You know, it's so great that an ordinary guy who is interested in all kinds of stuff can just go on youtube and quickly learn some stuff about concrete. You explain it really well, imagine 15 years ago, you wanted to learn a little bit about concrete. You'd have to either find someone in your social circle or go to the library and read complicated books on the matter. I'm so glad technology and personalities like you enable us to learn things so easily.
I wish I saw this the first time i had to order concrete, I used an online calculator to find out the amount of _concrete_ i needed and tried ordering that amount of _pure cement_
That Hydraulic Press Channel reference had me burst in laughter. Hilarious. I love it. Besides: This channel is really good. It is educative and easy to understand, yet friendly and with lots of information. Keep doing that!
As a site safety professional in the field of construction; I humbly thank you for your years of hard work. Your knowledge and methods of conveying a complex topic- saves us the stress and aggravation to seek this knowledge. I’m grateful for your channel and a proud new SUB
I was a construction and CMT tech for 40 years and your explanation was great. Suggest if you are going to break cylinders you might use a silicone pad on the top and bottom to allow more even pressure over the surface. Also build you a simple clear acrylic cabinet to protect you from shrapnel and still allow you to see and film it.
As a civil engineering student, I just want to say how much I appreciate all the time and effort that goes into your videos. Your videos keep me interested and excited about the field.
Practical Engineering, now with concrete examples! On the aggregate, this series will really cement your channel's reputation as a rockin' educational resource that really cures what ails the TH-cam crowd by constructing a solid foundation of knowledge. So, steel yourself for the road ahead. 👷
One of the more interesting application of concrete is shotcrete (also called gunite), where concrete is shot out of a high pressure cannon and sticks to whatever surface you aim it at. With shotcrete you don't have to make complex molds (called forms) in order to make complex surfaces, greatly reducing cost. Swimming pools are made using this technique.
There are several types of shotcrete. Essentially there are "wet" and "dry" methods. The name Gunite actually a name for the "dry" method. This is where the aggregate and cement is pre-blended and forced down a hose only to be mixed with water at the nozzle as it is sprayed. This is far less common than the wet method which is a premixed concrete that is Pi,led and sprayed together. There are LOTS of shotcrete mix design options. The best will depend on the application and performance requirements.
There are several types of shotcrete. Essentially there are "wet" and "dry" methods. The name Gunite actually a name for the "dry" method. This is where the aggregate and cement is pre-blended and forced down a hose only to be mixed with water at the nozzle as it is sprayed. This is far less common than the wet method which is a premixed concrete that is Pi,led and sprayed together. There are LOTS of shotcrete mix design options. The best will depend on the application and performance requirements.
These videos make me so happy... there's something really deeply fulfilling about learning about things I took for granted as unlearnable outside of a formal education program. Thanks for sharing your love for civil engineering Grady.
drowningflamingo You should hang out at or even get a job at a place that perform these crafts! People will tell you all the intricate details you’re willing to learn, for free and maybe show you where to get free or nearly free training on each subject.
I had to pause the vid just to thank you for paying homage to the Hydraulic Press Channel, which is actually from the city where I live in Finland. I've even met them.. pretty nice people :)
*parents jokingly barge into my room and yell "what are you doing in here with the door closed!?"* "watching videos about concrete and hydro engineering." *slowly closes the door
My first summer out of high school I worked for a concrete contractor. We installed driveways, sidewalks, patios and some basement floors. I learned enough to know that was not what I wanted to do long term. I was never told about what you explained so well in this video. Thanks. Now a retired telecommunications tech learning things on the web.
Excellent presentation!!! :) I'm a retired civil & structural contractor that started in concrete construction almost 60 years ago. Engineers primarily want concrete to be placed a low slump (water/cement ratio) to attain high compressive strength earlier. As a teen I hand mixed 1000's of cubic yards for foundations and slabs (Butler Buildings) in remote locations, with hand shovels and a 3 cu ft gas mixer, We mainly used bank run material (natural sand/gravel deposits) and sack cement...also added a bit of dishsoap to entrain air...cold regions up North. :) With a tough hard working crew of 5 we could mix and place up to 100 CY in a day...long days! When using a small mixer keeping the mix time to a minimum was aboulutely essential to production (we're being paid by the job not hourly). Creating a low slump mix that would keep a smile on an Engineer's face would take 5 or 6 times longer (dry materials take longer to become homogenious). We'd almost double the mix water. I know, I know...WATER CEMENT RATIO !!! We merely added another shovel of cement to the 10" slump mix. Cylinders were taken on quite a few pours and when cracked at 7 days the results were truly poor. However, 2 to 3 months later when a Smith-Blair hammer was used, strength always exceeded design loads. Back in the day, plasticizers, redi-mix trucks and concrete pumps didn't exist. If one watches any old old videos of concrete being mixed in a trough you can see the slump is like soup yet a lot of these structures are still standing. A project that I designed, tendered and constructed in 1986: www.4gto.com/Iona.jpg
I'd love to see more data about concrete strength of different kinds with different ratios of ingredients. I bet people have made some really cool 2d and 3d data visualisations of the configuration space.
vavanade 4d, sand, cement, gravel, strength. You don't need a dimension for water since the proportion amount of water is just 100% minus the other ingredients.
