Secret Tunnel/Garage Update #4
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- Опубликовано: 15 ноя 2023
- WELL I'M SHOCKED..........And very Pleased.
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Well i'm Surprised, Pleased and comforted by that discovery. What do you think, is it what you expected?
Definitely not but I was pleasantly surprised, I'm no expert but I think if you continue the concrete on steel without anything in between it'll work the best
I guessing that the polythene is trapping any moisture that is getting in. And the bare concrete would be more porous just a guess I’m no expert
Colin, you should put a window in the wall somewhere that looks out into the rockface.
Something to note could be that the moisture levels are different in the areas you drilled out compared to the roof, so is that a safe thing to use as a generalization? Also the top hole may have rusted more than the lower one simply because it got more moisture than the lower one.
You could use truck bed liner as a water sealer
I suspect the plastic sheet is acting as a kind of humidity trap for moisture, particularly when you consider the heat differential between the cool metal and the dirt/earth. The concrete likely does a better job of sealing against the metal, preventing moisture from entering underground. I'm all for this.
Yep, this. Put poly between concrete and soil. Let soil sit against metal, the concrete is porous and will wick away moisture (from hot/cold differences)
Like those cheap but really waterproof coats, where you end up soaked from sweat instead of rain. Concrete is more "breathable".
Not an engineer, but if I was to augment the concrete it'd be just a single layer of plastic between the concrete and topsoil to act as a roof and divert excess water to the sides where it can soak into the earth.
the boundary between steel and plastic works as a capillary, it literally draws in water. Ion diffusion takes care of transporting the salt, but it goes extremely slowly
Does make a lot of sense! Nice explanation 🙂
Yes your right 100%
I’m a bridge engineer. We use uncoated structural steel all the time for weathering steel superstructures and driven steel piles. Depending on the environment (coastal areas, corrosive soils, etc.), you can count on a certain thickness of section loss. However, as long as the steel isn’t disturbed, the outer layer of rust will protect the material beneath. Because you’ve encased all your steel in concrete, you’ve got nothing to worry about.
You're not an engineer! How does concrete cancer work then?
Embedded rebar rusting thus compromising the integrity of the concreate is not the same thing as here. @@hydorah
@@hydorah how about a half bar (about 5oz) of tallow wash per m3 of concrete... i dont know how old this technique is but i know its pre-skillset-lack of ww2... really interested please reply
Weathering steel is a specific type of steel designed to rust and form a protective patina. Its not being used in this tunnel.
I believe that you are referring to "Cor-Ten" steel in which the surface rust protects the steel underneath just like aluminum oxide protects the aluminum from further corrosion. Regular steel will continue to rust until it becomes 100% iron oxide. The US-Mexico wall is Cor-Ten steel. In the case of Colin's project, I would put as much epoxy primer and catalyzed urethane on the back of the panels as possible, knowing that the heat of welding would affect small areas. There would still be some paint residue to slow down corrosion.
I'm a constructions expert and I've been working with steel for about 6000 years. When building the pyramids we ran into some weathering issues when it started raining frogs, but if you stay clear of god's wrath you should be in the clear. Hope that helps.
Fellow engineer here and newcomer to this 2nd channel - This is fantastic! On the front of rust control, put the steel directly in contact with the concrete and have the moisture barrier agsinst the dirt. Your conclusion about alkilinity and rust corrosion is 100% correct!
Hello Colin, fellow engineer here. I would pour the concrete right on top of the steel. Rebar reinforcements are also poured into concrete without any protection, it is the concrete that seals the metal from oxygen and stops further corrosion. There will be some water content present in the concrete for some time, but it will dry and harden over time (even submerged in water!) In big civil engineering structures they usually inspect the concrete for cracks, as these can lead to water ingress. So I would be more worried about the concrete cracking over time then the steel corroding from the inside.
Rebar in concrete is a helpful analogy, thanks!
Also if u r worried of water going through the concrete, you can add a product like Xypex to fill the voids in the cement lattice structure. We use it for water retaining structures. Although looking at the second hole with no poly, I would just do that, 8 years, no rust, just go with it and if it fails in 100 years, it’s someone else’s problem
I totally agree here. I'm an engineer working for an electric utility. We create foundations for structures using concrete reinforced with rebar or we bury the steel poles directly. For corrosion you need moisture, steel, AND oxygen. Even when we direct-bury a steel structure we only cover the steel in preservative coatings deep enough to get past the oxygen layer. Beyond that: bare steel. We have structures in service over 100 years old and still going strong. Your roof is probably the only area at risk of significant rust (the rest is too deep) and you're encasing it anyway. The plastic outside the concrete as a moisture barrier is probably better than no plastic at all, but I'd argue not worth the effort as it can puncture/tear and then loses its effectiveness.
If you're really concerned, cathodic protection is absolutely an option. This can be a passive system that requires no electricity (that is a different type of cathodic protection used on pipelines). Dams and other steel things in sea water use blocks of zinc bolted to the steel. If you start to see rust in the future you can look to add it at that point.
Short version: don't worry about the plastic and do it exactly how you did the rest of the tunnel and you should be fine.
Love the vids as always!
To add onto your comment, rebar that's been epoxy coated for corrosion resistance has failed at a greater rate than uncoated rebar due to moisture entrapment and debonding. I'm not an engineer, I just watch a lot of youtube.
Agreed, the concrete should be enough. If anything, a waterproof layer over the concrete would be perfect.
I'm a structural steel detailer, I make the drawings that steel fabricators use. We always make sure to note the areas that are in contact with concrete to not be painted. The reason is that when the paint gets scratched water will get through the crack and stay trapped there, causing it to rust faster. Plastic traps water as well, which will lead to more rust over time.
With no coating the water will run right off the steel and through the concrete. That and the chemical reaction you mentioned protects the steel surprisingly well.
Well, please explain how we see examples of halftrack tanks from ww2, being pulled out of water, even with the original PAINT on it, looking brand new?
@@BinaryBunyip It is affected by the oxygen content and PH value of the water, In perfect conditions, rusting almost doesn't happen.
If the water is deep enough it does not contain oxygen. The iron in steel is not reactive enough to rust in deoxygenated water (unlike zinc or aluminium) so if there are enough bacteria in the water to use up incoming oxygen steel artefacts are surprisingly stable. @@BinaryBunyip
See also for this the sunken ships of the great lakes that are basically unchanged. Being submerged in fresh water is a lot less harmful to steel than saltwater.
Less oxygen, less rust.
I'm a NDT engineer (non destructive testing) and you can get a ultrasonic wall thickness measurement set for not to much money with which you can always check for corrosion on your backwall. The wall thickness itself is a give away as well. Asume you measure around 4.1 for new steel (factory over thickness). But you can also see if a backwall is corroded on your echoes (asuming you pick a ultrasonic wall thickness set that shows you echo's and not just a number. Love the channel!!!
I work in NDT as a technician using Ultrasonic testing and everyday, I look for corrosion between isolation and steel or concrete and steel. This is a realy good way of knowing for sure if you have and where you have corrosion issue.
