I've tested concrete before I discovered that driving a mixer was easier and paid better. There was a field test for air content that involved a pump and a gauge. When I first started this comment I though I'd forgotten how that was done, but after a minute or two the memory came back. Tyler Lee, I have yet to fully explore your RU-vid content. Have you done any on the field testing of concrete, as well as everybody's favorite, the break test performed with a hydraulic press in the lab? When I was doing it we were using molten sulfur to cap the sample cylinders, which were much larger than those I've seen used now. I'm now retired. Do you remember the killdozer that terrorized Granby, Colorado? I hired as a driver for Mountain Parks Concrete as they were rebuilding the parts of the plant Marvin destroyed. I've delivered concrete at -12 F. Amazing how fast water freezes at that temperature, even with hot water in mix and tank. When I was working I did not think delivering ready-mix was all that great a job, but looking back it is probably the best job I ever had. Especially since I was delivering to places in Grand County, Colorado, one of the loveliest places on the planet. I could tell you tales of concrete abuse, usually involving adding water to the mix, contractors request, so the five inch slump becomes a more workable seven or eight. This was during a luxury resort and vacation house building boom. Some contractors wanted to place quality concrete that lasts. Many simply did not seem to give a shit about that.
This all seems like common sense to me I've worked Concrete in many forms from forming pouring and finishing to demoing demo is where you really get to know the strength of your concrete's and cement . The need to get it down and get it finished so it can be used is the problem . Does not allow for natural cure time . Gives reason for the chemical cures . I don't know if things have changed but my day I learned the hardest concrete known to man or ever found was it the very bottom center up dams that were not forced to cure quickly but allowed to cure naturally . The toughest and hardest concrete I ever had to demo was the oldest concrete I've ever seen the footings and peers of the oldest Factory building I've ever been in . So hard using the Jackhammer was useless had to drill and use a hydraulic Rock splitter to remove them . from what was now being used as a showroom in what had been used as a basement for many years but originally built as a cistern . My Mentor in concrete when I met him had been working concrete for over 50 years . I'm just about the age he was when I met him now . You have to share studies he had followed and everything he had learned . He'd always say with concrete everyday you learn something new and I have found that very true . Very much the sample taker and studier of our biggest pores didn't worry much about the little ones . Always talking about his studies on Research done of core of the oldest dams . always very controlling with the moisture content when pouring always watching that shoot to make sure the mixture is mixed evenly not too dry not too wet . also while finishing never stepping on till just right and then always adding water, simply splashing it on with an old never used for anything else but splashing water tar brush . out of the same clean 5 gallon bucket and 2 and 1/2 gallon buckets that he'd been using since before I knew him . always promoting the importance of using the cleanest clearest water in finishing or pouring or curing your concrete . always tented every pore with plastic and cured for at least a week . tending to it 2 to 3 a day soaking it down with water or keeping it from freezing but holding a good moisture content . the commercial industrial contractor we both work for was pretty adamant about using these practices at least in their own pores . in the contract jobs where if you don't get things done by a certain day you start paying for the job you're doing . in comes the need for the chemical quick fixes put simply make it more stressful and harder . and truly give more need for rebar . from my experience especially in demoing concrete you can easily see the less need for rebar when you increase the cure time . I truly believe and see that it is the calcium and lime deposits left behind by water molecules that solidify and hold and give strength to the concrete or mortar . Those peers and footers had no rebar and are the hardest concrete I've ever had to demo and remove. all the concrete I've ever demoed so much easier when it has rebar or mesh in it . I have even used a blunt old bit in the jackhammer on little spots of exposed rebar from jackhammering . given enough time by braiding that rebar you can tear a