Nope. Mix designs intended to tolerate freeze/thaw conditions deliberately entrain air in the mixture. Measuring the water content is just as important as measuring the other constituents.
If you want some seriously hot ass concrete use a type 3 cement. In 3 1/2 hrs we was achieving a brake of 3000 psi and above. The ambient air temp averaged 60 degress and i only covered the samples with a blanket instead of placing them in an ice chest. It was poured using a volumetric truck.
Grady, love your videos!! My late father was a design engineer who worked for Bell Aerospace in Niagara Falls NY in the late 50's and into the early 70's and worked on the Apollo missions while contracted to NASA, I actually Met the Apollo 11 crew when we lived in Houston TX 1966-1968. The Engineering gene skipped me but found it's way into my youngest boy Daniel who is a Civil engineer here in Buffalo NY. It's great how you break down complex engineering issues into easy to understand (for the lay person) solutions.. Keep up the great work!! Tom Buffalo NY
Worked 25 years in QC for Master Builders who specializes in concrete admixtures, repair, and finishing products among other things. Really think you do a very good job presenting the basics on a material that literally is the foundation of the developed world. Had to chuckle a bit when you brought up the concrete vs "ce-ment" misunderstanding. We did our compression tests with 2" cubes and to say we had some interesting results - we had cubes from a run of Iron aggregate floor hardener that went over 17,500 psi at 28 days. The folks in the front office on the other end of the plant felt when the cubes failed.😅
I've worked in a factory that made concrete blocks for 4 years. Every block you've seen, we've made a variant. One machine would run a mix design that would use very little water 10-15 gallons per yard (3500lbs) of aggregate (cement, sand, mansand, rock). And the other would run 10-15 gallons per 1/2 yard of aggregate. I could tell you so much about concrete it's insane. The worst part was cleaning the mixers and the block machines at the end of the night.
I really enjoyed watching your concrete videos, I’m an architecture student and seeing you experiment with structural materials is far better than listening to a lecture in school. I hope to see more of your future explanation!
Might want to discuss the more recent notice of the importance to saltwater to the hardness of Roman Concrete. I think there was 3 kinds of Roman concrete also.
I was going to suggest this. I used to work for a Materials Testing Laboratory where they would test samples of concrete with hydraulic presses like you had there. The engineers used to say that the "best" (not sure whether they meant "strongest" but quite likely) sample they ever tested came out of an old Roman bridge: the authorities wanted to be confident it wasn't about to fall down, and they were not disappointed o.O Apparently this was at least partly because prior to invention of Reinforced Concrete, it had to hold itself together-that and all the bad stuff fall apart centuries ago ;-)
I'm in the geosciences, but I started off in engineering and still have some passion for it (damn you calculus). Concrete is an amazing material from a rock perspective - it's essentially an artificial conglomerate/breccia in the overall composition, but the matrix (the cement) is radically different. It can be anything from artificial limestone (from simple slaked lime cement, which is non-hydraulic) to something that probably more resembles an extrusive igneous rock under a microscope - portland cement is not a simple mixture, involving calcium, aluminium, and iron oxide silicates in its manufacture, at least some of which are reacted to form hydrates during the formation of cement and some of which eventually reacting back to the carbonate they came from, not to mention the calcium sulfate added to control setting. I actually can't wait to see more concrete videos, strange as that might sound. (Also, love the shoutout to Hydraulic Press Channel)
Limestone. Easily located, too - not only is it incredibly common, but it's easy to identify - drop a little bit of dilute hydrochloric acid on it, if it fizzes, it's most likely limestone or a derivative of it (such as marble, which is metamorphosed limestone). From limestone you can make slaked lime cement, which isn't the best but certainly works - take the limestone, break it into small pieces, roast it (you need to hit 825 degrees Celsius) to produce lime, mix with water (slaking it) to produce calcium hydroxide, and once all the excess water evaporates, the calcium hydroxide will start to be carbonated by carbon dioxide in the atmosphere back into calcite (calcium carbonate). Won't harden in water, though - but if you can get your hands on some aluminium oxide silicate material (which isn't uncommon - if you can find kaolinite, you can heat it to form metakaolin, or you can use certain rocks like pumice or tuff, or even industrial by-products like fly ash), you can mix it in to produce a cement that *will* set underwater. This is, notably, what the Romans and Greeks used.
