Don't Put Wet Rocks In A Campfire

hey guys backyard scientist here last week when I made the lava volcano in my garage I had molten aluminum spill onto the concrete floor oh and that could be very dangerous because I've always heard that when concrete gets really hot it can explode from the heat and that would be bad because aluminum could get flung everywhere inside the garage this is a phenomenon known as spalling more on that later but it can also happen to rocks around a campfire they can get so hot from the fire they can just explode or at least that's what I've heard so today we're gonna be testing how dangerous are rocks exploding at a campfire and is molten aluminum enough to make concrete explode and fling molten aluminum everywhere so first let's get started mixing up some concrete alright so we've been working on making our own concrete mixes to see if they explode or what so the first one we did was filled with Orbeez we shredded up a bunch of Orbeez like this and mixed him into the concrete and that didn't end up working too well beep well I mean it worked but it to split the concrete I guess because the Orbeez started expanding and broke apart the concrete but they are in there and we fix it up a little bit so hopefully we can still try this one we also made two more special mixes of concrete one filled with rebar which is really just chopped up wire and another one filled with a ton of tiny little stainless steel DVDs for sandblasting so the theory here is that steel expands when it gets heated so the steel will expand inside of the concrete when it gets hot putting a lot of stress on the inside of the concrete causing it to explode so while these are drying let's test out Roxanne account fire I heard that they can explode like a grenade but is that really the case let's put it to the test I learned in Boy Scouts don't make campfire rings out of the wrong type of rocks because you can just be sitting there enjoying a fire and then ulsan it sounds like freakin Vietnam going off with the book ok it's not that dramatic but sometimes the rocks do crack and explode so we got a bunch of different kinds of rocks here that we're gonna try out we've got like crayon it Jade some slates we have 2 different types of river rocks this thing this this is some little cement brick wall I made and we're just gonna light it on fire and see which kinda rocks explode the best after about 8 minutes of the rocks cooking in the fire we got our first crack rock I mean rock rock crack but that was only one rock and there's still a lot of rocks on that fire so we kept that fire going for fifteen more minutes because let me tell you there's nothing like sitting around a hot smoky campfire in the middle of they in Florida well we had a couple big pops with the dry rocks but nothing that I would be too worried about next we're gonna be trying the same rocks but this time I've been soaking them in water so here's my theory when water heats up it creates steam which will put a lot of pressure on the inside of the rock possibly causing the rock to explode so our wet rocks more dangerous than dry rocks let's find out so now I'm curious if any of you guys have ever experienced any exploding rocks and a campfire if you or your friend ever had any rocks explode in the campfire put this story down below in the comments you know was it loud did it scare you did it pulling off and hit you in the face we like to know put it down below anyway after only a couple minutes the wet rocks really started popping on [Applause] I'd say that the wet rocks were way more active than the dry rocks there was little explosions one after another throwing little bits of rock up to 20 feet away all in all though I'd still say that you're safe around your local campfire because we tried all different kind of rocks wet and dry and we could still never get a big explosion I mean theoretically I'm sure it can happen but I think the real danger is from little bits of embers being kicked out by the explosions and starting another fire somewhere else so now that that's settled let's move on to the concrete and see what happens there well first up is a concrete filled with all the steel bb's let's see how it performs well it looked like nothing was happening so we waited 2 minutes till it looked like the aluminum was cooled and then we went over to check it out ohmygosh right when I said that right when I said that it happened next up is the rebar cement and this stuff was super active after about 40 seconds that really started popping off Oh got one Wow look at it go little ones well once the aluminum cooled I thought nothing else was gonna happen so I turned off the camera and then this happens of course as soon as I turn off the main camera but hey we still got it in high speed so that's pretty cool dang look at all the bumps and bubbles yeah yeah and so look at that the whole top part just popped right off and I wonder it was because the little bits of rebar in the concrete this whole thing just went right up into the air and it's still high so why does concrete explode and I was wrong it's not because of the rebar one reason the concrete can explode in a fire is because of the heat of the fire turns the water inside of the concrete into steam putting a bunch of pressure on the inside of it blowing it apart this is the same reason why some rocks explode an acount fire porous rocks such as sandstone can hold and trap water and this would make them explode in a fire granite on the other hand is impermeable to water so there's really no risk of it exploding thermal stress is another reason the concrete explodes in fire the heat causes the outer layers to expand placing a bunch of stress on the concrete causing it to explode and it