pretty big pad apart much quicker and easier and definitely if you can lift that pad and get air space under it it'll fall apart really fast . the Footers and Piers I keep referring to it was easy to see they were a three-part mixture of crushed stone no bigger than 1/2 inch sand and cement to this day I like to mix my own using pretty much the same X but if I can get foundry or fly ash to mix in the best thing I've ever seen happened to concrete ! the only concrete we ever removed that had rebar in it was an old concrete bank vault with walls two-and-a-half feet thick number 6 rebar vertically every 3 in and a checkerboard pattern with number five every 3 in horizontally tied to that . with a 3 foot thick tap done in the same pattern but with the number 5 and number 4 rebar . it must been a great sense of satisfaction to be on the form and poor of that one . we didn't really get to demo that one we hold it to the landfill though they had a subcontractor come in with a big wet saw that cut it into pieces that we could load and haul off and the landfill would accept . well the learning never stops and I could go on much longer but it's time for me to go . if you want to see concrete fall apart quickly pour it and backfill it with soil high in metal deposits especially iron . peace light loving gratitude freedom I hope everybody gets their free and joyous share of it all !!!!!!!!9 HHBpHhelps
Thank you Sir Henry Phelps You sure help me I'm trying to build a oven In Mexico we build them with clay But in the Washington state its difficult to find it So I will go with cement Thanks
Hey Tyler, I'm craaazy about watching your videos. If you're ever having a really crap day and you're thinking to yourself, " I wish I was making a difference in some dudes concrete life down in South Africa" .... meet "some dude" Just started my ACI Fundamentals in Concrete and have had a lot of questions which you've answered through your videos. Thank you, thank you. God bless.
I worked a concrete project where the spec was simply "All concrete shall be air entrained." I asked about the spec before concrete work started, citing the recommendations for the floor surface coating ("...air content not to exceed 3%..."). Never got a response. The Corps of Engineers inspector enforced the entrainment spec. When I tested one load and found 12.5% in an interior slab on grade, the C-of-E inspector said, "That's all right, as long as it has air." Later, when they were compacting the aggregate base for the parking lot, the contractor refused to use the vibratory function on the roller because "...when we turn the vibrator on, the slab cracks."
I enjoy this as I have an interest in concrete. I met and did work for a gentleman years ago named Fred Oswald. He was in the business of manufacturing concrete vibrators, in fact I think he invented it, at least the backpack type of units that were being manufactured in L.I. New York.
Find a SO who looks at you like this guy looks at concrete. Seriously, though, great videos. You've got me learning by choice, and that's always the way to go.
I helped a Dam engineer build a bridge over a stream in New Mexico. He added a Ny-quil cup of a silicon substance he said was a by-product of the waste in growing silicon cylinders. One Ny-quil cup per 1/4 yard in our mixer. It added tiny air bubbles for freezing contraction and expanding. It was a beautiful bridge. It looked and acted just like a real bridge over a highway. it was beautiful. It held a convoy of cement mixer trucks and he poured a huge monolith slab for his mountain cabin. I wonder if the stream took it yet? its taken heavier ones but he didnt listen. Im gonna go check on that.
Really good video. Now i can't stop thinking about the validation and acceptance of new prototypes of air entrained admixtures just based on the percentage of air increased or permeability reduction. We can go beyond with the available technology of our time. Thank you!
In the 80s I worked in the r&d labs at FEB, the company that produced the world's first concrete additive "FEBMIX ADMIX" (I think!). Tyler mentioned soap in the vid. NEVER USE DETERGENT IN CONCRETE!! You'll only get large bubbles (entrapped air), a proper admix will give small bubbles (entrained air). I still use the "magic mix" ...3.2.1. 3parts aggregate, 2parts sand, 1part cement and then the correct additive for the job.
Hey Tyler! Love your concrete enthusiasm. I'm studying civil engineering in Europe, which means I'm using the European codes for concrete, do you know anything about them? If you do, could you do a video explaining some of the most important differences between American and European standards (except trivial things like the units)? And maybe which ones you think are better?