Hi Colin, dam and tunnel engineer here - As others have said (so I wont go into too much detail) and you stated, the concrete will protect the steel due to passivation. Providing the concrete doesnt crack you will not have an problems. Looking at the ground conditions, you are basing your structure on rock and so teh chance of deformation is low, reducing the possibilities of cracking plus you seem to have compacted the concrete properly during construction. However, you may still encounter shrinkage cracks over time. I do not know your mix ratios supplied by the batching plant, so can not comment on the longevity of the concrete. Dont use the plastic sheet, you want steel to concrete connection for a number of reasons but this is a difficult format in which to explain why. For the interior, if you want to keep it mill scale just spray oil and wipe down. I presume that you are using a humidifier in the tunnels?
Structural engineer here, its recommended to use the vapor barrier sheets on the dirt side, so you would put up the sheets against the earth , the concrete goes in between it and the tunnel steel. Great project!
Mechanical engineer here. I have zero idea about protecting structures, so I loudly insist you listen to expert structural engineers. Like this guy.
I am a computer engineer, don't listen to me.
Agree, for anyone interested look up A + C water proofing. A stops water getting into the concrete and C collects any water that sneaks past A. - architectural technician.
Software engineer here. Just test in production.
I’m a paper aeroplane pilot here and desperately need a shit as I’m typing this so I wouldn’t listen to me neither. I would strongly not listen to the mechanical engineer here and listen to the structural engineer way up the top here.
I've been working in concrete technology for the past 18 years. I have always been a fan of keeping things simple. Don't bother with the plastic sheeting, just order a concrete with a cement content at or above 400kgs per M3. Make certain you order one of the following cement types. CIIB-V+SR PFA blend or a CIIIA a ggbs blend. This will help control the temperature that is generated by the curing concrete. The high cement/cement replacement content will stop water even getting to the steel. If your still concerned about rusting you can always go with a waterproof concrete, this is more expensive but it's easy. Things to be aware of. Try and get proper compaction, avoid cold joints in the concrete where possible and don't be tempted to wet the concrete up on site. If you want it to flow just order an S4 so you don't change the water cement ratio by adding water on site. Good luck
This comment is 100% on point, I would let you pour all my foundations.
What about cracks that naturally form over time. You're going to want a barrier.
@@ds-1111 my understanding is that Colin is in a place where it isn’t very geologically active “earthquakes” so that risk should be minimal
That’s all good in theory but concrete won’t flow out the shoot if it’s to dry an ya don’t have a choice ya have to wet it down or it’s guna set in the bowel even though it slumped up perfect before it left the yard when it gets to site it’s completely different couple times we were aiming for a slump of 100 + or - 10 an it showed up at 80 put 10L of water an it brings it back to 100 we were only doing mass pour so it was the weight of the concrete that was more important not so much the strength you would loose
Civil Engineer here. I second the above. The poly sheeting is actually preventing the formation of the passivating layer. If left bare the passivating layer will protect the steel for years to come. Poly can also act as a bond breaker allowing any water that does make it into the soil to travel between poly and steel causing a larger area of surface rust. Use a concrete vibrator when pouring the concrete to eliminate honeycombing and voids. Water will cause some corrosion but the real harm is chlorides within that water. In Canada we have problems with the road salts used to melt ice and snow on the roads accelerating the deterioration of our reinforced concrete structures. Not sure if you have enough snow to merit use of salt but you will want to avoid salting your driveway to prevent accelerated corrosion.
As a former submariner, we use sacrificial anodes all over the submarine. It should be pretty easy to stud weld the interior and mount the sacrificial anodes to the tunnels and the bunker. My thought on the plastic is it trapped want moisture was in the air before the concrete was poured.
Yep! Zinc anodes!
My first thought, he could cut in and modify fairly easily.
Submarines once
Unfortunately anodes wouldn’t work on the inside.
Anodes need a conductive medium for them work. ( seawater, water)
In air, they won’t work.
Maybe if you put them on the outside where they have contact with the moist soil…
But nah, wouldn’t make a significant difference.
@EKEinc ya now that I think about it, they were in free flood areas and bilges.
8 years ago u done the bunker. Time flys ❤❤🎉🎉
Hi Colin, I’m a civil engineer. If you are going to use plastic it’s better to put it between the concrete and the soil than between the concrete and the steel.
If you put the plastic between the steel and concrete it will essentially trap moisture between the two which will marginally accelerate rusting.
If it’s between the concrete and the soil it will prevent water from getting to the concrete and seeping in through any cracks that you won’t be able to see.
In other words the ideal solution would be to line the hole with the plastic before pouring the concrete in but it should be fine if you didn’t
Alternatively you could use the more expensive option and use hydrophobic concrete
this dude smart smart
What about rubber bitumen on the outside of the concrete? I don't know how he could apply it to the sides if he's pouring to fill the hole but you could put some on the top when it's open.
@@TheKoisto could work. Depends how much you care about costs tho as that is more expensive than plastic
Exactly.. Just look at how they do basements with concrete walls. They put the plastic on the outside of the concrete and lay the dirt up against that. Worst case scenario, you can always pull the steel completely out later (if it rusts through and looks terrible, etc.) and just have a concrete bunker with no exposed steel. You may have to patch some ugly "bubbles" in the concrete that didn't fill in perfectly. I personally would paint the interior steel, at least with a clear coat-- so it doesn't ever rust on the inside. Eventually the entire interior will rust over just like the sheet you showed in this video-- due to humidity; unless you keep a layer of oil on it, like WD40 or something else that will block the moisture. But even paint will fall off and look terrible in 50 years.. Just look at old creepy bunkers that are 50 years old with lead paint peeling off.. :)
Yep the polythene should be on the outside of the concrete and I would have primed the steel too (a bit late now).
Hey Colin, I'm in a non-profit association, which restores old Fortresses and bunkers from before WW1. Some of them are rearmed in WW1 and/or WW2 with corrugated iron sheeting.
We were facing a similar problem, because parts of the sheeting was directly exposed to dirt. Thus the restauration requires as minimal change as possible because of it's historical protection, we decided to cover the entire sheeting with bitumen. Now, 10 years later there is still no rust on the outer side.
Also we discovered a bunker from the early WW2 which was covered in bitumen initially. There where only two or three spots of rust, after the farmer who found the bunker hits it with his plow.
That is a great idea but would it outweigh the effort it would take to get the sheeting removed, covered and then replaced. I don't think he has to worry about it for another 300 years. Its 5mm mild steel not 0'9 mm corrugated. The concrete and rebar will hold. Consider the the steel collateral and expendable in the grand scheme of things. Just leave it Colin!
Yes bitumem is a good idea, and I do like it. Only drawback is when the steel sheeting is welded, it would gas off or possibly set alight, but if applied after the welding work is done, before the concrete is added, then yes it would work well.
Wow, great info.
Conc. direct on steel is good as the alkalinity stops rust. Embedded steel rebar is nearly always rusty by the time concrete is poured and it doesn't rust. The rebar/steel will rust if the concrete is porous and allows water with chlorine/salt to penetrate or Sulpur pollution (sulphuric acid).
A membrane (plastic/ bitumen) will protect the concrete and hence the steel from these.
The other risk is the build up of moisture in the bunker that will rust the inside. Think of a saw left hung up in an unheated out house or shed open to the atmosphere and moisture. Ventilation whilst occupying is a must, but care needs to be taken when bringing air into the bunker that is high in moisture content. A problem with the British climate.
