamela5975 You do realize getting students past the first two pages of the book is often the hardest part? Besides, you're wrong - this is an overview of a section. Combined with other videos from this channel, they form a fairly comprehensive overview of the field. Then you have the students digging in, often with stills captured to point out specific things. And then there's the additional bits of non-textbook knowledge from experience that pops up - you do realize Grady is actually a working engineer, right?

@@Tara_Li Introduction/overview of course. That is it. As with many topics on YouTube. Be it history, cosmology or quantum mechanics-sounds interesting and profound for general audience. Not so after 10y actually in the field like in my case.

"Soil is heavy. They teach us that in college!" is the funniest thing I've heard today. Also, I learned that those "abandoned" highway construction sites that I have been complaining about for literally decades may not in fact be due to scheduling problems or lack of funding. They were probably just waiting out the settlement period. It's stuff like this that is why I love this channel.

In short you are just guessing. People need to be inform why they are having to suffer. Imo gov also use that to milk more fund out of the poor suffering and be tortured tax payer while at the same time the allocated fund direct elsewhere.

@@johnmicheal3547 Sounds spot on. Been driving past a bridge project the past two weeks, serious inconvenience with the shutdowns, and not seen a single worker any time we've gone by. Not one, not once, just barriers and two parked tractors.

What about "Guideline and Recommended Standard for Geofoam Applications in Highway Embankments for lightwight bedtime reading"

@@x--. Delayed shipping of needed materials due to the logistics jam the world is STILL experiencing thanks to Covid can mean something meant to be done now is done three weeks from now, or even later.

The problem there is one of communication. People should be told why the construction site is inactive.

Can confirm: I worked as an Operating Engineer and placed many thousands of yards of cellular concrete all over the country and our primary work was on bridge embankments and abutments, especially in the Bay Area of California. We also did many abandoned pipe fills using it for pressure grouting and some interesting annular fill projects too.

This was very interesting. I've seen the building of the Montréal, Quebec, Canada A30-bypass and that involved LARGE overpasses and new highway lanes on somewhat swampy land. I noticed that large blocks and sheets of styrofoam where on site and always wondered what exactly that was used for.

Same thing here in Ottawa! Now I know!

In Scandinavia it is common to use styrofoam as foundation material for buildings. The thermal disconnect is highly desirable when its -20 C outside, and it provides a very good stability when ground changes shape due to freezing water. Maybe an interesting subject for a video?

If done correctly the ground under the house does not freeze, in fact sometimes extra insulation is placed in the ground around the corners of the foundation to prevent freezing of the ground underneath the corner which could damage the house.

@@zapfanzapfanWow. Really? Profound statements and deep Knowledge in the comments:)

@@madistamela5975 If you have a poorly insulated foundation the house keeps the ground warm enough to not cause a problem by freezing but now with very well insulated foundations for passive houses it has become more of a concern. I was surprised the first time I saw it before I understood why.

I heard that a problem with this method is that animals can get into it and start digging it out, then it can be a big problem

I wonder if it this is how the floating islands were made along Norway’s coast.

Oh man I still remember when sand compaction video came out and introduced us to your channel., time really flies. Your content has been consistently amazing,, always looking forward to what you got for us. I'm not a civil engineer, but I just love learning from your channel.

About 25 years ago, I was part of a geotech team tendering for a second bridge across the Swan River in Perth, Western Australia. The ground was very soft alluvium, and the embankment needed to be quite high. We proposed a stabilised soil fill over foam-core solution, but were unsuccessful - the Main Roads Department were very conservative (and still are), and went for a conventional (and much more expensive) pile-supported solution. Nice vid, thanks.

Here in the Netherlands we need a combination of eps backfill and pile supported retaining walls after the ground was compacted by adding 3 meters sand on top(with vertical drains to 15m below surface) and let it settle for a year.

@@user-bu2mn8do6v The Netherlands virtually invented wick drains and preloading! I had no idea you used EPS, but it makes perfect sense.

There was a motor-road built in sweden and Norway in the 1960s. During the time from 1960 untill 2010 the road was upgraded to a full highway. The main part between Malmö and Göteborg in sweden was the first long part that was totaly finished some time mid/late 90s. The last section to be built was a fairly large Marsh like area. The old road went far around it, but when it was upgraded it was just not an option. The last bit built had to go right throw the swamp land. There was rock under, so it could be piled, but eventually they made it to a testbed for the first fully esp supported road. And to this day, almost 30 years later, it's one of the most even roads.

