Pouring a DRY vs WET Concrete Slab /// Cutting Them Open AFTER 90 days!! ///Home RENO Ep. 6

[@stevew.4935]

Over 30 years ago, my wife and I bought a new house and fenced the back yard with 4x4 treated fence posts and Cedar slats. I started out setting the posts with wet pour using bagged cement like you did. I got tired of mixing the cement about 1/2 way through the project and started just dumping the same amount of dry cement into the hole around the post. I tamped it enough to hold the post in place then ran a random amount of water into the dry mix. About 25 years later some of the fence posts started rotting out. I dug the dirt away from the concrete holding the posts in the ground and started chipping at the concrete with a heavy demolition bar. The dry pour cement broke after 2 or 3 hits with the pointed end of the bar. The wet pour cement wouldn't break. I had to dig them out. Dry pour made the replacement of the 4x4 posts a lot easier. So I guess the moral of the story... Pick your job carefully for Dry or Wet pours.

[@itsgabegutierrez]

I use fast setting Quikrete poured dry and adding water to the hole. Works perfectly. Hey, if you got 25 years I'd say it held up pretty darn well!

[@ron.v]

Great example. I just said basically the same thing using my mailbox post as an example. Dry pour was the way to go in your case.

[@descendingsouls]

instead of posts, you can either use a 6" or a 4" PVC pipe, and fill out with concrete inside, will last way longer, no need to paint, only thing is, to connect anything, will need a concrete bit and anchor bolts.

[@ATruckCampbell]

@@descendingsouls The PVC might be weakened or destroyed by the sun.

[@badstate]

I think the PVC is mostly just acting as a form for the concrete.@@ATruckCampbell

[@peterryan7340]

I have never done a dry pour. After watching this, I still won't. Thanks for this great video ❤🇦🇺

[@emilflognoid1532]

That's what I was thinking

[@diytwoincollege7079]

I did one for my shed. Came out great. It’s been over a year and no problem. I also added cement to the top inch or so of the dry pour so the top would be smoother.

[@paulliebenberg3410]

Dittto...!

[@PatrickKniesler]

same. definitive.

[@johndorian4078]

im sure some scientist though could make a dry pour mix, I dont think there would need to be as many rocks in a dry pour. Still not enough evidence really need to know how different ones work. i hear some just don't work.........

[@surfcitiz]

I love it when people are passionate about their work and have a healthy dose of curiosity in life.

[@peterhalick6226]

Great example of how KZbin makes the world better. All the experience in half the time. We’ll done!

[@Icedel777]

I'm a service plumber of 25 years. I must say you did a good job of being descriptive in this video, and you are very informative.

[@ellea3344]

Of why you should NEVER dry pour. That pad is a code violation and would need to be included in the price of the house to cover the cost of repair, or be fixed before the sale of the home.

[@Jake-by9ly]

Thanks for sharing your experience

[@Jake-by9ly]

​@@ellea3344codes to depend on each missability or state

[@kristjanvonerland6566]

It's refreshing to watch a professional who can explain everything so simply and accessibly. I hope you continue to create more videos and wish you success in your profession.

[@johndouglas1848]

This video was very interesting, thank you. Also please everyone, wear a mask if you are dry cutting concrete. In recent years concrete dust has been linked to respiratory problems like Silicosis. Great to see this comparison, many thanks.

[@MelodicTurtleMetal]

And the fibreglass rods. That stuff doesn't do wonders in your lungs

[@tea.dubs8532]

I couldn't believe it when he cut into the test slabs and it was a thick cloud of silicosis straight into his face. Man he really needs to take irreversible lung damage more seriously.

[@wallytangofoxtrot4721]

And when pouring the mix. Who knows what is added in the blending process.

[@karabinas]

I don’t wear masks. -Donald Trump

[@artnovak3259]

@@karabinas- any reasonable, self thinking American. Oh wait……. Thats just for the flu. Leave it to a libtard to make this political

[@TheSpartanBuilder]

This confirmed every suspicion of dry pour. There was a surprise though in how well it camouflages itself to look like a monolithic slab. Thanks for sharing. Cool channel

[@Openreality]

If it's mixed properly it works just as well as the wet method. Treat it like any concrete pad. Mix the water properly with the dry mix and you will be fine. This i know, is true because i did use the "dry" method, however i mixed the water properly with the poor and it was fine.

[@zackfelker]

@@Openrealityif you mix it that’s a wet pour

[@lauraiss1027]

@@Openreality What is the point of using dry pour concrete if you mix it with water?

[@Shifty-hb4fv]

​@@lauraiss1027 Only time I've ever seen anyone use it was for fence posts, dry bag goes in around the post, air gets tamped/poked out, water goes in

[@mrsatire9475]

@@Openreality lol

[@TommyVercetti-z2u]

Concrete finisher here. A few years ago when all these videos of dry pours were going around, it drove me absolutely nuts. I had a breaking point when my parents wanted to pour a patio and told me they were thinking about dry pouring it. I lost it lol

[@mikeyyoyo6464]

Welcome to crazy world mate 🤷🏻‍♂️

[@JackJones-ch4qn]

I am a concrete man myself. Rock on brother

[@AaaAaa-ye5ho]

So did you do the concrete work for your parents?

[@TommyVercetti-z2u]

@@AaaAaa-ye5ho The patio, no, they didn't either. About a year later they had bought a new home and I did the machine shed floor, machine shed driveway, removed the old driveway going to the garage and poured a new one as well as a sidewalk that went around three sides of their home. Dry pouring-bag or mixing any of that crap is just silly. If you need a quarter of a yard of concrete go for it. Most plants have a minimum yardage for them to deliver (here it is 2 yard minimum) so if it's below that sure maybe think about getting bags.. but it's silly and you can always just call the plant and say "Hey I only need a yard of concrete, if you have any trucks headed back with extra could I get it?" And 90% of the time they will say yep and you'll even get it for cheap, I've done that atleast 10 times. Also, I'll keep this short. A yard of concrete at a plant is like 160 bucks.. it is something like 50 80lb bags to make a yard- thats not including adding gravel. $3-7 depending a bag, with tax call it $200 for 1 yard worth of bag, and you have to haul it all, use your water to mix it. So add in the gas you used to travel to get it, the water you have to use to mix it and the time it takes. That all together is more than $200 total. It just isn't worth it. Although I will add, buying bags and mixing it is better than dry pouring. Both are absolutely silly though.

[@Alpejohn]

I have never heard of this so it was the first time i saw it. And it sounded like a really really bad idea from the start. Ended up just as i expected. Been working with concrete for 18 years.

[@Endorfen2011]

Great video! After 30 years in the trades doing concrete, etc. It's nice to see a real Pro using sound to assess the quality. So many scrubs out there giving clueless advice. Do it correctly the first time or do it twice. Measure twice, cut once.

[@qt3dot14ish]

Measure twice, correctly, cut once, correctly.

[@abetts123]

Measure, cut, swear, drive to the store, buy more, get home, realize bought wrong, drive to the store, buy more, get home, measure twenty times, cut again.

[@DIYTrepanning]

The knucklehead didn't even use a mask when cutting the samples. Maybe he wants silicosis?

[@treehuggerdeluxe5598]

As soon as you hit the dry pour with the hammer I knew it was bad. As a restoration mason, I get paid to hang off tall buildings to fix stonework, and also flatwork like parking garages. An engineer can see a hole and say "fix that"... but the way we masons know what to fix is pinging with a hammer. Bad concrete doesn't make the hammer ring like good solid concrete. Also, the chipping during your cut was a sign that the slab was compromised. Water infiltration will turn a bad slab into a pockmarked field with the freeze/thaw process. Great video, man, really enjoyed it.

[@mauisuzuki7857]

So you know, buildings that have withstood the test of time over 1000 years old are buildings being built with dry pour….still up and standing today

[@Crackocaine]

Fuck all of that. You couldn't pay me enough

[@Yielar1]

​@mauisuzuki7857 and it's weak and crumbly vs what it could have been. Listen to the expert above buds

[@mandowarrior123]

​@@Yielar1 he does have a point. When proper concrete goes it all goes, dry just erodes and is a step up from sand. Maybe that's helpful for 1,000 years?

