The TRUTH About Dry Pour vs Wet Pour Concrete!! Strength Test - You WON'T Believe the results!!
Dry Pour Concrete has been the craze lately on social media and testing has not been done to show its true strength compared to standard wet pour concrete. In this video we dive into everything you need to know about dry poured concrete and whether or not its stronger then traditional wet poured concrete.
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Geotechnical engineer here, my last job was in airport pavements. We test both new and existing pavements when performing construction and evaluations. There are some less industrialized countries that will dry pour patches, I’ve cored and performed split tensile tests on tens of thousands of samples, the dry pours were always laughably poor quality.
brilliant comment thanks
Is it possible that the issue is that dry pours require watering throughout the curing process, and that the curing process is extended to a much longer period of time? Just thinking out loud
I can’t wait until this silly dry pour fad passes. Imagine with all the structural and chemical engineers for hundreds of years busting their pencil points and and asses trying to develop the best methods to make concrete, that weekend warriors armed with a trunk full of Sakrete finally cracked the code. It must be a conspiracy by the shovel and hoe industry lying to the public all these years.😊
I think someone should experiment with the time and the misting process for it to cure properly. There is got to be a sweet spot where it can give better results. And when we reach that optimal result , we can decide if it worth it for certain applications
Glad I saw this, my forms are in place for a pad for a shed. I was going to dry pour, don't think so now.
I am a concrete engineer. No matter what, dry cure concrete will always be considerably weaker for many reasons; however, you can increase the strength by keeping the slab flooded with water and covered for at least a week. It would be better to flood and cover for thirty days. No matter what you do, it will not ever reach even half the strength of wet pour concrete!
I agree , The water in the mix is needed to start the hydration process, as long as moisture is present in the mix it will gain strength ( slowly) , If you only sprayed the dry mix sparingly the hydration process probably stopped as the slab dried out, The Myth that concrete dries is just that, a myth, Concrete hardens because of a chemical process known as hydration . Hydration is a reaction between the water and any ad mixtures added to the mix and the chemicals makeup of the cement powder. Typically more water is added to the mix than is needed for hydration but the excess is needed for workability ( handling/placing and finishing) Its also a good idea to tap on the forms or vibrate the mix to remove excess air voids . Next time do your dry slab by misting the surface and after it reaches an initial set ( maybe 24 hrs) move it into a tub of water or other location where moisture is sufficient to saturate the slab so it can have enough water to hydrate the cement in the mix, . Also after each time you mist it cover it with plastic to trap the moisture in the mix so it doesn't dry out. . Happy Easter :-) Ps cure your slabs 28 days for optimum curing time.
@@btpearce WOW! You must write for Bob Villa!
@@Carl_Jr No, But I take that as a complement. I worked for the Materials and Testing Division of NC DOT for 35 years, I use to teach the Concrete Certifications Classes . I had to know a lot of in-depth concrete information to be able to do my job.
Add three bags of calcium only on hot days
That's the problem with engineers. What you don't understand is that the point of dry pour is not strength. The point is the youtube algorithm.
This is why the teaching of basic science is still so critical.
1 outta 6 American's believe the Earth may be flat. Sleep well.
This comment is true.
Science is exactly the answer.
I loved this video as a learning tool, and I agree that basing knowledge on science is critical, but he would have learned more, more quickly, and more reliably by researching the subject on line than testing it himself.
I'm a civil engineer. We learned 40 years ago that dry pour concrete will always be very weak compared to a cured wet pour concrete mix. The difference can be 10 times stronger for wet pour, and the dry pour will have many pockets of weakness, the wet pour will be uniformly strong. Not a surprising outcome.
Yep. But I feel like we learned this 2,040 years ago. Then again, I don't know exactly what you meant by we. We humans We the people We civil engineers (not me) We jolly good few We dastardly do-gooders (this is me!) We-irdos (also me)
Love the spelling
Isn't civil engineering for all of the engineering student who couldn't do math?
@@yadda333 aren't comments like this from people who have an educational deficit?
Hmmm, I graduated from college 40 years ago. For some reason, I think those lowly civil engineers (I was in the mechanical eng program) knew the correct way to mix concrete then.
In the 80's we would use drypour for building decks and fences, it saved time. Then in 86 I got a job in the local cement plant and at one point worked in the lab. Cement is made by cooking limestone/marble, iron, shale together into clinker. Clinker is then cooled somewhat and ground down into a powder finer than face powder, at that point it is called cement. When you mix cement with sand and aggregates(rocks) it is concrete mix, add water and it becomes hard and is concrete. What happens when you add water is the cement powder crystalizes. This fills tiny spaces between rocks and sand and other crystals, bonding and putting pressure in all directions and during this phase change emits heat. Once the phase change(curing) has gone thru 3 days some 80% of the strength is there, some 3 weeks later and it is at 90%. It never stops curing. HTH
Your doing the dry pour incorrectly. Dry pour still requires water, it takes 28 days for concrete to cure. Concrete will set under water and actually will be stronger. You will get excellent results with your dry pour if you keep it wet. The water must completely soak the entire pour, take your steel trowel and run it over the concrete and water will be brought to the surface if it does not then you havent applied enough water. Dry pour ? It's just not what I would do even for a fence post.
110% correct.
@@vidxs Which leaves everyone to question how tf is having to keep a dry pour wet less work and or time spent as opposed to following the gd instructions on the gd bag? Morons...
W/C ratio. Concrete requires a specified water/cement ratio. Hydration is the chemical reaction that occurs once water is added to the cement batch. Simply misting the top surface of the dry batch does not give enough water. If no water is present, hydration does not occur. To dry pour, I agree, you must add the required water in the forms and mix it it place. There is no way I would allow a dry pour on any project of mine (civil).