@@matsv201 Our Principal was inspired by the use of EPF in the Nordic countries and I believe in some of the far northern permafrost zones in developing this proposal. His background was in London, as well as in the Gulf of Arabia, and he had an encyclopaedic knowledge of working with both soft estuarine sediments, such as London clays, and the calcareous, often weakly cemented sediments found in the Gulf and across much of WA, including around Perth and on the Northwest Shelf. I did a fair amount of work offshore while I was working for him, primarily in pipeline route surveys, but also in marine construction. It was an interesting few years :).

I worked for an EPS manufacturer many years ago and one of their contracted projects was scrap EPS blocks to go into the middle wall and other sections of a dual tunnel roadway. The grade was usually a SL or L grade (Super Light or Light) EPS block, up to 5 metres long, by 600mm by 1.2m. For its size, they're very light. Saved the joint venture construction partners millions in fill and related costs, plus gave the EPS company plenty of work besides making sheets insulation and lobster boxes.

I didn't know standard block forming machines could do 5m blocks, I thought they were standardized at 2.5m industry wide. Obviously making a double size machine is technically trivial, just not what can be easily ordered and shipped from a major supplier of EPS equipment.

As a native Mainer I thank you on behalf of our lobster industry

Do you have a number on that or is that a European thing? Here I can boy esp 60, 80, 100 and 120 and the number stands for I some unit (don't remeber what) pressure it can take.. pretty much forever. I calculated when I did my foundation and I needed less than 20 but that simply was not possible to buy. I know ir exist, I have seen it, but never seen it for sale.

I remember watching the Apple Park construction timelapses years ago and seeing them build the hills out of what looked like blocks of foam - it’s good to finally understand why that was!

A few years ago my exit on the Denver Boulder turnpike had a partial collapse due to soil settling/movement (soil expansion and contraction is common here because of high clay content). They ended up using styrofoam blocks as the fill material which probably wasn't an option back when the highway was first built.

I'm always impressed with the quality of content you and your team makes Grady! Keep up the great work

Chemical engineer here, but fascinated by the topics you cover here! Thank you for letting us into this mysterious world around us and making it simple to understand

A cool application of lightweight concrete is the concrete canoe competition a lot of civil engineering students compete in. As a mechanical engineer, it's really neat to see floating concrete!

Yeah

Seasteading too

Here in Canada when a section of the trans canada highway was being upgraded from two lanes to four lanes there was a section of about 2 km crossing a swamp, the swamp had muskegs that were over 90 feet deep, and the engineers used drills and bored into the swamp using tubes to collect the water, and diverting it into pumping stations, then the whole thing was built up with geofoam. All of the drilling and piping techniques are covered on this channel. Thanks for the great content:)

Is that the upgrades around Parry Sound?

@@theironrhino110 No on highway 11 just south of sundridge.

just one more lane, bro

@@zwojack7285 math is a tough on for you isn't it.

@@goodbyemr.anderson5065 Just two more lanes bro, it will solve traffic this time bro.

A few years ago I found a huge block of concrete just, sitting on the beach near my house. It was baffling how or why that could've ended up there but a piece of it was broken away and it was actually a block of styrofoam coated in concrete. But I was still very confused. Tried to look it up and found some stuff about styrofoam being used like that in construction, but not really why. This explains it.

That is what I live for--an easy-to-understand explanation of something I was only vaguely aware of. Grady, this is, hands down, one of my favorite youtube channels, and one that I share often with other people.

I really appreciate how you don't exaggerate the titles of your videos and don't do crazy "clickbait" images for the video "cover" or thumbnail that are highly exaggerated over the actual video content. The title actually reflects the content of the video in an interesting but still accurate manner, the same can be also said for the video thumbnail. Finally, the video content is high quality, engaging, and easily understandable without being watered down. This channel really helps me to appreciate what goes into civil engineering and how much more there is that goes into public works projects than meets the eye. (an embankment is just a pile of dirt, right?!? NOPE, not when put like that!) Thank you!

Thank you for this amazing explanation. I saw blocks being used for some roadwork (embankments) and I assumed they wouldn't be strong enough to handle the compression of vehicles going over, but you've proven me wrong. Also, I use that highway overpass many times a week and it has yet to fail. Also, I agree with your wife, waiting that long to get to dinner is a *huge* "I'M HANGRY!" problem.

I have been watching your channel since you were doing wood turning and Arduino projects. I got your book at Christmas and am enjoying it very much. Thanks for all the work you put into your videos. It is worthy of praise and recognition.

I think a major takeaway that transcends industries and disciplines, is the fact that the least expensive suitable material does not always result in the net least expensive finished product.

Cheap goods aren’t good, good goods aren’t cheap. Well, usually.

On the other hand, what's cheap now might not be so cheap later, if repairs need to be done because of improper material use.

