Does Concrete Turn to Dust in a Vacuum Chamber? Concrete Without Oxygen Experiment

okay everyone today we're going to be seeing what happens if you put concrete in a vacuum chamber so the reason that i'm doing this video is because i've had a ton of requests to do it apparently there are several videos circulating online with the question what would happen to earth if oxygen disappeared for five seconds and in all of these videos they always mentioned that if oxygen disappeared from the earth for five seconds all concrete structures would just tumble to the ground because they rely on oxygen to stay rigid so i've had a lot of people asking me saying does that mean that if we put concrete in a vacuum chamber it'll just turn to dust well today we're going to find out so i'm going to put concrete in the vacuum chamber and see what happens to it and then after that test i'll do one more test in the vacuum chamber and see if you actually need air in order for concrete to solidify so what happens if we have wet concrete and try to let it dry in the vacuum chamber will it dry or not okay so i have a concrete brick here so before i put this concrete in let's clarify the difference between concrete and cement so you use cement to make concrete basically you mix cement with sand and that makes concrete so usually when we just speak we interchange concrete and cement but they're actually different things so i'm using concrete which is a mixture of cement and sand or some other aggregate okay now is your time to take your guess what do you think is going to happen is this concrete block just going to tumble into dust or is it just going to stay just like it is or what's going to happen here so i want you to comment in the comment section with what you think is going to happen and how sure you are it's going to happen i know i have my guesses okay solid concrete in a vacuum chamber will it crumble to dust three two one we're decreasing pressure fast we're at a half an atmosphere now a third of an atmosphere how's it looking it doesn't look like much is happening let's get to full vacuum and see what's going on here okay we're almost to a full vacuum now let's give it a few more minutes any cracks forming let's see [Music] okay we're now at a full vacuum as much a vacuum as my vacuum pump can pull now and it looks pretty solid to me definitely did not turn to dust okay let's let the air back in and check it out looks as strong as can be solid concrete still no dust whatsoever in fact it has completely no effect on the concrete okay now let's see what happens trying to dry wet concrete in the vacuum chamber does concrete actually need air to dry okay here's our concrete mixture mix in some water okay so this is a quick set concrete it should be starting to get hard and set in about 40 minutes so one thing that i noticed right away is that this concrete is now warm so neither of the ingredients that i put into it were warm so that means that there's a chemical reaction taking place and that chemical reaction is called hydration okay so i'm going to put one of these in the vacuum chamber and one of them outside the vacuum chamber and we'll leave them there to let them set and afterwards we'll check and compare their properties see if one of them is harder than the other one or one of them stayed completely wet and never dried let's see what happens okay wet concrete in the vacuum chamber three two one okay here we go half an atmosphere so it doesn't look like much is happening to the wet concrete in there don't see any water boiling off of it or anything okay so i've got my two samples now so i'm gonna let this one set and come back and compare to the one in the vacuum chamber so you can see that the cement didn't really do anything in the vacuum chamber so why is it that all of these videos mentioned that if we were to lose oxygen from the atmosphere that all of these concrete structures would just crumble to the ground well those videos are actually a little bit misleading because they're actually mixing together oxygen oxygen gas and oxygen found within other molecules now obviously these two are extremely different and this is where the confusion comes in with concrete structures crumbling if you remove oxygen so the cement that holds concrete together has a lot of different components in it but the main component is called tricalcium silicate it's about 55 of portland cement and this is what a molecule of tricalcium silicate looks like it's made of calcium silicon and oxygen atoms but because this is such a big name to write a lot of concrete engineers actually use an abbreviated form of this they actually write it as c3s so if you're a chemist this is kind of confusing because this looks like some weird molecule of three carbons and a sulfur atom but this is actually just shorthand for this tri-calcium silicate here now this tricalcium silica reacts with water and it's called hydration and the chemical reaction when it reacts with water is this so as soon as you add water to cement it rapidly reacts with the water to release these calcium atoms and these hydroxide ions here so the ph quickly rises to above 12 as soon as you add water to cement and this reaction also produces heat so this calcium silicate and calcium hydroxide both begin to crystallize and harden so as these crystals grow through the cement it actually makes it harder for the water to react with the tri-calcium silicate and so it kind of slows the reaction down so the initial reaction is really fast but then after a while it slows down considerably because this water can't get to it very well so for example you have your initial ball of cement here and the water's around it and the water reacts with it and kind of forms this coating around it of this calcium hydroxide and calcium silicate and it crystallizes around it and so it makes it harder for more water to get into it so that's why cement can take so long to cure because that water has to diffuse all the way through this crystal layer here to get into the cement ball inside of it so you can see that in this reaction here i didn't mention a gaseous oxygen molecule at all so that means that this reaction doesn't depend at all on air just water so technically those videos were correct because if you remove the oxygen atoms from all these molecules of course it wouldn't hold together in fact there'd be a lot of stuff wrong with that if you just suddenly plucked out all of the oxygen atoms but i think where a lot of people got confused is they assumed that they were talking about molecular oxygen atoms like the gas oxygen that we breathe they assumed that that is what that video was talking about but really they were talking about all oxygen atoms even within molecules okay so it's been a few hours now so this is quick setting cement so it should set pretty quickly it's definitely not full strength yet but it should be good enough to compare the two so let's compare our cement drying and air versus in a vacuum chamber let's let the air back in three two one so let's see about how hard they are so let's try to break the one and vacuum a hat in half pretty easy at this point the one in air also pretty easy now it looks like there's not too big of a difference here the color is slightly different this one is a little bit lighter color than the one that was in the vacuum chamber so you can see that being in the vacuum versus being in air didn't really change any properties of the curing of the cement here so it looks like whether we have an already dried slab of concrete or whether or not we try to dry it in a vacuum or air it doesn't really matter it's going to dry either way or set either way whether or not there's oxygen or air around it okay so this is actually good news this means that we can actually use concrete structures in space the only thing of being in a vacuum chamber that could affect the cement is it evaporates more water from it so technically if you have the exact correct amount of water for the cement and you put it in a vacuum chamber and try to let it react in there some of the water is going to evaporate before it has a chance to react so you might end up with a more crumbly cement overall hey everyone thanks for watching another episode of the action lab i hope you liked it if you did consider hitting the subscribe button and hit the bell to be notified of my latest videos out and if you have any comments or questions let me know in the comments section and i'll try to get to them and head over to the actionlab.com to check out the subscription box if you haven't yet and thanks for watching and i'll see you next time

Channel: The Action Lab

Views: 3,826,655

Keywords: vacuum chamber, action lab, vacuum pump, arm in vacuum, no air, concrete, video, science, oxygen, crazy, disaster, qestions, earth, what if, cement, concrete in vacuum, hot knife, glowing knife, self pouring, o2, 5 seconds, science experiments, hydraulic press action, hydraulic press, slow motion, the action lab, vac man, iron man, foil ball, blackest black, how to, black 3.0, cool science, brightest flashlight, 32000 lumen, science tricks

Id: KWRwVXNOEt0

Length: 11min 21sec (681 seconds)

Published: Sat Feb 23 2019