Good one 😂
I have a degree in building construction technology.
The reason having a moisture barrier like a sheet over the metal is worse is that you are trapping any moisture between 2 impervious surfaces leaving water contact with your metal. If you were going to go that road you would want to use some sort of spray liner or closed cell foam around your metal so that it bonds to the metal and there is no room for moisture to contact the metal.
Unfortunately I can not speak intelligently about the PH interaction by contact of concrete but I feel like the PH of the moisture itself that gets into contact with the metal is what matters more. Keep in mind that concrete (unless its specially engineered to be) is not impervious and water does move through it at a very slow rate.
To the point though, With the rate of rust you are seeing over 8 years in your climate zone I wouldn't even bother addressing it.
G’day Colin, I’m a builder in Australia. We use a product called xypex which is an additive for concrete that makes it pretty much water tight. As I understand it, it’s a salt of some sort that expands when in contact with moisture and seals any micro cracks in the concrete… might be a bit of extra insurance…
Hi mate, if you speak to your local concrete supplier ask them about concrete additives they can add to your batch. You can get a totally waterproof concrete mix that they use in construction on projects that are affected by water like bridges, foundations to protect the reinforcement. This may solve the problem at a much lower cost. They should have brochures with typical ranges of different mixes to help you choose the right one👍
Couldn't agree more. It's called corrosion resistant concrete.
That is a phenomenal suggestion.
I'm sure that will have a similar effect as the polythene sheets, trapped moisture. The moisture will get in there against the concrete eventually in a short time. And might not dry out well in summer
Such waterproof concrete is great for things like swimming pools, or pits that are dug below the water table, to stop permeation in or out. But it's clear that Colin's excavations are above the water table - the limestone is full of gaps which are all totally dry. So it's not really necessary here. The chemistry of the concrete against the rebar will give all the protection that is needed for any structure above the water table.
A piece of advice from a civil engineer: Steel and concrete work really well together. Salts and water should not be a problem if you use proper water resistant concrete. We used to pour C30/37 water resistant concrete for reservoirs for wastewater treatment plant and I can tell you if concrete is well poured, vibrated and treated it will not let any water near your steel.
On the other hand membranes can trap condensation between the steel and membrane surface, making it worse in a long run.
Therefore I would recommend just a steel and a good concrete.
Love your content, keep goin!
I would add up: Colin, I dont know if you get snow during winter time there. If they use salt on the road infront of house you can expect the new part of your bunker to be in salty sourounding thus you should use proper concrete. As for the rest what you already done its more than great and will last forever.
Yeah that makes sense. The plastic is pretty impenetrable, but that means if something does get through, it won't get out
@@MkosAceOnline nah we don't really get snow, maybe few days a year max.
I would concur on not using plastic, particularly for the underground garage. Opening it to the elements to take the car out risks allowing some moisture to get between the plastic and the steel, thus negating the benefit of bare concrete and steel.
What do you think about a spray on truck bed coating, like Rhino liner? I have considered burying 3 conex boxes, welded together. (Shipping containers)
Or would the right kind of concrete effectively seal out water and corrosion?
Hey Colin,
i think the best way to deal with this situation is, to "cover" the soil walls itself with the polythene and create some kind of "pool" for the concrete. The steel gets covered directly in concrete, but the concrete itself is also protected from the moisture inside the soil and can´t soak in the water.
In germany the baseplate (groundplate) of most houses without basements are build that way.
Sorry, english is not my native language.
Above the under ground garage, when it is finished, where will rain water go? Normally rain water settles through your grass/dirt. If you are getting rid of the dirt below, and you put plastic and concrete where water would normally settle… your front driveway area (above ground) might turn into a “bog” (very wet area) until water can drain off. So you may want to put a slight slope to the roof of your under ground garage but do it in the direction you want the water to drain to (i.e. you don’t want the water to drain toward your house). You might want to consider making concrete drain tunnels that allow the water to go from ground level to below your metal floor. That way the water can still settle into the earth and off your under ground garage roof. Your bunker didn’t have this problem because your lawn is slightly sloped away from the house. Water naturally drains behind your fence or just into the surrounding dirt/earth. That’s my thoughts. Great work, keep it up! From Florida, USA
Mickey Mouse is gay
Structural engineer here, if you use a moisture barrier, it is best to attach it to the earth side of the concrete so that the water is never going to interact with the concert. If you want to use a sacrificial anode, it is pretty easy to install. You basically just attach it to the steel wall and power. Cost a couple of bucks a year to operate, but not much. But in general you can say that 1mm of Steal can hold about 10 years of normal rust activity, so in your case potentially more.
The garage interior however is a different story as it will be exposed to way more water and salt. There you should probably put a coating of some sort on.
i was suggesting the sacrificial anode too :)
another idea could de using an electrical anode (like how it's done in boats arbors) or using a concrete addtive to made it whaterproof (like penetron)
what is a cutting?
@@nd7368I’m going to assume it’s another term for coating
Which concert is that?
@@nd7368 meant coating, thanks.
The electrode thing is a good idea.
Or the electricity thing that Colin also mentioned. I think it's called catalytic protection. An underground environment is basically perfect for it, as it needs a permanent earth connection to work.
@TimeBucks
👍
Good
Thumbs up
That is so awesome to know! Thank you for digging a secret tunnel and updating us on it!
Steel is always used in concrete with no problems (reo rods etc), in fact they work brilliantly together (same expansion rate). The trick is to make sure it is all covered, no honeycomb, because moisture seeping in will start to rust the steel which makes it expand, which breaks the concrete, letting in more moisture. As the concrete gets older it becomes less 'active' and there will be less chemical help to neutralise the rust. I prefer the no plastic sheet method because any change in temp will cause condensation. Just make sure you vibrate really well so the steel is all covered. You are doing an amazing job, keep at it, it's going to be brilliant.
Hi Colin, as a structural engineer with a background in advanced concrete applications (all be it in blast applications & not underground tunnels!) I can provide some advice here:
- Ditch the plastic sheet, all this will do is trap moisture between the steel & concrete (especially during curing) which will go on to promote rust.
- Concrete is great at protecting steel from rusting, and time should be spent to perfect the mix design to yield the best protection results for your steel. Things to consider:
1) Cement quantity - more cement typically results in a denser concrete matrix & one with a higher pH (more calcium hydroxide aka CH). Moisture ingress will thus be more difficult & ions that would otherwise react with the iron in your steel (i.e. rust) are more likely to be neutralised by the CH (passivating layer of the concrete).
2) Cement additives - certain additions will bolster the passivating layer (produce more CH to protect your steel from rust) while others will subtract from it so choose wisely (e.g. choose a cement with a higher pH).
3) Proportion of fines & aggregate size - a finer matrix will typically be more dense and again prevent moisture and harmful ion ingress.
4) Water content/use of plastericisers - these can be added to the mix to greatly improve workability while reducing need for water (lower water/cement ratios will again yield a denser matrix).
- With regards to the science of it all that you touched on, concrete is natually alkaline due to the presence of calcium hydroxide (CH) in the concrete matrix which is a cement hydration product. This is what we refer to as the passivating layer which is depleted over the lifetime of the concrete due to actions such as carbonation and acid attack (both promoted by water ingress). Once harmful ions deplete this protection barrier, rust will begin to occur - rust is primarily a worry in reinforced structures as steel expands when it rusts at a much greater rate than the surrounding concrete and thus the concrete cracks.