It reminds me of how much extra time I spend at work dealing with the inconsistent and sloppily made recycled a36 steel versus how smoothly it always goes when I get to work with nice well made grades like 1144 or 4140.

In the computer networking field, we learn this the hard way. Equipment that costs less upfront often will cost more with reduced uptime and increased labor costs in troubleshooting or consulting fees. Buy reliable products out of the gate and save yourself a lot of hassle.

@@AllYourBaseAreBelongToU5 I see it all the time too! Companies implement the expensive, complex software and cheap out on the servers to run it.

Some houses already use shredded-styrofoam mixed with aerated-concrete (aka. cellular foam), to get roughly 80% of the strength of cellular concrete (aerated concrete) and roughly 80% of the heat insulation of the styrofoam, at the same time, with the right mixture ratio. Would be nice if you could research this subject and talk a bit about it in an episode/video.

I'm so glad I found your channel, I never knew how much I loved civil engineering. It really is fascinating how the world we use works

Hi Grady, thanks for nice video. I can confirm based on my own experience that this is working. I did time ago (as young engineer) the design of retaining wall (embedded structure, wall supported by laterally loaded piles). Because of mess in the project it turned out that wall has to be locally extended from 2m to 3.3m height (6.6ft - 10.8ft) during construction. To challenge that I thought that lateral force depend on backfill weight, so it needs to be replaced with lighter material. That was idea to use EPS blocks as most available light material. Then I did small research and discovered that similar solution was used in my country. That ensure me it is good idea and I implemented this into design. Despite structure is not impressive I am still very proud of that design. Greetings from Poland.

I used to make geofoam, actually did for that exact seattle project. We used something we dubbed 2 pound it is about 10 to 15 times as dense as what you get as packing peanuts, but each 4 ft by 4 ft by 8 ft block was only about 300 lbs. Light enough to be moved very easily. Some of these blocks were even cut to order at the plant before being sent to the project. They would then only need to make minor tweaks to the foam to ready it for the roadway.

This is literally one of the best channels on YouTube. You’re such an amazing teacher, Grady. The way you clearly and concisely lay out the information in a very easy to understand manner is one of your biggest strengths, next to your knowledgeability. You make me look at the world differently and wonder what things are for, and why they’re designed that way. This leads me down many internet rabbit holes of information gathering, but they’re not as fun as your videos lol

I saw the EPS used for an overpass in my area. The road needed to go over a train track, and was in a developed area so the embankment had to be as thin as the road. As well, the area was partial wetlands so settling was likely a substantial concern. I had always thought it looked like styrofoam, interesting to find out that it was exactly what it looked like!

Would you happen to live in SLC, Utah?

Styrofoam can have 50-100 psi compression strengths, in inherently spreadsouts out load well if it ever is overloaded, which seems unlikely given that most tires are more in the 30-50 psi range.

Over 20 years ago I worked on a project that had to be both extra heavy for one part and extra light for the other. The roadway under the bridge was going under the water table so had what’s called a “boat” section that was 4’ thick concrete on the bottom to offset the uplift of being under the water table. The abutment went right up to a tunnel going under the harbor and was built on the roof so had to be as light as possible so used styrofoam for the primary fill.

I love your videos, always so informative. You make learning about roads fun!

It's really inspiring to see your family (and cooking confidence lol) grow as your channel does! Keep up the great work, Grady!

My grandfather started an EPS company back in the 70s (Plymouth Foam). I was so surprised to hear they had a contract with a major local construction project to fill in under the new roadways and embankments. This was so cool to see on here. Thanks as always for putting out the entertaining and educational content you do.

I remember in elementary school in the '60s in the San Fernando Valley learning about all the ways the state was thinking of to fix the San Diego Freeway (I405). And there have been multiple times and ways the SoCal freeways have been "fixed"... 😃 Thanks for the very entertaining education. 👍

Grady, I just finished reading your book and it was such a pleasure! It was fun to learn so much about the "boring" world, and you've imparted your curiosity on me as well. The illustrations are awesome.

Does the book include a coupon code for Hello Fresh?

ok

Thanks for the informative video. Driving past the viaduct project I always wanted to know more. Please consider doing more videos on Seattle’s unique projects like the viaduct tunnel, West Seattle Bridge, or our many drawbridges!

I used to work near and frequently see work on the project depicted at 12:09 (this is at the southern end of the SR99 tunnel in Seattle that replaced the Alaskan Way Viaduct), and was always curious abut all the styrofoam they were using there. To put it mildly, the soil a lot of Seattle is built on, especially near the waterfront, is seismically questionable (one of the main reasons to get rid of the Viaduct in the first place) so it makes sense to make things as lightweight as possible in that area.

