Hi tyler, i'm working in concrete and building industry since years and now i'm teaching concrete class in university. I'm really grateful for your job and knowledge. Greeting from chile.
I’m a precast concreter of 14 years, and I’m glad I’ve found your channel! Lately I’ve been working on wall sections for fertiliser sheds, and since I need to lift them by crane in a short time period I’ve been using a superplasticiser at low slump. This has been quite problematic in the onset of the Aussie summer months. Especially with hot winds and air temperature. (Im working undercover from sunlight). As I’d suspected, my attack plan to counter it would be wind breaks and to get it in first thing in the morning. You validated my decision, which eases my concerns. Sincerely. One more subscriber and fan! (Kyle).
Im a traffic flagger in the Seattle construction industry, I find your explanations of issues I have noticed much more informative than the cement truck drivers who sometimes have an answrr and sometimes I know more than them
Finally i am happy that i know the reason of shrinkage cracks. I have been working from last one year in the construction field and i desperately wanted to know the cause of this. I could not get any better explanation than this video. So thank you very much tyler. Love from india.
45 years ago in learning formwork from old-timers we would cover new concrete with plastic to reduce the initial evaporation, then when it was finished we did it again. Sometimes we laid a thick layer of straw on it to block wind, UV from sunlight, and slow the surface evaporation. Key to it was to leave it alone with the plastic and keep the straw moist for 3 days, then check to see how it looked. If dry you put the plastic back for 2-3 more days. If straw wet it more. Minimal surface cracking every time and now you cut- not form- control joints no more than 10' apart and 8' is better. Now they want to rush through the process; faster and cheaper run the world now. Time and money are the ruination of quality. You can't force things into submission, but you can work with them as they are and they'll then give you the results you want.
Oh yeah. Finishing large slabs for apartment buildings. They would crack as we were finishing them. Someone had the smart idea to add fiber mesh. But it didn't help. The solution is to not pour concrete on hot windy days. But, there's always a but. The contractor needs slabs poured to fulfill the contract. Like the old saying "make hay while the sun shines". As a concrete worker you had to make as much money as you can or you will starve in the winter.
Here in the hot summer, we sometimes "make hay" when the sun isn't shining by pouring larger slabs at night when the temps are cooler. Hard to find guys to work that schedule but they're out there and most of them appreciate working in the cool instead of the sun.
nebraska summers , hot and high humidity ,,., ranch basements are an oven,., crack as your finishing., at least we saw cut it., seen new basements in other states were they just let it spider out..//. ugh
Ya man I agree. Here in Wyoming it's hot dry and windy or snowy windy and freezing. We would have no concrete if we waited to pour. Tyler's videos have helped me understand the problems and how to address them. Thanks tyler
We frequently have extreme drying conditions. I have found that accelerating the mix is often the solution. It allows more of the water to hydrate before it evaporates, and quickly gets some tensile strength in the concrete. Caution: Be prepared. Tyler, next you need to do a video of outside power-trowelled slabs going "rubbery" during extreme drying conditions. This is a lesson that I need to explain over and over again every summer.
Fred, Thanks for the tip. I love hearing about what works in the field. Can you tell me more about the rubbery slabs? I need to better understand what you mean.
When power troweling a slab in extreme drying conditions, the slab will feel spongy or rubbery. The very surface of the slab loses paste due to absence of water, and a w/c gradient occurs going down into the first inch or so of the slab. The lower w/c in the top inch or two of slab will accelerate the set in the way that lower mix water always does. This results in a raft of semi-set concrete floating on a much more plastic base. The feel is identical too walking on the stamping pads used for embossing. Finishers end up working extra hard to trowel the paste-less surface while the floor is getting more and more wavy. As the thin already rigid top layer flexes, it will start cracking a lot and causing need for still more trowelling. If using riders, it is easy to have the rider suddenly drop through the surface and get buried. This is commonly first noticed around the second pass with the power trowel. Water is then usually dumped onto the slab to reduce the trowel friction/pull and to try to create paste. All theory aside, at this point, this is your only hope, but you will never fully recover. This situation is very much aggravated by pouring on poly, or using retarders in the mix to "help" you deal with the heat. The bulk of the damage is done by the evaporation happening while waiting for the first trowel. I strongly stress that replacement water needs to be almost constantly applied to the slab during this time. There is a way to do this carefully without churning water into the surface, but if guys are "too careful" it is easy to lose the evaporation battle. Evaporation retarders help, and some days are sufficient, but my experience is that they usually need to be mixed much stronger than label directions. If you have skilled crews, what I have found to be the simplest solution, is to use a hot or fast setting mix with enough set delay to allow for transport and placing time, and then have it go off. The finishers will be finished troweling before the slab has a chance to dry. Certainly, if you combine this with the above above mentioned practices, you can have very good results.
Fred - Thanks for the awesome response. You have more experience than I do about this. What you are saying makes sense. Because of the finishing, the surface is setting up before the bulk of the concrete. Let me think about this topic some more.
I've been finishing concrete since 98 and I use your videos as reference material to instruct new finishers, laborers and even the company owner( sometimes lol). Thank you for the videos that you make. I've learned quite a bit from you about the technical aspects of concrete.