Hope the above points help.
You are so thorough I'd almost say robot-like! Great advice here, wow
As a bridge engineer, this answer is so thorough and correctly explained It could be recorded as CPD 😂 well done mate.
This guy concretes!
Rust at a much greater rate than the concrete? Concrete rusts?
Edit: I'm an idiot it doesn't rust it expands 🥴🙄 great explanation I just didn't read it properly.
This is a dope response, not building a tunnel but super cool info.
Your name makes me think your some anonymous engineer hah
As the wet concrete cured, it created heat. From that heat, condensation built up underneath the plastic sheeting. The concrete fully cured, trapping the condensation indefinitely. The trapped moisture is accelerating the rusting process. Which is why you have less rust in the lower test hole, as it is not covered by plastic sheeting. Great job Mr Colin, great work ;))
I was literally thinking the same thing. Better off without it from my experience. You want that concrete in direct contact with the steel.
It only trapped that condensation until it all reacted up with the steel. So it's not going to be trapped forever. And there likely hadn't been enough to react with all the steel.
How does heat produce condensation?
@@aspuzling Steam?
@@aspuzling Until the concrete is cured, it's wet. Add heat and you get water vapor. Cool steel gives it a place to condense. Any behind plastic isn't in contact with the concrete to cure into it.
Love the giggidy you snook in there 😂😂😂😂
I was looking for the comment
Sacrificial anodes are easy to install. Connect one wire to whatever and leave the anode in moist soil.
I used to build cell tower foundations with bare steel I-beams encased in concrete for the guy anchors. These anchors were often in swampy soil. Sacrificial anodes kept the rust away.
They are also used on earthworks equipment here in Canada and work great.
I worked offshore for 15 years in the salty North Sea and I can honestly say painting Blue Steel Rust Convertor is the best thing ever for putting on bare steel. Looks like milk and so easy to put on using a roller brush and wont change the colour of the steel much. The steel will outlast you I promise you!
i'm not an offshore guy but this sounds like the best option tbh. the rust converter probably makes a small film that does what you were hoping the plastic would initially.
Definately but make sure you got over the top with ventilation, that stuff is nasty
I think you need some rust on the steel first? Could be wrong?
@@Guvnor100 I think the idea is that the solution forms a film over the steel so the sooner the better, it is probably designed to be used on something that you want to stop from rusting further but it probably works just fine on new steel for the same reason. Don;t quote me on this though I don't know anything about it that's just my "intuition".
@@Guvnor100if you have it there before, and the steel rusts it will instantly stop the rust.
I think you've actually chosen quite a good steel for this project, especially combined with it all being buried in thick concrete. You may want to look into more aggressive rust prevention for the garage interior though as that's going to be exposed to far more outside air, salt, and moisture than your other entrances
I agree with this. Definitely treat (paint) the interior surfaces in the garage, and if it's not already part of the design, consider an air-lock doorway between the garage and the rest of the complex.
I'd also suggest visiting some other local underground complex, like the sewer system or even a historical castle. It won't show what concrete backed steel looks like, but it will give an idea of that humidity cycles in that part of England can do. Obviously a storm drain is a lot wetter than Colin's nice cozy Fullmetal Hobbit Hole, but he'd be able to get a look at the metal pipes and fittings and see a sort of worst case scenario for painted metals vs exposed.
This needs to get seen great idea 🎉
@@hunterfreeman8662 its an obvious idea 😂
On top of that such a large room with dark steel will be very dark. If he paints the room a lighter color like grey or white it will feel even larger as well as making the room brighter.
Deicing salts will be a big issue I would think. However seeing as it’s a deloren he is putting in there it’s a question of if the car rusts first.
I could feel that Ryobi crying! Interesting regarding the rust. I worked on a concrete and cathodic rust prevention system on a Marina arm many years ago. They ran low level electricity through a titanium mesh and cathodes inserted into the concrete to prevent the steel inside the concrete corroding further. The marina arm is still standing so im guessing it works! Saying that it was fairly costly enterprise!
Good luck with it all, what a project!
As a former engineer on a diesel-electrical submarine for 7 years and a civil engineer for pipeline operations for 15 years, I have the following comment:
Although, submarines and any metal boat / ship must have sacrificial anodes (various materials have been used), that is not always the case with buried pipes (or bunkers for this matter). Cathodic protection is mainly used to and one of the most effective methods for preventing corrosion on a metal surface. Due to the potential difference between the anodic (less noble) and the cathodic area (steel), positively charged metal ions leave the anode surface, while electrons leave the surface at the cathode. This results in reducing the thickness of metal. The simplest method to apply cathodic protection is by connecting the metal to be protected with another more easily corroded metal to act as the anode (passive cathodic protection). Zinc, aluminium and magnesium are the metals commonly used as anodes. For buried steel pipelines with large diameter we also use active protection that uses an external source of electrical power provided by a regulated DC power supply, often referred to as control panel. The control panel provides the current necessary to polarise the surface to be protected.
With all that said if we use Reinforced Concrete Pipes (RCP) for buried applications, there is no need to provide cathodic protection for the steel rebars used inside the concrete, but the rebars must be properly galvanized preferably by the hot dip method and then given a protective coat of bitumen or epoxy paint to give you years of corrosion free service.
In your case, you should benefit from investment in passive cathodic protection with zinc anodes directly connected to the steel inside. I can help you to calculate the amount of the anodes (by weight) for free if you need help with that.
Amazing work Colin! Can't wait to see your new videos.. Keep up the good work!
I believe oil rigs use a big magnesium sacrificial anode for corrosion protection. Sounds expensive but it would probably last a long time.
I would put the poly on the out side of the concrete to separate that and the ground soil. That is what you do when digging out and pouring concrete for a garage floor or basement. You lay poly down over the dirt then pour your concrete over it. In your case you want the reverse. You pour your concrete and then lay the poly then backfill. That should give you the best protection, and the least amount of moisture to seep into the concrete.
That's exactly how we do it in South Texas on the coast.
Exactly what I was going to suggest. Concrete against steel then waterproof the outside of the concrete to reduce moisture ingress.
yep needs more upvotes
Pouring the concrete then covering with plastic would require a lot of concrete forms down in the hole ... and space to remove the forms
I was also going to suggest this but then it occurred to me that as concrete is full of water, that water will need a way to escape to avoid trapping it between the polythene and steel. Perhaps its best to simply cap the top of the concrete with polythene like a flat roof with a bit of an overhang beyond the bunker walls, and leave the concrete to the sides free to wick moisture away into the surrounding ground.
The polyethylene sheet is definitely holding moisture against the steel. Here in Florida, we don't use moisture barriers in our walls like the rest of the country does, because it will trap moisture and cause mold.
If you want a consult, Grady at Practical Engineering would probably be happy to lend some Civvie Knowledge about rust. He even already has a video on it.
now that is a collaboration video I'd like to watch. "Colin and Grady tunnel research institution"
Oh man, a Grady/Colin combo? That feels almost as fun to say as 'Toblorone Rolo combo' in a geordie accent
This would be the most amazing collab ever!
I'd love to see this collab!