We had a section of a 4 lane divided highway near us that just kept sliding down the mountain. After decades of lane closures and repairs, they finally just removed the soil/clay in that section and replaced it with Styrofoam blocks. One would never know that you are driving over thousands of giant Styrofoam blocks. I marvel at how stable the area is now, while wondering how often I am driving over Styrofoam on other roads.

"You are an amazing engineer! Your hard work and dedication is inspiring. Kudos to you for your fantastic achievement!"

One of our local bridges has an approach underpinned with Styrofoam, it wasn't protected properly and rats got in there and made enough tunnels that the surface of the approach started to subside.

I’m a 3rd year Civil undergrad and man. I love these videos so much! Winding down my day after dynamics and mechanics of materials to see the application and connections from the learning is awesome! Much love from Florida 🤘🏼🤘🏼📐🔩

Yes! There's annoying bumps on each end of bridge going over the freeway. I believe problem could be fixed by filling the transition points with a smooth material, or by covering with rubber mats.

Approximately thirty years ago they built a new bypass around the port, and one high overpass required substantial onramps to the highway. Because it was built on once - soft river sediments, they told us they were going to use styrofoam blocks to lighten the load on the base. Everyone thought this sounded ridiculous and destined to fail, especially because of the heavy truck traffic entering the port. I have to admit, thirty years later those ramps are perfectly solid and in constant use.

In Germany the usual workaround is to build up an even larger pile of sand at first to increase the load on the bottom part, thereby speeding up the settling process. Later the pile is reduced to its intended size and the removed material is used on the next construction site. Probably only works in areas with enough space available next to the site to accommodate the larger base of the structure though.

Watched these blocks being placed on a project near work and had no idea what the purpose was. I had (incorrectly) guessed maybe it would aid in digging back down in a temporary setup. This now makes perfect sense! They were filling about 35 feet over a newly installed drainage system.

Haha, awesome! I have seen those gigantic styrofoam blocks used as floating devices and have even lifted one (it feels unreal how lightweight it is, given how huge volume it has) and also seen them being used during construction of pipelines for district heating (in that case for heat insulation). But I could never think they would be strong enough to use for whole road embankments, haha. That's cool. The foamy structure and light weight also means very little material can be used to fill up a huge volume - which cuts down cost and environmental impact during manufacturing.

In theory, one could argue that using styrofoam as backfill could count as carbon sequestration, reducing the environmental impact even more compared to using a similar volume of styrofoam for disposable cups and the like.

Those blocks, with a concrete top, and a mesh and gunite covering, are doing sterling service in the harbour as walk on moorings for the yacht mole, where they form the spine and walkways used to tie up the boats. there is a steel rim on the top used to provide the hard points to fix them together, and to carry the piping used to provide power and fresh water to the boats along it. easy to expand as needed, and as they float, they only need a chain to a bottom concrete block anchor, with slack to handle the tidal difference, to keep them in position, and a rolling gangplank to allow access at all tide heights. Been there for decades, and still going strong.

I have only heard of their use in construction, but I have seen and handled slicing them into panels by pushing entire blocks through a frame of hot wires spaced according to desired plate thickness. This was between 1970 and 1990.

The second half of your comment just repeated the video :P

I travel across a bridge that had a rough and jarring bump. The DOT repaired the entrance by drilling holes and pumping some material under the existing slab on the embankment. It was interesting that it took maybe an hour to complete the entire process, and the bridge entrance feels almost level as a result.

I tend to consider a larger environmental impact of highly processed substances such as plastics compared to naturally occurring backfill soil. However EPS has inconceivably low density around 20-30 kg/m^3. In EPDs I reviewed, both Global Warming Potential and Energy Use during manufacturing are lower than even wood products for unit 1m^3 of element. Maybe one also needs to check its interaction with its environment, impact to local ecology etc. Great video btw, Grady!

A few tears back. A 2 lane highway was expanded about 20 miles south of me. One of the things done was to replace an old, narrow, steel bridge. As I watched the progress of the construction of the new bridge. I noticed they were using huge foam blocks at both ends of the approach the the bridge. It's been in use now for several years, and I've passed over it countless times. I have not noticed any detrimental effects because of it. Time will tell though. I understand that the weight of the roadway, and vehicles, which includes trucks is spread over a large area because of the large blocks. Still impressed that so far, the blocks themselves haven't compressed even more than they normally would. It's now a modern 4 line highway.

This video made me think about arrestor beds installed at the end of some runways. I'd love to see a video on those and it was interesting to read how some of these same materials are used.