Excellent insight! I rarely saw this until I started doing concrete in the Mideast. Too hot, too windy, low relative humidity and the cracks are coming. Everyone hates the words "plastic cracks" btw. They don't understand it. We mist them down, cover with wet burlap, cut them the next day and then pond them for a week.
We stopped using pozzolana because it caused such terrible shrinkage cracks later I realized reducing w/cm ratio could have reduced it. Thanks Dr Tyler this was 360 degrees
I like the idea of the paste being not to ratio to allow for the contraction... that is, typically, no stones or on the surface of those plastic shrinkage cracks... my experience... The paste being bought to the top with the mag trowel... evaporation and ratio of the paste to it's ''span'' (on the surface)... Thanks Tyler for your videos. Also, there is a cool app for the evaporation rate...
I think I understand what you are saying. I like your idea about the span between the stones. We are doing some research on this topic and we can try to look further into this. Thanks so much for the comment.
My great grandpa used to literally whitewash over these problems. He said the water helped keep it hydrated and the lime filled the smaller cracks and reflected heat. On really hot days it took several coats and the final product looked like a giant slab of limestone.
I’ve been watching several of your videos, gradation vids! Is there anyway you could cover like mixtures for desert specific, and humid specific cm. If ya had a vid that covered the basic recipe of concrete, might have missed it. But slacked lime, gypsum & ash\slag = cement/OPC? Still great vids, thanks. Learned a lot, 😝 lot more than I did cutting the slabs. Thanks.
Tyler, I have always wondered about new types of concrete that could include other materials. I've read recently about bioceramic building. It seems to be as much a political movement as an architectural and I'm not interested in living in an HOA Village so I won't be buying into their concept. But the idea of combining a ceramic product with cement seems like a win win. I do sculpture with a product called DAS Stone it is made by Fila group in Italy.. I use it to patch pots that chip. It air dries rock hard and so far holds up well outside. It is also much lighter than concrete and so far hasn't cracked. Like most clays it has some minor shrinkage and it is expensive, far too expensive to build a house with. I have no idea of the chemistry involved but given the bioceramic idea, there has to be a way to make a concrete that is stronger and lighter than what we currently have.
How about covering to avoid water evaporation ? Over here in France they cover it with plastic . I've seen concrete side walks covered with plastic for a few days.
So 2 questions. #1 wouldn't vibrating solve the issue of settlement cracking? #2 is something I've been wondering for some time. You've spoken about using burlap on horizontal surfaces 3 to 14 days to slow the rate of hydration, how would that work on say a placement that has been power trowled? It doesn't seem unlikely to affect the finish Thanks Tyler
I'm getting ready to build a form for a pillar for my patio roof. I think I have everything planned out properly, but there's on thing that I'm concerned about. How do i seal the bottom of the form? It's going to be poured directly onto the existing concrete of the patio, anchored with drilled rebar. But the way the form is shaped, I can see it will have upward pressure on the form. Obviously i can increase the weight i place on it, but I'm still concerned that there will not be a perfect seal at the bottom of the form, and i don't want an extra gap down there where i would have placed wood or something. I was thinking using some silicone sealant, or even large amounts of hot glue, to seal the bottom of the form to the existing concrete might work. Will that work? Is there a better way?
My concrete contractor experiences a much higher incident of plastic cracking when the slab is on a vapor barrier. His solution is an add mixture of GAF CRA 007. It seems to work but is very expensive at $38 a yard. The literature on the product makes me believe it is intended to prevent drying shrinkage cracks. I assume it helps the plastic cracking as the product might not evaporate as readily as water. Is there a better/less expensive solution and why does my contractor only experience the cracking when placing over a vapor barrier. Thanks. PS, my next pour will have fine plastic fiber and a wet cure but my contractor still wants to use the CRA 007.
I'm interested in concrete ponds but leakage from cracking is a concern.(without excessive thickness costs) Are there formulas to ensure low leakage when raw strength isn't a big concern, as the load is just evenly spread water not truck tires or above grade structure. I've heard of self healing mixes where they actually regrow crystals in fine cracks, and mixes that cure with no shrinkage to even being slightly expansive. Active reinforcement is not generally applicable due to the shapes and low thickness not to mention cost, [maybe with a cube like shape?] and of course mild reinforcing just limits the width of cracks, so I feel like non-reinforced concrete is the material to design around. It seems to me that a pond approximating a hemisphere would generally be under compression and avoid cracking but then there are other stressors and resulting strains like thermal and aging, even soil shifting. My local area has some mild freezing, but most lakes do not freeze over, January averages in the mid 30s and I don't recall seeing any freeze damage to local concrete slabs, curbs, blocks, etc., not even homeowner mixes.(clay bricks will flake if not under cover)
I had the opportunity to place concrete pavement in Las Vegas NV in the summer. 100 degrees + 10 percent humidity 25 mph wind - no wonder we had cracking problems... Contractor tore out three days work on I-15. I enjoy your videos.
Dear Tyler If we have a flat slab supported by columns and if the top and bottom rebar have equal area, then should we consider the shrinkage effect in considering deflection? Regards. Ahmad.
Hi, id like to ask the difference of drying shrinkage and plastic shrinkage. Ive read somewhere that drying shrinkage happens when there is a higher amount of water in cement:water ration. Is this correct? thank u!