You say it'd be easy to confirm it's limestone via using hydrochloric acid- but what if you lack easy access to supplies of the stuff? How would you confirm it at that point?
While it's not too hard to get your hands on (it's often sold as a cleaning agent as Muriatic acid), there are a few other identifiers (if not as definitive). Depends on the type, of course. Fossiliferous limestone will, as the name implies, often have fossil imprints or even full-on fossilized remains in it. Oolitic limestone has a distinctive texture (being comprised of tiny ooids, or spherical grains). Travertine has very distinct layering and banding along with a crystalline structure. Micritic is probably the hardest to identify without acid, if only because it shares a lot of properties with other fine-grained sedimentary rocks - I suppose you could resort to hardness testing (limestone won't scratch a steel blade, but a quartz-based rock will). Possibly one identifying feature you could use to tell an entire bed at a glance is weathering patterns - limestone is very easily weathered, giving crumbly, pitted outcrops. I suppose a geology field guide might be added to the list of books and reference materials you might want during a zombie apocalypse.
We're talking about in a post-apocalyptic scenario here; obtaining hydrochloric acid won't be as simple as walking down to your local hardware store. First part of Mark's question, after all: "so, going primitive... let’s say humanity falls (zombie apocalypse, nuclear war, basic Armageddon)..." thus the query. I'm quite familiar with hydrochloric acid in use for cleaning, myself.
dude on primitive technology made cement from snail shells. a lot of big limestone deposits are formed from ancient seabeds covered in shells. basically you cook them in a hot furnace and then crush it up. fly ash is pretty simple to make, it's the ash that flies up from a coal fire, chemically different from bottom ash which you could use to make soap. if you can make an electrostatic doohickey you can collect it while you bake your shells, or raid an abandoned coal power plant. mix those together and you got cement.
I am super confused how the driest samples were the strongest ... yet you mention earlier how insufficient water can screw up the mix, and underwater curing can provide stronger concrete? Fascinating video nonetheless, great job.
As someone who is certified in the concrete industry, great explanation, just like every video of yours ive watched. Man, i could have used your help back when i was trying to learn this stuff. Great job, sir!
I am sad there was no "extra content" at the end. But in general, this was a very good demonstration of why you should not add more water to make the thing flow into form easier.
"You dont build structures from pure cement the same way you dont build furniture exclusively out of wood glue" Holy shit that is the best way to describe the purpose of the rocks and pebbles...
Ok you just blew my mind with the old throwback to the Finnish hydraulic press channel. Hilarious and only to be enjoyed by those who have spent sufficient time in this rabbit abode...
Working for a company that produces additives for concrete production has opened the world of concrete to me. I never knew how both simple and complex concrete production could be. Great video! :)
@@Yajurshridhar it's hard to write it on the Web and make it look right, but pronounced "f sub c prime" is the compressive strength of concrete, typically expressed in pounds per square inch (psi)
Videos like yours make learning way more enjoyable. My old schools could have learned a lot from your methods. Thank you for explaining the topics in a concise and fascinating manner.
You know, it's so great that an ordinary guy who is interested in all kinds of stuff can just go on youtube and quickly learn some stuff about concrete. You explain it really well, imagine 15 years ago, you wanted to learn a little bit about concrete.
Love your videos! Can you explain why submerged concrete "will set and harden just as well, or maybe even better, as if it were dry" yet demonstrates the greatest compressive strength with the smallest w/c ratio? Does it somehow not absorb as much water when the sample is completely submerged? Thanks!
Yes please! I was looking for a comment with this exact question. Sad to see there are no replies after two years. Great video otherwise besides leaving this contradiction hanging as a question mark.
This might require more tests to show different real-world applications -- e.g. long-term wear and tear, what if with rebar, what if exposed to water, what if exposed to heat-cold cycles for how long, what if layered, what if sharp trauma, what if vibration trauma, etc
This dude made a random question that just came into my head take up more of my interest than I expected. Great video, made concrete much more interesting and intriguing
Wow, this video provided such a fascinating and comprehensive explanation of what concrete truly is! I never realized the intricate process and ingredients involved in creating this versatile building material. It's amazing to think that something as simple as cement, combined with aggregates and water, can result in a substance with such incredible strength and durability.
They would probably deteriorate in the water. Also, if the cylinders were not cured in water, a tube would allow the water to evaporate too quickly and not give a proper result for testing. However, masonry grout is actually tested in cardboard tubes for this reason. When you fill masonry walls with grout the masonry will absorb some of the water so the cardboard gives some sort of parallel to this affect.