[@JamesP4620]

@@mauisuzuki7857 LOL, you have zero idea what you are talking about and it is really funny.

[@nerapsnart]

I have a walkway to do. I'm older and broke. You just convinced me that dry pour will work well for my project. I wouldn't do a dry pour for a large heavy project but my walkway is already cement and very, very old and cracked in some parts. I will be adding more water though. I didn't think enough water was done on the dry pour and after reading the comments, it confirmed my thoughts. Thanks for your time and effort in producing this video. I have watched many of them and yours was pretty informative.

[@AStanton1966]

I don't know if it's too late, but they do make a concrete refinisher. It might be a cheaper and easier way to go.

[@lorihamlin3604]

I did a dry pour 5 x 5 slab 2 years ago because as as a 70 year old lady I couldn’t handle the wet pour method. It’s been fine..I don’t drive anything heavier than a golf cart on it. I intend to do a larger patio area this spring using same method. Best and cheapest way for me to go. No complaints at all. If you have a mixer and preferably some more muscle wet pour might be better but not an option.

[@tj48649]

Plus, you're not doing anything 'structural'.

[@jasonenna3544]

70?! respect!

[@lorihamlin3604]

@@jasonenna3544 Well it’s spring and I haven’t started the patio yet. My mother was still gardening and running a vegetable stand at 95 so 70s would be young to her..she passed away at 97. Wish me luck with patio! Unless you were being sarcastic…

[@jasonenna3544]

@@lorihamlin3604 I was not being sarcastic! im 50 and arthritis is killing me.its awesome you took that on at your age and I love ladies doing such things at any age. I think it is wonderful, take care and good luck

[@barbaluti]

I'm 37, you have my everlasting respect without any sarcasm. Girl power at any age !

[@bonniemechefske3838]

Mr. Komar, this was by far the most instructional dry vs wet pour. I have watched so many but the hammer test made it perfecty clear. The sound difference made me nervous! Wow! If this doesnt convince anyone i don't know what will. With all the babysitting of the dry pour, to me, it seems easier to do a wet pour anyway. One and done.thank you!

[@TheMatthooks]

Wet pour, you control the moisture content and can give the cement exactly the right amount of water to make sure it hardens fully without leaving too much water, which causes pores in the concrete which weaken it.

[@davidvanni]

In 30 years of residential construction, I've poured slabs, set posts, and many other concrete projects. Many times, I have been tempted to do a dry pour just because it was quicker and easier. In the end, I could never do it. It never made sense and just didn't seem right. Thanks for the video, I'm happy to know my instincts were right.

[@LogicalNiko]

From what I've seen with multiple experiments is that wet pour concrete almost always exceeds 4000 psi (usually 4000-4200 psi depending on curing temperatures and water, etc.). Dry pour tends to have a higher variation and be about 60-85% strength, about 2600 to 3500 psi. I believe with dry pouring there is more trapped air in the pad and less interlocking at the microscopic level. Hydrated Cement (calcium-silica-hydrate) creates long chains of silica tetrahedra (4 armed molecules that form very craggily chains) surrounded by and holding onto pockets/layers of calcium oxide (quicklime). In normal concrete the length of these chains is limited mostly by time and adjacency of open ends as initial curing kicks off. I think by dry pouring concrete the silica tetrahedra chains are probably significantly shorter and tighter...there is less tangling around the calcium oxide. This probably makes it generally crumblier. Now 2000-3000 psi is fine for non-structural use, and I think it greatly depends on how well its watered (sealers/coating tend to be good to help with surfaces). I've seen people be very successful laying the dry powder in 1" layers and misting as they go, and then after 18-24 hours start soaking the slab as much as possible. But it can definitely take 6-9 months to reach its optimal strength. I don't know if curing additives and superplacticizers change this impact, or how things change with using high-strength concrete mix.

[@katarh]

I figured there was something chemically different happening. I'm not a materials scientist, but to borrow a metaphor from cooking, it's probably not unlike the gluten in bread flour. If you just pour the water directly on top of the dry mixture of a bread flour without actually kneading it and expect it to make bread, you're in for a bad time.

[@LogicalNiko]

@@katarh Your analogy is dead on. Long carbohydrate chains in gluten is extremely similar to what is probably going on here.

[@davedave672]

This is the best dry vs wet pour comparison I've seen. I wont be dry pouring!

[@mhughes1160]

This is pretty much what I suspected after watching these dry pour videos for the past couple of years The dry pour will be much easier to remove . LoL 😂 Perhaps the manufacturer put directions on the package for a reason

[@virgilwalker683]

pay attention, two different kinds of application, one if dry motar and the other is pre mixed Rock Concrete. How is this even remotely the best Vs?????? You can't compare moter to rock concrete. That's how I can tell you know nothing what your talking about. smfh. if you was a home owner, you would robbed. smfh

[@OG1GTP]

​@@virgilwalker683 he used the same concrete mix for both you idiot. Same bags.

[@TheRawdawg]

The sound test says it all.

[@virgilwalker683]

to someone who is experience.@@TheRawdawg

[@BelleChasseHome]

Ive done dry pours for multiple projects and it depends on what you are trying to achieve. I used some old bricks and dry poured about 1 inch over them and the rest was similar to grout. The bricks used to be covered with years of growth as a pathway. I reused them and did the dry pour, except I wanted to SHOW THE aggegate/rocks to go with the rock landscape around. It works perfectly, and was easy for me. 3 years later still looks the same. I made planter box PADS the same. Im not a PRO cement person like many of you...but it does work and it does hold. Just used the board to even, them mist, wait wait about 20 min them spray, at that time you can smooth and put the boarder around it like regular mix. I spray about 3 times. Like cement it cures best when wet. Im older and not one to MIX BAGS when I can just pour where I want them. But for REAL CEMENT WORK like my new driveway...MIX BABY MIX...lol Blessing to each.

[@johnrussell6620]

I have done a lot of bag concrete work lately and after contacting the bag concrete company technical support (both Sakrete and Quikrete), both said to follow the bag instructions. Both said to limit the water to the amount stated on the bag, more water will result in weaker concrete due to trapped molecular water causing voids in the cement matrix when it does finally leave the slab during curing. I mixed 50lb bags to 1/2 gallon of water exactly, and 2/3 gallon for 80lb bags. the consistency was like barely wet dirt and gravel. Your wet mix was extra soupy. When I mixed extra soupy I was using about 50% more water than recommended, and then I added more dry concrete to get to the recommended consistency. This stuff was so dry I was confused how it could possibly be correct. I shoveled it into my forms and it just piled up and up, then I vibrated the mix in place and it collapsed into the forms and water started coming out the top and sides of the forms. It really was the right amount of water. ... I think your wet pour was too wet, but it was better than the dry pour that was too dry. Your sample pad was very much too dry and did not cure, there was not enough water to activate all of the cement reaction. You should mist more water for more times. Your eight, 50lb bags, needed 4-5 gallons of water. Do you think you misted 4-5 gal of water? Your wet mix probably had 8-10 gallons of total water and some of that went into the ground faster than it evaporated up and out of the top. It at least had a chance to activate and cure even if it does have more microscopic holes in the matrix where the extra water was trapped until it finally molecularly worked its way out 90 days later, the dry mix test slab never actually cured. You might be able to finish curing the dry test slab by continually keeping it wet and maybe you could submerge your sample slab in a bucket of water for a few days to see if it will fully cure 90 additional days later Thanks for your presentation, and get and use a mask around dry dusty cement. Silicosis is in your future otherwise. Be safe!

[@amb7440]

@johnrussell6620 Great response. Saying all the things I was thinking to say as well, and then some! Nicely done.