Your channel is just the most amazing thing! Stuff that seems incomprehensible is suddenly made clear, even to me! I cannot tell you how much I appreciate this. Too many engineers are so entranced by the science that they forget to explain the form, function and desired outcome. Thank you for being different! 🇨🇦💕

As a person who is not an engineer, civil or otherwise, thank you for this video. I had a feeling that, this is why many projects around town take forever. I know this is just a primer, but still valuable information none the less.

well 90% of the work is just waiting ... just like in military... sometimes you are just waiting for that BRTTTTttt~~

If only they would put up accurate signs of what we are waiting for as we are stuck staring at an abandoned work site blocking our daily commute. This would create a clear distinction between necessary inconvenience and incompetent mismanagement. For example, my commute has been seriously disrupted for years by a never explained decision to relocate every pipe and cable under a major road allegedly to prepare for an already controversial project on the surface. As a commuter I always felt that was an unnecessary step as they could probably have used pillars or horizontal load spreading to support the surface project while leaving most of the substructures unchanged.

A huge demand to speed things up.

@@johndododoe1411 They do this very, very frequently. Public review of projects is mandated by a lot of places, people just overwhelmingly don't participate.

Then what would make public reviews simultaneously more popular and also not prone to trolling or the twisting of results to support a group? Because having accurate opinion and having lots of people act on it are unfortunately exact opposites.

This has opened my eyes on why I see so many construction sites that looked abandoned. I just hope half of them are really waiting for the soil to settle!

As a retired mechanical engineer I absolutely LOVE following your channel. VERY interesting info presented in a fun way. Keep up the good work Grady

I watched a road crew use the styrofoam bricks to build up an embankment for I-44 a while back. they were building an entire new interchange with 44 that used fancy J turns. it completely relieved all traffic that was waiting to get on or off 44. pretty sweet!

I only know of one bridge in my area where the ramp was built with high density styrofoam, and its also the one bridge where they had to rebuild the ramp. In my area, weight isn't a huge problem since you typically find bedrock just a few meters down at most. The bigger problem is usually drainage and soil movement due to frost during winter. Anything that is full of holes is a recipe for disaster. It accumulates water which causes massive problems as soon as frost takes hold.

In model trains and other scale miniature dioramas, styrofoam or other foams are often used to create and shape terrain - really funny to see it happen in full size to make roadways as well

Thank you, I have often wondered why. I see a lot of styrofoam used at the on and off ramps of bridges. There is a particular place where I live where it's used in the road construction, going over a marshy area, two places in particular, and it's a noticeable drop after only a few years. They have replaced one of both sides of the short stretch a few times, since I have lived in the area, the most recent being last year after a once in 100 year flood eroded the sections of the highway significantly. I am curious as to why they would continue to replace these two sections the same way every few to several years, knowing that, in my opinion, it is not a permanent fix?

Hard to say for sure, but it could be that the permanent fix would take the road out of service for too long during construction.

Could also be budgetary--for example, the permanent fix might be $1mm, while it's only $100k for the temporary fix. If you will never receive a $1mm appropriation for that road fix, well, you can't do the "correct" fix, so you just do the repairs you can afford. Especially if you can get sued if somebody gets hurt, so you can't wait to get the alignment back up to standards. Same way that somebody might be driving a beater car that eats repair dollars. They know full well that it would be cheaper overall to buy a good used car, but they also know they'll never have all the cash required to pay for the newer car in one place at one time, and they can't not go to work for a couple years to build up the bank account. So you spend the smaller repair money you actually have on hand. One other thing that can't be forgotten: it might be cheaper overall to just do the cheapo repairs. If the "permanent" fix is gobsmackingly expensive enough, you might want to just eat the ongoing costs as that will be less money. To continue with my toy example from the first paragraph: if the permanent fix is $10mm, you could do that "temporary" fix *100 times* before you add up to that permanent repair cost. If you will only be doing it every 5 years, it is better value for the taxpayer to just do the temporary fixes. (This assumes that you're not having the road closed unduly long--as Grady points out, that has a cost of its own.) The first rule of civil engineering is "Every Hole Is An Adventure." You don't *really* know what's involved in something until you actually start construction. In my own field (structural) you might have as-builts that purport to show where the reinforcement is in concrete, but prepare to be surprised once workers start drilling in anchors. When digging a foundation, most of the information comes from boreholes on fairly wide spacing, and they can miss entire geologic features between the holes that then impacts your design. You start digging in a marshy area, you don't really know what's down there, and a "permanent" fix in those conditions might be very, very expensive.

One of the most fun things to do if you work in a concrete testing lab is to toss the foamy grout cylinders at other people. They look exactly like normal concrete cylinders except they're light enough to float, so people react as if you've just tossed a 10lb chunk at them when it's actually like 1lb and is so soft you can dent it by tapping it on a metal surface. Also was once on a construction site doing an inspection. Had some of the guys doing rebar ask a question on what the difference was between styrofoam and geofoam. Told them that the geofoam is more expensive, lol.