Well Hoover Dam !!
I didn't have any plans to use dry pour, but thank you for providing me with armour against anyone trying to persuade me that it's a good idea.
So you gonna let one test persuade you? Do you even realize that not every brand of concrete reacts the same to the dry pour method? Of course you don't because you saw ONE TEST on one brand of concrete and think this is the definitive TEST.
Was really considering a dry pour for my shed build but after your video I'm sticking to the wet pour. Thank you it was a very educational video.
I wouldn’t chance that either
I was thinking the same thing just now
Look into the addition of basalt fibers in addition to rebar if you want to turbocharge crack resistance.
@actionanimations4879 Rebar doesn't prevent cracks, it adds strength. Concrete always cracks that's what control joints are for.
What time and labor do people think they are saving by dry pouring?
I’m in concrete many years and definitely knew the results even though I have never done what you did to test it, I have my definite instincts that it would be crumbly by what happens to a bag of concrete after it gets rained on. But you are the man! For making a video and doing the test. Bravo 👏
Dry pour fills the gap between dirt and concrete. It's great for fence and pole barn posts if not stressed for a week or 2 and you pour water in the holes.
@@Bob_Adkins hey Bob, I found putting concrete around wood or metal poles tends to rot, even treated, so I soak it in used motor oil first and it’s been keeping them solid.
@@Xrpurple Yep, done that, seems to work. Lately though, I put a handful of copper sulphate in each hole, it acts as a strong algicide/fungicide and also discourages roots and termites.
@@Bob_Adkins sure its great to have week posts.
I'm glad to see the experiment completed, but can't see how anyone would have predicted a different outcome. The strength of the concrete comes from the cement and water being mixed in and helping everything stick together. There's a reason why you don't see manufacturers recommending it. Dry pour concrete is like baking a cake without mixing the ingredients together. You get similar undesirable results. Thanks for demonstrating what a bad idea this is.
Great analogy to baking a cake
There was some home improvement dude on youtube a few months ago that was insisting it's fine to dry pour for walkways and stuff, kept doubling down
My woman makes a "dump cake" that's made kinda like dry pour. It's genuinely delicious
like a traditional scone, yuck, unless you like to chew powder, un done bits. I like scones that have been "ruined' with proper mixing then baking.
And yet, Hoover Dam was entirely done as dry pour. When the engineering is right, it works.
Great video! I watched a few of the dry pour videos and figured it was the easy way to do an inferior job. BTW, please wear a respirator while cutting concrete. The powder causes major problems to your lungs over time.
Yes, please! I was thinking the same thing as I watched the growing cloud of silica-bearing dust. Or better yet, wet saw it and still wear a respirator.
Thank you, even the holding your breath method doesn't work. And we are talking respirator too, not a useless dust mask.
Use a wet saw.
There's a reason no professional concrete finishers do dry pour, you wouldn't want mortar or grout that had moisture in it, if it cures at different times as in some parts were exposed to moisture in the bag and were lumpy while other parts were dry powder they would not bond right. You are essentially drying it in layers that will not bond together correctly and the first layer will somewhat properly cure while shielding the center section and bottom from getting enough water to properly cure.
I work in the cement manufacturing business. There is a lot of science and engineering that goes into the process from extraction at the mine all the way through to the finish cement product that is all based on the product being used in a wet pour. Concrete which is 17% cement is also designed specifically for a wet pour to maximize strength. Cement and concrete could be designed for a dry pour by changing its chemical composition and ingredients, but almost all big projects are easier to build using the wet pour/pumping process. Only small projects benefit from the dry process.
@@goofyjumperthat's an interesting take, if accurate; and, as I'm less than a layman, I have no foundation (cement joke) to argue counter. But, it does seem that if what you're saying about the benefit being only for "small" projects, then virtually all bags could be mixed for dry pours as they are almost certainly all used in "small" projects.
Maybe someone should market an additive to mix in with a standard concrete bag to adjust it for dry pour method
@@jurban7998or maybe you follow the manufacturer instructions and stop trying to cut corners 😂
@@jurban7998 The reduction in strength was HUGE, the dry pour doesn't have 1/4 the strength of the wet pour. If you mix the concrete more than the minimum, you will increase the strength even more due to evaporation of ( a slight) excess water, and more thorough distribution of the water and chemicals in the mix, causing a more complete setting of the mix.
I worked as the QC in a precast concrete factory many years ago and later studied civil engineering. I literally had no idea anyone would 'dry pour' even a basic concrete slab due to the inherent weaknesses highlighted in this video. Thank you for the video.
Thanks for doing this. I've responded to some of these DIY dry pour videos. Concrete curing is a chemical reaction that is dependent on the proper ratios of concrete mix and water. The chemical reaction bonds the concrete particles and stones together by generating heat that is uniform throughout the slab (as long as the correct ratio of water is MIXED in) and is critical to the slab reaching its potential PSI rating. Dry pour, even under the best circumstances, will only ever reach a small fraction of the mixes rated PSI.
Thank you for definitively proving for us what I had always suspected. Great video.
We used to sort of mix in place, pouring the concrete around poles, wetting it, then packing it in with a 2x4, then adding more concrete, wetting it, packing it, in lifts of about 2 inches. We'd finish to the top of the square form we used around the pole tops, then strike off, wet, and float. It looked good and we never had any failure issues, but I'm now the lab qualification manager for a state road department and I have learned a LOT more about concrete from out stuctures engineers, our lab managers and technicians, and I'm qualified for C39 which is the concrete compression test. It's fascinating how much strength varies with the % of water used in the mix and proper curing.
