Slab tips - Pt 1 - how to build driveways, patios, house slabs, and roads.
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- Опубліковано 10 лип 2023
- This video gives useful tips for building slabs, driveways, patios, house slabs, and roads. It talks about how to decrease cracking and choose your slab thickness. This is part 1 of several videos.
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Thanks to Branson Edwards for editing this video and to Hailey Goodale for being the director of awesome. - Наука та технологія
Hi Tyler I'm commercial flooring installer. I love the videos. I've enjoyed learning how things go wrong in the pouring of concrete. Something to think about as in grinding and filling and leveling. Fixing concrete is about 60 % of my job
Awesome videos! I am going to use your advice, thank you for sharing!
I'm building a house and thanks to you and your videos, I have stronger, better concrete. I specified Fiber in all the concrete.
I have learned so much from your channel. The two layers of plastic makes sense. What do you do if you flatwork is on a slope and it’s long? Footing at the top and bottom?
A good one for professor Ley to answer..
Thanks for the question! You can try and anchor it to something else like another slab or you can toe it into the ground by building a footing. The footing doesn't have to be that large. Sometimes you just can't do this and plastic is not a good choice. You can put it on sand and that is a nice inbetween.
Two sheets of plastic instead of one is one of those genius insights that seems so obvious in hindsight, but I was under the impression that we put mesh in slabs to prevent such cracking?
Mesh doesn't prevent cracks, it keeps the cracks smaller if they are in the right place. More on that in Vol 2.
waiting for part 2 and please make sure that you address the edge loading/cracking issue. 👍🙏👷
Thanks! What specifically do you want to know? Typically, we need special designs for edge loading.
Thank you so much, Mr. Tyler.
Thank you for watching!
I didn't know u were back to full time uploads again, dope. One of my subs told me u were and he knew I was a fan
Thank you Tyler, always spot on
Thanks so much!
Welcome back after a Long time🎉
I love your videos Tyler!!
As a concrete finisher, I always appreciate engineering and science behind mix design. However every time we use a water reducer, for some reason, it becomes way harder to finish. Gritty, and harder to work cream to fill holes. Not sure why, but it seems to always happen.
I’ve noticed the same thing too. We use it in the south because it’s so hot.
Thanks! Not all water reducers are created equal! Some wear off over time and this may be what you are seeing. The more expensive products often last longer. That could be something to look into. I have done a lot of slabs with pretty heavy water reducer dosages and they finish well.
@@TylerLey I love your channel by the way…. I’ve learned a lot from you.
It’s because there isn’t much water in it. So it doesn’t behave like normal concrete. It does have a weird texture to it.
Sometimes superplasticizers can make the concrete a bit "sticky" - giving you the finishing experience you describe here. It usually means that you've used too much superplasticizer and there is not enough water in the mix to get the "smoothability" you need. But you also don't want to add too much water to the mix, so we usually say "split the difference" (i.e. adding a few fewer bags of superplasticizer and a few more gallons of water). This will help you maintain the strength of the mix, and also get the finish you want.
Brilliant video!
The material is great for the GC test. Your enthusiasm is fantastic.
Music to my ears, I have read about SOG from a PCA publishing. I really love the way you illustrated the design procedure after connecting the dots with that publishing.
Have you ever thought about the fact that we as people have deciding we're too good to walk on the ground😂 I find that hilarious
More slab videos please! Very interested in learning about flatwork concrete
What do you want to learn more about? There are so many things that I could talk about.
@@TylerLey I would like to learn things that would help flatwork contractors deliver a better product, such as your explanation on how to minimize restraint. 😊
Thank you so much, you make concrete design so interesting and fun, God bless you! Have a blessed and wonderful day!
Such great information. Thank you. What about edge beams on slabs, even in the middle?
Dear Dr. Ley, I am your big fan and followed from very beginning. For quite a time, I engaged with "tarantula curve" & " coarseness factor chart" [shilstone chart], with my own created intrument, let the specimens for shrinkage test ASTM C157 lay down in flat for measuring of each ages of concrete shrinkage.
I collected over 60 records and over 40 of them with 360-day records. From this I can tell you, your experiments of aggregate optimizing is excellent right, conbined with Shilstone chart give me confidinece of my mix design.
