Dry pour concrete - An Experts Opinion Dry pour concrete slab details
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- Опубликовано: 7 сен 2023
- Dry pour concrete has become a popular way to produce concrete slabs. Dry pour slabs are used because they are easy to pour, do not require a lot of equipment, and can be used to create amazing finishes. This video gives you insights into dry pour concrete
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This has to become an Oklahoma State research project. We need slabs to core and beams (reinforced and unreinforced) to break to see how it compares to standard concrete mixed per the manufacturer - this could be a whole series that either debunks the practice or identifies some best practices and recommends where to use it.
We are on it! Keep thining about what you want us to look at!
You could easily spend more time mixing up the dry mix beforehand as well to improve the recipe. I think the curing process will be a big deal for dry pour, if you water cure for 1 month or not.
@@VenturaIT
Dry poor concrete is strictly for lightweights. There is no way you can get enough water into the mix to properly cure the mix to make concrete of any strength. Brownie is an appropriate description of what you get with dry pored concrete since it is about as strong as a dried out brownie.
This seems closer to the super dry mixtures used for roller compacted concrete, or dry pack used under a lot of tile jobs. It would be interesting to see if you could densify it with some type of roller or a vibrating compactor.
That is a good idea. We will see what we can do!
Dr. Ley- Thanks for finally dipping your toe into "dry pour" concrete. I understand your biases lean toward commercially processed concrete, but you made several critical assertions of dry pour in this video that should be fully tested to confirm. I refer to your remark that dry pour will not achieve similar performance to wet pour, I infer your contention is related a less homogenous mix with dry relative to wet process. I think, however; we all would agree that overwatered wet pour, mixed "in the wild", underperforms , probably due to large aggregate migration "to the bottom" of the pour. The "curing" of cement + aggregate into concrete is a chemical process, it requires "adequate" hydration to proceed to full "cure" at about 30 days under normal circumstances. The "Cajun Country" hydration regimen is not scientifically derived, it empirically seeks to stabilize the slab "top crust" and hydrate the slab for cure promotion. It could probably be simplified into a 2 step process; first, crust stabilization could probably be achieved with 2 mistings at 10-15 minutes apart, and second, the timing of hydration soaking is less relevant, as long as the top of the slab stays moist or wet the slab will hydrate quickly (see video from renetto for visual evidence). You refence "air voids" as a problem in dry pour, but if you might research a quantity of dry pour videos, you will find people have addressed this issue by, for instance, impacting the dry forms with a rubber mallet prior to or after screeding and before wetting, yet another ingenious fellow attached a palm sander to the screed board attempting to achieve a smoother surface. This is probably adequate for small projects up to 4'x4', I would guess. Your critique of dry pour lacking "air entrainment" for freeze/thaw protection warrants merit, but where do "air voids" end and "air entrainment" begin. As I peruse the comments attached to this video, I am struck by the high percent of commenters requesting "testing" of dry versus wet pour methods. The the video testing of dry vs wet here on RUclips is not scientific, and often "tests" concrete that is not yet fully cured with methods that are "empiric" but not "quantifiable". Since you have access to the required lab equipment, might I suggest the following tests. It would be most helpful to the DIY community to know how dry and wet pours compare with regards to cure time, final strength, and density (permeability). At a minimum; a comparison of dry pour versus wet pour with big box bagged dry concrete mix at 3,7, and 30 day interval testing, a bonus would be to add samples of commercial mix (from truck or yard) with similar specs. Your assessment of the final quality (compressive strength, density, and air entrainment) of concrete produced by each method would be highly valued by all who follow this channel. Afterthought: perhaps you might run a few samples of concrete prepared with both PLC and straight Portland to see which might be a better choice for the small batch DIYer who might seek to add fiber to a bag mix or self mix with a small portable mixer, and still dry pour a small slab. We appreciate your efforts and insights!
I have never nor really plan to pour concrete. But I love your channel for the practical science and the deep knowledge of the subject.
Thank you!