Thanks for ray, honest reveal and test of both dry pour and wet pour concrete! Great job!
I’ve been waiting for a pressure test on dry pour. Thanks!
I have too. My question is was this a losey dried pour or was it a compacted dry pour? The compacted pour should do better.
Awesome video and you got yourself a new subscriber! I was going to do a dry pour for my backyard slab due to all the KZhead videos on dry pour. Thanks for saving me
Thank you I’ve always wondered about those been interested in the results. Very informative thank you.
buddy~!! the aggregate in concrete is loaded with silica and you are liberating a ton of it. You gotta protect your lungs. In my business (law) There is an expression: "Silica; the next Asbestos." The stuff gets in the lings and doesn't come out so the damage is compounded with each dose.
So what you're saying is, keep breathing it in because it will be your future retirement plan when the class actions start?
@@johndorian4078 I don't think that's the correct take away
@@johndorian4078if you were to meet the requirement for a class action about silica dust, you won't be alive for it.
Yeah, what Raul wrote.
You got that backwards. Silica and silicosis was the main killer of people who worked with stone since ancient Egypt. It was only after silicosis was brought under control between the world wars that people realized that asbestos was also bad.
Nice follow up from the original video, thx 😊
This is exactly the test I have been telling people they need to do to see the real strength difference. Thanks.
Saves me lots of work, thank you!
wow thank you for taking the time to fill the internet with real information! priceless
Gotta love data, it doesn’t lie! After watching this, I don’t know if I would ever do a dry pour for anything, not even a stepping stone. There is just not enough integrity ! Thanks for doing this test and sharing! Kinda like a myth-buster episode, without the explosions! 😮
I've seen other tests that would disagree. But the methodology and material differed. That said, I wouldn't vouch that it's as strong as a wet pour.
Unless you are walking elephants on the stepping stones, dry pour would probably suffice.
Perhaps you were viewing fraudulent videos. @@TimGallant
Glad to see the mixer i bought last fall won't go to waste
Definetly not. Speaking of which, need a new friend? I can help you keep the lube dispersed in those bearings! Seriously, I don't mind at all... I'm good at dispersing other lubes too! 😉
Great experiment. Thanks for the trouble you took and for the video you put up.
THANKS KOMAR! GREAT VID!
Great video, thanks for sharing some good data.
Of course you know, all of those who've done dry pours for slabs in a shop, garage or whatever will be losing sleep after seeing this video. Good info.
LOL
And that there is why I've never dry poured concrete
Anyone who did a shop floor or garage slab with dry pour deserves to not sleep, this is just a ridiculous debate, I have been in construction all my life and never seen anyone use dry pour.
@@H43339 LOL me neither , probably became a thing due to people's laziness and impatience
@@H43339 Lmao. The only use I could see for it was if one needed a light-duty, temporary slab for whatever. It could be easily broken up at a later time.
I dry poured a spillway for a farm pod. I was a bit skeptical but it has worked well and looks good. It doesn’t carry a heavy load just provides a water channel and prevents erosion
I used dry pour on a post for a pergola several years ago and had to take it down for a bigger project and it was crumbly underneath so lesson learnt
try them with a moisture meter - they look like their mositure retention is way different - setting on the mortar scale should work OK
Morning show DJ here for many years... keyboard warriors disappear when something is proven opposite of what they think it would be. Even I knew what the outcome would be. Great video!
Nice job! I look forward to seeing your other content too! Subscribed!
Great video - thank you! I always wondered about this and always thought that there was no way the dry pour could be as good as a wet pour. The delivery of moisture to the curing compound is not consistent and uniform even if you mist it very uniformly. With wet pour you're mostly guaranteed to get everything wet and the chemical reaction will occur correctly. Great video!
Thank you very much. I certainly won't be living in a high-rise apartment building that used dry pour.
Finally somebody to verify what I have believed all along. I've seen so many videos proclaiming dry pour is just as good as wet pour they almost had me thinking maybe my thought process is not correct.
Ya I don't trust youtubers at all. Though I do pick up tricks from them. They crowd source people for the next hot trick, I crowd source youtubers, so my next hot tricks are curated. I use youtubers similar to a coffee filter! There's tons of bad info out there though. As a professional in the industry, I can often spot issues. One cool trick I've found recently is the superglue and activator trick. I use it for so much now! No more nailing cleats for my hardwood or using hot glue. I can glue tabs on transition pieces to keep the surface of floor transitions perfectly flush. Same for stair treds. Today I used it to temporarily glue a straight edge perfectly level setup at the height I want to make the perfect cut in the perimeter of a deck. (I'm changing the elevation/slope to meet code) My newest tool is the stabila tech 196 dl digital level. $356. It's a dream to use. I was able to establish my perfect 2 degree slope, get my perimeter flushed to level, and set another slope off that slope @ 90 degrees to keep a staircase step level across the top. I'm going to install some venetian tile flush with the perimeter.
most us rednecks never claim its "just as good" we slap the "it will do" label on it, cause it was less work and will do what we wanted it to do.
I knew it was too good to be true. Thanks for pointing out the flaw before I poured a dry slab.
Always had my doubts anyhow about the dry stuff. Thanx for showing why.
Over the years I have done a few dry pours and it takes months if not years for them to fully cure. Dry pours also heavily rely on absorbing moisture from the ground. It will never be as strong but these are weaker then they should be.
So we should wait longer than 30 days for full strength? To me that seems a little excessive vs standard concrete. But everyone can do what they want.
@@brandonm9359there's a reason people usually only do dry pours with fence posts. I had no choice when I did the few pours I did.