Regards, Billy Liao from Taiwan
Thank you Billy! It is great to hear from you and I am excited to meet up again!!!
thanks for the info about the two layer of plastic. we had a slab done over the top of an existing slab and it had massive amounts of shrinkage cracks. i suspect the concrete co added extra water to make it easier to finish. the slab got epoxy coated, but the epoxy has cracked where the concrete cracks are.
i've used plasticizer when we replaced some concrete work a builder screwed up and it works very well. had to make some high strength concrete to handle forklifts.
Thanks for sharing! I am glad the plasticizer worked well for you.
Thanks, Tyler!
Thank you!
Concrete is never "easy" but it seems easier now by far. Schwing pumps on ever big job, no more disturbing the base with scoot-crete buggies or bobcats. All the wire is placed before the pour. HRWRs available at most batch plants so it pumps easy. On hot, windy days, getting it down fast with no hot loads waiting in the sun seemed like the most important thing. If we could get a bull float on it and slick it down, we usually had good results. Hot loads killed the crew, slowed things down and pissed off the batch plant so we would get interruptions in delivery and cold joints.
I agree! I think the industry is getting better. Let's keep the momentum going. I think people are learning a lot.
I got hung up on one detail early on in the video and hoping you might explain where my thought process is off: You mention the loads are more critical at the edges because there is less soil/sub grade support at the edge, but I was under the impression that what’s changing is not the soil conditions (which ideally should be consistent across the site) but instead at the edges and corners you have less concrete to support the point of load application and distribute it throughout the pavement? That’s why corner loading is always the highest stress - it has only one quadrant through which to redistribute stress vs 2 for edge loading and 4 for interior loading. But I’m mostly self-taught on this, so if I’m wrong I’d love to be corrected! Also, and maybe this is already in the part 2 video, but if not, I’d love to learn more about using thickened edges on pavements to manage some of that stress. I’ve seen them but I haven’t seen much regarding when and where to use them. Lastly, it’d be wonderful to have a discussion about the interplay between the structural design of pavements and the materials design. Most of the resources I’ve found treat them completely separately, but like everything else with concrete, this is a system and we should take a more wholistic approach to thinking through how to optimize the design. 😊 thanks for another great video!
You got it right. Technically there is less subsoil support because of what you describe.
Thanks for the comment! It looks like I need to add more discussion about the edge loading. There are lots of reasons that edge loading is bad. There is less concrete and foundation to distribute the load and the slab may curl from drying and so it may not be in contact with the soil. That will have to wait until vol 3.
There is interplay between strength and thickness of the slab but this is pretty complicated. People use finite element models or fancy design software to handle this. This is tough to get across in a UA-cam video but I will think about the best way. Thanks for the question!
you the king!
This is great! Im planning to build a 5x6x1ft slab on standoffs the application will be used as an anker for load/stress testing applications. Trying to get as many tips for a proper long lasting construction. Thanks
Awesome thanks for the info looking forward to park 2
Thank you!!!
@@TylerLey Thank you!would you be able to make a video sharing any information on Dry Pouring concrete your thoughts,, insight on strength potential,, can it be as strong as traditional wet pour,,, insight on pros and cons,,any science behind the Dry pour method,, potential strength and weakness of this method,Thank you!
You rock!
Awesome!
Thanks!
Thank you another video! You are great and your videos are really informative. You may want to look into getting an audio engineer for your videos, the sound is a bit low.
Thanks! I will let my editor know. I don't think this was an issue in the past.
Interesting. I haventbtried your method yet but am sure I will try it.
Awesome! Let me know how it goes.
I was going to say that a layer of sand might also reduce friction but I was thinking smooth precast slabs, but since cracks come mainly from drying shrinkage it defies the purpose. Thanks for the neurons stimulating video.
Pat - sand can work but the plastic is usually cheaper and easier. I have measured moisture at the bottom of slabs with an embedded gauge and I don't see them dry at the bottom. I only see them dry from the top. Take care!
Extraordinary informational video.
Couple questions.
1- could you please explain what it means 6” Slump?
2- 564 lbs. total cementisius materials?
Thanks!
1. Slump is a measurement of the flow of the concrete. You should look at some videos on it to learn more. You need a pretty flowable concrete for some applications and 6" is a good estimate of this.