[@tracy419]

Great comment that makes perfect sense. I've only ever done a single concrete pour in my life for a pad like this and my experience was similar to yours with being just barely wet. I was sure I was doing it wrong because it didn't pour, or look at like so many videos I've seen. So far so good.

[@Pamela.B]

I LOVE reading the comments. Herculaneum came to mind as I thought of him breathing in that concrete dust. Working concrete is a science & an art. Go men! Thank you!

[@papabuggaming1654]

Thank you Mr. Nye

[@tomred868]

Air is actually an additive that can be beneficial in some situations. You truly cannot have too much water. The curing process is an exothermic reaction and often the water needed for a complete cure will evaporate. Some people cover and steam their pores to ensure saturation.

[@WestVirginiasBigred271]

My cousin made himself a walk way and he just dumped dry concrete in the form and in about two years he was walking on gravel with gravel growing up through it. As a concrete finisher. Not only do I care about the look of the finished product but the strength of it. I have poured sidewalks , driveways, and basements or garage floors that 20 years later still have not cracked and looks great today. I also did HVAC work for many years and my boss would pour a pad and he would just screed it level and let it sit up. I started finishing the pads and using an edger and he really liked the way I was doing it the results of finished concrete looks so much better than someone just half way doing the job.

[@thealteredstate4203]

idk how the idea of a dry pour even comes into someones head. do they not know how concrete works? absolutely moronic.

[@davidanderson9845]

And I think finished concrete lasts longer

[@johnclements6614]

@@davidanderson9845 Troweling will remove some of the air from the concrete and concrete is stronger than air. That is why the dry pour is weaker, the cement can not form a paste with the water and push out the air when its worked.

[@dalegreer3095]

I like your willingness to experiment. My daughter’s a lung doctor, “Do you work where there’s any kind of dust produced by power saws or grinders?” is one of her standard questions she asks her patients. It’s a long list.

[@paparoysworkshop]

I've seen a video a while back that had me thinking that I might try a dry pour on some concrete work I need to do this summer. After watching this video, I've just changed my mind. Wet pour only! Thank you for this video.

[@ron.v]

Almost all my uses for concrete are dry pour. One wet pour example was when I poured a pad for a very heavy garden statue. Wet was the way to go for stability and strength. My best dry pour example was for my mailbox post. I dry poured around the post to set it and make it stable. As expected, sun got to the wooden post and cracked it. Also, the wood twisted and bent over time. After 10 years, it was time to replace it. The dry pour concrete around the base kept the post quite stable all those years but was also quite easy to break apart with a mattock and shovel. It made the thing very easy to remove so I could set a new metal post in the ground. Had it been an unnecessary wet pour, the base of the old post would have created a great deal of extra work trying to remove it. Dry pour serves me well in such conditions.

[@thaboss32]

had you used a metal post, your mailbox wouldnt need to be replaced every decade. that also doesnt include other factors like if something was to hit your mailbox, the dry pour wouldnt hold up, and youd have to start over again. same with fencing, sure the wood looks great, but if you use a metal post as a base and build off of that, you wont ever really have to worry about replacing the whole fence, just the wood. also with a wet pour, since it doesnt fall apart so easily, you can simply dig around the footing a bit, rock the post loose, and pull the entire post/footing in one go, not that youd really need to since it would last much longer than a wood post/dry pour combo.

[@ron.v]

@@thaboss32 That's a valid point. I didn't have metal and, at the time, the wood was plentiful and cheap. All I lost was a little labor for the next 10 years of use. I then replaced it with a metal post. The dry fill I had used around the wood was an advantage since it was much easier to remove yet it had served the purpose for a decade. You're right, of course, metal would have lasted longer in which case, a wet pour would have been the proper base. There was a wet pour base used for our metal fence. I've seen such fencing last a lifetime, thus proving your point.

[@veno8mm]

So you just explained that if you want a semi permanent solution that is easier to remove. Go with dry pour. Gotcha.... I'll continue to chop mud and pour per usual.

[@ron.v]

@@veno8mm You're right. Your usual method is always best in most cases. My case was unusual but best for me.

[@sethcarter8371]

Wild that you made two entire slabs without knowing if one would work AND THEN did an experiment to see if it would hold up. Mad man.

[@jkiker7918]

He's not landing a 747 on the pad... just an AC.

[@sethcarter8371]

@@jkiker7918 You right. Those are cheap, easy to replace, and nobody will be upset if it fails shorty after installation. What was I thinking.👍🏻 Id personally not want to redo a project I just did. I want my stuff to last so long that whoever has to come demo what I'm building cusses me every day for the amount of help they have to hire to tare it down, but everybody got their own ways. To each their own.

[@jaredreid2661]

@@sethcarter8371 yeah but you're also not making bank off of a youtube video. Thats why we watch them and they do this stuff so we won't have to turn around and pour another. in 2 years time you'll see the " what happened to my dry pour pad" 10 minute long video that recaps this one.

[@B30pt87]

Wow, saved by the video. I was almost talked into doing a dry pour for my new steps. I'm glad I found this on You Tube before I took his word!

[@shinobuoshino5066]

How do you almost get talked into doing something this retarded? Lmao humanity is doomed, if you didn't know that it's objectively better to mix everything first before using it.

[@UnknownUser-xs7dg]

if you already know how cement/concrete works on a chemical level, you already know the answer to this question. basically, what makes concrete strong are the CSH gel produced when cement reacts with water. So with a dry pour, you're only basically relying on the moisture of the air to react with the cement so only the surface actually becomes "concrete" and the inside is just a mixture of sand and cement.

[@KimoKimochii]

if you have common sense you already know the answer lol

[@moki7685]

Great and informative video. I was a contractor for a long time and never thought of a dry poured slab. There are many people out here that don’t know anything and are here to learn. Some of them will hang on to your every word and actions. Reconsider showing people how to use that grinder without a handle, with an oversized blade and guard less. I have seen some bad things happen with that setup. I also wish someone told me to wear a mask when I was younger,I just didn’t know. Keep up the good work

[@summerforever6736]

Very good points

[@mrsatire9475]

Masks are for Libs

[@moonblink]

yes, his thumb was 2cm from the blade!! 13:21

[@TonyVRailfanning]

I did a dry pour sidewalk repair in front of my house two years ago in central Alberta it was 5‘ x 3‘ and so far it has not cracked or moved at all, and it has gone through two winters

[@sgsax]

I've always had my suspicions that dry pour was not the way to go and this video confirms them. Wet pour all day long. Thanks for sharing!

[@jerrybennett6034]

Case closed!!!

[@patty109109]

Yeah it’s one of these silly ideas propagated on KZbin. Ever bag of concrete ever says to mix water-except post holes where strength doesn’t matter much.

[@black_dragon-carpentry]

Doing dry cement is recommended for fence posts or other in ground none load bearing applications. It works well enough for that . Don't know why people try to do it for other things.

[@lucaschapman1966]

What a load of nonsense

[@black_dragon-carpentry]

@@lucaschapman1966 to what?

[@benlake710]

Thank you for putting together such a careful video. You really show the difference in the results from the 2 methods. I have worked in construction for many years, and this shows what you get from a proper mix versus an expedient alternate. The wet pour benefits from all of the cement becoming fully hydrated and the fluid paste creating a complete bond with the sand and aggregate. Hydration is critical for concrete strength. The mix needs enough water to saturate all the material, but it should not have too much water, creating a soupy mix. When shortcuts are taken, a crew might make a wetter mix because it is easier to place, but it will not have the same strength as a correct mix, and you'll probably see the surface scale off later due to the excess water. The concrete should be vibrated to consolidate it and help release any air bubbles. This further consolidates the mix and ensures a good bond between all the components of the concrete. Moderation in all things, vibrating concrete is good but too much may cause the larger aggregate to settle out - so just use a modest amount. After placement, proper curing is critical. Once the concrete has set, then keeping it damp will promote the strongest cure (Ideally concrete will continue curing for 28 days). So even though you don't want to use too much water when you place the concrete, keeping it wet, using a sealer, or covering it in plastic after it has set, will produce the best concrete. Plenty of sidewalk slabs get poured and left to dry out in the sun. Obviously this works, but giving the new work a sealer, or light spray with the hose or a plastic tarp, even if you only do it for a day or two is still better than nothing. Your excellent video demonstrated this very clearly, thanks again for such a well done test. Sorry for the long reply, I hope it helps inform viewers. I try to take great care in my concrete work.