@@revtoyotaI don't understand why anybody would think dry pour is as strong. If you ever seen concrete get wet in the bag and then harden would know.
@@roscoeshepard Check that same bag after 5 years outside.
It makes sense. There is no way for water to fully seep down into the bottom of the pour, so it doesn’t get wet enough.
Thank you for clearing this up
Thank you for doing this for us!
Soil technicians do this daily across America on core samples taken from construction sites. Defending concrete strength is like defending the 7 kingdoms from white walkers, an ever waging struggle that requires vigilance. If you don't pass the soil techs inspection, you shall not pass! Like the Balrog trying to get by Gandalf with his shifty concrete.
Awesome. Thank you. Btw .. when you breathe in concrete dust it turns back into concrete, you're dry pouring your lungs and your sinus cavity. 🤣 Mask up, brother!
You breath in cement dust not concrete, so it turns into what is basically limestone in any body fluids.
Doesn’t work quite that way but appreciate the sentiment.
My uncle worked in concrete for years and didn't wear a mask. He ended up needing a lung transplant. Mask up is right.
Just look up Silicosis.
i was yelling during the clip of him cutting them and once all thr dust cleared you could see his bare face 😳
The first couple of waterings should be light mist. After that, drench it with water. It needs to absorb about a gallon of water per bag used.
Yep, he didn't do this. not enough water.
I quit watching the video... he sounded to bias at the beginning of the video. I didn't see the pressure gauge on camera when he went to the dry pour, so I stopped watching..... thought there might be a reason he wasn't showing it. Maybe he did later, but I also don't think he did the dry pour method right, either.
@@blythdunlap8408 he said he did the misting too heavy... people having been doing dry pour for fence posts forever and making retaining walls out of bags forever... I left some mortar mix intended to be used for a shower pan in the bag, not even concrete, left out in the driveway for years and it's as hard as a rock and is now used to weight down our portable basketball hoop, never even watered it, it just got rained on during rainy season in socal... hard as stone
@@blythdunlap8408 I don't have a side in this ongoing debate but there certainly did seem to be a bias out of the gate and the test was anything but scientific when he admits to not using the correct amount of water at the start. What's the point of bothering to test if you didn't do it right in the first place?
A picture is worth a thousand words. I used dry pour for my fence post corners and stretchers but some pour water in the hole first and poured a bit throughout the fill process. I would never use dry pour for a walk or slab. Very well done tests.
I had seven large steel fence posts to install on my property. The holes were large and deep, and I was tempted to dry pour. A couple of knowledgeable people told me to just mix all the concrete and do a wet pour. Glad I listened to them.
Really interesting and well thought out. I had always wondered, because dry pour would be so much easier! I look forward to you doing the other blocks and seeing if it just takes longer to cure. Thanks for doing this.
Nice follow up
Thanks for doing this. It confirmed what I thought
Very informative & useful. I made decide for wet pour for my small DIY thanksa
Great video! I have no idea why anyone was doing a dry pour in the first place. Pretty soon they'll probably be eating raw chicken because cooking it is too much work.
That is the raw foods diet and has been around for a while and yes it includes raw meat though many on it are vegetarians.
Why do anything hard? Tightening all the bolts on my car's wheels is too much work. I only finger tighten them. Look at all the time/effort I have saved. Who's the jammy bastard now?
We were served raw chicken in Osaka, Japan. We didn’t eat that course, but the locals did.
They are doing it because in most cases that's all the strength you need. and it's a lot cheaper. and easier to remove for temporary uses.
@@johndorian4078 it will fall apart a lot sooner so that's a huge disadvantage, I do agree about temporary uses but I have never heard of someone using concrete for a temporary purpose nor can I think of a situation where it would be used for one.
You validated my thoughts... Who has 6 months to wait for a slab to cure?
Concrete cures for years typically even wet pour is only at 75 to 80 percent of strength in 28 days that's why most concrete contractors tell you know heavy traffic for at least 30 days
I'll admit I've done dry pour many times around post (never nothing structural) but after watching this I'll never do another dry pour again, on anything. Thanks for sharing the video, you answered one of the age old questions.👍🏻👍🏻
Great video, thanks for posting. I did 2 dry pour several years ago. One pretty quickly cracked, the other one has really disintegrated.
It's actually harder to control the process than wet pour, and will never be as strong no matter how careful you are. It's for farmers with small budgets and worn-out backs.
I've been doing a hybrid of these two methods for decades, it's easy and it gives results that look and apparently perform like wet pour. I mix in place. Just fill the form with premix, wet it well with just about as much water that you would use for mixing and use a shovel in a vertical chopping motion for just a few minutes to mix then finish the top. Works great, is faster, a lot easier and has less cleanup than a wet pour. I have slabs that I have made with this method that I've driven fully loaded pickup trucks over and they've held up perfectly.
short cuts. . .
I think that the outcome will differ depending on how much water you use. With a wet mixture, there is more control.
Yes he should test your method
Yeppers! Not too much water though! Consolidation and even distribution! Smart! : ) Be Safe
Would you drive an 80,000 simi truck over it like a wet poured slab.
I used to take care of a building of retirees. One of my tenants was a former materials tester for construction projects. One thing he told me forever sticks in my head, and that is concrete gets continually harder for the 1st 28 Y E A R S of its life! Then it turns around and goes the other way.
Except that Roman concrete mixed 3000 years ago is still holding up the aqueducts it was mixed for.
@@damnhandy that's down to a combination of being unreinforced so no internal corrosion. Use of pozallano ash in the mix. Use of a low-slump hand-laying technique that's too labor intensive for modern large scale construction but leaves far fewer internal voids. And using a mix that cures very slowly at relatively low temperatures. As in literally orders of magnitude slower than the cure on most modern concrete mixes.