3:41 you mention that aggregates can increase the strength of concrete. Are you sure about this? I'm a Civil Engineering student and have been told that aggregates are only used to save on costs, since the aggregates reduce the strength because the boundary between the aggrigate and the cement is always weaker than the cement itself.
Isn't it because aggregate holds itself better together than cement does? So it's basically lots of strong spots held together with weaker material in the "hope" that the strong spots take all the load. And "hope" in quotations because it's more of science than blind luck these days :D
my buddy from high school did construction for awhile with his dad and I asked him about concrete awhile back. His answer to this was that "fence post concrete" excludes aggregates entirely and it's the weakest kind of ready-mix concrete you can buy. I'm not an engineer or physicist, but that's certainly a data point.
Part of the benefit of large aggregate is that cracks cannot take a direct route through the cement matrix. They have to divert around large particles, so must grow larger before the material fails. Think of them like wood dowels holding together two planks to stop them sliding past each other. Rough aggregates (as opposed to smooth pebbles) are especially good because of friction at the grain boundaries. (I'm speaking from geological training more than engineering.)
Motoko Urashima "aggregates entirely" would be like a bag of rocks with some cement on top. Hes not wrong but the type of aggregates you use can change the dynamics
I should recommend your video to our customers. We are concrete block manufacturer company located in Turkey and our customers ask about concrete mixing ratio and other details. I will recommend your video from now on.
Here in New York City I observed highway builders use something like large canvas tarps and leaking hoses (hoses with many holes in the sides?) and they would leave them over fresh concrete pours for days at a time. Maybe two or three days/nights they would leave them. I figured it was part of the cure but I didn't know how till now. :)
You nailed it, the idea is that drowning the surface with water protect the concrete from the weather and doesn't allow the water to evaporate, in some projects we build the forms 5 cm higher and fill that gap with water for 5 days.
Let me guess the topic of the next video! Concrete, while excellent under compression, is very weak to tension. This is why you often reinforce concrete with prestretched steel rods that ensure that the concrete is always under compression.
Leonard Kielland , yes but what matters are the steel rods themselves. The "stretching" part you mention (pre-stressing or pre-tensioning) are special high performance variants, but they're not essential to the principle. Often, the design just calls for rods to be placed at rest. Where you place the rods (and how much) is critical, though.
I have a question. In the construction industry I’ve always heard that old concrete is harder/stronger than fresher stuff. The longer it sits the stronger I gets. Is this true. If so why? It seems that after the curing cycle it could only get weaker. Idk.
I think it does start getting weaker after the curing cycle. I believe, though, that the curing cycle can take years(even decades) to fully complete. I'm sure it's not linear (ie. greatest effect on strength in the first days or weeks with diminishing effect tapering off as the cutting cycle completes over many years). I'm not an expert. This is just my best guess.
Generally the concrete is designed with a warranty age, this means the concrete get it's 100% strength after this period (usually 28 days), but it's true, this doesn't mean after the warranty age the concrete strength stop growing, but it's grown is not the same. From 7 to 28 days the concrete increases from around 70% to 100% and from 28 to "x" days grow from 100% to 105 or 120% max. This tested on laboratory of course. OK then why gets weaker? This is because external facts like weather (rain, wind) and of course time, the concrete is a formidable construction material but is not inmune to mother nature forces.
According to Wikipedia concrete strengthens with age due to absorbing CO2 gas from the atmosphere, and converting calcium hydroxide into calcium carbonate over several decades: en.wikipedia.org/wiki/Concrete#Curing A rule of thumb is maximum strength around 75 years, by then the corrosion of rebar will be weakening the overall structure.
Because concrete finishers don’t generally isolate themselves for weeks at a time hanging with cattle, talking to no one then blow all their cash on drunken binges once they hit their destination. Somewhat like sailors except Cowboys’ charges get slaughtered intentionally at the end.
Good start to learning about concrete. First time I made concrete was at age 15 on a roadworks job. Since then, I have mostly worked for pay or at home with pre-mixed concrete delivered by truck. I loved both kinds of concrete and have studied the history of concrete from Roman times.I am an economist by profession and have not been employed in construction since age 17.
Felipe Goleta plastic like water bottle plastic may not be a great idea. I know that fibers made from polymers are used in concrete mixes to increase strength!
I'd be careful with this "diving into concrete" thing :D I have a question though, Is'n the sand actually crucial to the curing of concrete? I remember from school it actualy takes part in the process as a substrate.
It's crucial to the strength, but it takes no part in the reaction. You can have small aggregate (sand's part in concrete) that does react, but silicate sand does not.