[@jacksmith2315]

Yup. Exactly. When my buddy did is concrete floor in his garage, he let it set w plastic over it for a week or so, then every day for the 30-60 days (or however long required) we went out and gave it a light spray once or twice a day, and put the plastic back over it. When it was done, it was smooth as glass/ice. Never seen concrete so smooth before.

[@qt3dot14ish]

As the Gastroenterologist would say, $hit in, $hit out! You just proved their point! In the kitchen, there is a reason we sift the flour prior to mixing the batter. There are probably hundreds of other examples, but shorting the concrete process is not going to end well for the end user. One of the keys is that the cement should be added to the water and then mixed to the proper consistency, not the other way around. Just like when making batter, if you add the liquid ingredients to the dry ingredients. it just immediately curdles and no amount of mixing can make a fluid mixture all the way thru. You will have lumpy bread. That situation is exponentiated with the concrete. "Shake well before using"! Thanx for the video and the ultimate truth.

[@DonziGT230]

Thank you for doing this. All the other dry pour videos I've seen made it seem like it's just as good, none of them cut the slab or tried breaking it to show how much of a difference there is.

[@BGdev305]

Your the first to HONESTLY compare these two methods! Those other channels of people trying to sell dry pour need to see this!

[@MrInnovativeEnergy]

Always been Leary About dry pours after decades of concrete work, now I can see why. Great demonstration!

[@cassie.m.0723]

You're the only person I've ever seen on the internet that knows the word LEARY and also doesn't replace it with WEARY (instead of wary)

[@michaelbradley7529]

If you are going to use rebar or equivalent in a pour, it really needs to be suspended as close to the middle as possible in the pour depth (as opposed to laying on the gravel at the bottom of the pour) for it to have the effect you're looking for.

[@Bob94390]

Rebars are there to take up stretching forces. When the load is in the center of the slab, the stretching will be at the bottom of the slab, so having rebars below the center makes sense. Steel rebar will rust and break up the concrete if they are not covered with some centimeters of concrete. So if the slab is thin, as in this case, it makes sense to have rebars in the center if they are made from steel. For rebars of non-rusting material, this is not an issue.

[@dzoltan82]

I was looking for this comment not to be the first one. I noticed this too. Leaving the bars at the bottom is sloppy work

[@piopacheco2998]

I did both dry and wet, its a huge difference in time and labor, my personal advice is, if there won't be heavy and frecuent traffic, (like pathways, in house sidewalks, even a patio)do the dry, its time and effort saver, but if you're doing a driveway, or some kind of parking space go with the wet concrete.

[@Retiredkiwi]

As a now retired heatpump installer and serviceman(in trade 45+ years), i feel i should mention, how many systems i have seen, that had rusted out bases of the outdoor units. Almost all of them were directly fixed to a flat base - usually a concrete pad. We always installed on top of 4x4 treated timber or hard wood blocks(fixed to base). The reason being, when fixed direct, leaves and debris build up under unit, and stays damp most of the year, whereas raising unit above pad on wood blocks, gives a lot more clearance for rubbish to dry out, and makes keeping underneath clean easy. I do not see any drains fitted either, do your systems not come with a drain fitting, and rubber bungs for the drain holes in it? Direct fixed and draining water onto concrete pad, is imo and personal experience, likely to cause unit to rust out its base within 5-10 years.

[@711yada]

Thank you. Great comment.

[@mattmarzula]

Yeah. This dude is sloppy. I have no idea why someone would claim to be a pro and do such amateur work.

[@FishFind3000]

I’ve got 2 ac units both on concrete and they have no rust issues. Both pads are elevated the thickness of the pad off the ground. I also keep them clean and clear so it could be the environment and the user that makes a difference.

[@Hip_Hop_An_Onymous]

​@FishFind3000 I found @retiredkiwi's post extremely accurate and helpful. He was sharing experience from a lifetime of working. Logically, what he said makes sense. Could it be the user? Perhaps...less logical to think metal is rusting more from a user error than from conditions and matter exist simultaneously in the same place. It is logical to see how buildup of organic matter directly against metal could cause serious oxidation issues. Although nothing is always, as there are exceptions to most things.so it is possible that the directed attack at valuable information with a slight like somehow the OP is using the ac in a manner that could cause the exterior metal components to prematurely oxidize.

[@Jade7073]

I agree to this the alkaline and calcium inside the cement "Portland" it will react with other metals and allow for rust to build up. Usually this is where the painted surface though is damaged, which can easily occur. So yes proper drainage and or a plastic drain pan, or even PT wood, something in-between the unit and the concrete will help provide more protection to slow down any possible rusting to occur.

[@joeldarr8118]

Mr. Komar - thanks for the objective comparison. A few tips to improve your future concrete projects: 1) place bars or wire mesh on chairs instead of the ground. 2) measure the volume of water you add to the mix (you'll never achieve the 4000psi design strength if your water/cement ratio is too large). 3) After screeding/finishing, cure the concrete by keeping it moist (either with burlap, misters, or a chemical curing compound.

[@paulwatts1704]

Great adds - esp measuring the water volume. I only just figured out the importance of that to getting the target PSI after speaking to a firm who make cement (on a long truck) to order on site.

[@rameshpersaud7131]

Hats off to you for your teachings the proof is the wet poured concrete, for temporary jobs still wet poured,dry poured too much of water times with insecurity TK U again for your kindness

[@devanirnf]

I have never ever heard about dry pour concrete (probably because I work with computers). I don't even realize why this video popped up. But I'm glad IT DID! Highly informative! Genuinely nice tests! It would be nice to make a beam and test how many kilograms both sustain.

[@steve-dq7hh]

Love your honesty......haha

[@Stickerz94]

A common trend online is to pour the concrete mix straight out of the bag into whatever mould you're using and then just use a hose to apply the water to get it to cure / harden. Lazy people just looking for a short cut to actually mixing the concrete before pouring and doing it the right way.

[@jakefriesenjake]

​@@Stickerz94not because they are lazy... Cheap! Imagine a job where you would definitely have to hire it out... You're paying mimimum double for the labour alone. There are limitations for the dry pour method. Yes, wet pour is definitely better, especially if building a high rise building, a foundation and an industrial driveway. Typically those jobs are so big, calling in a concrete truck is already a must. For building a pad like he just did, perfectly fine. And if you are really worried about the strength, because it is the part is heavier than normal, use more rebar and add an inch or 2 to the thickness of your slab. I'd also suggest that the top layer of the slab (1" or so), be without gravel, and a stronger psi mix. Easier to screed out

[@ManKidRides]

Love the kind thought of using safety glasses to protect your hat, not enough people consider the safety hazards that their hats face. Bravo!

[@professorg8383]

My only comment on safety, is to wear a mask wnt cutting!!! If you get that dust in your lungs, it's not going anywhere! Your body can not absorb it. There will be silica in the dust and that can cause silicosis. Wear a mask! It's safer!

[@pebkac1245]

just like how we did it at the precast...whats life without black snot and getting something in your eye every day?

[@dorse72]

thanks construction Karen! and gloves and steel toed boots and plenty of water 😆

[@percyfaith11]

@@dorse72 You're welcome phony macho man! That dry cough is sounding pretty bad.

[@nastydave6334]

​@@dorse72 making fun of somebody for protecting themselves from workplace injury, hilarious.

[@peaceprayer595]

This is a KZbin life lesson for me. Watched a lot of vids that said dry poor was fine. I'll never EVER do that. Wet all the way. Thank you!