I found a natural Spring under a Driveway that had complete compromised the concrete.. So we built a drain with pipe and covered it with gravel and then poured. The concrete cracked within a week, right on the corrogated pipe. I assumed that the air in the pipe made the soil a different temperature, and there for the concrete dried or cured at a different speed. Any ideas how to prevent this in the future?
Thanks for the message. I have been working on a video for fibers and I should be able to do one in the future. I am working on videos over concrete durability right now. =)
Thanks Tyler for great explanation. I am looking for articles/papers or any experimental works related to your explanation. Could you possibly share it if you have. A lots of thanks, Bhupendra
Hi, Tyler I have question what happens when the plastic settlement seen at the bottom of concrete, I raised a Non conformance report on inspection in a slab for this plastic settlement at bottom (because of formwork deformation) of slab but the contractor said it was because oiling of the metal plates and joint tapes so client has agreed with contractor. what is your opinion about this case? the picture which you have shown for plastic settlement , was exact what I have saw for the panel, but I guess it could because of missing of cover in that area also, Please help me to decide.
Yeah the reobars showed up on me the other day. I put it down to the concrete being too thin as I was trying to make the water drain in one direction, thus the concrete became too thin on one side and bang!! The bars are now seen popping the concrete. How do I fix it now???
SRAs reduce the surface tension of the water. This means when the pores empty there is less pull on the walls. It might be helpful to watch my videos over shrinkage cracking. You can find them here: th-cam.com/video/Qk5Ua81g6SA/w-d-xo.html
Was this the same thing that happened to me today? I definitely would say there was plastic cracking between loads, but I was getting bubbles rising to the top and forming blisters 32c2 1 hour retarder 5 % slag
Still I am not able to understand that when concrete particles shrinks . There will be a compression. it means particles comes closer for each other. Then how cracks will occur? since the concrete is good in compression
I have. Was confused about it but not now. I was pouting a patio here in windy dry wyoming over a hour from the plant. Using fiber reinforced concrete 3500 psi the truck showed up super wet like almost a 8 in slump. I told them to retard the mix for two hour. So we get it down floated and a early broom to make it rough do no slip for older people. Looking like rain. I go home 45mi. Round trip to get plastic when i come back all 7 yrds shrinkage cracks everywhere but still workable. So if get on it with a wood float. I know not best for exterior because it removes air. Bur rework it realy good with my father brooming behind me and it still good and strong 6 years later in Wyoming's extreme temperature swings
I had a slab done a couple of weeks ago from a reputable licensed concreter and paid full price and it has these plastic shrinkage cracks , not impressed tbh.
I would jokingly explain to my customers that I used a special type of concrete. It was made of Leaverite, which meant that at some point, I guarantee that it would crack somewhere. Secondly, that nobody would ever steal it. The reason was the Leaverite. That's because you leave er right there.
here is a real time example, PLANO TEXAS 1988, BATCH PLANT ON SITE , company from Iowa , amazing fast and efficient , hot summer months, i recommend sprinklers on course and fine aggregates keep absorption / flash set from happening, the whole boulevard alligator cracked , retarder and air too low also............ ......but that comapny would not listen to 19 year-old concrete expert lol from OSU lol, after huge meeting i was in spot light as ??? the HERO them the zero hahhaa solution same epoxy used in the Francisco earthquake , goes into thin as hair , stronger than concrete psi----- hater of poor speling , sorry disabled photographic brain full ride at OSU , academic lol-ssdi asorbtion 3.2 % sand then and 1.5% limstone, 105 degrees amibieant , mix 92 degree oh they added ice per my recommendation after the meeting all i recommended was done 0.0 problems
was inspector on stealth bomber for 2+ years site at WAFB, 25 employess under me ages 38 to 45 lol me 20 s early ahhahaa knowledge is power , unlimited budget heehheee got love the haters , brought my own crew i trained in dallas, every one i trained power hitter in ASTM , common sense inspections , real life testing not just lab fiction lol
what do u do when slump is 3 inch max on 8 ft x 12ft x 75 ft mono pour? in summer heat dry modified proctor ground , well not going to work with rebar 2.5 inches apart 1.5 in limestone..... nuke igloos too similar .... pours placements :) well its not ........?????? :) sensored for the pencil pushers lol, corp of engineers 5 years later heard my recomendation after modified protor not goinf to work on weatheread shale lol like sponge over time hydrauliclly lift the tiny 14 inch footing on 10 foot correction. got phone call inlaw suit, if u call me again will charge u 5000.00 usd this one is free lol go back in moblie lab last shelf is narrower than last , open it up if still got the trailer semi , yes, there was all my paper work soils samples, approvals for their screw up age 20+ winns lol dumb book following fools but JE Dunn loves me ahahhah
This is pathetic. The romans made concrete that has lasted over a thousand years, while our bridges need to be scrapped and totally replaced in 30 years. It's the self- serving bureaucracy and the profit- driven companies conspiring against you and I, John Q Taxpayer.
Hmm...I've been to Rome. I didn't see any concrete works the Romans built a thousand years ago that had hundreds of cars per hour, and 50 ton semis pounding over them all day every day. I guess I just missed them.