I've placed concrete with traditional and dry pour methods. I think dry pour has its place in a few scenarios, but those few scenarios cover quite a bit of the applicability of concrete around residential houses. Dry pour is so much cheaper for typical slabs, coming in at about 30% of concrete contractor bids and it's taking off because homeowners are being priced out of simple projects by today's wet pour prices. Some dry pour test ideas are:
-Strength tests using quality methods that provide unbiased results for typical 4" to 6" flat pours.
-Can the mix be compacted during placement, and is that a benefit? Anecdotally I've noticed that we can compact dry pour mix with foot traffic during placement. My gut tells me that's likely a beneficial action but a test would indicate whether there's an actual benefit.
-What is the adherence of dry-poured concrete to reinforcement steel as compared to wet pour? Is it adequate? An aside on steel, I think dry-pour concreters do a far better job at centering rebar in a flat pour. Nearly all residential pours have "hooked-up" rebar or mesh, and that's of little or no use. Placing steel in dry pour is amazingly simple, and you don't need chairs and almost no wire tying. You place half of the dry mix, smooth the surface, place one direction of steel, seat it in the dry mix with foot traffic during placing, place the other direction and apply more dry mix to hold it, and nothing moves. No wire, no chairs, no tying labor.
-Installers can perform limited but noticeable compaction to the dry pour during placement using common foot traffic. Does material compaction make a difference?
-How do dry pours perform in freeze-thaw tests? Does dry pour need a permanent sealer applied to it?
-Is it better to begin misting dry pour just after sunset and water through the night? (I haven't figured out how to cover the dry pour during initial misting without marking the surface)
-Is use of a mortar mix as a thin layer of surface ok, or does it create a potential spalling layer?
-Is there a practical method to create a smoother, more polished surface than what is achieved by the paint roller finish method?
-What is the practical limit of dry-pour slab depth? If a person is pouring a 4" slab but wants a footing (8", 10", etc.) around the perimeter, can this reasonably be achieved? Does thickness of the slab affect final strength when using typical dry pour wetting methods?
Thanks!
Hydration has always been the key to good basic concrete formation. Even truck mix can go off if not correctly hydrated. If you investigare this further i believe you will find some plastizers, chopped fiber and colors will work acceptably in a dry mix method. What this method is missing is a solus testing regimen to verify what strength, permeability, and wearability is possible using dry-placement concrete.
I've used dry mix concrete technique for femce and gste posts for decades...... my technique includes wetting the adjacent dirt well prior to dumping in the bagged concrete. My train of thought is that the concrete wants water, and I want good concrete. So i provide starter water in wetting the dirt that is gong to come in contact. MrEric
Interested on your take of the issues with RAAC, some of our uk schools are falling apart due to the stuff.
Thanks!
When it is done right then I think it is great. When it is done wrong then it is big trouble.
Excelent video. Objective and rational. Great summary of pros and cons. Now the testing can start.
Thankyou for this Tyler 👍
Thank you for watching!
You've got students who need term paper projects. Pour 5 concrete slabettes using this method and another 5 with the regular method. Maybe do a set with rebar, another with fibers. Maybe one 4" deep and another 6" deep. Then cut them into 12" strips. Do a visual exam for uniformity, do a dye test from both top and bottom, do a compression break test and do a tension break test. Having just these empirical numbers will help me understand if this is appropriate for anything but decorative concrete. Then have your students publish and present that paper at ACI. Fame and experience for everyone.
Thanks! These are good ideas!!! Watch for a future video over this.
i'm interested to see the strength testing of it, especially a comparison with different strength concretes. compare standard vers high strength vers fast setting etc.
also the difference between wet and dry ground.
also i wonder what the effect of a water reducer admixture added to the spray water would do.
Cool ideas! We will definately compare to different concretes. I am not sure the water reducer spray would do much. Water reducers move cement grains apart in water and the dry pour is not really saturated.
water curing for 1 month will probably make a huge difference and possibly raking it out to mix it a bit more at the start...
I saw you on a Sunday Morning segment today and I am waiting on delivery of 24 bags of concrete to pour a 4X8 slab in front of a French door. I have done a fair share of concrete for a DIY er and I spent time in construction but I am 77 now and this job is in a resort town where it’s difficult to get people and its expensive. I agonized over this and finally decided to give it a try. I feel much more confident after your video please do more research. I have more projects.