[@arcee33]

This has been one of the best wet pour dry pour comparison that I have seen with concrete. Great job showing this to us.

[@thebenjilos]

I mean if dry pouring was so good every concrete worker would be doing that instead of wet pouring concrete on these small jobs.

[@Alladin-n5j]

​@@thebenjilosI strongly recommend not to dry pour, the finished product will be much weaker than normal water mixed with sand aggregate and cement. Dry poured slabs tend to crack on the edges, especially if not enough water was sprayed on them, you f you are silly enough to do then do in winter when there is lots of rain and expose to the rain for at least 4 weeks, this will make stronger, however there are no real advantages of a dry pour and leveling and finish is very lousy compared to a normal wet pour

[@jaygremillion]

Thank you for this video. I've seen so many "dry pours" used for things like a patio or even the base for a deck or something and always felt like it was a disaster waiting to happen and this confirms it. I think you are spot on. Anything like a patio or something you need a base for...wet pour has to be the way to go. Now, if I'm just needing some smaller slabs to use as a walking path or another use that isn't structural...dry pour may not be a bad direction.

[@vlratcliffe1]

It's got to be 20yrs since I done my post for my decking an pond now hot tub sauna room and I used the dry mix .added water next day built up the floor laid the decking its a fair size 10x12 ft wooden hut now all I did was fill the pond took the banister down and build the wooden hut . The floor post have never moved iv had a 9x9 ft hot tub on the deck still going strong even added new steps . So dry for me way easier spent too many yrs in construction..

[@JackmanWorks]

I like how the dry pour seemed like more work than the wet pour, so there's really no benefit anyway haha

[@anthonypaul210]

Dry pour worked great. On day 2 we soaked it and kept the framing on for about a week until we needed it out. We soaked it every day with the shower mode. It has not cracked or chipped and it’s been 1 year with cars driving on it.

[@KimoKimochii]

lies

[@thomasbolton8373]

not really a dry pour if you soaked it hey,,,

[@mandowarrior123]

​@@thomasbolton8373yes it is

[@thatoneguy94512]

​@thomasbolton8373 you pour it dry first. That's the first step, it's dry, buts it's not a dry pour? Make it make sense

[@parkershaw8529]

​@@thomasbolton8373it's a dry pour as long as it's dry when poured into the form. It doesn't matter how much water you add later. The value for dry pour is saving the effort of mixing.

[@jasonstarr6419]

I'm expanding my front porch. When this house was built, the builder decided a front porch running across the enter 69' front of the home was sufficient being just 3'6" deep. So, wifey, the "construction expert" has been telling me I should "just do one of those dry pour slabs". Since I'm also expanding the roof to cover the 4' expansion of the porch slab, there will be a fair amount of weight resting on six columns. Just like I would never use bell wire to try to power an electric oven, I will never use a dry pour slab for any serious slab project. Yes, mixing two or three bags at a time in the portable mixer is a lot of work, but so is replacing a failed roof due to a failed slab.

[@benjaminreinhardt259]

I've used a harbor freight mixer (the larger one) for a few slabs around the house. I find two 60 lb bags at a time is good - not too much for the mixer or me wheel barrowing it. I have the wife help me on the bigger pours (20+ bags), she fills a bucket with the water for two bags (measured out beforehand and marked on the bucket) while I spread the last batch of concrete. 5x10 is about as big as I care to do in one pour. Can do a larger pad in cooler weather - don't want the beginning of the slab setting up before you pour the last of it.

[@usapatriot1234]

I have a "construction expert" also. Actually an "everything expert" I have no idea how I get anywhere I need to go when she is not with me or get any project completed when she is not around.

[@jasonstarr6419]

@@benjaminreinhardt259 Yeh, that's probably my limit - two bags at a time, although I was using the 80 lb ones. Hurt for a week... we have two more sections to do - about five yards.. this time, we're having the ready mix company bring it over.. and after checking the calculations on price... i'll be saving about $3-400 bux by using them as opposed to getting bagged crete from our local supplier... we're about 30 miles out of the big city, so prices here are a bit higher than at the "in town" big box stores.

[@jasonstarr6419]

@@usapatriot1234 I love the comedian who says that about his wife when she's with him when he is driving... "funny, but I have NEVER asked "why did i park there?"".....

[@edwardkay7299]

I'm not a sailor/boater at all, but love seeing the progress in this massive project! Thanks for sharing, you guys inspire me to take on bigger challenges around my land-based house! 😅

[@budlee5274]

First class video & audio and excellent slab prep! The sales rep for the ready-mix company who supplied our jobs for forty years always said: “We offer two guarantees, our concrete will get hard and it will crack!” He was grinning, but he was dead serious too. I do have a few suggestions and verrry strong recommendations. PLEASE always use a good dust mask when cutting/sawing concrete and masonry materials: silicosis is no joking matter! A mask when pouring the dry mix out of the bag is also a really good idea. Safety glasses, gloves, and hearing protection are also excellent items to preserve your health for the decades to come in your life. NeVeR use a grinder without a proper guard. The damned things are useful as can be, but would just as soon cut off your nose, toes and all points in between, and faster than it cut those blocks of concrete. Tapping all along the sides of the forms will eliminate most of the air bubbles, commonly called bug holes. Your comments about the relative roughness of the top surface of the dry-pour are right on. This roughness is very likely to get worse over a series of freeze-thaw cycles in the winters to come. Adding water to the top makes that surface weaker, less resistant to freezing, which will result in more flaking and pitting. Concrete is weird stuff; it has to all get wet to start the chemical reactions that bind it all together. Too much water will make it a lot weaker. Not enough water or incomplete mixing will yield what you’ve shown in the dry mix sample. Then to make it all more difficult, the longer the water stays in the concrete the stronger it will be. So on sunny or windy days you have to take extra steps to protect it. Never let it freeze, that’ll ruin it completely, worse than the dry pour. Dry-pour is a really bad idea for a host of reasons, some of which you describe so well in these videos. Thank you for all of it, especially the break tests. P.S. 30 days is plenty of time for concrete to cure unless the temps are below 50 all the time. It should reach about 75% of its design strength in less than ten days.

[@YouCanDoIt2]

Fabulous demo!! I always assumed that the dry pour was an inferior way to pour concrete slabs...nice to see a video that proves it! Great job 👍

[@demon_stalker6247]

Concrete expand a little when it get wet. So when you do a dry pour the concrete in the middle will expand into the hardened surface layer forming small cracks , that's why it crumbles like biscuits.

[@lodrbyroni]

Ive never even dreamed of doing a pad with dry pour... but did use it when doing fencing... drop it in dry spray some water and fill it in... I also live on Florida so the ground is fairly wet only 2 feet down so it gets a ton of moisture under ground while curing plus isn't ever visible so looks never mattered.

[@Oldcrow77]

Curing isn’t drying Curing is a chemical reaction of the lime in the portland That is why they can pour concrete footing under water. And it’s wet mixed not dry. Expect to replace your crumbling Fence footing within 10 years So your building it twice Not to mention the demolition and haul off of material. So it’s not a better or easier method Me: 64 year old retired pool builder

[@FSEAirboss]

Interesting for sure. I think the dry pour is more like aircrete in that all the air voids that would be closed by wet-mixing, and overall bonding would be of course less. Thanks for taking the time to do this experiment and sharing.

[@eturnltube]

Wow. I wonder what the percentage of GCs, or HVAC contractors would spend that much time & effort with site prep - clearing, scraping, digging, tamping, graveling, tamping, forming, staking, leveling. Just to pour a pad for an AC condensing unit/heat pump. I bet it's minimal. I appreciate your quality of work, sir.

[@percyfaith11]

Invest in a dust mask. Your lungs will thank you in 25 years.

[@operator8014]

That's a pretty long-term investment. I'll check with my portfolio manager, but I just don't think the smart money is in respirators.

[@tommartinez62]

@@operator8014

[@percyfaith11]

@@operator8014 If you invest your money like you take care of your health you don't need a portfolio manager, you need a bookie.