@Edward Raney Thanks for replying. I was wondering if the rounder holes were creating kind of bridge shaped areas in the concrete with the same science behind the strength of bridges. I am newly fascinated with concrete. It appears to open up worlds of opportunities. I just remembered, at school many years ago, in science we were discussing the strength of an egg because of its shape. Doesn't that do a similar thing inside concrete? Just very curious. If some say it makes it stronger and some say it doesn't then I am not settled in my mind about it. I may need a science lab. Lol
Good job👋👍 I watched your video that my lecturer suggested it. l liked so much😅😁👌 i will watch your other videos😁 i study civil engineering in turkey this year is my last year at the university..😅😊🙃
Not all concrete is the same though - it depends on the specific purpose that it's used for. I think it's worth to make some deeper studies in the area of concrete and various mix types. Sometimes you want a hard solid surface with a much lighter fill between the surfaces for improved insulation or weight reduction. Much like bones in a skeleton - hard on the outside but a truss work on the inside.
Your passion for concrete is really unmatchable Dr Ley. Thank you for sharing it with us.Sir,aerated concrete blocks are being used in my city a lot, recently it's being reported that these blocks are cracking along the edges quite often.The weather conditions are quite hot and humid at most times of the year.What could be the reason?
Kushal - Thank you so much! I am working on a video over aerated concrete and I will talk about this. Could you send me some pictures of the cracks? Any place you have a re entrant corner then it will have higher stresses. The holes in aerated concrete increase the cracking potential. This makes it easier to crack at that location.
We build power poles from concrete - where the concrete is responsible for the dynamic loads of cabling systems. It also stands up against the freeze thaw process, and cars hitting them. There's a concrete testing regime at play when the batch is manufactured. It's got to be right - or it's rejected. On an unrelated note - my driveway is pretty good and strong these days :)
With my limited knowledge of concrete, I believe that Air Crete is not as strong. I also like the idea of Air Crete but so far I don't think it has the capability to be as durable. Would also love to see Tyler do a video on it.
Hi Tyler, I accept your explanation, but please explain why vibrating concrete is so important in removing bubbles and helping it to move into voids. I do understand that it needs vibration with a concrete poker, but not over-vibrating. How does this fit with the information that you have presented here? Kind regards, Lee
Somewhere in an MTO spec or contract I read “xx% air entrainment minimum, entrapped air is not allowed” or something to that tune. The larger bugles are what they defined as Entrapped air, or air that contributes little to the F/T durability. Just something to help y’all remember!
An excellent ancient example of the value of air in concrete is the free standing round domed with central oculus temple in Rome known as The Pantheon. It was built with concrete, but in 120 AD the engineers knew the concrete would be too heavy to be free standing. It would collapse under it's own weight. Their solution was to add air bubbles to the mix, certainly not for the engineering reasons which you illuminate and likely more and larger air bubbles than would be done today but hey, 2000 years later it's still standing!
Romans were pretty good with concrete 2K years ago. Ask yourself this - why are many old Roman concrete structures still standing, and yet there are abundant examples of modern concrete failures?
I love your videos Tyler. Keep up the awesome work. I think science is the key to the future of our concrete industry. With that being said. I would have to say Portland cement was better in the 1950s. We did not need air added to it back then. Or did we and no one told us about it? Well I mean back in the day. You did not ask for it from the ready mix company's. When I was a kid. My dad use to hand mix concrete using Portland cement bags he bought. Along with a pile of sand and gravel. I visit these structures and slabs still to this day. They are holding up just fine. I don't think a bag of Portland cement is what it use to be. They changed the recipe. I think they changed Portland cement during the 70's & 80's. Probably changing it still to this day. I know the admixtures are giving us greater possibility's then ever before. I am all for them. Can we ever get that recipe back from the old days? Is1950s Portland cement not practical anymore? This kind of reminds me of an old song "Someone left a cake out in the rain. By ‘MacArthur Park". I sure do miss that Portland cement from way back when :-( . But I know it is time for bigger and better things now. You are definitely an inspiration to the concrete industry.