So now the cracking is caused by stress fatigue ? That's another factor ! Wish you'd have mentioned it before.... fact is, some of those Roman bridges and aqueducts are still in use today. All they did, was add volcanic ash to the mixture. That's a known fact, yet today's builders choose to add planned obsolescence instead, at my expense.
Pons Fabricius. 9Ponte Vecchio. 8Ponte Di Rialto. 7Khaju Bridge. 6Shaharah Bridge. 5Cendere Bridge. 4Anji Bridge. 3Ponte Sant'Angelo.....Roman concrete lasting and in use to this day, just Google it. Yet here in Pensacola FL we're building a new 3- mile bridge to replace it's predecessor, after only 30 years. And the new one, not yet finished, has already been exposed for shrinkage cracks. Why ? Profit- driven practices ! At your expense, Mr John Q Taxpayer.
I couldn't have mentioned it before, as that was my first response. I did check some of your examples, but I'm not sure why you used them. All of them are stone arch bridges or structures that maybe use concrete mortar. And the Anji Bridge is 100% stone, so I don't understand any of their relevance. Interestingly, I've been to a couple of your examples in our travels, they are brilliant examples of old world engineering and construction. The key to their longevity is as much related to well thought out geometric design as construction material. To your point, if you think that volcanic ash is the secret ingredient in concrete, it isn't. It`s not used today as volcanoes with commercial quantities of ash are hard to come by in North America, and the quality wouldn't be uniform anyway. Fly ash is used as a pozzolanic material instead as it has the same siliceous chemistry that adds strength and workability to concrete. You mention profit driven practices. All construction, be it highways and bridges, condos and houses, commercial buildings etc, is profit driven, it has to be. I imagine that when you go to work you take home a paycheck, so I guess you are profit driven too, at your employer's expense. I'm responding because I don't subscribe to the planned obsolescence conspiracy theory. Keep in mind that corruption in some builds is not an engineering failure. However, if you feel that bridges can normally and cost-effectively be constructed to last for 200 years of millions of car and truck crossings, corrosive salt applications or salt air, untold freeze thaw cycles, endless vibration, and remain standing while all those loads are on board during a magnitude 8 earthquake, then you've missed your engineering calling. Maybe you have the skills that others don't. Please, if you can find a concrete design bridge example as I just mentioned and as you seem to think is possible, anywhere in the world, just cite it, I`d love to see it. And no, I am not in any way involved in construction or the concrete industry.
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Hi tyler, i'm working in concrete and building industry since years and now i'm teaching concrete class in university.
I'm really grateful for your job and knowledge. Greeting from chile.
I’m a precast concreter of 14 years, and I’m glad I’ve found your channel!
Lately I’ve been working on wall sections for fertiliser sheds, and since I need to lift them by crane in a short time period I’ve been using a superplasticiser at low slump. This has been quite problematic in the onset of the Aussie summer months. Especially with hot winds and air temperature. (Im working undercover from sunlight). As I’d suspected, my attack plan to counter it would be wind breaks and to get it in first thing in the morning. You validated my decision, which eases my concerns.
Sincerely.
One more subscriber and fan! (Kyle).
Im a traffic flagger in the Seattle construction industry, I find your explanations of issues I have noticed much more informative than the cement truck drivers who sometimes have an answrr and sometimes I know more than them
Thanks so much!
Finally i am happy that i know the reason of shrinkage cracks. I have been working from last one year in the construction field and i desperately wanted to know the cause of this. I could not get any better explanation than this video. So thank you very much tyler. Love from india.
Thank Chintan!
I am glad the video helped. There are more videos about shrinkage coming but these occur after the concrete has hardened.
@@TylerLey yeah i got that
45 years ago in learning formwork from old-timers we would cover new concrete with plastic to reduce the initial evaporation, then when it was finished we did it again. Sometimes we laid a thick layer of straw on it to block wind, UV from sunlight, and slow the surface evaporation. Key to it was to leave it alone with the plastic and keep the straw moist for 3 days, then check to see how it looked. If dry you put the plastic back for 2-3 more days. If straw wet it more. Minimal surface cracking every time and now you cut- not form- control joints no more than 10' apart and 8' is better.
Now they want to rush through the process; faster and cheaper run the world now. Time and money are the ruination of quality. You can't force things into submission, but you can work with them as they are and they'll then give you the results you want.
I wouldn't want to trap bleed water with plastic before finishing, but I do like a nice water cure after it's all finished!
Summertime in AZ, the first trucks out began at 3:30 am. That was my first defense against cracking.
Oh yeah. Finishing large slabs for apartment buildings. They would crack as we were finishing them. Someone had the smart idea to add fiber mesh. But it didn't help. The solution is to not pour concrete on hot windy days. But, there's always a but. The contractor needs slabs poured to fulfill the contract. Like the old saying "make hay while the sun shines". As a concrete worker you had to make as much money as you can or you will starve in the winter.
Thanks Patrick!
Here in the hot summer, we sometimes "make hay" when the sun isn't shining by pouring larger slabs at night when the temps are cooler. Hard to find guys to work that schedule but they're out there and most of them appreciate working in the cool instead of the sun.