[@percyfaith11]

@@operator8014 If you take care of your finances like you take care of your health, you don't need a portfolio manager, you need a bookie. 25 years seems like a long time but it goes by in a flash. Lung disease is cumulative and progressive. You'll have debilitating effects for a long time before it ultimately kills you.

[@SVW1976]

You'd have a case indoors. Outdoor would be pointless.

[@gladdenhandymanllc962]

I have guys here who swear by dry pouring. It never set well (pun intended) with me, but I couldn't put my finger on why. Thank you so much for doing this experiment. This is fantastic information.

[@whitexeno]

It doesn't make much sense to me, its nearly as much work as a wet pour I guess people want to feel special and brag about doing it differently 🤣

[@anderssrensen7533]

@@whitexeno TBH i would say a dry pour is even more work, you have to water it xx times with xx minutes between, but on wet pour you mix it, make it smooth and then wait for it.

[@scottbitz5222]

​@@anderssrensen7533except you don't need to carry heavy wet cement, mix it, shovel it in, and clean all your tools before it hardens and you're only watering every so often

[@anderssrensen7533]

@@scottbitz5222 well the strengt of dry pour really scare me, it looks really really weak compared. if you carry 20 kg dry or 20 wet cement its the same weight :p and he said wet and dry took same amount cement, also the dry pour need a heavy babysitting cause of watering xx minute xx times

[@jacksmith2315]

But the wet pour your not just carrying the weight of the concrete, you're also carrying the weight of the water. Still, not an excuse not to wet pour. I think there is a way dry pouring can be done better, but its much more work. Set some dry, wet it, compress it, set more dry, wet it, compress it, continue til full. The reason the dry pour isnt as solid is because its not compressed/theres too much air in it. You can hear that when he hammers the two. With wet pouring, its compressing as your mixing, and as your pouring because its heavier.

[@richardfritz2436]

Thank you so much. I had thought about dry pour as it would require less effort, but the proof was evident. I had seen others swear by the dry pour and I don't want to risk it.

[@norm5785]

Thank you for sharing this with us. Everyone stay safe, warm, happy and healthy. From Henrico County Virginia

[@JustinMurray170fin]

I'm presuming this guy is a professional but for anyone who isn't used to using an angle-grinder, keep the guard on and keep your body to one side of it! Interesting video👍

[@aculpoca]

For sure, face shield, as well, if available.

[@JustinMurray170fin]

@@aculpoca Indeed.👍. Ear defenders & a mask too. Chased many a wall & cut many kerbs/lintels, the dusk is no joke.

[@ck17350]

Yeah, I reflexively winced when he started cutting without that guard. Good video though!

[@johnclements6614]

@@JustinMurray170fin Yes Silicosis is no joke.

[@junkname9983]

Pro or not, this guy has no regard for his own safety. Use your own judgement and don't follow him just because you see him on youtube.

[@stevens7409]

No dry pour. Thank you for this video! I appreciate the extra effort of cutting through and the hammer test.

[@t0kinl3lunts]

I think the two biggest issues with dry pours are 1) you end up making a concrete foam with microscopic voids everywhere and 2) there isn't enough moisture content to bond the aggregate. The first issue results in the surface being much softer and weaker (larger chips and duller sound in the hammer test). The second issue causes large sections to chunk off of the edges and corners, which is made worse by the first issue. I really want to see a 5 year follow-up from somewhere that has frequent rain and hard cold snaps all winter. I think that would be one of the hardest environments for dry pours to deal with.

[@KomarProject]

I saved a few samples and think I’ll do a one year follow up

[@dead_redux]

the biggest problem is there's no mixing with dry pour, simple as that

[@t0kinl3lunts]

@@dead_redux Ok, why does mixing help?

[@dead_redux]

​@@t0kinl3lunts Portland cement consists of five major compounds of calcium silicates and aluminates ranging from 5 to 50% in weight, which all undergo hydration to contribute to final material's strength. Thus, the hydration of cement involves many reactions, often occurring at the same time. As the reactions proceed, the products of the cement hydration process gradually bond together the individual sand and gravel particles and other components of the concrete to form a solid mass.

[@chrissekely]

​@dynamicdreamsgaming8409 So, would thoroughly mixing the dry component first help to at least form a better case hardening of the final, fully cured result? I do understand that the primary motivation for doing a dry poor is the convenience and all this theoretical effort would undermine that advantage.

[@fhobbs7956]

In a past life I used to work in the oil patch. For walkways in muddy sites they used to dump dry mix on the ground and lay ply wood on top, no water added. When it came time to move you needed heavy machinery to break up the "sidewalk".

[@alexfullmer4707]

Sorry, but I got stopped at the "past life". How far back was that???

[@fhobbs7956]

​@@alexfullmer470720 years ago.

[@shinobuoshino5066]

Something being cheap and fast for low tier jobs in shit conditions where road quality doesn't matter doesn't really change the fact that noone should do this for their walkway.

[@valeriegaines1319]

Liked the examples in the video. Safety note: wear a mask when pouring dry concrete. The dust can damage to the lungs and cause silicosis.

[@ekids.bassment]

I did also test both ways, and I'll never touch dry pouring again. I knew it was gonna be bad, but I had to see it. Good video

[@rupe53]

I do feel that part of the problem with a dry pour is the sand and Portland cement separate. IOW, the finer the particles rise to the top and never fully blend into the mix like they do when you stir it up with water.

[@Oldcrow77]

Spot on Most people don’t understand the curing process is not just dry, but the forming of crystal structures If your ingredients aren’t mixed they won’t bond correctly I ask the people that advocate fry pour. Do you just pour cake ingredients in a pan and bake. But thinking and mixing seem to be above their abilities

[@gapch1964]

Thank you, thank you so much 😊. We were going to use a dry pour, but you truly taught us a hard lessons before we got started pouring. Going be placing a heavy structure on top of the concrete. Wet pour is the way to go. ❤

[@MG-kw1kb]

I've been in a few arguements with folks on KZbin who insist there's no difference between wet- & dry-pour results... Thank You for this video! i'll be sending this link to every future KZbin "Expert" who needs to be taught a valuable lesson.

[@ParkerSayler]

If he had done the dry pour correctly... You cant wait overnight to saturate it like he did after misting it. No, a dry pour isn't "better", but is sufficient in some applications. This video is misleading as he misted it, then let it sit overnight before saturating it. This will lead to a brittle surface and edges and unbalanced curing.

[@jakepadgett5569]

Did dry pour for fence posts when I was a kid ( 15 years old)and had to rebuild my girlfriend’s mom fence. Had to replace every post after 6-8 months. Did it the right way the next time and it’s still standing 20 years later.

[@leelunk8235]

BS BRO I DRY POURED MANY POST 2.5 FEET DEEP AND THEY ARE AS FIRM AS MY PEE HOE ON TRIMIX

[@nicocesar]

I never thought I would watch a 20 min video about this, awesome job putting all information together. Thanks!

[@JustMe-te8cz]

Place a piece of open cell foam over the dry pour. Keep it wet for 3 weeks. Initially, the water will travel through the dry concrete and fully hydrate it. Keeping it wet for three weeks will eliminate cracks and give it the best compressive strength. Not enough or too much water is resolved, as the concrete will only take what it needs. If you have ever poured concrete underwater, you will understand.

[@alexfullmer4707]

So now after three weeks we can start walking on our side walk. Great, I was hoping for a month delay. 😊

[@ShadowManceri]

That dry slap reminds me of packed dirt more than concrete. Could be that it requires much more water over long periods and curing time is a lot longer.

[@steffen707-]

@17:35 you discovered the best sculpting mix of all time. 🎉😂🎉

[@SylwerDragon]

I think you are correct.. they looks like fully cured but they are not...also dry pour has lower strength compared to regular wet one and i think even with time and years it would not improve much. So once it isn't done properly at the beginning you can't fix it later on :)

[@JohnDoe-gg6kc]

If dry pour made sense industry would use it everywhere

[@TimeSurfer206]

Rather like the concept of, "If masks don't work, why do Doctors ever buy them?"