Man I just love how passionate and informed you are on engineering processes and challenges.

In the netherlands we always use a concrete slab that rests one side on the structure, the other side on the ground. This way, the "bump"' created by settlement, is also distributed more evenly. We still use lightweight materials a lot too though

I'd seen foam blocks used to build embankments, just figured it was a logistics thing: the cheap (light) hauling offsets the cost of manufacturing, and it's already mechanically stable which could shorten the project timeline. I had never considered that a pile of dirt is still a structure beholden to the load capacity of the dirt underneath, making the lighter building material more advantageous.

I'm glad you mentioned buoyancy, we have an opera house with a deep cellar that would float up at high tide if not for being anchored into the bedrock.

love this channel. VERY educative and makes us think more about the vital infrastructure important to us all

Educational?

From your lapse in grammar, it sounds like you could use some Hello Fresh food. Order today!

@@User0000000000000004 what?

I saw this process being put to use recently on the I75 rebuild through Metro Detroit, watching this jogged my memory of driving the the office and on the northbound lanes seeing giant blocks of foam being used to build an on ramp between 2 large concrete retaining walls going from the service drive at ground level to the subgrade roadway below.

I'm a bridge engineer. I designed a foam fill approach ramp to a bridge in Seattle (south of the Alaskan Way Viaduct site. Foam fill was selected to reduce settlement during an earthquake. The soils were prone to liquefaction and this was one of many measures to limit the concerns.

I'm much more intrigued by the floating concrete than the styrofoam, to be honest. It's in that category of "ordinary thing given counterintuitive properties," like making clear wood or boiling water at below-freezing temperatures in a vacuum. Weird materials are fun in general. Carbon nanotubes! Aerogel! The mysterious sticky stuff my nieces leave on surfaces they should have no reason to touch!

I was expecting it once he mentioned foamed glass since that's basically man-made pumice.

You inspire me. You make me feel at home for wanting to be an engineer who wants to help people. Thank you so much, Grady. For lifting my spirits. For showing me there are other people who care about the weird nerdy stuff that I like and won't make fun of me for just trying to help.

Two really great lines in this: “catastrophic loss of function”, and “soil is heavy, they teach us that in college”

The issue with the lightweight fill used in near waterways, is that it will also saturate and hold water quite a bit longer. Then you have to deal with more erosion. Especially when you're dealing with sheet walls and reinforced anchors. There's no such thing as free fill. Usually cuts and fills are equalized to reduce costs, but by doing so, you often create scenarios where you're placing things at less than ideal elevations. When I hear there's excess fill available near a waterway, either they increased the size of the water frontage, or they're under building the surrounding infrastructure to make things flatter or more esthetically pleasing. Not always the greatest idea in terms of longevity. Sometimes free fill comes from not actually hitting compaction specifications (but saying they did). Fantastic video as always. I'm an industrial/construction surveyor, and I'd love to see Grady's (a perfect name for a civil engineer btw) take on soils load testing. I've seen some questionable approaches to it in my travels. -Specifically field measurements and different techniques- Eg: Plate load testing on compacted fill before raft footings.

I'm a Geotech Engineer who mostly works on PennDOT and PA Turnpike projects, and I approve of the definition of "a heavy pile of dirt" haha. We geotechs are often pretty chill because we spend lots of time playing in the dirt and working with that understanding that so much of what we do is working with nonhomogeneous materials, interpolating between borings limited by funding, and factoring for safety. I'm fairly young, so I haven't had the chance to work with lightweight fill material yet.

You make engineering look so easy. Just the way it is.

I'm a DOT certified inspector and I've worked on a road project where they built up a section of the roadway 3 lanes wide about 40' long and 15' high using styrofoam blocks because they didn't want the weight of the fill on top of some old but still live pipes under the roadway.

Thank you for another wonderful video! Speaking of using styrofoam for thermal insulation, I work for a small mountain railway where we sometimes battle with frostheave (also a video idea? ;) ) We experimented with using styrofoam in the subgrade to prevent the ground from freezing. It worked well as insulation, but unfortunately the ballast stones have a knack of punch through the sheets under load!

They also use it to protect the permafrost up in Alaska on the Dalton Highway for the same reason (and dang that road can create some epic frost heaves!). From what we could see they used some sort of fabric membrane between the aggregate and the foam to avoid the same problem.

It's worth saying that what people often call styrofoam, that is eps is not actually foam. It's made in a other way. Pollyuretan foam is actual foam. It's twice as good insulator but also twice as expensive (hence 4 times as expensive per volume) If you need a lot of insulation for a very low thickness that is what's needed. (Insulated water heaters and garage doors are often made of that. It's yellow and quite fragile.