2. this is how much cement + fly ash or slag that is in the mix per cubic yard. I have other videos about mix design that could help you learn more about this.
I learned tons from your videos and im now doing a catchup, but im soecifically after your take on the "self healing" properties that seem to be caused by "improper mixing" in the roman concretes and whether unsllaked quicklime pockets might be incorporated to reproduce this property?
Is there an optimimum size for those clasts?
How to incorporatevthem?
I was thinking nano encapsulation?, preprepared sizes of embedded clasts.
The seawater cure effect is fascinating as ive for some reason decided to try to design a concrete boat/barge using basalt fibre concrete mix.
Thanks!
Self healing is something that people have studied for a long time. There has been lime mortar concretes for a long time. This is where lime is added to the cement. There are good things about it but it is not widely used because the lime pockets are porous and they allow outside chemicals to readily penetrate the concrete. I guess I need to make a video about this because lots of people ask about it. In short, I wouldn't use lime added to concrete to try and self heal it. I would just try and stop the cracks in the first place or keep them small.
@@TylerLey my design has changed somewhat ,the clast infused self healing properties seem to be rather specific to seawater exposure, somewhere you know thaose cracks are to settle under only exposure to salted water. Such as a seawall.
In fact quite specifically a seawall or caisson.
Ironically the thing that makes it better than modern concrete in many ways is the one thing that prevents its use in the modern world.
One diesel spill on the dock and the entire wall could be history....
My design has changed somewhat as well, the concrete (probably sika waterproof concrete blend or other propietary blend? A video on that stuff perhaos? )embedded with basalt rebar and mesh will be a large ballast plate, hull base but with hdpe upper hull.
Thinking budget houseboat, fooating home
And i suspect the entire endeavour wont make make it off paper anyway!
But a floating sea home?
Protected by paint too. Regulalrly maintained?
Some sefarers swear by concrete sailing vessels, the spread weight keeps them very stable in choppy waters but they die of concrete cancer pretty fast, seawater rebar and a few bumps here or there they begin to crumble away.
There are mumblings out there about people using basalt rebar in boats but its mostly stationary pontoons.
In the 1st world war the british built a series of concrete narrowboats, soon pit out of service due to cracking.
One sits in a museum repaired in london.
This and the concrete dday pontoon that sits sunk out off out the coast of britain that got stuck before the landings is still there and aolid as a rock.
Git me thinking if a cincrete boat could actually be made that could cope with actually moving through the british canal network.
A new steel hull is both very expensive and time consuming andbresource heavy to create.
How would it cope if you hung it up on a lock. Which is your worst case scenario.
Oerhpas a history of marine cinctete video incorporating the roman self healing stuff?
Ive written half the trivia inserts for you already...thank you for the reply.
I keep trying to makebthe answer be concrete i promise, last time i qas viewing your videos i was trying to think of cheap mould making material for carbon layup. The answer wasnt concrete then either...
Wasnt HDPE either ...
Thats a huge revalation that this foray into marine engineering taught me this time.
Old wheelie bins will replace epoxy.
Its recyclable, tough as all hell, self healing to a point, self lubricating, and weldable.
A plastic narrowboat already exists, they used a steel skeleton but in genuinely think a big reinforced concrete tub would be far better and solve a ballast , balance and insulation problems in one fell swoop.
What about 2 inches compacted 3/4 minus really wet down well before casting? I would imagine that the restraint is high because it’s gripping a whole layer of angular rock below it for stability. We definitely cut it up well and usually it’s cold out so the surface cracks are t even too much of a problem. I’ve found no matter what direct sunlight over 70 degrees destroys the paste shell more than any other factor lol
That is called open graded base. It provides a lot of restraint and typically causes surface cracking. You should try some plastic and see what happens.
@@TylerLey it never hurts to try! Thanks for the advice man
Thanks for another excellent video. Could you provide some ball-park numbers regarding how much the concrete shrinks while curing/drying. (mm shrink / linear m)
It depends on the concrete but a good estimate is about 1/16"/10' or 1.6 mm/ 3m. You can reduce this by about 20% with a low paste volume or you can increase it by 20% with a high paste volume.
@@TylerLey Thank you.