Thanks Dave, It would be cool to learn more about the older structures that you talked about. Even old concrete that gets critically saturated (sorry for the nerd word) will damage once it freezes. I do agree that our cement has changed!!! We are trying to get earlier strengths as fast as possible and that causes lots of problems in our concrete. The best way to simulate older concrete is to use fly ash and slag in the mixture. This slows things down and gets better hydration. Check this video out - ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-0wOCn7smmIs.html Thanks so much for the nice words and for watching!
Humm. What about the tropics? No freeze thaw there. So other criteria must apply. And we don't know about the compression strength of aircrete which I want to use to build my basaltic rebar reinforced dome.
Fantastic information!! I'm a residential contractor who occasionally does concrete. Read everything about concrete I could get my hands on 20+ years ago when I started but haven't learned much about the science since. How are the bubbles entrained in the concrete? By mechanical mixing at the plant or in the truck? With admixtures? A combination of both? Will too much mixing or agitation either in the truck or in the forms with a vibrator cause loss of bubbles? How do I make sure the concrete supplier has put good, small bubbles in the concrete? Thank you for making these vids, SO very helpful!
Thanks Matt, The bubbles come from an air entraining admixture that is added during mixing. It is soap that makes the bubbles. The bubbles are kinda finicky and they are easy to lose. Too much vibration can cause them to be lost. The best way to check for the bubble size and spacing is to use the Super Air Meter. More on the Super Air Meter here: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-xabCt_CibJY.html More on air entraining admixtures here: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-CXg6kvZWeO0.html
@@TylerLey Thank you so much for taking the time to reply! Saw 2 links that I will watch shortly, could be more but RU-vid won't let me scroll down to see them. Can additional admixture be added to truck and mixed on site if meter shows not enough/correct size of bubbles? I mainly work (residential contracting) in a very small, remote town (Valdez, Alaska) with only one concrete supplier who doesn't know their backside from a hole in the ground and threatened to refuse to sell me concrete when I complained about his 15" slump (it's basically grout with footballs of dry Portland cement in the mix that it's the customers job to deal with) The more I know about the science of concrete, the better product I can give my customers. I'm going to watch your channel's entire library. Was fascinated with concrete early on but "fell out of love" and have tried to avoid it as much as possible due to the terrible quality of the concrete available to me. Fun Fact: Whenever you hear anything about how safe and well built the Trans-Alaska Pipeline Terminal in Valdez is, remember, the guy who sells me the crappy "Sea-Side Slurry" (his name for it) sells the same crap to all construction jobs on the pipeline terminal. They, of course, have inspection engineers who do occasionally reject batches but I think the design engineers have just resigned themselves to over-building projects using junk concrete. Next closest batch plant is 120 miles away.
Matt, Thanks again for the comment and story. You can add air on site to bring it back into spec. Alaska DOT is in the process of adopting the Super Air Meter. I talked with them last week. Maybe that will help bring it to Valdez.
My take on this is that the approved design mixes should include testing to confirm they get an appropriate bubble size and distribution that aligns with the aci charts for air content. I currently don't see any of the major labs in the nyc area doing that during mix design and I get to see almost all there mixes on a regular basis. Is this astm test for air content distribution/size typically being conducted after problems are observed like in a forensic arena or is it actually required for mix design codes.
Kevin, People are using it for mix design approval and then verify it in the field. NYDOT is doing a lot of work on this. Many other state DOTs are moving in the same direction.
Years ago I was at a resort in FL. The swimming pool apron was wide concrete and had lots of recliners. What was very strange was despite the brilliant sun, the concrete remained cool! It was almost disturbing. You put your bare foot out and life experience told me "your foot is about to sizzle...", but no - it was cool to the touch. How did they do that? My best guess was they injected the mix with air, but that was only a guess. Any clue?