Your going to need 56 bags of concrete for 4x8x4 slab. For a 3in slab you will need 42 bags.Just saying. I done this before and its very rewarding!!
@@nonchalant159 simple math assuming a 4 inch thich slab: 4x8x4/12 i.e. 4x8x0.33 = 10.66 cu ft. Using a 60 # bag which is about 0.45 cu ft you divide 10.66 by 0.45 = 23.7 bags. So buy maybe 27 bags.
we need a dry-pour-concrete test for sure
It is coming. Keep thinking about what you want to see. We will start them soon.
@@TylerLeyaccelerated test on longevity compared to the same sacked concrete mixed in a wheelbarrow.
@@TylerLeythere are gong to be LOTS of variables..... the water content involved will be one of the largest ones, I would think. MrEric
@@MrEric_API measure the water applied vs direct mixed to determine the hydration of the mix.
Great Video! We did an 8'x6' slab outside our back door in late August of this year. Hottest most humid day of the year too. We didn't follow the Cajun Country Family videos exactly because we are in MN and used rebar and I wanted a stronger base with some sand and class 5 based on what I do for a living and am used to seeing. Was it necessary to put in a base or could we have done it directly on grade?
We also did way more than 4 sprays because in our 1'x1' test pour the water didn't go all the way down and it was just the bag mix. So we misted twice as directed and then sprayed every hour for maybe 12+ hours and then at least 3 times a day for 6 days all while curing it with plastic for the typical 7 day wet cure. The plastic staid pretty wet and we could see the moisture disappear into the mix. No cracks yet and feels solid!
We are having some slight surface scaling. Not terrible, but our dog runs off of it and his claws leave little marks on the surface. Any thoughts on following just the 4 sprays vs. what we did to prevent scaling of the surface?
We are hoping to do more pours next year as it only cost us ~ $300 for the nice size slab (because of the base we used. Would be cheaper if we just put the dry mix on the dirt). It is so much nicer than having dirt outside our back door and we hope to do a few more after the spring to see how it held up through the freeze/thaw of a northern winter.
Great video...always learn something...concrete rules
Thank you!
I plan on dry pouring a shed floor. Not a lot of weight on it, and it won't have to support vehicle travel. For this purpose, seems like a great and cost saving idea. Thanks for the info.
I appreciate it, professor. I like it. It is far too simple to manufacture. The way concrete is mixed will alter as a result.
Thanks!
I do this for my backyard floor... I mix cement with sand manualy and spread to form pour water on it, and for surface i use cement paste... Its done with no need mixer and less effort compare with wet mixing...
Thanks for the note!
Very kind delivery. So this method is not to be used for structural concrete, but has its place.
Yes!
👍KEEP UP THE GOOD WORK
Thanks!
Hey Tyler, thanks for the amazing video. I can't wait to see your experiments with dry pour. Let me ask: I have near zero experience with concrete, and I'm in a project of building myself a 28x16 concrete slab for a patio and cover it with a pergola and polycarbonate sheets. Since I don't have experience, I'm thinking in pouring it dry for simplicity. I have already excavated a little bit and put gravel. Next steps are leveling the gravel, build the mold and pour. So, I'm thinking about what would be the easiest-sill-good-enough way of fixing the pergola posts. Here are the options I'm thinking about: 1) just put the post holders into the dry concrete and let it be fixed when soaking the concrete. 2) fix the posts afterwards by drilling into the concrete. 3) dig deeper holes for the posts and use wet concrete or even expandable foam to fix them. Am I being too optimistic in thinking this would work? What would be good options? Any additional advice would be appreciated. Thanks again!
I need a slab to park my trailer on when it's not being used. It's a 5 x 8. Could a dry pour work or should I use a mixing type?
Has your lab ever tested the strength of dry pour vs wet pour?
Not yet but we will!
@@TylerLey I'm across the water in Ireland and I'd love to hear from a concrete expert about other brands of pre-mix rapid set concrete apart from Quikrete.