I recently saw a Video about a Professor of Geotechnical Engineering (Civil Engineering) Lecturing his Class on Conçrete with Rebar or Wire Mesh.
He made the comment that he didn't like using Wire Mesh as a Substitute for Rebar because Wire Mesh was nothing more than "Temp or Temperature" Steel. QUESTION: What did he meany by that Please?
He had worked on a lot of "Big Jobs" such as Water Reservoir Dams VERSUS Concrete Slabs for Houses.
Excellent explanation. What is your opinion on the "Dry Pour Concrete Slab On Grade" topics on UA-cam? Thanks.
Thanks! It depends on what you want to do and how long you want it to last. I guess I need to make a video about it. =)
@Tyler Ley, I’ll be pouring a footing for a deck in one pour and the post column in another pour. GFRP for the column will be installed as part of the first pour. Should I stick 2 layers of 6 mil plastic between the two pours to help prevent cracking at the base of of column?
No, you shouldn't get cracking unless it is a large flat element like a slab. You may want to put in extra rebar at the corners of the column. Watch Vol 2 for more insight into this.
I want to watch an episode on underground/below grade concrete and the best way to waterproof in freeze that areas.
Xypex in the mix which is expensive or you spray it on. Spray on products are endless. Peal and stick is an option also.
@@sparksmcgee6641 I agree. Most people go with spray on epoxies.
Tyler here in Alaska we put styrofoam under our slabs. I would like to see a video talking about that
Do you have a source/reference/paper for the use of 2 layers of 6 mil poly to reduce restraint and shrinkage cracking? It may be hard to convince other engineers/contractors to do this without evidence. My brief google search is coming up with nothing. Thanks.
Similar question . If I am using subslab rigid foam insulation on top of good gravel base, , then lay a single sheet of poly over it , probably no benefit for the second layer of poly?
@@johnwhite2576 Maybe if your base is even more perfect, you get even less cracking? Base=smooth and even thickness + 2 layers of 6 mil poly without wrinkles = less restraints and even less cracking? Expect more cracking with sloppy work than with top notch efforts? Never do a better job than what you can get away with?
Tyler, do you have a video on how to repair suspended slab from fissures and avoid water through.
That is coming but you will have to wait a little. We have some really cool research that we have done on it.
@@TylerLey Looking forward and thank you for the excellent content.
Is it advisabke to pour an 8 cm thick Reinforced stamped concrete slab on an existing 10 cm thick of an existing reinforced slab??
Thanks for the video 👍.So, are we concrete freaks or concrete maniacs 🤣🤣🤣
Both!!! Take care!
@@TylerLey bro, I love your videos and 👍
Thank you for the upload! I've seen metal wire grids that people use to reinforce slabs. I've used it in my project too. There is fiberglass mesh that is meant for dry wall. Is there a fiberglass mesh product for slabs? If not, why not? I know you can add lose fibers into the mix but I don't think that will do anything for slabs. And rebar can get pricey and kind of overkill for small projects...
loose fibers helps. he has a video on that.
@@tweake7175 Yes, I'm aware that it mitigates small cracks. But I'm sure it won't do anything for you if the ground erodes or shifts beneath the slab. My question was about methods of keeping the slab intact under severe duress aside from using rebar.
My other reply has disappeared. He has a video on frb, fibre based rebar.
You have rebar or high strength mixes, which cost more than rebar. I use micro rebar and rebar. The cost savings in that is labor. Micro rebarr cost $3-4 pound standard is less than $1 pound
@@SashaXXY Thanks! I cover this some in my Vol 2 video. I say in the video that you can use fibers to replace mesh and in some cases to replace rebar. If you expect the soil to errode under the slab then I would NOT replace rebar with fibers.
@Tyler Ley, I listened to two of your past videos, one on the importance of wet curing to improve strength and another on the negative effects of wet curing as it increases curling? How do you address this seemingly conflicting data on wet curing on roadways? Perhaps I missed some videos along the way so I apologize if you’ve already addressed this.
If you are in a place where you get severe drying (desert, southern California, high mountains, any place with an average RH about 50% or lower) then you need to be careful how long you wet cure. If you are not in those environments then it doesn't matter. If you are in those environments then limit your wet curing to about 3d. I have written papers about this that you can look up if you want. In summary, long term wet curing is not a problem in most locations but there are a few where it is.