Aerated concrete block or aerated autoclaved concrete block autoclave block cost more but if you can make at home your own aerated concrete blocks you can build a home that has a r-value of 20 to 50 the concrete is also waterproof fireproof and soundproof it's the best building material for the new mini ice Age approaching
Can you put polystyrene balls in concrete to create circular holes within the concrete when it sets? I was thinking how a bridge is strong if it has the arch because of the way the weight travels down the arch sides removing the problem of weight just pressing onto the top...if you know what I mean? And if this is a good idea is it better to have a larger or smaller polystyrene ball size? And also would they be better used dry, kind of sprinkled on a layer of wet concrete with the next layer quickly poured on top? Or better to mix them into the cement? (I don't know why but I am so fascinated by cement! Amazing stuff!)
Good question. That would be fun to try. When we vibrate concrete we locally reduce the forces of gravity and allow the voids to float out of the concrete. This means that vibration typically only allows bubbles to leave from the concrete.
for coastal construction.. in florida what kind of rebar would you suggest for columns and beams and walls? i see galvanized is just 10% more would you recommend it
Thanks for this video :-) You can also tell something about capillary absorpion by concrete with air bubbles, please? What are possibilities of use this type of concrete for foundations...
Hello Tyler really great videos! I am trying to cast cement mortar in a wooden mold. The shape I want to achieve consist of 2 walls of 30 cm height and 15mm width. The shape's top view is like a capital T with the difference that the horizontal line (wall 1)is twice the length of the vertical line(wall 2). Now on the vertical line there is a rectangular block of 2cm (height_)x 10cm(width) that is screwed 10 cm above the base level of the mold which as stated earlier, is 30 cm tall. This will create a groove that will allow me to slide on a wooden shelf. In my mortar The ratio I use is 6 Portland cement, 5 blond washed sea sand, 0.25 Fiber glass fibers, 0.5 sika latex, 2.5 water. When filled, the mold is air sealed with a plastic bag and covered with a blanket. Demolding happens 36 hours after filling. 1) How does a mold that is thin, tall and encloses the cement mortar can affect the curing? There are narrow openings on the top to fill it in. 2 openings of 10cm length x 1.5cm width on the top of the horizontal line.(One on the left and one on the right side) and 1 opening of 10cmx 1.5cm on the vertical line. The rest of the mold is fully enclosed. 2) I use birch plywood that consists of exterior use adhesive for bonding the layers. Is this material ok for such a size and shape? Will varnishing the wood and sealing the sides with silicone used for windows help? Some vaseline is used and so far there are no issues with demolding 3)To fill in the mold, since there is no visibility to where the mortar has easily traveled to, shaking and vibrating the tabletop is necessary to fill it. How could excessive shaking affect such cast? And if possible define excessive shaking 4) Is there a way to eliminate the cracks that appear next to the desired groove? 5) The edges of the cast after it has been cured are a bit brittle and feel like a cookie when cut in half. Is this an indication of a sort and if yes what sort of indication (mortar, curing, liquid amount) I am really struggling to make this work well and have a smooth finish If I can send you images please let me know how I could reach you! Thank you so much Tyler!
When is concrete looking material not called concrete? What is it, specifically? For example, does water + Portland cement + air bubbles (aircrete) = concrete? If geopolymers are the binder, is that concrete?
Is modern day air ad-mix like a surfactant? Every mixer driver should keep at least 20oz of air in the truck if there is no company QC on the job they can always call with job specs yards in the drum and if water has already been added or needs to be added. As you know water added is a factor in air percentage
Sounds like you are looking for the correct ratio of bubbles, vs permeability vs durability. A patent solution like that could be worth big bucks. Probably incorporate existing patents too. Doing the red tape maybe harder then invention. Not clear to me if the industry knows what it wants, just does not how to get there or if it is anyone's guess what they need. I don't know the size of bubbles or density wanted.