The thermal insulating properties of EPS foam have also been used in geothermal areas to reduce heat damage to the pavement. It was interesting watching construction of several hundred yards of roadway in Yellowstone National Park.

Jeez you'd intuitively expect than anything hot enough to damage the road would first melt the foam, but I'm sure they've got it figured out.

@@ithecastic have you ever seen EPS foam get soft in the sun? Because I have seen Asphalt doing that.

Hi Grady. We had pipes burst this winter due to freezing, and it got me thinking: How does the city get water to people in the winter without pipes bursting all the time? Perhaps you could do a video on that if you think it would make a suitable topic.

8 years ago we built a net zero energy home. In addition to our solar array, we are heavily insulated. We live in MN so insulation was very important to our construction. Our footings and concrete sub grade walls are wrapped in EPS foam to reduce thermal bridging. this means the weight of our entire house is resting on foam. After 8 years I can tell you that this system worked for us, we are living a warm life in our cold MN winters! Cheers!

Before I began following this channel I thought of infrastructure as marginally boring and something that, well, could be given for granted a little bit. Got slightly pissed off at some irregular sections of highway, found bridges nice or ugly and that was about it. Now, after being a subscriber and having watched a lot of these videos (many a lot of times) I find it extremely interesting, a real engineering product and something to get excited about --this video in particular reminded me of a huge shopping center that has been built close to my home, and how they were making the structure lighter by adding EPS to the reinforced concrete where it was possible. Also, next Friday I will probably obsessively looking for bumps before driving over bridges, although I must say that I hardly remember any. But I will probably pass a construction site where they are widening a highway that needs to go over a bridge: maybe I will get a glimpse of how they are constructing the embankment and let you know if they are using something interesting to fill it.

I really enjoy your videos. With all the plastic waste we have, has anyone tried to use this plastic as a filler? Unlike the wood fill, most plastics are said to never decay. And it would be nice to see something done to utilize some of the waste.

When a highway where I live was being extended, one of the huge challenges was a sub soil called leda clay. It's probably one of the most unstable soils around especially if it gets wet. There was no way to reroute the highway, so the engineering solution was to install a capping membrane, then use styrofoam blocks on top to build the bridge embankments. The styrofoam is ballasted with normal aggregate materials and paved. It hasn't shifted in the 10 to 15 years since it was built despite the heavy trucks that run on the highway.

Hello Grady, I really enjoyed your video about light weight structural filling material. I was surprised about the unexpectedly long service life of wood chips, that might possibly extend the service life of some infrastructure itself. And I wondered if buoyant concrete would be able to bring the lateral soil pressure in harbour walls down to nearly zero. That could make things quite easy, right? I even enjoyed the sponsor part of your video. It's heart warming to see you having a nice time with your loved ones. All the best wishes from good old Germany 🇩🇪

Fascinating! I had no idea this was a thing! I have a question, though, Grady... One of the problems with EPS is that it's notoriously unrecyclable and non-bio-degradable. Obviously that's part of _why_ it makes a good lightweight backfill material, but I can't help but notice that they're freshly cast blocks made specifically for this purpose. Could shredded post-consumer/post-industrial styrofoam be used instead, like an aggregate? It'd be denser and a little heavier than the blocks, and weaker, but it would also be basically free (possibly even negative cost). Possibly a good compromise between the engineered blocks and the foamed/expanded aggregates? Or would it be too springy? I'm picturing something kind of like sandbags filled with shredded EPS, so there's some interlocking and added strength, a little like the reinforced aggregate from your early video.

Probably can be as simple as shredded EPS packed into polyester bags, like gabions are, with the bags then placed in position, and then filled with a thin slurry of foamcrete to set the bag into position, locking the EPS into position. Then the exterior gets a gunite layer applied to it, and a mesh reinforcement in between the 2 spray coats, and then the final fill soil is added to it. The bags will hold up quite well, and are also a thing that has to be disposed of, leading to them being able to come pre filled, but very light, to the site, and needing only a telehandler to position them, then use the existing concrete pump you have there to fill them, with your concrete batching plant making the light slurry on site easy enough, using shredded foam that has been coated to allow concrete to adhere to it well, and thus not separate during cure. Coating is just tumble in a mixer while spraying cheap acrylic paint onto it, then tumble till they are more or less dry, and add the cement and water.

Styrofoam can be and is melted down and repurposed. Just because these blocks are freshly cast doesn't mean that the original material is freshly procured. Shredded material in bags also wouldn't be very stable.