Absolutely. These two knuckleheads getting together?
"Well, we were in two different continents, so we figured a bridge would be the best way to connect--"
I have no worries pouring up against steel. Make sure you vibe it well. You always want excellent consolidation. Too much Air is bad. The poly I always put up against the terra, which is where any moisture is going to originate from. I try not let concrete free fall out of the pump for more than a few feet and directly over rebar to avoid as much segregation as possible. Unless you are actually BLOWING YOUR CONCRETE INTO TIGHT SPOTS WITH A MIXTURE CALLED GUNITE. This technique is also used to free form the vertical walls of swimming pools and tunneling when you are not using steel forms. I always poly against the earth side no matter what. Before I put down an exterior slab I put a nice thick 6 ml poly down on my Compacted aggregate base, then steel, then mud.
I am super excited to see how you tackle the next level down ... under the entire foot print of the property. We may need to do arched beams at 20 feet tall spanning the width of the property. A warehouse soccer pitch under the whole existing tunnel system !!! That will be Banananananans !!! And fun !!!
In construction with reinforced concrete, the rebar has to have at least 1" of concrete around it.
This is to protect the "coating" resulting from the reaction between concrete and rust from incoming water, be it from weather or from ground.
Coworker just built a house and talked to the concrete specialists.
Greetings from Phoenix, Arizona! I have over 30 years experience in the construction trades. The plastic sheet is a vapor barrier, and it should be placed against the moisture trying to get in, i.e. the dirt. If it was my bunker/garage, I would be putting the vapor barrier against the dirt, then pouring the concrete in. You could easily accomplish that beforehand, with a very slim chance of actually getting it so hot that it melts from welding. The fact that you have no surface rust on your previously built sections, really tells the tale. I can’t wait to see when the garage is finished! :-)
That makes sense. Im a professional youtube watcher and i aprove this message. But seriously you may need to drill more test holes to confirm
Best yes
9 years in construction and 100% agree with this. Or you could get galvanized steel but that expensive.
I'm a brain surgeon lmfao 😅😅
I once listen to 7 minutes of a podcast on digging and I too approve this message
I'd love to see a window out onto the limestone rocks with a light in it in one of the walls! I think it would be a nice funny addition! :D
It would be pretty cool, but it would have to be a sealed window, considering the amount of humidity it would let into the bunker.
I think you're forgetting something, you can't see through concrete.
@@Loberless sounds like someone doesn’t have X-ray vision
A little nautical window and a mini cave on the other side with real-sized model dwarves with pickaxes and classic beer steins perched on a rock.
@@retnepracnow that would be great!
You could paint the outsides with softened roofing tar such as underground oil tanks. Might be a bit late now and also there is the welding heat to consider. The tar would also hold plastic in place on the sides for an added barrier. They also make rubberized cement.
Hi Colin, I'm personally dealing with some infiltration problems at the moment. If you are worried about rust, you could do some resin injections into the structure. This doesn't only protect the steel, but also fills the concrete cracks that naturally occurs during years, making the concrete watertight again. Good luck with your projects!
Hi Colin, structural engineer here. Ditch the polythene. Because the joints are not waterproof it will trap moisture between the concrete and the steel. You have the proof of this as the bottom hole show no signs of rust. If you want better protection, you could decide to use a better concrete mix, a formula that resist better to salts and/or admixtures designed to reduce cracking. Or, if the frost depth in winter is a couple a feet (5-6 feet here in Montreal), you could use air-entrained concrete (the micro bubbles leaves space for the water to froze, thus reducing cracking). I love to see that you are thinking about the longevity of your tunnel!! Congrats!
So much fake engineers today LOL
@@nooooheyyyand yet you have nothing to add
@@nooooheyyyJudging by the fact you can’t use proper grammar and say “so many fake engineers” I’d doubt you have any more credibility than anyone else.
lol@@CheatcodeGamingOfficial
@@nooooheyyymany* stay in school😮💨😮💨
Definitely get an ultrasonic thickness gauge. You can non-destructively test the thickness anywhere you want. I use one daily at work. You could even get in a local UT NDT inspector to come by. I'm sure they'd love it!
Jumped on here to say this as well. Get a UT scope!
that's brilliant
Only sensible comment here! Lots of 'engineers' who think rust sleeps. You're suggestion is great. Actually test. Actually know what is happening
The only issue i might see is the fact that the steel he bought will most likely have variations across the surface do to stress relieving and inaccuracy in whatever machine rolled it (assuming it is rolled steel) im not a construction worker or engineer by anymeans but was just wondering if those variations could amount to inconsistency in the data
You find any issues with UT scans at 4mm thickness?
Good luck. Smart luck. Keep up the good work.😊
A coating of synthetic 0w 20 or mineral oil plastic on top of that concrete with calcium chloride to absorb excess water on top of that plastic on top of that then your dirt. Oil is going to add some protection and also give something for the plastic to stick to.
Has it already been 8 years since I followed this bunker build? Man time flies...
I was shook when he said that.
i almost died when he said that
My jaw dropped
I was like "already"?
Hi Colin. I'm an engineer specialising in silos, including reinforced concrete ones. Simple answer - LEAVE OUT THE PLASTIC FOR BEST PROTECTION!
The key, as you said at the outset, is in the chemistry. Steel does not go rusty in an alkaline environment. So as long as the concrete is touching the steel, no rusting will occur. Even when the concrete is buried in the ground below the water table (not in dry rock like you are) the presence of the cement against the steel will protect it. In especially severe environments, like submerged in seawater, you would have to ensure you had a sufficient thickness of concrete to step chlorides permeating through to the steel (a few inches). Without it you can get "concrete cancer" due to the rebar rusting and blowing out the concrete - old bridges, silos etc often need repair if there was not enough coverage of the rebar. The other reason for concrete cancer is the concrete cracking and letting excessive water through to the rebar. This occurs when the concrete flexes and cracks, which is a natural thing for reinforced concrete under tension (eg the bottom of beams). Nowadays we used post-tensioned reinforcements to make sure the concrete is always in compression. However, flexing is unlikely in your case because the concrete is under absolutely minimal load. In addition, your environment is very friendly towards steel - the limestone itself is alkaline, so even any water seeping through the normally dry limestone will also be alkaline, so there is very little danger of rust.
The really important thing is to have the cement touching the steel. DO NOT put plastic in as it can seal in moisture between plastic and steel and actually prevent the alkalinity of the concrete doing its anti-corrosion job. Rebar is never coated! Always provided with a rusty finish and as long as there is enough coverage of concrete and no cracking, rusting is not a problem.
NO PLASIC PLEASE!
Mike
Wow succinct and informative - always wondering
hey Colin, love your content. I would encase the steel with the concrete and then cover the concrete with an additional water barrier (sheets or brushed on.) Perhaps some French drains for whatever comes. Since this will be under your driveway/deck, I assume there will be much more water penetration from rain then your previous tunnels. It does rain in your part of the woods.
How thick will the finished roof be? Maybe one of your fancy elevation drawings to show your roof structure in the next vid. metal, concrete, sheeting, dirt, sand. pavers, surface
thanx again
French drains would do absolutely nothing.
Your doing great just keep doing what you are doing with the concrete
Colin, don’t worry, we‘ll be here watching you patching the steel in 40 years!