Pat Konelectric you crysy amigo...... chcahchacahcha
nebraska summers , hot and high humidity ,,., ranch basements are an oven,., crack as your finishing., at least we saw cut it., seen new basements in other states were they just let it spider out..//. ugh
Ya man I agree. Here in Wyoming it's hot dry and windy or snowy windy and freezing. We would have no concrete if we waited to pour. Tyler's videos have helped me understand the problems and how to address them. Thanks tyler
We frequently have extreme drying conditions. I have found that accelerating the mix is often the solution. It allows more of the water to hydrate before it evaporates, and quickly gets some tensile strength in the concrete. Caution: Be prepared.
Tyler, next you need to do a video of outside power-trowelled slabs going "rubbery" during extreme drying conditions. This is a lesson that I need to explain over and over again every summer.
Fred,
Thanks for the tip. I love hearing about what works in the field.
Can you tell me more about the rubbery slabs? I need to better understand what you mean.
When power troweling a slab in extreme drying conditions, the slab will feel spongy or rubbery. The very surface of the slab loses paste due to absence of water, and a w/c gradient occurs going down into the first inch or so of the slab. The lower w/c in the top inch or two of slab will accelerate the set in the way that lower mix water always does. This results in a raft of semi-set concrete floating on a much more plastic base. The feel is identical too walking on the stamping pads used for embossing.
Finishers end up working extra hard to trowel the paste-less surface while the floor is getting more and more wavy. As the thin already rigid top layer flexes, it will start cracking a lot and causing need for still more trowelling. If using riders, it is easy to have the rider suddenly drop through the surface and get buried.
This is commonly first noticed around the second pass with the power trowel. Water is then usually dumped onto the slab to reduce the trowel friction/pull and to try to create paste. All theory aside, at this point, this is your only hope, but you will never fully recover.
This situation is very much aggravated by pouring on poly, or using retarders in the mix to "help" you deal with the heat.
The bulk of the damage is done by the evaporation happening while waiting for the first trowel. I strongly stress that replacement water needs to be almost constantly applied to the slab during this time. There is a way to do this carefully without churning water into the surface, but if guys are "too careful" it is easy to lose the evaporation battle.
Evaporation retarders help, and some days are sufficient, but my experience is that they usually need to be mixed much stronger than label directions.
If you have skilled crews, what I have found to be the simplest solution, is to use a hot or fast setting mix with enough set delay to allow for transport and placing time, and then have it go off. The finishers will be finished troweling before the slab has a chance to dry. Certainly, if you combine this with the above above mentioned practices, you can have very good results.
Fred - Thanks for the awesome response. You have more experience than I do about this. What you are saying makes sense. Because of the finishing, the surface is setting up before the bulk of the concrete. Let me think about this topic some more.
My old roomie was a concrete batcher, did a lot of batching for interstate projects. I never knew concrete was so complex until he explained it to me
I've been finishing concrete since 98 and I use your videos as reference material to instruct new finishers, laborers and even the company owner( sometimes lol).
Thank you for the videos that you make. I've learned quite a bit from you about the technical aspects of concrete.
I just saw the case you mentioned regarding cracks over rebars.
Excellent insight! I rarely saw this until I started doing concrete in the Mideast. Too hot, too windy, low relative humidity and the cracks are coming. Everyone hates the words "plastic cracks" btw. They don't understand it. We mist them down, cover with wet burlap, cut them the next day and then pond them for a week.
Thanks Steven!
I agree that the term plastic is weird. I tried to explain it in the video.
I have no real plans with concrete, but I like learning material properties, and like your moxy!
Thanks so much!
so good to have an intellectual explain the processes of concrete! great job
Mister, I am so impressed with you. I'd wish to have such passionate teachers at school!
We stopped using pozzolana because it caused such terrible shrinkage cracks later I realized reducing w/cm ratio could have reduced it. Thanks Dr Tyler this was 360 degrees
Glad you like it!!!
The trick is finding the right amount of pozzolan plus water reducing admixture
I like the idea of the paste being not to ratio to allow for the contraction... that is, typically, no stones or on the surface of those plastic shrinkage cracks... my experience...
The paste being bought to the top with the mag trowel... evaporation and ratio of the paste to it's ''span'' (on the surface)... Thanks Tyler for your videos. Also, there is a cool app for the evaporation rate...
I think I understand what you are saying. I like your idea about the span between the stones. We are doing some research on this topic and we can try to look further into this. Thanks so much for the comment.
Well explained ! I do inspect Bridge decks and Concrete Pavement and this video is really helpful ! You explain concrete in a easy way !!
Thank you!!
Thank you A LOT for the detailed yet not-boring-to-listen kinda video!
Great and detailed explanation! A big thank you from Cape Town.
Thanks for watching!!!
Thank you Tyler for your explanation.
My great grandpa used to literally whitewash over these problems. He said the water helped keep it hydrated and the lime filled the smaller cracks and reflected heat. On really hot days it took several coats and the final product looked like a giant slab of limestone.
That sounds great.
This video cracks me up
I like his style. Very different
I’ve been watching several of your videos, gradation vids!
Is there anyway you could cover like mixtures for desert specific, and humid specific cm.
If ya had a vid that covered the basic recipe of concrete, might have missed it. But slacked lime, gypsum & ash\slag = cement/OPC?