@@KainYusanagi Where are you getting that? My understanding is that while it is _possible_ to recycle styrofoam, it's prohibitively expensive, because you can't just melt it down thermally; it takes solvents and a multi-stage chemical process. Plastic recycling in general isn't anything like as successful and common as people tend to be lead to believe, and my understanding is that styrofoam is one of the _least_ recycled, at less than 2%.

@@barefootalien EPS styro is actually pretty simple to recycle as far as styro materials go. Other forms of styro such as XPS are more difficult if not impossible to recycle.

@@DerpyPenguin4747 Expol, who manufacture EPS products in my area, recycle offcuts and waste EPS by shredding it and casting back into blocks for this sort of use. Just needs the right combination of heat and pressure to make all the bits stick back together.

I saw a road being built in the late 90’s with big blocks of styrofoam. Now that I think about it, it was right next to a bridge. Thanks for explaining why they used styrofoam.

Perhaps the most interesting point this video really brings home is that, though we think of civil engineering structures as static, it turns out that, like all other engineers, civil engineers too are designing dynamic structures. They just move much more slowly than typical mechanical structures.

I had a summer work on a road construction a few years back. The site was on a former seabed and wasn’t hard as rock. We used expanded clay as filler on embankments. There was a huge pool of it after the bridge. We used also tons of expanded clay concrete under the roads.

I know those huge Styrofoam blocks real well. In Nov 2012, I worked with Superior Construction delivering precast concrete wall panels to a new bridge over railroad tracks on Industrial Highway (now renamed Airport Road) in Gary Indiana. The bridge deck was steel/concrete, the approaches were done with six levels of these huge foam blocks topped with sand/asphalt. The wall panels we delivered contains the sidewalls to keep the foam blocks from shifting and to keep them from rising and/or floating away during periods of flooding. Important since this location is only 3/4 mile away from Lake Michigan. This project coincided with the expansion of the Gary Chicago Intl Airport. The local rail line that used to cross the north end of the airport property where the expansion occurred was moved further north to join the railroad east/west mainline, which also utilizes the new bridge, East Chicago Ave between Cline Ave and Industrial Hwy was removed. It was an impressive project which is highlighted on the airports north end on Google Earth. I took a few photos on the project and now 11-years later, it still stands. That was the first time in my 39 years in construction transportation being involved with a project that used Styrofoam as a base material. Besides the airport, the area is heavy industrial with heavy truck use and it has held up very well.

Great video. Didn't know so many options existed for lightweight fills.

I love your videos so much, and they’re one of the reasons I fell in love with civil engineering and why I’m studying it in college. Thank you for your hard work and incredible videos!

On our most recent Alaska trip we watched workers install EPS sheets as part of the Dalton Highway out to Prudhoe Bay. Waiting in yet another construction delay we enjoyed talking to a couple of workers who said the material not only helped by lowering the weight of the road surface, but also acted as insulation against blacktop and vehicle movement-created heat affecting the permafrost under the road.

10:55 EPS Expanded Polystyrene foam 13:16 used in Seattle Alaskan Way viaduct replacement. (Here in the Boulder area, geofoam blocks were used to repair 2019 US36 sinkhole at 104th in Westminster)

ive seen big cubes of styrofoam under a road during construction and thought it had to do with frost management, but now that ive seen your video i remember that it was on some part of an embankment for a highway overpass... gotta learn something every day!

Your videos are so good! Its like what I wished those 'how stuff works' videos should have been.

Wow, "one of the first videos I ever made" That video of structural sand was one of your first??? I remember that like it was yesterday. I have watched your videos since basically the beginning! I look forward to your releases and every MONDAY I look on Nebula for your pre-'tube launch of your (now) Tuesday vids... Anyone ever tell you, you should be a teacher??? The way you explain and demonstrate things is fasinating! You can make the most boring subject very interesting! I loved having teachers like you in school.

The replacement for Seattle's Viaduct was the tunnel. A huge section of Seattle's downtown used to be Beacon Hill, until settlers pushed the dirt down the hill to extend the city. This might be less-dense than traditional soil, wight might be part of why they used polystyrene. But parts of that area are below sea level. Would be interesting to get some more details beyond "it was used in the project".

There's a big highway construction site not far from my place and I saw these huge white blocks. I was wondering what they were about and dismissed "Styrofoam". Wow, was I wrong! Thanks for the great learning opportunity!

Grady's new book "Engineering in Plain Site" is a must have! Got it in the mail a few weeks ago and enjoying one section a day and learning tons. Fantastic!

I have been on alot of job sites and almost all of them use conventional dirt fill. First time I ever saw foam used was at the sales force tower in San Francisco and as an electrician, I couldn't be more happy to work with it over dirt.