Fantastic video! Thanks for the information 👍
Good to know about the dry poor product.. thanks for the video.
As I saw it, you had no idea how much water was added to the dry pour, whereas my bet is you mixed the wet pour with water per mfg. recommendation.
I dry pour for coops and such on the farm. I do soak it very well though. Mist the surface to get that set (maybe 3 or 4 times over a few hours) then flood every few hours for a few days. I’ll have to make my own test to compare the two (wet versus flooded dry). For my use, I’m not putting a 5 ton point load on the surface so the plate test is more representative of the usage. Fine for compression but may be weak on sheer. We’ll see.
Yes it's weaker. Dry pouring does not meet building code. In commercial construction. Your concrete gets core sampled by a soil technician. This is your concrete inspection. If it doesn't pass, it gets demolished and replaced. You also get yelled at by the general contractor for holding up the entire jobsite. I asked the general on a Costco job what's the fastest one has gone in. 92 days! WTF! The soil tech is also in charge of testing soil compaction anywhere people dig. Sewer, water, gas tanks, storm water tanks, etc.
I'd really like to see your test results - I think most of these "dry pours" take the term dry too literally. I definitely think a flooding stage is necessary to even give these a chance.
@ronniekeates3349 I'm not a soil tech. I just get inspected by them for soil compaction, so I talk to them regularly. I have seen him hauling off a box of core samples. I asked him what he was doing. He was taking the core samples to be tested. The concrete came in on mixing trucks.
The fact is dry pouring is outside manufacturer recommended specifications in America because the specific concrete blends they create are made to be mixed wet to achieve the strength rating listed on the bag and called for by specification. I talked with someone who works in the industry and he said dry pour concrete is done in 3rd world countries, but they blend a concrete made to do so and achieve the strength they are looking for.
@@brandonhoffman4712 Yup, at the building I worked at the shop floor was found to have major problems both due to poor soil compaction and then a bad concrete pour. Our next building on the site, the next contractor (years later) got feet held to the fire for both soil compaction (two to three re-do's to get the contract compaction number) and concrete strength. Fool me once.... How do I know? I was working in a trailer across the driveway waiting for the new building, so had to listen to the machinery going back and forth for the compaction, over and over for hours of backup beepers every day.... 😖
Thanks for the video. It's helpful to see how dry pour preforms so that we know where and where not to use it. I've been considering dry pouring a light shed slab that I suspect I'll want to tear out in a few years and dry pour seems like the way to go. Strong enough to walk on, but should break up easily with a sledge.
This is the key. How many uses require 5 ton of pressure around the home? Dry pour will probably suffice for that. Anything load bearing, a driveway or house pad, then go wet. Having said that, one wonders when a dry pour compound will come out that will be an improvement over the current product/method.
Great job. Thank you 😊
The problem is the dry pour is just not getting enough water to complete the chemical transformation
I think there is a place for dry cured concrete but definitely not where you would normally place concrete. I think using dry pour in areas prone to erosion might work. The reason dry pour doesn't cure is inconsistent hydration and the inability to monitor the water to cement ratio. ALL concrete has a maximum water to cement ratio that should not be exceeded. It would be almost impossible to control that with dry pour. Quantities matter. Also, frequent misting of dry pour will expose the aggregate, which is very bad if you live in areas that freeze. Really, for exterior concrete that resides in areas that freeze, you need air entrainment. There are no bagged concrete mixes that include air entrainment. You might be able to get some from you local Redi-mix supplier....maybe. But it is something that should be measured accurately. My advise is that if you hope your concrete will last 50 years, you'd better get a Redi-mix truck to deliver it, especially if it's structural. If your concrete is not that important and easily replaced, I say roll the dice and take a chance. Personally, I use dry pour in fence post holes. I put in about 4 inches and mist the top..repeat until the hole is full. I have also seen bags of quikcrete placed in front of bridge abutments to secure the soil...kind of a manmade riprap. After an amount of time, the bags solidify and form an erosion barrier. Works pretty well. 😊😊😊
Love your video! Great information. I would be very cautious in the future of cutting or drilling concrete dry or without dust containment or protection as Silicosis is a serious condition to deal with.
Thank you for this very educational and informative video. Now I know what.
I (poured) a slab in a shed with just class 3 cmb road base (crushed miscellaneous base) (asphalt and concrete recycled) for those who don't know. No cement at all. Several years later I upgraded to a poured slab but I had a buggar of a time busting through that cmb slab that had cured into a pretty hard block. I have a pretty good sized skid steer and really had a tough time of it. Time to cure is the key? Many wet cycles in that example I gave.
Time to cure is hugely important. Nearly all modern concretes are mixed for a very fluid pour and relatively fast cure to reduce labor. Labor costs money. But if you are willing to spend more time and effort on labor, low slump mixes that can't just be poured and have to be hand-packed and frequently vibrated to reduce voids. Those mixes end up stronger. And the longer the cure time the stronger the concrete ends up being. Turns out the reason roman concrete has lasted so long as a combination of it not being reinforced with metals so it lacks the problem of internal corrosion expansion and cracking. A low slump mixture that started out with just enough moisture to cure. And a curing time that could last years. Parts of the pantheon apparently took nearly a decade to fully cure deep inside the thickest parts of the structure.
he didn't follow the instructions that worked for others, he said that he did the initial misting with too much water, there are instructons that work and if you don't follow them you get this kind of result where there was no bonding formed between the CSH...