He will have a hard time getting anything up than.
No, robot limbs
No, he'll just build a slightly smaller stainless steel tunnel inside the first one. 😂
@@randywl8925 Yo dawg, I heard you like tunnels...
I duno, from the samples, it looks like theres not going to be much need for repairs even in 40 years :)
Keep in mind that the garage is going to have exposure to the elements through the car lift and having a potentially very wet car inside of it. Might need to have extra strong moisture extraction methods!
He needs an airlock!
@@SP4CEBAR or a decontamination unit! jet powered hair dryers? lol - more funny because I can imagine Colin actually doing that.
I'm wondering just how water tight the doors will be. I'm worried heavy rain could flood the whole thing.
To your question at 4:32 about the plastic sheets on the wet steel, reminds me of videos where mechanics criticize the use of rubberized rust-proofing undercoats. Once hardened, they tend to peel away and crack a bit and leave this thin gap that draws in moisture by capillary action and then keeps it there with no air flow. Once rust starts to form, the rough and crusty steel surface wicks in water even more, while oxide formation pushes the gap wider. So I think you have better longevity on the bare-poured steel with its weather-facing surface chemically bonded and stabilized with the concrete.
My great grandfather taught me a few about concrete from what I learned as long as the concrete doesn't shift to hard to form any cracks then the concrete is protecting the metal but the metal with the tarp on it has rust due to the tarp holding moisture in.
Ship builder here (cruise ships!)
Floating dry docks use a hard coating as they are designed to be in water for 50+ years, but overkill for this, as is any sort of plating such as nickel or zinc. The polythene barrier used on the bunker may accelerate the corrosion by preventing moisture from escaping. Long and short is that concrete is porous, therefore moisture will get through! An impressed current cathodic protection system will help, but you will need multiple grounding rods around the tunnel and some aluminium or zinc anodes on the outer shell (which you can get to to replace) and a system to control to the current balance (again, overkill).
Cheap and easy is an oil based coating with some minor oxidation ("flash rust") before applying. This will slow to a near stop any further oxidation, but will eventually disappear through the porous concrete. Other ways is to use an additive to the concrete to reduce its porosity.
Either way, you will be dead before you have any issues.
Colin, you should put a window in the wall somewhere that looks out into the rockface. the rock fae looks so cool and it's all covered up!
Probably not great for structural integrity
The required concrete will just cover it unfortnately
Ooohhhh I definitly like *that* idea! :D
This is such a cool idea!!!!
How about a window that has a view into a small cavity that has the skeleton of a Morlock in it....
You could use the Xypex admix product mixed into the concrete as a waterproofing, done in below grade tunnel building applications all the time.
I was a concrete technician back in the late 80’s and have concrete technology quals, where did your concrete supply come from, down here in South Wales we use sea dredged sand which contains chlorides and salt, pit sand doesn’t contain as much chlorides so will not react as fast, cement has chemicals and silica’s in which react with moisture, I’d say it will outlast your lifetime Colin👍
Red oxide paint before concreting would probably be the most helpful... I put up a hand made chimney cover 15 years ago for my next door neighbour which was just welded sheet steel painted with red oxide. I can see it from my hallway window and it's not rusted even though the paint seems to be wearing off from the weather.
... and it's slow and heavy for cutting steel Colin! not "hyper speed" you'll melt everything. lol
I think it's just a waste of money and effort to add that, especially after having seen that sample that was straight against concrete.
Exactly what I had in mind, I hope collin sees this :)
@@DrTheRich
To be fair, I wrote that while still watching the vid though there could still be wetter areas once its all done that would benefit.
Besides, you can't put a price on peace of mind.😉
@@STUCASHX "Besides, you can't put a price on peace of mind."
I mean, if you're a super anxious person who doesn't test and try out, research and asks experts, then sure.
If you know what you're doing than you can have piece of mind without wasting money.
Nothing better than a Colin furze tunnel video ❤
True
Yes
I agree 👍
Winning the lotto?😂
how about TWO Colin furze tunnel videos? :D
Bitumen on steel is a perfect mega protector BTW. It comes in some very runny forms too so you could coat the upper part no problem.
I'm not involved in construction or groundworks in any sense but I had done a fair bit of DIY over the years. I would imagine the best coating you could use to stop rust occurring would be bitumen paint. I've used it for various waterproofing applications over the years & it is yet to fail me.
Architect here. Who lives above a WW2 bomb shelter. So 80 something years old. The steel beams in the structure arenow completely rusted though but the 400-500mm thick concrete is still holding the house above it up. I'm sure your structure will see you out ! Love your work #keeptunnelling
We need more information on why and how you live in a WWII bomb shelter.
That’s what I was going to say!
Just like it’s an everyday thing lol! 😂
Do you have a RUclips channel good sir?
@@glenmorrison8080 He lives *Above* a WWII bunker, not *in*.
@@chshrkt If I could tell you I lived "above" a WWII bunker you better bet your butt I'd spend as much time as I could in the sucker XD
I thought an Andersen shelter owner might pop up with some useful advice!
giggity 8:17 😂 i can't hahaha
I used to work at a utility tower plant for imbeded base sections were always galvanized, coated in a spray epoxy, or both. For the interior you could remove the rust then take a torch to it and then braze zinc onto it (what galvanizing is made of) if you spray a bit of muriatic acid it would darken the bright zinc considerably.
After sanding your buggy for new paint you spray the steal with an acid water mix and let it dry on then paint you do not rins or wipe it off. This pasivates the surface potasium in the steel slowing rust. I recomend this then use a paint roller to apply slow set roofing tar thinly befor pouring the cement against the steel.
I make below grade waterproofing products. Try to avoid the plastic liner if it isn’t adhered (without gaps) to the steel as it will trap moisture in once it finds its way in.
Paint is always great for steel. Consider a solvent based coating to prevent rust and mineral degradation.
You can also prime the metal, put a polymer modified cement on it, add a water based acrylic membrane, and then the concrete. That would be bullet proof.
Feel free to reach out if you have any technical questions. Family has been doing this sort of thing for over 40 years. CHEERS!
welding steel plates would burn off everything arround weld
Sacrificial anodes of zinc on the concrete side?
edit: Ah, he mentioned those.
They don't need electricity run to them. The galvanic reaction takes care of that.
@@MonkeyJedi99great solution, only problem is they have to be inspected and exchanged regularly. Not impossible though
Right, you would have to prime and coat post weld, which is typically the standard in below grade practices. @@panzer8as
Structural engineer here! Commonly used in the baltics is bitumen on the outside of the steel before concrete or dirt. Recently oversaw excavated underground transformer housing for military installation from the 60s to extend it again for water pump. It was dug, metal struts installed, steel panneling boxed, bottom 10% concreted and the rest just soil and mud compacted down. The oustide and inside of the steel painted with bitumen. The only parts that rusted out were the parts that were later extended in the 80s and it was just concreted around shoddily. Sections of the metal were sent off for spectral analysis from both eras and they were exactly the same Soviet composition yet massively different outcomes. I had a younger engineer working along side us for his phd and that data will be available in 2024. The exact methods of original construction werent documented but would recommend laying your steel out on a hot day, blowtourching the steel to open its pours and apply a thinned layer of bitumen primer (steel should be colder than the flash point of the bitumen primer 😂)
That is wildly interesting. I’d be excited to see that data when it’s published
bitumen is water proof isn't, so it kind make sense. An tough than any paint.
ok
Isn't bitumen pretty dangerous to work with?