K-Post, Blue Circle, Kilsaran K-Pro to name a few that are available here and in the UK.
There's a video out that says about 70% which is higher than the guy doing expected.
haha, I guess I've been waiting for this video since I learned about dry laid concrete
Thanks for watching!
In terms of the dragon scales or star wars inscriptions. At what point in the anti-chicken process do you think of doing it?
Understandibly, a repeating pattern like the dragon scales can be quickly stamped on with a normal pour.
Hand writing stuff, or striking with like a stick,You can't really do it dry because the dry mix will push out of the groves, and create weird lips.
Do you do it after the first or second mist?
I would do it before misting. If the aggregate from the dry pour is causing problems with your marks then you might need to run the top 1/4" of the bag of concrete through a sieve.
Thanks. Would it be possible for you to do experiment between dry and wet pour and measure the pressure to failure with hydraulic jacks. I assume the 2 are not even close.
Yes! Stay tuned for that!
They do use a sander to vibrate the forms that have the 2x4s
Any idea when you'll have some test results please? I'm thinking about dry pouring a small slab to put a pizza oven on and dry pour would be heaps easier for me. But i would be keen to see what your tests show before I decide!
can you make dry-pour test cylinders and crush them please? i need to know the psi grade compared to what the wet mix of 3500psi sakrete. can you test a 8"-12" thick footing that is dry-poured 40"-50" below grade, left for 28 days and dug up again?
everyone is testing the dry pour slabs that are misted every 1h, but what about dry mix that is just in contact with soil and left for a while. there's got to be a difference.
I am thinking of using the dry pour method with a paver form to make a walkway. It seems to me I could either make an outside sides form with wood for the entire length, fill it with dry concrete, spray it with water then stamp the whole thing with the mold form to make the pattern OR just dry pour each one in the mold form without the wood sides, but what about the form release without the sides falling out? I would think if you got the top wet, the side would not be the first time, but if you did many spray / wait cycles the mold might not release from the part of the concrete that is now hardened? Is there way to do this with just the mold form for each paver? Is that something you could test?
Use a mold made of plastic or latex. You could also use plastic or saran wrap around the mold.
Thanks, I was not sure if 'dry pour' would get stuck in the mold since the top sections would harden by the time the bottom would be wet. If one put plastic or saran wrap around the mold I would think the sides would release but I still wonder if the hardened top might jam the mold from being removed? @@TylerLey
Hi Tyler.
You are the one person to be a little more scientific in this discussion.
Do some compression testing of samples and the adhesion to the rebar.
I have done plenty of dry pours for small things over the years.
But I normally do half the level, saturate quite well then rebar mesh then dry mix over the top.
Not sure the finished surface is hard enough, or compact enough.
Cheers from Oz
Thanks!
We will try that coming up!
Not a huge fan of dry-pour concrete but if you’re a DIY’er doing a new a/c pad or a dog house pad or maybe even a small back yard patio, it may have some useful applications. But if there is any chance whatsoever of a possible concrete failure leading directly or even indirectly to any kind of life/safety concerns, it should not be considered for use.
Nice
Thank you!
If water curing for 1 month was added it might improve the recipe and make it stronger... so I think this works better down in Louisiana where it rained on their slabs right after they were done vs in a place where it did not rain or it was very hot right after they completed the process.
We tried it! New video is coming where we share the results.
What is the Professor's opinion on "Dry Cast" Concrete as used in the Concrete Pipe Manufacturing Plants?
It can be great! it all depends on what properties you want.
@@TylerLey -- THANK YOU Sir! The most important property we would need is ZERO SLUMP.
Is the addition of Water Reducing Admixtures (with very little water) what separates Dry Cast from Dry Mix (with absolutely NO water added to the Mix?).
Do a video about autoclaved aerated concrete and see your viewing figures in Britain go through the roof!
I would like to see a video on AAC as well. Is AAC common in England? In the Western US it has to be special ordered and shipped from Mexico or Florida. It would be nice to be able to pick it up locally.
Thanks! i will see what I can do.