@@VenturaIT u will get that result regardless
@@timfuscaldo3024 nope, others have poured entire slabs that stand up to heavy use... it's the people who intentionally don't do the process correctly that have these results... concrete is concrete... doesn't matter how you mix it just so the amount of water is right, people have been setting dry post foundations and other dry uses for concrete forever... but if you half-way wet it then wait too long or it's too cold then it won't work... concrete has to be poured above 45F-65F or it wont work
@@VenturaIT Sure others do, good for them, love how people like to take the short cuts and believe folks like you. It is a free country and folks are free to be ignorant.
I was wondering about this and you validated what I thought 👍
You want validation on wet mixing concrete. Watch how they built the hoover dam! Took a lot of dam truckloads!
@@brandonhoffman4712 They went wet? 😆
Ya, they lost 14 people in the concrete. Anyone who fell in, just shloup' (sound effect) Siyanara, no more konnichiwa. Jk 😜
@@brandonhoffman4712 You can't make an omelette without breaking eggs... J/K 😆
@tradermunky1998 That's what I imagine they said when building the great wall of China! Jobsite saftey hadn't been invented yet...
I have poured a few slabs in my 60 years and without any doubt wet cement is superiour to dry. Concrete was made to be poured wet.
Very interesting test. I can see dry mix in post holes situations, but wet only in slabs.
Curious if you only misted the dry pour or if you did the soaking that I've seen as required after the top surface has cured? It looks like not enough water was used. I'd expect the dry pour to be weaker than traditional concrete, but not as extreme as what your test showed, so trying to fully understand your dry pour process. Thanks for an interesting video!
If you set concrete dry, and you soak it without then intermixing aggregate thoroughly, you will create a separation effect. Also, if you add to much water you create an integrity issue for same reason. You literally wash the aggregate away from each other. An easy test would be to put dry mux in mixing box pour water over it and let it sit. The end result will be aggregates separating from each other and not combining.
he did it wrong, he said so at the start, hence why he got a sandy darker appearance, happens when people make up their own system and not follow instructions that have worked for others
I've always wet-poured slabs, and pilings and post holes. And because I do, I've been ridiculed by some of my buddies who swear by the dry-pour method.... I can't wait to forward your video to them. I think a big issue with the dry pour is that the ingredients are not properly mixed as well, and that the proper amount of water doesn't get where it needs to go for the proper chemical reaction.
Well, for post holes, they're still correct. You don't need 2 tons of structure for a fence post. The ground will give before the concrete, whatever the method, and nobody will care if the edges get a little crumbly.
Depends on the soil conditions. It's not about 2 tons of structure; it's about lateral sway/weakness. In our soft, zero-rock, weak, sandy and/or muck soil, when using the weak dry-pour you can manually push the post (4X4's, 4X6's, 6X6'x 8X83s side-to-side, breaking the concrete, months after the cement is 'cured'. It requires large diameter, and deep holes for any type of post/piling. I will still use wet-pour.@@TheBrothergreen
got news for ya... it's not the water getting to where it's needed, it's the fine powdered cement and the larger particles of sand / gravel separating into layers during shipping. If everything is not evenly distributed, then it becomes weaker.
In my soil a 4in post will snap off before the dry pour breaks. Not really an intentional test, but just saying. I use a 36in deep hole 6in auger. Fairly rocky soil. A dry pour slab should be considered temporary though.
Yer on to something bud!!! On the "wet" ... you mentioned "mix" and proper amount of "water" and "chemical reaction". There's a lot going on with what you say!!! Dry-pours can be made if conditions allow and dependent on application but not favorable. Most dry-pours are incorrectly done but suffice due to application (think buried with little or no-load or sheer) and containment; regardless, some sort of mixing should happen (rodding), working out any large air-pockets and consolidation (*for even distribution). Soil types play a big role in containment, think hard-packed (density) and ability to retain moisture. Stop the chemical reaction (hydration) in any part, it's done - it won't restart! 2thumbs up! : )
Great info, thanks so much.
Not even a fence post would work as a dry pour. Glad somebody chose to produce this exemplar. Thanks
Fence posts work if you just use dirt. Dry pour is stronger than dirt.
You're doing the internet community of DIYers a great service! I hope this gets in front of as many eyes as possible before they venture down the road of doing a dry pour. If you come across any of those hyped-up dry pour videos, it sure makes you think it’s viable. This proves in a way a layperson can understand, it’s not the way to go. Thank you!
I think the application matters. If you are building a pad for your AC unit like he did in the earlier videos the dry pour is more than strong enough. Similarly, if you are making a small concrete patio outside your home a dry pour (with some hogwire mesh) is again going to be plenty strong. Neither slab will ever experience a couple thousand pounds PSI of pressure.
@@RandomGuyDan yep, I dry poured a big slab to park my lawncare truck on so the city stopped screaming at me for parking in my grass/backyard. its held up well and I didnt give one lick if it looked good/pretty, it had one job, keep the city off my butt.
@@RandomGuyDan I wouldn’t. Any vibration from the AC later in its life (yes, it can happen) could soon cause crumbling in that sub-standard base.
I did a sidewalk repair with dry pour, direct to dirt, so it cured by bringing up all the moisture from the ground every night, trucks go on it no problem. The difference was about spraying the concrete at each 80lb bag, not just the top. It also depends of the aggregate quality, most pre mix have round and smooth pebbles like marbles even the cement doesn't stick to, when they get mixed for 10+ minutes they sorta get sand blasted for a better adhesion, another advantage for wet pour. A bag of premix in your area might be completely different in another town or state, the aggregate is sourced locally.
also during testing by concrete labs, each block is cut to perfection on both side, extremely parallel, that's the only way to have accurate load distribution
A dry pour may be sufficient for your needs, but it will never be near the rated strength and never as strong as a wet mix. Percolation kills the mix… segregates the different ingredients, causing a sub-par mix.
