Why Some Roads Are Made of Styrofoam

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Published 2023-02-07
What do you do when soil is too heavy for the job? Use lightweight backfill!

Over the years, engineers have come up with a lot of creative ways to mitigate the settlement of heavy stuff on soft soils, but one of those solutions seems so simple that it’s almost unbelievable: just make embankments less heavy.

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All Comments (21)
  • @unvergebeneid
    "A catastrophic loss of function" is just the most hilarious and accurate engineer-speak for "the building collapses on you."
  • @burke615
    "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.
  • 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.
  • @alexpyattaev
    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?
  • @marcberm
    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.
  • @cyclonicleo
    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.
  • @FreekDijkstra
    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.
  • @Grunttamer
    Two really great lines in this: “catastrophic loss of function”, and “soil is heavy, they teach us that in college”
  • @osukaa71304
    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.
  • 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.
  • @Maleko48
    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.
  • @chazzard3746
    I love how you demonstrated EPS' weakness to fuel spills by essentially making Napalm.
  • 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:)
  • "Soil is heavy! They teach us that in college." -- This is the type of engineering humor I expect here 😆
  • @SafeTrucking
    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.
  • @armandgun
    Your content just keeps getting better and better! Big fan of EPS and using it more and more in my industry too.
  • @cavemaneca
    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!
  • 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.
  • @jomiar309
    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.