I agree. It is not common in the US. It requires a lot of energy.@@honeytubs
Since this is another way to sell bags of concrete, I would think the folks at Quicrete would be doing all sorts of experimentation to make dry pour concrete more of an accepted practice.
I like my brownies w aggregate lol j/k
Have you done a dry pour and strength test? There was a lot of “I don’t know” comments in video.
I’d really like to know and put this to sleep once and for all.
Conceptually it seems like dry pour could be stronger w a typical DIYer since it’s not oversaturated (as most DIYers wet mix is way too wet and weak).
Please test and report! Would be a great video! 👍
Dry pour will never replace a nicely finished professional pour IMO.
Something i have wanted to know for many years is how much water it takes to change an average interior slab mix from a 4" slump to a 6" and if that is a significant change in the water to cement ratio
All in all , seems a bit easier to just add water?
Interesting
Thanks!
I saw your name on ACI report: Guide to Durable Concrete, was that you?
Mike Haduck showed all those points you mentioned and why he would not recommend dry pour, no big deal.
I recently placed a 14'x6' slab as an extension for an outdoor kitchen using the dry pour method. My yard slopes quite a bit and ended up using 87 60lb bags. I compacted the bottom half, added rebar, then filled almost to the top of the forms with the concrete mix, compacted again, then topped with just a sand mix. Way overthought it! Compacting and adding more on top made the layers not bond to each other as good, so I had some areas of delamination on the top with a couple of ugly holes opening up just using pressure from a water hose. This morning I ground off the loose material from the top and tomorrow will patch the holes with CementAll, then put a layer of NewCrete over the entire surface. But I could be overthinking this, too.
My next project will be mixed using portland cement and supersacks of fine and coarse aggregates along with a superplasticizer/retardant additive. No more dry pour for me. Great to see this and your other videos. If I wasn't so old and lived so far away, I'd love to sit through some of your classes at OSU.
Thank you for the comments! Sorry to hear you didn't have good success with it but that is how we learn.
Let me know how your next project goes and would love to catch up with you at some point!
Sounds like you modified the process. I have yet to do a dry pour, but plan to as my project is impossible for a truck to get to and I don't want to be tied to the timeline and manpower required to mix on-sight. I will definitely learn from this.
In the Philippines, I have never seen any premix concrete bags for sale. We would still need a mixer to mix sand, gravel and cement. Additionally we could not store the premix as the sand is always wet. Therefore we would have none of the advantages and we practically cannot even try it out.
If you compacted the dry concrete prior to screening and spraying, I can't think that the overall density/composition would be all that different from a wet pour. Obviously it would need to be tested, but I'd be shocked if there was a detectable difference in compression or shear strength beyond ~10%.
How about a video on Rammed Earth? or stabilized rammed earth? (aka the kind with cement in it). Also, at 5:00 he's standing on epoxy coated rebar. The SHAME!!!!
Rammed earth is a good idea. Let me see what I can dig up. =)
Totally right about the epoxy rebar.
Just started watching this video, looking forward to your opinion. The whole idea sounds wrong to me but that why I’m watching. Edit: Having watched the video, guess I’m a Mandalorian.
hehehehe
I totally understand. I would do it the old way as well.
Can a person use fiberglass rods instead of rebar to extend the life of concrete?
Maybe even a bag of fiber reinforced mix..? Rebar would probably create more voids, and the added complexity would be better applied to more traditional methods. I could add nuts to the betty crocker brownies, but beyond that I might be diminishing the convenience benefits of using a boxed product. At some point, there is greater benefit to using traditional "wet" methods.
Ti Ylin world famous Chinese bridge engineer uses Bamboo as rebar in China for decades on large projects .
You can in certain applications.
@@fargley001 I would be worried about how well the dry mix bonds to it.
@@MitzvosGolem1 TY Lin is one of my heroes. I love his work.
Your preface set the entire point: dry pour is for small, lightly loaded applications.
Truth!!! Just like bringing box brownies to an office party! Thanks for watching!
saw a guy do some informal testing, driving his car on different slabs and smashing then with hammers and stuff. seemed like it held up the same as anyone watching could tell
We are working on a new video for this. I was really surprised (in a bad way) about how the dry pour performed.