Still great vids, thanks. Learned a lot, 😝 lot more than I did cutting the slabs. Thanks.
your way of explaining is amazing thank you soo much
Tyler, I have always wondered about new types of concrete that could include other materials. I've read recently about bioceramic building. It seems to be as much a political movement as an architectural and I'm not interested in living in an HOA Village so I won't be buying into their concept. But the idea of combining a ceramic product with cement seems like a win win. I do sculpture with a product called DAS Stone it is made by Fila group in Italy.. I use it to patch pots that chip. It air dries rock hard and so far holds up well outside. It is also much lighter than concrete and so far hasn't cracked. Like most clays it has some minor shrinkage and it is expensive, far too expensive to build a house with. I have no idea of the chemistry involved but given the bioceramic idea, there has to be a way to make a concrete that is stronger and lighter than what we currently have.
Thank you as a concrete finisher! Must know information.
How about covering to avoid water evaporation ?
Over here in France they cover it with plastic .
I've seen concrete side walks covered with plastic for a few days.
Really? Doesn't the water condensate inside of the plastic surface then?
@@sevvalkursun16 Yes, we want to prevent water to evaporate, plastic keeps the water in.
@@laurier3348 Yeah, it does keep water inside the plastic, but eventually water will condensate and pour down on the concrete again. Am I wrong?
@@sevvalkursun16 Yes and it is good that it pours down on the concrete again, isn't it ?
@@laurier3348 Oh, right!!! Lol, I just realized what a stupid qn I'm asking. Thanks for indulging tho! :D
That was a great explanation of the problems, implications, and mitigation! Subscribed!
Mr Tyler Ley,
if you don't mind, please share the references of your explanations on the videos. appreciate your great job.
So 2 questions. #1 wouldn't vibrating solve the issue of settlement cracking? #2 is something I've been wondering for some time. You've spoken about using burlap on horizontal surfaces 3 to 14 days to slow the rate of hydration, how would that work on say a placement that has been power trowled? It doesn't seem unlikely to affect the finish Thanks Tyler
Oh and soil stabilization sor the slab, you covered in one of the vids using PET sheets. Thanks.
Or if you or someone can point me to the correct vids
I'm getting ready to build a form for a pillar for my patio roof. I think I have everything planned out properly, but there's on thing that I'm concerned about. How do i seal the bottom of the form? It's going to be poured directly onto the existing concrete of the patio, anchored with drilled rebar. But the way the form is shaped, I can see it will have upward pressure on the form. Obviously i can increase the weight i place on it, but I'm still concerned that there will not be a perfect seal at the bottom of the form, and i don't want an extra gap down there where i would have placed wood or something.
I was thinking using some silicone sealant, or even large amounts of hot glue, to seal the bottom of the form to the existing concrete might work. Will that work? Is there a better way?
Is there any remedy of this problem or it will recommend for remove and replace?
Dear Tyler, could you please post some video regarding the response of rocket launch pad due to exhaust loading. thanks.
Should I be pouring concrete in the winter?
My concrete contractor experiences a much higher incident of plastic cracking when the slab is on a vapor barrier. His solution is an add mixture of GAF CRA 007. It seems to work but is very expensive at $38 a yard. The literature on the product makes me believe it is intended to prevent drying shrinkage cracks. I assume it helps the plastic cracking as the product might not evaporate as readily as water. Is there a better/less expensive solution and why does my contractor only experience the cracking when placing over a vapor barrier. Thanks.
PS, my next pour will have fine plastic fiber and a wet cure but my contractor still wants to use the CRA 007.
@Tyler Ley in hot climates 30+ degrees C what are your thoughts about adding ice to batch in place of water?
Yes you can close them up but even with machines alot of the time the open back up
Pls give insite on how much is optimum water+ Cement content needed
It is my favorite channels thank you sir
I'm interested in concrete ponds but leakage from cracking is a concern.(without excessive thickness costs) Are there formulas to ensure low leakage when raw strength isn't a big concern, as the load is just evenly spread water not truck tires or above grade structure. I've heard of self healing mixes where they actually regrow crystals in fine cracks, and mixes that cure with no shrinkage to even being slightly expansive.
Active reinforcement is not generally applicable due to the shapes and low thickness not to mention cost, [maybe with a cube like shape?] and of course mild reinforcing just limits the width of cracks, so I feel like non-reinforced concrete is the material to design around. It seems to me that a pond approximating a hemisphere would generally be under compression and avoid cracking but then there are other stressors and resulting strains like thermal and aging, even soil shifting.
My local area has some mild freezing, but most lakes do not freeze over, January averages in the mid 30s and I don't recall seeing any freeze damage to local concrete slabs, curbs, blocks, etc., not even homeowner mixes.(clay bricks will flake if not under cover)
I had the opportunity to place concrete pavement in Las Vegas NV in the summer. 100 degrees + 10 percent humidity 25 mph wind - no wonder we had cracking problems... Contractor tore out three days work on I-15. I enjoy your videos.
Thanks!
Dear Tyler
If we have a flat slab supported by columns and if the top and bottom rebar have equal area, then should we consider the shrinkage effect in considering deflection?
Regards.
Ahmad.
so what is the solution to stop or mend those pesky cracks? destroy and cement again the slab?