[@KeterMalkuth]

@@TimeSurfer206 While I don't disagree, that's irrelevant to the current video and you know it's going to start a big argument in any comment section filled with typically right wing laborers and DIYers. That'd be one thing if you thought anything constructive could come from it, but people don't get into fights on YT for the sake of open minded, complex discussions. All that said, it's pretty rude to the Komar Project channel to be trying to start a fight in his comment section.

[@scottbitz5222]

No, they wouldn't because a wet pour is set and forget and no sane contractor would insure a project that relies on the owner to water the slab at specific intervals.

[@johndorian4078]

The problem though is it depends where you 're at. The Wet mixing doesn't matter where you live dry area, wet area..........the results are more consistant. Dry pour though would depend on where you're at. I'm not an expert,nor do i play one on tv, but in my area when pouring concrete for fence posts you can just pour it dry and it will become rock hard. But in dry areas like arizona there's just not enough moisture in the air so it wont really work there

[@Bob94390]

@@scottbitz5222 A wet pour should be kept damp for many days, preferably weeks.

[@Fldavestone]

I do not understand why anyone would even take a chance on a dry pour.

[@COALROCK8642]

Dry is lower weight for logistics and save by using clients water and electricity.

[@sethdavid2117]

Fence posts, that’s about it

[@lesshaventures8894]

On windy days you can cover a very large area

[@danielboyer7545]

Called a "dry" pour but still use water. I would call it a moron pour.

[@evilbliss1895]

@@danielboyer7545😂

[@elephantwalkersmith1533]

I noticed that your test pours had plywood floor. Part of the tech here relies on wicking water through the ground. I’m an engineer and noticed this difference in the test.

[@SeanBlader]

Needs a re-test with proper water amounts and better ground surface.

[@BoycottHollywood]

Good observation. However, the top where he hit it with the hammer was weak. The soil wicking is for the bottom half. The top half is supposed to get gravity soaked by the hose. I doubt the wicking will wick all the way through to the top.

[@highlandermachineworks5795]

Engineer. What kind of engineer? Software? Mechanical? Fluids? Civil?

[@Rambleon444]

Train : D@@highlandermachineworks5795

[@kikixchannel]

​@@SeanBlader The dry pour is just sand that 'melts' in water surrounded by said water. The wet pour is the same sand, but mixed so that the sand actually sticks to sand directly. It's obvious that the dry pour has less strength. The grains of cement aren't actually stuck to each other fully. The dull sound comes from the fact of there being plenty of empty space with miniature amounts of air in-between the individual grains simply because they were never compressed with each other with any force other than their own weight. No amount of retesting will change physics. More contact of sticky substances = more adhesive power and more mixing = more contact. It's as simple as that.

[@jeffsim8664]

Nice job on letting cure for 90 days.. your the first to wait that long that i have seen. Now need to find your compressive strenght vid

[@shinobuoshino5066]

90 days is nothing, concrete takes years to age properly. And while correctly mixed concrete will continue standing, the "dry pour" will have been replaced 5 times.

[@CGT80]

@@shinobuoshino5066 Yes, but no one really cares about what it will eventually reach for typical residential and commercial jobs because we will use it soon. It reaches a large amount of it's strength in the first month so we are interested in knowing when it is safe to build on it or use it and then the time frame to test the core samples. We do set fence posts on government jobs with the quick setting concrete but we do alternate between adding dry mix and water and mix with a shove enough to get the water all the way through. Then again, we would stretch barbed wire the same afternoon or the next day, or set gates on the posts the next day. Yes, I will stick to wet mix for anything other than fence post holes. The dry mix seems more like sandstone because the components are not blended to make a uniform cream. The granules stick together and bind the rock, but the "glue" is not formed.

[@shinobuoshino5066]

@@CGT80 back in my day, posts were premade in factories instead of being mixed on the spot...

[@CGT80]

@@shinobuoshino5066 Are you talking about posts made of concrete? .......... We use galvanized steel posts and set them in concrete.

[@PRC533]

We don't need to wait for a compressive strength test because it's obvious the dry pour has next to no strength just from his hitting it with a hammer.

[@ilikesundays4312]

Who'd have thought that you need to mix it first. What a revelation...

[@jenkor513]

The dry pour videos I first saw made it abundantly clear that this was a quick fix for foot traffic only. They would never use it on a driveway. They used it onder a chicken shed and as a small slab out the back door. Context of purpose is everything here. Imagine if you are older or disabled and just want to get rid of that muddy path from garage to house. Mixing and pouring wet cement may be too much for them. Also the original was done in an area where the ground is usually damp. I would not try this in the desert. But like he states, it is working fine for his air conditioner.

[@chesslover8829]

I'm using the dry pour method to create a 2.5-inch surface on top of a six-mill plastic vapor barrier for the crawl space under my house. For that application, I'm not having any issues. Note that I'm not beating the dry pour with a hammer.

[@katarh]

Yeah, dry pour seems like a good quick and dirty method for a non structural type of thing that only has to last a few decades at most. Other examples in the comments have been for fence posts or mailboxes; pathways and anything that won't need a bolt through it are probably all fine too. But for anything that you want to last 50 years, that has to support the weight of a building, or that has to have stuff anchored to it, the wet pour is probably the better option.

[@chesslover8829]

@katarh I agree with you, but let's take your observation one step further regarding an important project: I would never use the wet-pour method relying on concrete from a bag; I would always use the services of a concrete contractor who pours concrete from a truck and uses concrete from a commercial plant.

[@ellea3344]

The lesson is NEVER dry pour. This is NOT a thing describe on the back of a portland cement bag for a reason. It's foolish. It will fail. It is a material defect on any home inspection report.

[@ellea3344]

In fact, this could prevent the sale of a home if noted on an inspection report until it was fixed or the repair costs were deducted from the price of the home. It is called a "material defect." HVAC units require a perfeftly level, and structurally sound pad to rest on. Placing an HVAC unit on that pad is a code violation.

[@meatpopsicle42]

I'd like to see what the difference is between wet and dry when anchors are installed, like Tapcon screws or sleeve anchors.

[@KomarProject]

I’m going to add that to the next strength video. Good idea

[@TheDreamIrene]

Thank you so much for making this video. I have a concrete project I’m planning and I was going back and forth about using dry pour or wet. I’ll definitely be using wet pour since it is a high-traffic area. Thanks again - great content!

[@QuentinStephens]

I'm not sure why KZbin's algorithm suggested this video because I'm not a builder but I enjoyed it, particularly your narration. There's one small problem with your test pieces: you had wood underneath. This will have prevented (or reduced the capability of) the dry pour piece from pulling moisture in from underneath.

[@jacksmith2315]

The both test pieces had the same frame, if that was the case, the wet pour would have failed too. Not only that, but the larger pads are poured on top of gravel, the gravel is the shed/drain water, therefore the concrete wouldnt be wicking/pulling in moisture regardless.

[@QuentinStephens]

@@jacksmith2315 The difference in the test pieces is that the wet pour did not need to draw in moisture whereas the dry pour did. You're right about the main pieces, of course.

[@webeducation]

This is exactly right. Thats why its recommended to hose down the sub surface before doing your dry pour.

[@jacksmith2315]

@@QuentinStephens i dont think that would have mattered. It wouldnt wick enough to make a different. The dry pour doesnt get mixed/packed enough, which is why it sounds so hollow. Dry pouring is jsut not a good idea. Why keep babysitting it and spraying it every couple hours when you can just mix it once and be done w it? Its kinda kind bondo. If you spread the bondo then just put the hardener, its not going to harden evenly, and is going to have too much air in it because it wasnt mixed. Dry pouring is just not a good idea no matter how you do it. If its not structural/holding a lot of weight and you dont care if it last long, sure. But why not just do it right and not worry about it?