@@RobinTheBot It use all the time in highway construction, so it doable.
As an architect (and have been called an engineer) I have to mention that concrete is somewhat porous. Some moisture can get through it if it is not sealed with some kind of impervious membrane or self sealing exterior lime plaster, drainage mat, or something. Also, when steel rusts it gains volume which can create other problems. Sometimes expanding 10x. Not something that would be a problem for decades though. I assume.
Cathodic protection can help, either through sacrificial anodes, zinc coatings, or even a low voltage reverse current system like is used in some bridges and such. Also proper grading and waterproofing can help minimize wet soil near the steel.
If you have a 100mm of concrete over your steel you are safe from corrosion issues if you are still concerned use zinc anodes (like on ships) to reverse the corrosion current but this would be a bit of over kill.
I enjoy watching your secret tunnel programs you do excellent fabrication work.
This video and some comments reminded me of another concern for underground bunkers:
Radon Gas!
The UK Radon map shows your area as having high concentrations, so you will probably want to consider Radon ventilation in the new larger areas. A few simple steps can make a big difference!
The bunker is pretty well sealed, so I’m not concerned about radon ingress. Definitely a consideration.
If the steel lining is air tight, which I think it is because it’s completely welded. The radon is not likely to seep in…
He does have ventilation in the bunker at least, but he should definitely get a radon detector or two down there.
The radon won't be able to penetrate the steel bottom (and the concrete underneath), so there probably is less radon in the bunker and the tunnel system than in the house.
I thought he tested this on the bunker build already?
Holesaw trick: After drilling the centre hole (and JUST marking out the main hole), drill another hole at the edge of the main hole. This will improve the cutting efficiency tenfold as the chips have a way to leave the groove of the main hole.
Good tip! It's also worth checking you've got the right holesaw for the material.
Carbide tipped, carbide grit, diamond and bimetal are the options you'll find at a hardware store and each is best for some metals and horrible on others.
There's also the tooth geometry to be aware of.
Annoyingly there's a bit to it but it's worth reading as choosing the right one saves you time, money and gives a better hole.
That’s a really good tip actually. Thanks
@@drakessupersecretchannel6086
Most metal saws have small teeth on them. Saws with larger teeth are designed for wood and wood like material. Steel reinforced concrete with larger aggregate usually require carbide or diamond impregnated saws to get through all the different materials easier.
Wood saw will work on metal, but you could see that using the wood saw on the sheet metal resulted in him smoking the drill motor.
Great tip - thanks for sharing this
This! It helps in wood, metal, or especially fiberboard that loves to clog the teeth
I was thinking of what you'd do for drainage inside your vehicle bunker. Perhaps a bar grill covering a French drain would suit the room well with a small sump tank. Not sure how many gallons available you'd need w/pump. Obviously, a demudifier might help with the condensation as well as a plumbing vent tube for the car exhaust, etc.
I'm glad it's still in great condition. They make a Rust-Oleum paint to help prevent rust if it ever becomes more of an issue in the future.
Hi Collin, concrete mix design expert here. At our company we offer concrete chemical admixtures that can waterproof concrete and also something that will act as a corrosion inhibitor, this keeps the rebar in concrete from rusting and will probably work very well for your application.
Holy crap I did not realize it's been 8 years since you started this project and I started watching honestly to me it does not feel that long
Hi Colin, love your work and tenacity. Look into a sacrificial anode 👍
I've been a welder for over 20 years and made various things but when I used to make silos or storage tanks which went underground of forecourts and petrol stations we used to coat the cradles they sat on with red oxide paint,when they were dug up to be replaced or serviced 15-20 years later the cradles were rust free...In short I think painting the side the concrete is being poured onto with red oxide paint 1st would be a great protective barrier...great content as usual 👍
Red Oxide paint is good, had a car painted with it and it resisted rust quite well. They use it all over Saldanha in the western cape on the Iron Ore export machines.
red oxide is good stuff BUT when the put steel in the ocean they wrap it in Tar and Grease (Denzo Tape)
I was thinking this as well, worked as a fitter helper at a place for a short time, and they sprayed that same stuff, nothing bypassed it., They would acid etch, then spray that on to the vessel.
Red oxide is good to protect steel, but having the alkaline concrete in direct contact with the steel is more effective!
Pppp
"Asking questions to us, thinking about it, comes up with his own solution."
We are glad to be of assistance, Mr Furze.
Always a pleasure to work with you :D
Sometimes it's just really nice to have someone to talk it through with.
We're just rubber ducks he can talk at to think things through
We’ll of course still mail him an invoice for building engineering consulting services.
Came to say the same thing - I love the internet@@Soken50
Basically me with my sister whenever I lose something. "Hey, have you seen my... Oh, I remember now!"
So effective I even called her a few times after she'd moved out of state to ask about something she couldn't possibly know lol.
what a cool thing, that the fastest and cheapest method was the best way to do it. 10/10 Collin!
This is so cool!!! I dream about doing stuff like this to my house. Love the videos. Keep 'em comin'!!!😀👍👍👍
I think a lot of us love the tunnel videos because there’s that almost childlike obsession of building pillow forts or camping in your yard. And for be I’ve thought it’d be really cool to have a bunker or secret rooms behind bookcases. That’s the Maine thing I always loved.
He really should make one of those bookcase secret entrances. Or possibly a swiveling fireplace.
I remember as a kid there was a rumor of a guy in the town that had a tunnel and bunker underneath his yard. Was of course only a rumor, but I’m glad to know that in Colin’s town that rumor is true.
@@corentinoger yeah, he could have a bookcase in his tunnel even and behind it would be a secret room or something.
@@fredrikjohansson oh yeah that’s awesome. I mean who knows if Colin has a bunker and a tunnel it’s fully possible that those rumors were true. I know there was some bunkers being built during the wars in certain areas.
Im in texas so its rare but every now and then we get a tornado and the thought of being able to go undeground literally sounds like a potential blessing lol
I worked at a submarine base in the middle east, during its construction we did lots of tests on steel/concrete combinations to see which would last the longest as we were dealing with saltwater. We found the best method for support beams was concrete filled steel tubes that we left in direct contact with the salt water. We didn't paint the steel just left it as is. The concrete inside the steel reacted with the saltwater on the outside and created a sort of barrier that prevented any rust at all. For the 10 years I worked there we saw little to no surface rust form on the steel and no loss to the structure.
I live on the coastline in Norway and often see something being build in the sea. People building peers, ferry stations, etc. utilize this method aswell. They pile drive large diameter steel pipes in tho the bottom, fill them with concrete and continue building upon them.
I wonder how that works chemically, sounds like magic tbh. Very clever idea if it's that effective!
The concrete inside the pile did not protect the exterior of the pile, there is no mechanism by which it could do so. When you say you did not see surface rust, I assume you are not referring to the sub-surface steel which would presumably be covered in marine growth anyway. Steel directly exposed to seawater with no protection system applied to the sea-facing side will absolutely be actively corroding. It's nevertheless not uncommon to do this anyway, and simply add a greater mass of steel to achieve your desired design life.