Thanks for the question
Check this video out!
th-cam.com/video/AXvWlMfQk_4/w-d-xo.html
Great work.
Can you u add recycle plastic to concrete . shredded motor oil to asphalt ?
Great video, thanks!
If you are patching a cement slab or don't need strength you can add a small amount of bentonite to the concrete,,no cracks will appear
hi I am new to your channel , can you discuss retrofitting works in concrete.
Hi, id like to ask the difference of drying shrinkage and plastic shrinkage. Ive read somewhere that drying shrinkage happens when there is a higher amount of water in cement:water ration. Is this correct? thank u!
I found a natural Spring under a Driveway that had complete compromised the concrete.. So we built a drain with pipe and covered it with gravel and then poured. The concrete cracked within a week, right on the corrogated pipe. I assumed that the air in the pipe made the soil a different temperature, and there for the concrete dried or cured at a different speed. Any ideas how to prevent this in the future?
I have totally seen the cracks in the grid pattern. But i didn't catch how to keep it from happenning.
Could you do a video on fiber mesh? Many people are under the misconception that it adds benefits after the concrete has hardened.
Thanks for the message. I have been working on a video for fibers and I should be able to do one in the future. I am working on videos over concrete durability right now. =)
I know it dose make it harder to clean your concrete mixers out. I seen were they made the ready mix guys mix it in their trucks because of this.
Thanks Tyler for great explanation. I am looking for articles/papers or any experimental works related to your explanation. Could you possibly share it if you have.
A lots of thanks,
Bhupendra
Hi, Tyler I have question what happens when the plastic settlement seen at the bottom of concrete, I raised a Non conformance report on inspection in a slab for this plastic settlement at bottom (because of formwork deformation) of slab but the contractor said it was because oiling of the metal plates and joint tapes so client has agreed with contractor. what is your opinion about this case?
the picture which you have shown for plastic settlement , was exact what I have saw for the panel, but I guess it could because of missing of cover in that area also, Please help me to decide.
Hi Tyler. have you considered the direct sunlight to prepare your graph? I'm from Sri Lanka and I have faced this problem.
Thanks.
U ear one subscriber. Plz upload more videos on cement and concrete science.
Yeah the reobars showed up on me the other day. I put it down to the concrete being too thin as I was trying to make the water drain in one direction, thus the concrete became too thin on one side and bang!! The bars are now seen popping the concrete. How do I fix it now???
Great Videos Dr.
Thank you very much.
Thanks so much!!!
What is the causes of transverse cracking of the concrete?
SEEK THE TRUTH
AMAZING !
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“Your Favorite gravy holiday “ !!! 😂 😂 😆
Why is that when I use concert to patch up wall holes, when dry it's powdery and kind of lose?
Sir,
Can you explain about shrinkage reducing admixture and it's mechanism??
SRAs reduce the surface tension of the water. This means when the pores empty there is less pull on the walls. It might be helpful to watch my videos over shrinkage cracking. You can find them here: th-cam.com/video/Qk5Ua81g6SA/w-d-xo.html
What a bout increasing concrete cover to avoid settlment cracks.
Good video.
Thank you for this.
Thanks for watching.
Was this the same thing that happened to me today? I definitely would say there was plastic cracking between loads, but I was getting bubbles rising to the top and forming blisters 32c2 1 hour retarder 5 % slag
Amazing!
In hot weather, add sugar water to the cement mortar, it will not crack
Still I am not able to understand that when concrete particles shrinks . There will be a compression. it means particles comes closer for each other. Then how cracks will occur?
since the concrete is good in compression
How about post-tension? cheers
Wow ,perfect bro...
Love this vid
briefly explained
I have. Was confused about it but not now. I was pouting a patio here in windy dry wyoming over a hour from the plant. Using fiber reinforced concrete 3500 psi the truck showed up super wet like almost a 8 in slump. I told them to retard the mix for two hour. So we get it down floated and a early broom to make it rough do no slip for older people. Looking like rain. I go home 45mi. Round trip to get plastic when i come back all 7 yrds shrinkage cracks everywhere but still workable. So if get on it with a wood float. I know not best for exterior because it removes air. Bur rework it realy good with my father brooming behind me and it still good and strong 6 years later in Wyoming's extreme temperature swings
Dr.: No mention of curing compound. Discuss 😀.
Got more from this
5:00 Did he read that graph completely wrong or ....like..... do i need to go back to school please someone respond i am very concerned.
Cooking is chemistry
Thanks sir
I've been waiting for a new video! Yay me!
Glad you like it!
why do my concrete cracks after 3 to 4 weeks?
I always wet the concrete several times for a day or two afterwards.
finally i got the answer from youtube, not in lesson....
Is nobody going to talk about that thumbnail?
I had a slab done a couple of weeks ago from a reputable licensed concreter and paid full price and it has these plastic shrinkage cracks , not impressed tbh.
What if one pours into an enclosed formwork?
That would really help. Anything that slows down the evaporation at the surface will help.
Freaking Awesome Mr,tyler thank you for this nice simple lecture < your Explanation more greater than mt teacher haha thanks
why is light levels in videos is needed, answer that 1
I am playing with a new lighting setup for the videos I am shooting this week. I hope they are better.
Duuuuuuuuude❤!