Overall sand is a bad thing for concrete, unless it is a low alkaline mix, or the sand is resistant to alkaline attack. But initially it is a good thing because the silica turns into a gel and hardens, and is actually a part of the cementing process. So in the short run increases the strength of the composite. Also much of the larger aggregate likely has a lot of silica because it is a common part of other minerals. The problems with sand come in the long term. Silica alkali reactions continue through the life of the concrete, and the gel volume of each original sand particle increases leading to intense internal hydrostatic pressure. That, along with potentially the rusting of the rebar, is why old concrete begins to spall. en.wikipedia.org/wiki/Alkali-silica_reaction
According to me sand and stone is just a "filler" the actual strength of the concrete is determined only by the cement water ratio. The sand however plays a big roll in the amount of water needed.
effyou128, this wouldn't surprise me since it's a very complex science. However since you don't give any reasons, and or links to back up claims.. that and the whole f***you name... and calling us retards..... hmmm.
This is why GGBFS (ground granulated blast furnace slag) is now popular as an additional pozzolan... not only does it mitigate ASR, but also assists in reducing permeability and heat generation.
So I don't get it (maybe I have to watch the video again). How can the water be so important to curring (so that it can harden under water), but too much water is bad for compression strength? How does that mix up? I mean, how are birdge foundations made, if concrete with too much water is nearly useless?
That is a point i wish he had brought up during the video. But the short answer is that the amount of water used only matters during mixture; after concrete hardens (which could take from 15 minutes to 2 hours, depending on its characteristics and if any special chemicals were added), it should ideally stay submerged to prevent the water added during mixture from escaping. The reason for this is that the water added during mixture will increase the volume of concrete, increasing the spacing between the cement molecules and making it weaker, but after concrete has hardened, the spacing between molecules is somewhat fixed, so water is used for curing to ensure that hydration takes place properly (to ensure that cement has enough water to bind / react with so it gains strength continuously).
@I know Cause I'm BatMan. Well yea. After it hardens the chemical reactions in the concrete cause heat and that leads to the water being evaporated which is bad as the mix is already hardened which leads to spaces formed between the particles and that lowers the strength of it due to cracks being formed. so it is best to submerge the concrete for a few days pervent that from happening
probably concrete, the applications of cement dont really require quantities that are more than what 1 person could mix by hand(or on site machine) for 5 or so people at once.(Cement often being used to describe mortar)
I'd say the name is same mistake as when people call concrete as cement, but yes, they carry concrete. Cement is often transported in a tanker truck where it is pumped in/from with air pressure. Concrete mixer trucks are the ones with the distinguishable rotating "cylinder", which is there to prevent the concrete from settling inside the cylinder. Especially relevant during extreme temperatures. Source: Worked at a concrete plant for a few years, mixing concrete for construction sites and for use at element walls.
Concrete trucks carry everything already mixed including the cement. So if you're going by the terminology in this video then concrete trucks carry concrete. The only thing that is added in the truck is additional water
Wonderful and educational video. Really like the simple testing of the importance of water content vs strength testing. I would like to see a video about concrete additives, like fiber material, plasticizers and bonding agents. Basic explanations of what they do, how to use them, and for what type of projects they would benefit.
That demonstration just confirmed all my doubts about water/cement ratio as it affects concrete strength. Now I will REALLY be careful with the hose and maybe start using plasticizers. Thanks a lot sir.
I am from Poland and I made 2 canoes. First was for Beton Kano Race 2016 in Arnhem and second was for Concrete Canoe Regatta 2017 in Colonge. If you want to know what was the mix here it is (for 1m^3) -1000kg of 52,5R cement - 200kg of silica dust - 200kg of H20 -300kg of 0,2mm sand -500kg of 0,4mm sand - and 60kg of some nasty chemical stuff (Superplasticizer etc.) Test: cube dimensions: 150x150x150mm weight: 7521g density: 2228kg/m3 destructive force: 2375kN compressive strength: 105,6 MPa I can say that these concrete canoes give so much fun. You can actucally make something with your own hands (make computer design and wooden formwork and ofc conrete). Only thing you need is 10 people, around 3 000 $ and free time :D I also took part in 7 bridge competitions (steel and wooden) and only thing I find more fun than this conrete canoe is building wooden bridge and than destroying it. :D
It's a bit more complex than this, but here's a very basic explanation. When the cement particles encounter water, the hydration process begins.... in which case they begin growing "crystals" that bind & interlock with the crystals from other cement particles. Think of two cement particles as sawhorses, and lay a single 2x4 across them... the sawhorses are the cement particles, and the 2x4 is the crystal between them. If the sawhorses are very close together, and you push down on the 2x4, it will be very difficult to bend, let alone break... this is a low "water/cement ratio". Now, as you add more & more water, it takes up volume that pushes the cement particles farther & farther apart so those crystal bonds aren't nearly as strong... as you move the sawhorses farther apart, the 2x4 becomes easier & easier to flex until it becomes very easy to push down & break.