The part you thought was "texturing with a paint roller" is somewhat texturing but is part of the Cajun Couple's patented part of the "striking process." If you fail to paint roll it with the fluffy paint roller you will have a rough, bumpy and rocky surface. Also, dry pour concrete probably must be done in a fairly humid environment as it cures from the other side via the wet/damp ground (Louisiana.) Otherwise, it will probably take much longer for the concrete properly cure. I would use reinforcing of some kind fiber mesh, wire / wire mesh or rebar and some method to reinforce the corners. Best regards.🖌🛼
Question : if i move to the east coast of Mexico - will my ICC certs or ACI certs mean anything over there??
Aci: concrete
Icc : soils
Reinforced masonry
Reinforced Concrete
Steel & bolting
Etc
Anyone have any knowledge of this industry from our southern brother ?
It can. It depends on which projects you work on and what requirements they have for their quality control technicians. I think it will help on high end projects.
Sounds sort of similar to those bags of premix for setting posts and with all that time to hydrate it also seems a complete waste of time compared to how must faster it is mix it up conventionally.
I think it depends on the size of the project. Some people get overwhelmed by the labor and if they are "doing it right".
I make all my cakes this way , I put the ingredients in the pans, sprinkle a little water, and put them in the oven.
They rise and bake up firm and moist.
No, they don’t. It’s a cooked egg in the middle of dry mix.
Like I said elsewhere, like pouring a mold full of plastic resin and just spraying some hardener on the top . It should cure completely.
So if I dry pour my concrete it will not taste good but if I mix my concrete it will be delicious
I watch your videos at 1.75 times speed.
Its much funnier.
Quicker to mix it with water
Really cheap out: Mix pure cement into the top of a rocked surface (like class II base rock) with a rake. Did that for the chicken coop and run area. Smooth, easy to clean, and can't keep the chickens off of it.
That is like stabilized soil. I agree that can be awesome in some applications.
Go chickens!
Check out Mike Haduck, he did a small scale experiment with a small slab where he used dry pour and wet pour. there is no comparison. Don't do dry pours ya lazy bums
I really liked his video.
It has its place. An intermediate surface between gravel and concrete. Great for my bike shed.
Thanks! I wouldn't make anything out of it that I needed to last long term. It will be fun to do our tests on it and compare the results.
I think it's just stupid. Thats what I think
I get it =)
Anyone not mixing their concrete should be forced to do the same with their oatmeal in the morning ... while watching Disney's Star Wars.
hehehe
I havn't tried that one yet.
No matter the type of pour, PPE should always come first and a plan for it’s use (preparation is everything). What grade do you think the Oklahoma State Medical School would give the couple from Louisiana for health and safety ? 👨⚕️🤔.
Lol! “I think dry pour concrete has its place”. That’s good! Because concrete IS “placed”, not “poured” ;)
Ha! It depends on who you ask. =)
mmmmm
It’s great for small jobs. Ironically small jobs are easy to mix so why wouldn’t you? It just seems pointless. Plus how you finish the surface can affect the durability. This is a tik tok fad, a hack that leaves you with an inferior product.
I think it may have its place.
@@TylerLey I was really hoping you’d get into the science of this, I get your hesitation to write it off. A lot of people are intimidated by concrete and this allows them to possibly save money and do it their selves. But you of all people understand how concrete works,it’d be nice if you told us what you really think.
It's a shit poor idea. It's a weaker pour. If half ass is what your looking for. Then go for it.
All you diy guys: do this method for an AC pad because by the time you need to replace the AC unit you will also need to replace the pad. Dry pour does not hold up to weather. It delaminates the surface and then will just fall apart. Sacked concrete in bags has usually been stored poorly allowing moisture to cause the cement to be weak. If you want to make something that will last you have to do it the right way. Clean gravel, clean sand and new cement from a reputable supplier that has stored it properly. Follow the recipe and do the work. Take no shortcuts.
Thanks Parker,
That is what I would do if I was making one.
This is the stupidest explanation I’ve seen on RUclips