I would jokingly explain to my customers that I used a special type of concrete. It was made of Leaverite, which meant that at some point, I guarantee that it would crack somewhere. Secondly, that nobody would ever steal it. The reason was the Leaverite. That's because you leave er right there.
Think I’m firing my concrete guy
Hosea...quick no gringo s are looking ...add more water to the truck...Undalay reeeba
mitzvos Golem lol
here is a real time example, PLANO TEXAS 1988, BATCH PLANT ON SITE , company from Iowa , amazing fast and efficient , hot summer months, i recommend sprinklers on course and fine aggregates keep absorption / flash set from happening,
the whole boulevard alligator cracked , retarder and air too low also............
......but that comapny would not listen to 19 year-old concrete expert lol from OSU lol, after huge meeting i was in spot light as ??? the HERO them the zero hahhaa
solution same epoxy used in the Francisco earthquake , goes into thin as hair , stronger than concrete psi----- hater of poor speling , sorry disabled photographic brain full ride at OSU , academic lol-ssdi
asorbtion 3.2 % sand then and 1.5% limstone, 105 degrees amibieant , mix 92 degree
oh they added ice per my recommendation after the meeting all i recommended was done 0.0 problems
was inspector on stealth bomber for 2+ years site at WAFB, 25 employess under me ages 38 to 45 lol me 20 s early ahhahaa knowledge is power , unlimited budget heehheee got love the haters , brought my own crew i trained in dallas, every one i trained power hitter in ASTM , common sense inspections , real life testing not just lab fiction lol
what do u do when slump is 3 inch max on 8 ft x 12ft x 75 ft mono pour? in summer heat dry modified proctor ground , well not going to work with rebar 2.5 inches apart 1.5 in limestone..... nuke igloos too similar .... pours placements :) well its not ........?????? :) sensored for the pencil pushers lol,
corp of engineers 5 years later heard my recomendation after modified protor not goinf to work on weatheread shale lol
like sponge over time hydrauliclly lift the tiny 14 inch footing on 10 foot correction.
got phone call inlaw suit, if u call me again will charge u 5000.00 usd
this one is free lol
go back in moblie lab last shelf is narrower than last , open it up if still got the trailer semi , yes, there was all my paper work soils samples, approvals for their screw up age 20+ winns lol
dumb book following fools but
JE Dunn loves me ahahhah
This is pathetic. The romans made concrete that has lasted over a thousand years, while our bridges need to be scrapped and totally replaced in 30 years. It's the self- serving bureaucracy and the profit- driven companies conspiring against you and I, John Q Taxpayer.
Hmm...I've been to Rome. I didn't see any concrete works the Romans built a thousand years ago that had hundreds of cars per hour, and 50 ton semis pounding over them all day every day. I guess I just missed them.
So now the cracking is caused by stress fatigue ? That's another factor ! Wish you'd have mentioned it before.... fact is, some of those Roman bridges and aqueducts are still in use today. All they did, was add volcanic ash to the mixture. That's a known fact, yet today's builders choose to add planned obsolescence instead, at my expense.
Pons Fabricius. 9Ponte Vecchio. 8Ponte Di Rialto. 7Khaju Bridge. 6Shaharah Bridge. 5Cendere Bridge. 4Anji Bridge. 3Ponte Sant'Angelo.....Roman concrete lasting and in use to this day, just Google it. Yet here in Pensacola FL we're building a new 3- mile bridge to replace it's predecessor, after only 30 years. And the new one, not yet finished, has already been exposed for shrinkage cracks. Why ? Profit- driven practices ! At your expense, Mr John Q Taxpayer.
I couldn't have mentioned it before, as that was my first response.
I did check some of your examples, but I'm not sure why you used them. All of them are stone arch bridges or structures that maybe use concrete mortar. And the Anji Bridge is 100% stone, so I don't understand any of their relevance. Interestingly, I've been to a couple of your examples in our travels, they are brilliant examples of old world engineering and construction. The key to their longevity is as much related to well thought out geometric design as construction material.
To your point, if you think that volcanic ash is the secret ingredient in concrete, it isn't. It`s not used today as volcanoes with commercial quantities of ash are hard to come by in North America, and the quality wouldn't be uniform anyway. Fly ash is used as a pozzolanic material instead as it has the same siliceous chemistry that adds strength and workability to concrete.
You mention profit driven practices. All construction, be it highways and bridges, condos and houses, commercial buildings etc, is profit driven, it has to be. I imagine that when you go to work you take home a paycheck, so I guess you are profit driven too, at your employer's expense.
I'm responding because I don't subscribe to the planned obsolescence conspiracy theory. Keep in mind that corruption in some builds is not an engineering failure. However, if you feel that bridges can normally and cost-effectively be constructed to last for 200 years of millions of car and truck crossings, corrosive salt applications or salt air, untold freeze thaw cycles, endless vibration, and remain standing while all those loads are on board during a magnitude 8 earthquake, then you've missed your engineering calling. Maybe you have the skills that others don't.
Please, if you can find a concrete design bridge example as I just mentioned and as you seem to think is possible, anywhere in the world, just cite it, I`d love to see it.
And no, I am not in any way involved in construction or the concrete industry.
If our structures were to just stand there and not bear any loads our concrete would last just as long.