Thank you for going to the work of making this video for us to instruct us in the science of concrete. We appreciate it. You would make a good school teacher.
You know, it's so great that an ordinary guy who is interested in all kinds of stuff can just go on youtube and quickly learn some stuff about concrete.
You explain it really well, imagine 15 years ago, you wanted to learn a little bit about concrete. You'd have to either find someone in your social circle or go to the library and read complicated books on the matter.
I'm so glad technology and personalities like you enable us to learn things so easily.
I wish I saw this the first time i had to order concrete, I used an online calculator to find out the amount of _concrete_ i needed and tried ordering that amount of _pure cement_
@@arthas640 lmao
NoobCanoe yes
@@malcolmparkins1935 no
Hilarious
That Hydraulic Press Channel reference had me burst in laughter. Hilarious. I love it.
Besides:
This channel is really good. It is educative and easy to understand, yet friendly and with lots of information. Keep doing that!
André Bartels 5:41 “Aaaand here we go!”
Heooooodlrawlik plress. Aaaand heere ve go!
Recognized it right away! Jumped out of my seat! Nice nod to a fellow TH-camr
Thought it sounded familiar
Holy sheet!
As a site safety professional in the field of construction; I humbly thank you for your years of hard work. Your knowledge and methods of conveying a complex topic- saves us the stress and aggravation to seek this knowledge.
I’m grateful for your channel and a proud new SUB
I was a construction and CMT tech for 40 years and your explanation was great. Suggest if you are going to break cylinders you might use a silicone pad on the top and bottom to allow more even pressure over the surface. Also build you a simple clear acrylic cabinet to protect you from shrapnel and still allow you to see and film it.
As a civil engineering student, I just want to say how much I appreciate all the time and effort that goes into your videos. Your videos keep me interested and excited about the field.
you got a job?
Practical Engineering, now with concrete examples! On the aggregate, this series will really cement your channel's reputation as a rockin' educational resource that really cures what ails the TH-cam crowd by constructing a solid foundation of knowledge. So, steel yourself for the road ahead. 👷
He who'd pun would pick a pocket!
Rebar and curing double entendre; I love it!
*no pun intended*
Max Power : So, we're not being "pun-nished?"
Awwww daymm, nice puns son :)
Chris Sloan, DU-BUP-PSH!
One of the more interesting application of concrete is shotcrete (also called gunite), where concrete is shot out of a high pressure cannon and sticks to whatever surface you aim it at. With shotcrete you don't have to make complex molds (called forms) in order to make complex surfaces, greatly reducing cost. Swimming pools are made using this technique.
OMG if I had such a "Gun" I would have fun for the rest of my life... And everything would be covered in concrete... ;)
You know how in cartoons characters get covered head to toe in something like paint or melted chocolate? Now they stay in place.
I believe it's used in tunnel construction as well.
There are several types of shotcrete. Essentially there are "wet" and "dry" methods. The name Gunite actually a name for the "dry" method. This is where the aggregate and cement is pre-blended and forced down a hose only to be mixed with water at the nozzle as it is sprayed. This is far less common than the wet method which is a premixed concrete that is Pi,led and sprayed together. There are LOTS of shotcrete mix design options. The best will depend on the application and performance requirements.
There are several types of shotcrete. Essentially there are "wet" and "dry" methods. The name Gunite actually a name for the "dry" method. This is where the aggregate and cement is pre-blended and forced down a hose only to be mixed with water at the nozzle as it is sprayed. This is far less common than the wet method which is a premixed concrete that is Pi,led and sprayed together. There are LOTS of shotcrete mix design options. The best will depend on the application and performance requirements.
7:22 one little nugde and we would have seen full Civil Nerdgasm.
AvE hi AvE
OMG AvE follows the same channels I do... omg omg omg... ok be cool be cool...
Sup?
**That was so stupid**
AvE always follow awesome channel!
Sup lads. What are the odds Grady tests self-cleaning titanium oxide concrete?
@AvE No way I'm wading into that mess. I have a license and employer, both of which I would like to keep ;)
"You don't build furniture completely out of wood glue." You know what I want to do now.
Don't worry, we're almost there. It's called OSB.