@@acinonyx6333 There was no rust at all, the steel sort of blackened over time. We measured the outer diameter twice a year and it never lost any mass in my 10 years there. Also there was no "marine growth".. this was a military installation not SeaWorld.
Sea world... lol.@@adamwilliams5426
Loved the giggity - had to rewind to confirm 😂
Collective knowledge is immense. So impressed
Colin! You could use “Sacrificial Anodes” by attaching zinc anodes to the steel like they use on battle ships. The zinc will corrode instead of the steel.
Wow I made this comment 2 seconds before he said it in the video 😂
I think the issue there is that the anodes need to be on the outside of the steel where he wouldn't be able to change them. They'd potentially buy some time, but once they're gone, corrosion would resume as normal.
Isn’t that what they do with petrol storage tanks at forecourts?
Zinc is more for sea water, it would be magnesium
@@AdamTheJensennot too sure as some anodes can last years just depends on the soil around and what it’s back filled with
It seems like you've summoned the engineering task force on this one. Amazing how many engineers watch your videos
As an engineer who approves water and sewer pipe infrastructure designs for a living, it's pretty cool to see another engineer build things that are far more interesting haha
@@Craigzoidzyours is more interesting to some people. Just like how a lot of kids look at the garbage man being a fun looking job and enjoyable job. But they only think that because their trash doesn't stink so they don't experience the full job 😂
It's like watching people play with the toys we always wanted but couldn't afford. These days only the CIA or support villains want secret tunnels and those contracts are hard to come by or ethically dubious
Armchair engineers….much like all the ex navy seals who comment on don Shipley’s posts, considering only a fraction of applicants make it into the navy seals, there’s seems to be tens of thousands of navy seals on RUclips
@@Steve.._. It's why my Mom used to say, "Hire a teenager now, while they still know it all!"
Hello Colin. I'm an apprentice for construction material inspector.
To cover the steel with plastic is not a good Idea because as you said the steel gets protected by the alkality of the concrete. It shrinks with the time but considering it is underground it should be really really slow. especially when you consider it is surrounded by clay wich has not many big pores through wich new carbon dioxide can come in. The same is the same for water. This kind of Material with lots of Silt and clay in it doesn't transport water really well. It has a pretty high water content, but the water stays in the soil. In adition to that the cracked limestone you have under the bunker is a great drainige system so not alot of water should accumulate. The salt could be a Problem, but there are special concretes you can order wich are resilient to defrosting agents (exposition class XD_) or sea water (exposition class XS_) . In adition to that you can order concrete wich is especially inpermeable (WU concrete) I'd be worried the most about defrosting agents, because they could be commmon anywhere. As I said above the water shouldn't be a problem in my opinion.
the hole saw giggity was the best insight into your feelings about the rust lol
I'm sure this has already been said, but Grady from practical engineering has all of these answers in several videos. It would be fun to see him make an appearance on your channel.
My wife is a structural engineer and she says:
I've actually been thinking about this a lot since you started the tunnel videos, so I'm glad you brought it up. One of the worst things you can do for steel is put it through wet and dry cycles. All wet is better than cycling, so if the conditions around it are more consistent, then that would be better. I don't advise the plastic sheet for the same reason another commenter mentioned, trapping moisture between the sheet and the steel would accelerate rusting. I also agree with him that using the plastic as a vapor barrier to the soil would be a better use. This is actually why some states in the US will not allow epoxy coated rebar to be used in bridge construction. Little pin holes or gaps in the coating will allow moisture in and keep it concentrated in that specific area. This area is more likely to rust through and cause problems where as, if they just left it as metal, it would have developed a more even thin layer of rust without section loss. You could paint the back if you wanted, but seeing how the uncovered steel is doing after all this time, I don't know if I'd bother. Since this is your drive, I would maybe look into alternatives to salt for melting ice in case it seeps into the soil.
Happy digging!
Hi Colin, I am an IStructE. my suggestion is to use waterproof concrete mix, put some reinforcements to minimize crack width of concret, seems like you didnt put any reinforcement in your concrete, and usually only heavy reinforcement will do the trick, but sth better than nothing. and lastly apply waterproofing material on the concrete surface after its dry to avoid the soak away water gets on the concrete.
hope that helps.
Hi Colin, here's a thought you might want to look into. in Canada where cars like to rust because of the snow and putting down salt on the roads to melt it. there are several products that are used to coat the underside of the car to prevent the rust. I don't know much about it, apparently the coating Toyota puts on is good for 10 years. there is also other companies who do an oil spay and some other compounds or something.
Hi Colin, was intrigued to see you talking about rusting steel in concrete and how to prevent it because this is what I do for a job! If you are worried about the condition of the steel there is a method of non destructive testing you can do (known as a half-cell survey) that will tell you what condition the steel is in without having to visually inspect it. If you were looking to protect it there are several methods like you stated, but the one I and my company deal with is a Cathodic Protection system. (This is the method you mentioned) there are two main types of CP systems, Galvanic anode (sacrificial anodes) and Impressed current (the electricity one). both are viable options for protecting the steel. Both methods have their merits and draw backs. the galvanic anodes will run out eventually and will need replacing after time. Where as impressed current can be expensive to install and requires a constant power supply to ensure that it is working. There are many other factors that would affect the effectiveness of a CP system and how easy it would be to install on the tunnels and i'm not going to go into all of them in the comment as that would be too long. Good luck with the rest of the tunnels
I own a electric protection device for trains railways. It’s simply a power supply. But you need an earth too. Very difficult to have an earth grounding to meet your bunker surface. Will have an electric bill not cheap by year.
I'd definitely go with a sacrificial anode. It won't interfere with the construction of the garage/tunnel at all and it should be fairly convenient to do. The entire steel structure is electrically connected so all you'll need is to do attach a cable at one place and link it to a block of zinc at the other end
Depending on the salinity level of the moisture, you might want to use aluminium instead of zinc, but yes.
Maybe a magnesium anode. I think that will work even better.
why not all three
I never understood how that stuff works, seems like magic.
@@nalissolus9213 Magnesium oxidizes easier than steel. So when electrically connected it "sacrifices" the magnesium first. Corrosion is an electrical process, you can also induce a current and stop the electrical potential for corrosion to occur.
love you, Man!
Impressed current is by far the best method to prevent long term corrosion. This is what communications and electrical towers use, where you do not want to loose any metal as it affects the structural strength. In areas where this was not applied there was considerable deterioration of the metal over the years.
It's pretty common to use sacrificial anodes on underground steel tanks and such. They're pretty cheap, like under $50US. Much easier than coating the steel in anything, and can be used on your existing tunnel and bunker as well.
I came here to say this. We use sacrificial anodes on buried steel pipe all over the oil and gas industry
Sacrificial anodes are the easiest thing to test and know whats going on with the steel once it's been in the ground for years. I spent 5 years working on cell towers using these and testing year over year in corrosive soil. They help a bunch feel free to reach out with questions. They are a cheap alternative.
Biggest question I've had over the years, this is awesome
I watched the Video and was reading the comments. I think I have learnt more about steel and concrete than I will ever need to know. Thank you Mr Furze and all the Clever people who commented. I might have to go and geek out on this subject now.