[@robertbarnes432]

Did you track the amount of water you used on the dry pour, do you think that the lack of strength has anything to do with not enough of a key ingredient, water, that is needed for the chemical reaction in the curing process?

[@al9709]

Good point

[@FactsOverFeelings23]

Tbh it actually seemed too wet compared to the other, it was darker and sounded duller which just seems like a wetness issue to me. I also wonder if you agitate it better with a vibrating rod if it would help.

[@danielpullum1907]

I've seen the dry process and have still not tried it. Ur presentation has renewed my interest. I've got two slabs 10X18 and a 10X15. I would use ready mix but can't get a truck in that area. Renting power buggies, etc. just drives up the cost. I've always used a hoe to mix concrete and pull it all to one end and then back three to four times. Much easier than jamming a shovel into that dry mass. I also measure the water within a pint or two to achieve max psi strength in the concrete. Other wise it always goes too wet thus lowering the concrete strength. Ah, after the cure test Youve convinced me. One of my slabs will be enclosed on all sides, the other slab will be exposed on three edges. THANKS>

[@hassansahouani3684]

Brother, you are a true scientist. best demo I have seen. Thank you.

[@CosmoWenman]

My grandfather was a steel reinforced wet pour slab man in WWII in the Pacific, and every time he and his platoon went up against the Japanese dry pour slabs the Japanese would completely crumble -- they were barely even cured and just burst into dust and aggregate the moment they saw action. After the war Grandpaps eventually became an accomplished typewriter salesman even though he couldn't type worth a damn -- concrete fingers LOL -- but always took great pride in his wet pour heritage. A few years after he retired the neighbor's bamboo spread into his yard, sent roots under him and eventually grew up through him and tore him apart. What a way to go. RIP Slabs. Miss you.

[@erichester9076]

Great information from your video, I have done 6 dry pours so far on walkways with no issues other than an edge sometimes needing repaired but your video definitely shows wet pour concrete is definitely stronger and will probably last a lot longer. My dry pour jobs have been small jobs nothing bearing a lot of weight.

[@itmike23662]

Could it be you didn't use enough water in the dry pour? The color difference and the chalky, clay like, attribute makes me curious.

[@allenhall7675]

That's what I suspect as well. I have seen other videos where a dry pour slab did not chip at the edge and took expanding sleeve anchors and even Tapcon screws just as one would expect w/o chipping out or cracking.

[@towdoctor670]

Cutting without a mask gave me an upper respiratory infection just watching you.

[@anotherfreakingaccount]

Useful experiment! Superficially, the wet pour had a prettier finish on the top as well. I heard something interesting a while back, that one theory behind ancient roman concrete is that it would have been poorly mixed compared to modern concrete, which left pockets of dry material inside the wet material. Then when the concrete eventually cracked, water would seep in and saturate the pockets of dry material, which would create a sort of self-repairing crack. If youre pouring something that doesnt need to carry any structural weight but needs to last a long time and span a long distance like a walkway, it's possible this ability to repair cracks is more beneficial than the extra strength of well mixed, or wet mixed, concrete Carbon steel and concrete have extremely similar thermal expansion rates. Fiberglass has a thermal expansion rate that is greater than concrete, and expands more in the direction of the fiber grain than in the other direction. I'm not sure what the specific heat tolerances of this are, but it seems that fiberglass rebar in concrete will fail due to expansion from heat faster than steel rebar in concrete would. Probably doesnt mater for a small pad which is in direct contact with the ground, which acts as a pretty decent thermal sink

[@SuperHaptics]

Cured yes mixed no. So as the cement powder settled where it wanted it could have not encased every grain of sand and stone equaly. Its not homogenous like a liquid mix that is agitated so it cannot glue all the aggregate in a uniform way. Some spots will be strong and others weak

[@uoislame]

I think this is the real answer. If you did this with just cement without any aggregate, I'd wager there isn't a huge difference.

[@crafterlula1328]

Cement mason here, thank you for making this video (you did a great job fyi, no notes). The reason the dry pour acts that way is due to overhydration. It's fully cured and nothing can fix it. Im not 100% sure on the science of how over-hydration weakens concrete, but the results are obvious. It leads to flakey and brittle concrete that doesn't adhere to the aggregate. That's the reason chunks were flying off, the cement and course aggregate didn't bond properly. I'd bet money the middle of the drypour is significantly stronger than the top or sides, but is still weaker than any portion of the wet-pour concrete. The top of a dry pour will be the weakest, hence why your hammer did so much damage. I suspect the middle would take a few hits with a little more grace Also, you were very correct about rebar. Any structural concrete needs rebar or other kinds of reinforcement, even if its touching the ground. Physics are weird, but basically when weight applied to the top of the concrete, there's a small tensile force being applied underneath the slab. If there's no rebar, that small tensile force is enough to make a small crack. Over time, it'll widen enough to be seen by the naked eye. For those unaware, tensile force is basically bending. Rebar-reinforced concrete is a sum of its parts, having nearly the tensile strength of steel alongside the compressive strength of concrete. It also slows the time to failure (ie the time it takes a comprised structure to fall). I am a massive nerd for this shit xD

[@ellea3344]

Excess water isn't the issue. It's the opposite, a lack of homogenious mixing with water, and aglomoration of cement particles which creates natural weak points within the concrete.

[@phildoucette7603]

The thermal expansion (change in size with temperature) is the same for steel and concrete. So when they expand on a hot day, they expand together and don't create a stress between them. The steel takes the pull force and the concrete takes the push force. Together, they are an amazing material.

[@Eric-yt7fp]

I'm going to be pouring a small landing for my deck stairs later this summer and was considering doing a dry pour because some people just won't shut up about it. But after this, I'm gonna go ahead and do it the right way. Thanks for the video, really good stuff!

[@t0kinl3lunts]

Man, I could smell the dust through the screen when you were cutting.

[@stevemoore5053]

Me too.

[@ryangross5446]

i used to do masonry work and my boss said before that the wetter the concrete is, the stronger it cures. so the inverse of that says that a dry pour, and giving the concrete the minimum amount of water will give you the weakest concrete possible. looks like thats what you got basically

[@montebarger866]

It's not the wetter the stronger, adding too much water will dilute the concrete and weaken it. However the longer you keep it wet while curing will make for a stronger end product.

[@ryangross5446]

@@montebarger866 Yes youre correct i believe he was referring to once it has began to set up

[@EnWorks]

Technically, the dryer the concrete mix the higher the compressive strength. But the key issue here is the microscopic pores: wet mixes will tend to reduce pore size and encourage interparticular bonding. Your dry mix would have been improved if you’d compacted it first with a tamper.

[@ryangross5446]

@@EnWorks cool nice to know! I always love having more facts about concrete under my belt

[@drrydog]

i just finished a driveway solo, last year in 104 degrees. it was the hardest 11 days of my life lol. wheel barrel, all of it, and hand mixed in a mixer that holds about 2 80lbs bags at a time. did 8'x16' slabs, 1 each day. then cut each pad in half with a saw

[@CharlesGilley-q4g]

13:25 - please put a mask on ;)

[@alphamech79]

Bro loves breathing silica lol

[@te01guy]

Who was worried about his new windows in the background when he started chipping?

[@rchavez5056]

Not me.

[@HB-600]

Not me.

[@DeadHermit]

I dry poured around my drain boxes and added a water channel for the runoff from a porch. There haven’t been any problems or cracks yet, but I also don’t have weight on them.

[@mattcy6591]

His lungs probably have a better concrete slab than the dry pour.

[@andresflores6948]

Yes. Concrete it's a very dangerous thing for the lungs.

[@jdjd0711]

Hey I wonder if the test is the problem. The test was in a sealed bottom, but the ac pad was open to the earth moisture to wick up into it. How about doing an open bottom test on the ground for dry concrete. I'm not a big dry fan but iv done dry post settings and later pulled them out and they were set and cured like regular cement

[@lennym1636]

And that effects the top of the slab how?