@@TylerLey this comment made me drool.
Are there situations that cause a sloped slab to start walking, when it has been stable?
⭐️⭐️⭐️⭐️⭐️⭐️
Thanks!!!
What about elevated slabs any tips. Do you ever use double steel mesh instead of rebar?
You could use double steel mesh if you get enough reinforcing in them.
I am a big fan of low paste volume and fibers for elevated slabs. See Volume 2 for a little more on this.
I though plastic is for stopping moisture and it turns out it is for shrinkage 😲 But still does concrete need moisture from below or blocking it's even better?
Also, should we paint the patio slabs? How properly fix cracks?
Plastic can stop moisture as well but you don't need two layers of it to do that.
Moisture from below is bad. This can cause the slab to curl.
I would not paint concrete. I would just stain it.
I will cover cracks in another video. It depends on a lot of different stuff. We have some really cool research coming out on this soon.
Still waiting for your take on Graphene in Concrete...
The short answer is that the literature is all over the place about it. Some say it works and others say that it doesn't. There is something that we don't understand yet.
Does sand works instead of plastic or any other fine particulate material? Maybe a sand layer and top it off with lime or talc. would that work?
Yes, they will all work but they are typically more expensive then the plastic.
@@TylerLey thanks. Wanting to hear more about other restraint reducing techniques, also more about crack prevention and management in suspended slabs.
Have a good one Prof.
Thanks again.
Why Concrete roads (PQC) are saw cut ? what is the science nehind this exercise? Pls explain in detail
hey tyler how much sugar do i add to a 60lb bag of quickrete concrete ready mix if i want to use sugar as a plasticizer?
thanks for mentioning that, i did a read up on in it. basically the amount you use per bag of ready mix is extremely tiny. so tiny that you will most likely accidently use to much which then stuffs the concrete. its to much of a risk to use on small volumes, its really only useable if your doing truck sized volume and then the concrete plant will use the proper stuff so there is no point.
I wouldn't use any. It will put the concrete to sleep and it will take a few days to gain strength.
Do you have any moth balls? You can ground that up and add it to the concrete to make it a plasticizer. Be careful because if you add too much you will delay strength gain.
@@tweake7175 thanks for the responses. quikrete sds says each bag contains 10-30 percent portland cement by weight. so .3 x 60lb = 18lbs portland ... then .06 percent of 18 = 4.9grams sugar per 60lb bag... is this calculation correct? thanks
@@lobsta1124 thats sounds about right, but its a maximum. i would drop it back to 4 grams. if the bag has less cement then your in trouble, so you might best to use 3 grams. there is not much margin for error. worse thing is forgetting if you put it in or not.
i used a plasticizer from the concrete place and its rather forgiving even if you put in 10x to much it still works. i would check your diy stores, they may stock some.
I'm going to watch "Slab Tips 2"...electric boogaloo
Dance it up!!!
Wait! Concrete CURES versus dries. A chemical reaction. But I guess excess water has to dry
Thanks!
No plastic! I have a slab patio from 1954, 4" thick, grooved every ~4', on a decent bed of sand (I know because I just cut a section with a wetted diamond walk-behind blade). Slabs need to be on grade, that plastic will yes slide, keep the concrete 'sponge' from drying out both sides, is an unnecessary cost in money and time, and will degrade into a brittle fragmented mess when growing tree roots uplift the slab, and from sitting wet oxidizing and normal heating/cooling cycles.
Dr. Ley, why don't you say something about "dry pour" concrete slabs?
Because they're stupid. Low quality just to be lazy and not mix it.
I answered a comment about it in the "how to order ready mix concrete like a pro". I guess I need to make a video about it.
@@TylerLey If you would, I think it would help a lot of people. The many "How to", Dry Pour videos are... IMO... misleading people. The finish, compressive strength, and lastability, of Dry Pour, are all significantly inferior to "Mix and Place" concrete.
Any concrete geeks on here for hire? I need a concrete engineer.
I love it!
concrete is the most important building material this side of wood....
I am so glad we have wood to hold our concrete in place before it hardens. 😊
@@TylerLey
wood goes great on kitchen cabinets...