Mesh doesn't prevent cracks, it keeps the cracks smaller if they are in the right place. More on that in Vol 2.

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.

Thank you for watching!

Thanks! What specifically do you want to know? Typically, we need special designs for edge loading.

Thanks so much!

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.

I agree! I think the industry is getting better. Let's keep the momentum going. I think people are learning a lot.

Thank you!

Thanks!

Thanks for sharing! I am glad the plasticizer worked well for you.

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!

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 Billy! It is great to hear from you and I am excited to meet up again!!!

Awesome! Let me know how it goes.

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 KZfaq video but I will think about the best way. Thanks for the question!

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!

Thanks! I will let my editor know. I don't think this was an issue in the past.

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

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.

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.

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.

Thanks!!!

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.

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.

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.

Both!!! Take care!

@@TylerLey bro, I love your videos and 👍

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. =)

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.

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.

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?

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.

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.

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.

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.

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.

Dance it up!!!

Thanks!

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.

I love it!

I am so glad we have wood to hold our concrete in place before it hardens. 😊

@@TylerLey wood goes great on kitchen cabinets...