Not make furniture completely out of wood glue? lol
Are you on that yt video rn
Epoxy furniture.
the king of random-lets do it
These videos make me so happy... there's something really deeply fulfilling about learning about things I took for granted as unlearnable outside of a formal education program. Thanks for sharing your love for civil engineering Grady.
drowningflamingo You should hang out at or even get a job at a place that perform these crafts! People will tell you all the intricate details you’re willing to learn, for free and maybe show you where to get free or nearly free training on each subject.
well said couldn't agree more
@@johndix1820 where ?
I had to pause the vid just to thank you for paying homage to the Hydraulic Press Channel, which is actually from the city where I live in Finland. I've even met them.. pretty nice people :)
Joonas Loppi I'd paused at the same moment, to look for reference for this channel in comments)
Welcome to the manually operated press channel ;-)
ensoniq2k It was a really good nod to them honestly XD
Now you need to say that again in heavy Finnish accent :D
*Edited.
Just say vittu perkele saatana a few times and you should mostly know Finnish.
fadetounforgiven *Finnish
SUCH A GOOD TRIBUTE
IT LOOKS VERY DANGEROUS AND IT MIGHT ATTACK AT ANY TIME
*parents jokingly barge into my room and yell "what are you doing in here with the door closed!?"* "watching videos about concrete and hydro engineering." *slowly closes the door
So that's what the kids are calling it these days?
The kids are alright
studying human anatomy, the miracle of life and fluid dynamics
You're lucky that your parents closed the door man. Mine just leaves with the door wide open
"Hello, 911?"
My first summer out of high school I worked for a concrete contractor. We installed driveways, sidewalks, patios and some basement floors. I learned enough to know that was not what I wanted to do long term. I was never told about what you explained so well in this video. Thanks. Now a retired telecommunications tech learning things on the web.
Excellent presentation!!! :)
I'm a retired civil & structural contractor that started in concrete construction almost 60 years ago. Engineers primarily want concrete to be placed a low slump (water/cement ratio) to attain high compressive strength earlier. As a teen I hand mixed 1000's of cubic yards for foundations and slabs (Butler Buildings) in remote locations, with hand shovels and a 3 cu ft gas mixer, We mainly used bank run material (natural sand/gravel deposits) and sack cement...also added a bit of dishsoap to entrain air...cold regions up North. :) With a tough hard working crew of 5 we could mix and place up to 100 CY in a day...long days!
When using a small mixer keeping the mix time to a minimum was aboulutely essential to production (we're being paid by the job not hourly). Creating a low slump mix that would keep a smile on an Engineer's face would take 5 or 6 times longer (dry materials take longer to become homogenious). We'd almost double the mix water. I know, I know...WATER CEMENT RATIO !!! We merely added another shovel of cement to the 10" slump mix. Cylinders were taken on quite a few pours and when cracked at 7 days the results were truly poor. However, 2 to 3 months later when a Smith-Blair hammer was used, strength always exceeded design loads.
Back in the day, plasticizers, redi-mix trucks and concrete pumps didn't exist. If one watches any old old videos of concrete being mixed in a trough you can see the slump is like soup yet a lot of these structures are still standing.
A project that I designed, tendered and constructed in 1986: www.4gto.com/Iona.jpg
As a retired structural engineer, I found this to be extremely well presented. Well done.
I'd love to see more data about concrete strength of different kinds with different ratios of ingredients. I bet people have made some really cool 2d and 3d data visualisations of the configuration space.
vavanade Yeah but try plotting a 4D graph on a 2D screen
Its 5D if you add time as well...
vavanade 4d, sand, cement, gravel, strength. You don't need a dimension for water since the proportion amount of water is just 100% minus the other ingredients.
Nope. Mix designs intended to tolerate freeze/thaw conditions deliberately entrain air in the mixture. Measuring the water content is just as important as measuring the other constituents.
If you want some seriously hot ass concrete use a type 3 cement.
In 3 1/2 hrs we was achieving a brake of 3000 psi and above.
The ambient air temp averaged 60 degress and i only covered the samples with a blanket instead of placing them in an ice chest. It was poured using a volumetric truck.
Well done sir. As a concrete finisher of several years, I appreciate your common sense approach to explanation.
2022, and this video still helps people (especially me as an engineering student) a lot. Clear and precise content. Thanks for making this!
Grady, love your videos!! My late father was a design engineer who worked for Bell Aerospace in Niagara Falls NY in the late 50's and into the early 70's and worked on the Apollo missions while contracted to NASA, I actually Met the Apollo 11 crew when we lived in Houston TX 1966-1968. The Engineering gene skipped me but found it's way into my youngest boy Daniel who is a Civil engineer here in Buffalo NY. It's great how you break down complex engineering issues into easy to understand (for the lay person) solutions.. Keep up the great work!!