@@VanillaIceCoffee No they aren't, they are put into test cylinders.
@@brock8199 for the ones you get at the truck yes, not always tho, only one side is flat. core samples and other blocks are polished, the lab I deal with doesn’t trust the cylinders, they polish them anyways it’s super quick
At 6:50 you mentioned cutting them open to compare the cure on the inside, then you went straight to the press. I imagine it wasn't much different from the outside but I was so excited to see the inside. I feel so let down. :) Great video and tests.
I like the look of the dry pour myself.
1:51 the key issue with dry pour is the lack of publically available standards and process instructions. Proper hydration is essential for strength and integrity of concrete. Without proper hydration, "curing" is partial at best. IMO, "misting" of dry pour slab is only the preliminary step for hydration and serves primarily to stabilize the free surface against erosion during high flow wetting. If the dry pour doesn't have a ponding step, there's a high likelihood of insufficient hydration.
yes, wet curing/ponding for up to around 30 days will make any concrete stronger, mist once, wait 1 hour, mist lightly again as to not to disturb the surface preparation, then wait 1 more hour, then water heavily but no so heavily that you disturb the material, water 2 times for every inch of your dry concrete, so a 4 inch dry slab will get 8 waterings separated by 1 hour... another thing is that you can't do this in freezing or cold weather... it has to be probably 45F or warm to hot... but not too hot... i've seen it fail in dry and arid locations... the Cajun Country Livin people have rain that is a natural wet curing process after they do their process, which actually gives it more strength...
@@VenturaIT Cajun country has the advantage of continual wicking of moisture from the ground ...
I was planning on using dry pour concrete for some stepping stones in my yard. I suspect that that would be a decent use case since they won’t ever be under more load than a person’s weight.
What so hard about mixing concrete? Use the right tool (a hoe) No not her! And don't try to mix it all at once.
Why? Do you really think your saving any time or labor?
@@zoso1123 I think so. It may not be true, but my mental walkthrough has made it seem like less labor for a part of a project that needs my attention elsewhere
@seankrake4776 The hardest part is carrying the bags. Still gottacarry open and pour whether u mix or not. If you worried about working hard, buy your stepping stones pre made. Then you save time and money.
Dry pour stepping stones are FINE. Perspective, people. It can work in higher stress areas, but it's kinda luck of the draw. Are you in a wet climate? Can it draw from the ground? I've done dry pour posts for years. They are still solid more than a decade later.
I read an article years ago, but it was only 2 inches thick, sand underneath, after misting it and forming a skin, they flooded it. It was for a walkway or decorative panels.
Nicely done
The biggest reason the wet pour is stronger is the mixing that’s involved, it is ensuring that all of the concrete mix has the correct amount of water on every tiny particulate matter in it. This is the same as making a cake, you wouldn’t skip mixing the dry ingredients with the wet ones. The only way a dry pour is going to have a chance at being strong is to have an additional form above to hold water and let it slowly drip down into the mix. It is very clear that the dry isn’t meeting the ratio required for the concrete mix.
Once concrete begins interlocking its crystal structure, it will shed more water than it will allow through. Simply dripping water on top is not enough. Maybe if you had a system of sloped baffles, similar to those self mixing epoxy tips. And sprayed a heavy dose of water as you dropped concrete in there it might do something. But I bet it still wouldn't pass a soil techs core sampling and testing procedures.
So basically you get the better concrete by not being lazy and just doing the extra work? Huh, who would've known? 😂
Thanks for the time you put in this no nonsense video. I was lucky enough to see your last video, forgot about the follow up and just stumbled upon it. There was never any doubt in my mind that taking the lazy way out would produce an inferior product and your test proved that. All these people cheerleading for a dry pour are the typical contractors that simply want to cut labor cost for their gains while they screw the customer. If you didnt add "enough" water and concrete never "stops" curing then set them both outside and we'll see the outcome prove itself again in 6-12 more months!
I bought a MudMixer last Fall, and poured 188 bags for a slab behind my house. It worked great and I have many other projects planned when better weather arrives. I used one leftover bag and some scrap 2x4s to do a dry pour step, for the side door of my 20' car hauler. It worked fine for that, but it only takes 2 minutes to mix it in a form that small, with no clean up, so that will be my only experience with dry pour. Great video! 😁
188 bags at what say $5 a bag (since the price does fluctuate between like $4.50 and $6) that would be about $940ish for slightly over 4 yards of concrete, concrete suppliers (the company that mixes it in the trucks) are currently at like $150 a yard or about $600 and maybe an extra $200-$250 for a "short load fee" since you where only ordering half a truck load, you still would have come up cheaper and not needed to buy a mixer or spend the time mixing 180 bags of concrete (or moving them around for that matter). You really should sit down and do the math on each project to find the point where you are better off just calling a truck in.
@DanielRichards644 You are brilliant! I would have never thought to call a concrete company! You should stop by sometime to tell me exactly how I was supposed to get a truck (without a pumper) behind my house, and also how to afford to remove and replace the massive oak trees that line my 1/4 mile driveway, since a concrete truck couldn't make it to the house, let alone around back, without removing half of them. I did it the cheapest way I could, and I have several other projects that are in even harder to access places on the property.
@@DanielRichards644correct, only if your able to do a set straight from chutes. In many instances, depending on where you live and the amount of foliage, it requires a pump system to get over the house which does add considerably cost.