turns out that concrete and rebar have about the same expansion ratio from the heat and the rebar actually ends up protecting the fire by carrying the heat away and evenly distribute again so it seems like if we want to make our own exploding concrete we're going to need a lot of water and low permeability and I think I've perfected the mixture just right Wow so now that we've learned why concrete spawns and what circumstances and materials caused it to fall I've went ahead and reverse engineered that list into this this is my own DIY super spalling concrete mix number one it's a very strong high-performance cement number two I've added diatomaceous earth into it to really clog up the pores and really build up the pressure on the inside of the concrete in number three I've been soapy and water to really increase the moisture content of this so what this is it's a block of concrete with a void in the center it's basically eased one of these little 1 quart buckets on the inside of it like that so we're gonna pour molten aluminum inside of it this time instead of just on top of it so it'll be in contact with the molten aluminum a lot longer and hopefully it'll heat it up enough that the whole thing will break apart well it doesn't look like things are off to the best start I spilled half the aluminum at first and then all the smoke is from the bucket that's on the inside I thought it would catch on fire but it ended up just obscuring the view of everything still I don't think all hope is lost just yet yeah you can tell that I'm a little bit excited about how well this worked I didn't have high hopes for it and ironically this was way better of a volcano that I made in last week's video and it was totally an accident well that works pretty well you can see the aluminum all over the grass here it probably shot up about 15 20 feet straight up in the air and also you can see that I spilled almost all of the aluminum barely even anything in there so we're gonna try this again and I'm not gonna spill the aluminum this time notice how I prepare for this by taking the propane tank away but I'm still a little bit unsure how well this will work because the hole is still a little bit plugged up with molten aluminum and there's still a bunch of molten plastic in there that needs to be burned away nevertheless I'm always an optimist so let's see if this works out [Music] yes that is exactly what I was hoping for the first time you can see that the entire block split in half and the molten aluminum shot straight up like some kind of shaped charge Wow now that was more like if that thing look come over here and see this it totally crapped the concrete in half right here boom it can't it cracked that in half spilled out the side here still super hot over there to look at the crack over here yeah so that thing exploded and there's stuff all in the grass over here check this out little bits in the grass like that and it went far to let me show you how far away so well number one my poor orchids it landed on the roots of the orchid over here oh man poor thing but it went all the way in the leaves it's like sprinkles it sprinkles but still that's 25 feet away so yeah it's still hot it's wrinkled still hot luckily arraigned because nothing's on fire right now otherwise everything would be on fire right now cuz it really scattered the aluminum you know 20 feet in all direction and this is the perfect reason why you don't pour aluminum in a wet mold because it will crack and explode and sputter all over the place just like that I want to do an autopsy on this and see what's on the inside well I think that settles that are definitely pouring molten aluminum into something that has water and it will cause an explosion especially with our super spalling cement anyway we have one more test and that's to pour molten aluminum on the driveway to see what would happen because that's what would actually happen in real life if I spilled it we just need a good control in this experiment so let's try this so this is what would actually happen if I spilled molten aluminum on my driveway while I was working on something and to cover all my bases I made sure some of the cement was wet and some of it was dry but nothing really happened and I think that's because the aluminum really spreads out and cools quickly totally solidified so there we go one giant piece of aluminum that I spilled on my driveway and no explosions well we tried everything we could do to try to get the concrete to explode we filled this up with a bunch of aluminum he did it up pour it down the driveway and there was no explosion but either way I hope you guys learned something about rocks and concrete heats falling and you know until next time see you later also a special thank you to my brother Riley and my girlfriend Sandra for helping me film and make these videos they helped me all the time and I really don't thank them enough so thank you you guys can help me too just by liking the video commenting on the video sharing it with your friends anything helps and thank you guys you're the best see you next time

Channel: TheBackyardScientist

Views: 3,213,946

Rating: 4.9229593 out of 5

Keywords: the backyard scientist, backyard scientist, thebackyardscientist, Spalling, rocks in fire, concrete in fire, rocks explode, concrete explode, cement in fire, cement break heat, concrete break heat, concrete spall, concrete spalling, cement spall, cement spalling, rocks spalling, rock spall fire, rocks break fire, aluminum on concrete, aluminum, concrete, rocks, cement, fire, spall, spalling, aluminum vs concrete, aluminum vs cement, aluminium, aluminum in wet mold, wet mold, science

Id: -v-II1FPFSU

Length: 10min 21sec (621 seconds)

Published: Sun Feb 02 2020