This may sound like a stupid girly question but I suddenly thought about it and want to know....what would happen if you whisked egg white up and folded it into concrete? I know I could test that theory but I am hoping someone can just tell me. Although it would probably cost a fortune...I don't know how much it would take. Just fascinated with concrete! It's such fun stuff!
Why don't you answer questions in the comment section? You even say to leave comments below. I'll ask anyway. Why is it that the concrete poured over 100 years ago is still there but if you pour concrete these days you can stand there any literally watch it crack and fall apart? And those holes? Up north here if you don't fill them in they'll catch water and freeze and bust up the concrete.
Je, Lots going on and it is hard to get to all the questions. Thanks for your response. A lot of the times that concrete that we see that is 100+ years old is the concrete that has survived. Aka they got everything right when they made it and it was in a great environment. When you look at the young concrete that is having trouble you think that more young concrete has problems because you see it deteriorating. This is called survivor bias. That means we base everything on what survived and we don't take into account what doesn't. I talk about some of this in my video about Roman concrete - ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-PMed3YtN-Fo.html These "holes" are critical to make your concrete long lasting any place it is cold and freezes. It is common practice in the concrete industry.
Tyler... is it correct to believe that the greater the impermeability of the concrete the less the need for air entraining? And, the greater the permeability, the greater the need for air entraining? If this is true is there a relationship between impermeability and compressive strength? Density? I have the idea, please correct it if I am wrong, that the greater the compressive strength (or is it density?) the less effective/useful/needed a PRAH like Kryton KIM is?
Hi, to a certain extend the compressive strength of a concrete correlates to its permeability. A low water/binder ratio during mixing leads to less capillary pores within the cement matrix which are the main „transport routes“ for water and other substances. Keeping the of capillary pores percentage low leads to 1) higher density, 2) higher strength and 3) less permeability. However, note that some high-quality cements may reach high strengths even with higher proportions of capillary pores. If air-entrainment is necessary depends on the circumstances the concrete is used in (f.e.,temperatures, change in temperatures). Even very dense concretes do have a proportion of capillary pores, which soak water into the concrete hence leading to possible freeze damage. In Europe, the freeze-thaw resistances are usually tested via the „CDF“ or „Slab-test“ methods if you want to read further.
Hi! I am looking for the way to make irregular natural bubble textured concrete to make the candle bottom! But I am frustrating because this is so new world to me. Can you help me with this? I want to make self-rising bubble concrete when I pour water in to the mixture. (I saw this in someone's video) But I don't know how! Then I found AAC concrete , can you tell me how can I make this at home using the materials like cement, lime?, calcium hydroxide, etc. ( I saw this ingredients in somewhere) Thanks
PolskaWalczaca I think you mean those ratios in the reverse otherwise you wouldn't have concrete. You'd have a puddle of mush which when set you could crumble in your hands.
I have difficulty understanding the accent... may i request if u could add some subtitles? Heheheh anyways i love your videos, it help me as an Engineering student. With love from 🇵🇭
Haven't read all of the comments, but, can you nor just use micro spheres to solve this problem? If a large sphere is needed, ok small ok. Can we pour a mix then implant what we want? I have a few other concerns..
Question: if I’m pouring a chimney crown and I’m using a bags of quikcrete, do those come pre-air entrained or would I be recommended to air entrain it. If so, how is this done?
Hi Tyler, my concrete is hissing like cricket bugs. Does this means that it has small or big pores? It is 8 weeks old. Once I splash it with watter I can hear the hissing and see previously not seen (when it was dry) capillaries like spider web... Will it help if I put sealent on top of it. We are near Canada border and winters can get decently cold.
Thanks for your interesting videos my name is marouan from Morocco .do you have some studies on fiber glass AR alkaline resistant? If you can give me your opinion thanks
My girlfriend's head just expanded by a factor of 0.008 while watching video and now she's comatose. Her dad says that they air entrained around 6% back around the early 2000s. Is there any remedy?