@@anthonydilugi4672it was an extra $500 to get the pump out for the day when i had mine done, that would still be cheaper then the bagged concrete and buying a mixer, plus the wear and tear on your body moving that much material and the time involved in moving that many bags, even if it cost $500 more it would be well worth it just in the time savings.
Interesting. But, well ... all the dry pour recommendations I've seen are to do it with quick set. Is that what you used? I suspect that would make a significant difference. There are also methodological issues. Some concrete manufacturers do recommend dry pours for fence posts with quick set. But in that instance, there is a lot of moisture absorbing from the surrounding soil. I don't think a dry pour misting only the surface in a dry box is ever going to work well. FWIW, I dry poured my swing set posts, and it's rock solid, even though it has no angled supports, just vertical posts.
No, trust me it's not, I did a dry pour to set my mail box post years ago, when the post rotted out I pulled out the concrete and it broke into several pieces, the reason dry pour works for fence posts is because it's a mass and surface friction to the dirt that keeps things solid, not the quality of the mix, you aren't relying on the compressive strength of concrete to hold your posts up.
And, I would add, I would never use a dry set for anything structural or anything necessary to keep people safe let alone my children. But, I also would never use dry set period. Only a few occasions where we put fence posts in using quick set material which has polymers designed to decrease set time and increase binding.. Current UCC code in almost all states does not even allow the setting of posts in concrete because of corrosion affects and water sitting in bottom of hole created by post allowing for puddled water to do what it does best: erode things over time including concrete. Code requires all concrete piers to be a minimum of 2-3" above grade with structural post brackets set into concrete while wet.
i left a mortar bag out in the driveway for years, just forgot about it... it was for a shower pan, but then didn't go that direction... now it's as hard as stone, it's not even concrete and this was years ago, now it's used to weight down our portable basketball hoop, probably the first winter it got a lot of rain on it that saturated it... once the concrete is set (misting) you can't use too much water... but you can ruin it by misting it with not enough water, then waiting too long so half or a portion of the CSH bonds set then watering it and then waiting too long, you see he made up his own instructions with 45 minute intervals and those aren't the instructions that work... I watched the Cajun County Livin channel again, their instructions that work for them are light mist wait 1 hour another light mist wait 1 hour then do heavy watering once per hour for as many hours as 2x the inch thickness so you water 8 times for a 4 inch slab... theirs turned out grey like concrete, not dirt color which makes me think the guy in this video added too much sand to his concrete
the difference is in a dry pour on the ground the concrete will draw moisture from the ground which is inhibited in your test with a plywood bottom
And still not strong enough for a dry pour to pass the inspection of a soil technician when he comes and core samples your concrete on any commercial construction site. Might as well dry pour the hoover dam instead of keeping a continuous line of wet concrete coming. Oh wait, we don't want the dam to fail like it was made in China...
doesn't matter, an uneven mixture of water and cement will ALWAYS BE WEAKER, PERIOD FULL STOP, stop trying to justify your mistake.
@@DanielRichards644thank you
Thank you 👍🏽
Good videos! Makes sense when you consider that portland is like glue around the aggregate. Wet mix bonds the portland evenly around the stronger aggregate and even if randomly mixed, allows a matrix to form. Veritasium just did a neat video about metalurgy and katanas. Id say the idea of a matrix is similar, relying on bonds and matrix to create strength
Dry pours seem like a bad idea. By spraying the outside surface, you create a shell that resists absorption for any additional sprays.
Concrete is hygroscopic. Water wicks right through it.
Love your vids!!! But, please, buddy, wear a mask, your health man!!!! It's important!!
Merci from Montreal Canada
I didn't know this. I was considering a dry pour but thanks to you, I think I'll do a wet pour. Now I just need to figure out the ratio of water to concrete.
line the box with plastic and fill with water and then pour the dry cement into the water filled box until the water is all washed out. misting the outside does not get it all saturated with water, so by pouring into a water filled container it should all get wet. i think it would be as strong as the wet pour, but without mixing first.
This method seems impossible for anything larger than a 12x12 inch square then…
Water isn’t the issue. It’s the segregation of the ingredients due to percolation. Your concrete mix… is much less mixed. The wet mixing remixes it.
Anybody who has had bags get wet in storage knows how “strong” a dry pour can be. But, no… nothing structural should ever consider a dry pour. For post holes? Sure… for a quick barrier? Maybe… support for anything? Not me..
Back in the 70's, Popular Science had an article on what they called "stabilized dirt" where some places in California were dry mixing cement and a couple of inches of dirt together from the path they were working and spraying it. Seemed to work great for walking trails. I did the same to part of an alley easement where the trash bags were placed and it worked really good compared to the previous mud. Drove the truck over it by accident trying to get a long trailer in a skinny driveway and not unexpectedly, it cracked very badly. I have just started seeing people doing dry pour whatever recently and thought "not for me, thanks. been there, done that." Thank you for taking the time to prove it up, this should help some people make the right decision for the right application.
I enjoyed watching this test tho I was fairly sure of the outcome. When I have installed fence posts I always like to wet pour altho for many companies it is common to dry pour the posts in place. It takes a few minutes longer for each post but I think you get much better results.
I kinda wish you would have weighed them to see if they were significantly different. When you screed the dry pour, you're compacting all of the solids tightly together making it more difficult for moisture to get in AND out, thus taking much longer to cure. I'd expect the dry pour sample to be heavier due to a higher density (more concrete solids packed closer together) and higher moisture content (taking longer to cure).
Oh that is an interesting question.
he's got too much sand in his dry mix and not enough concrete, that's why it's dark like a sandbox... in the examples you can see online where it works the result is a very grey color and dries overnight or even in a few hours