Tom Buffalo NY
Hahaha that reference to the hydraulic press channel :-)
Kind of ironic xD love it.
and its just for the insiders! :D
I mean, WOT DA F***!?
Stoked about the reference!
Nice hydraulic press channel reference.
I have sooo much tension waiting for the next video!
David exactly! Haha
i see what you did there.
Did you just
This video reinforced my love for concrete.
David It shear is exciting to watch these vids as a Civil Eng'g student
Worked 25 years in QC for Master Builders who specializes in concrete admixtures, repair, and finishing products among other things. Really think you do a very good job presenting the basics on a material that literally is the foundation of the developed world. Had to chuckle a bit when you brought up the concrete vs "ce-ment" misunderstanding. We did our compression tests with 2" cubes and to say we had some interesting results - we had cubes from a run of Iron aggregate floor hardener that went over 17,500 psi at 28 days. The folks in the front office on the other end of the plant felt when the cubes failed.😅
Grady's voice has a calming effect. He should be a hostage negotiator.
It would be better without that annoying background musak. Why do they do it? Grrrrrrr
“How strong concrete do you want for the hostage?”
"I have the money you requested, but more on the that later"
AND HERE WE GO
AY DAS PLITTY GUD
lol WAAAW. DIS AX EES AMAASINK
Such a strong solid subject
The TI-89 has a battery protect function which prevents battery drain from uninformed comments.
Made 2 Hack
Non US engineers/student use casio calculators
Sadly it doesn't have antitheft function which is how I lost my beloved Ti-89.
@@red__guy nope I am moroccan and use an Nspire
George, she left you for bigger nerd
Im american we have smart phones in the usa noone has calculators anymore.
I've worked in a factory that made concrete blocks for 4 years. Every block you've seen, we've made a variant. One machine would run a mix design that would use very little water 10-15 gallons per yard (3500lbs) of aggregate (cement, sand, mansand, rock). And the other would run 10-15 gallons per 1/2 yard of aggregate. I could tell you so much about concrete it's insane. The worst part was cleaning the mixers and the block machines at the end of the night.
I like that you present concrete examples.
I really enjoyed watching your concrete videos, I’m an architecture student and seeing you experiment with structural materials is far better than listening to a lecture in school. I hope to see more of your future explanation!
Finally some concrete science!
krawacik3 "proceeds to jump off cliff"
Yeah Science !
I'm hoping you'll explore the ancient Roman concrete, as well, and perhaps even describe some other sources of the quicklime, like shells.
Might want to discuss the more recent notice of the importance to saltwater to the hardness of Roman Concrete. I think there was 3 kinds of Roman concrete also.
Primitive Technology recently uploaded a video where he made lime from snail shells.
I watched it. as well as every other video he's ever published. [and about 5 other similar channels, but yeah!]
I was going to suggest this. I used to work for a Materials Testing Laboratory where they would test samples of concrete with hydraulic presses like you had there. The engineers used to say that the "best" (not sure whether they meant "strongest" but quite likely) sample they ever tested came out of an old Roman bridge: the authorities wanted to be confident it wasn't about to fall down, and they were not disappointed o.O
Apparently this was at least partly because prior to invention of Reinforced Concrete, it had to hold itself together-that and all the bad stuff fall apart centuries ago ;-)
Hand up anyone who has stood inside the Pantheon in Rome, with its 2000 year old concrete domed roof: en.wikipedia.org/wiki/Pantheon,_Rome
It’s sparks great joy when one TH-cam channel I like references another one
Hi! Just wanted to say that I recently discovered your channel and am enjoying it! Great stuff!
Welcome to hand-cranked press channel
And here ve go!
It still is hydraulic.
You're right. I didn't think about that.
Concrete is domesticated rock, fight me
So then also is glass
🤛🤜
I'm in the geosciences, but I started off in engineering and still have some passion for it (damn you calculus). Concrete is an amazing material from a rock perspective - it's essentially an artificial conglomerate/breccia in the overall composition, but the matrix (the cement) is radically different. It can be anything from artificial limestone (from simple slaked lime cement, which is non-hydraulic) to something that probably more resembles an extrusive igneous rock under a microscope - portland cement is not a simple mixture, involving calcium, aluminium, and iron oxide silicates in its manufacture, at least some of which are reacted to form hydrates during the formation of cement and some of which eventually reacting back to the carbonate they came from, not to mention the calcium sulfate added to control setting.
I actually can't wait to see more concrete videos, strange as that might sound.
(Also, love the shoutout to Hydraulic Press Channel)
Limestone. Easily located, too - not only is it incredibly common, but it's easy to identify - drop a little bit of dilute hydrochloric acid on it, if it fizzes, it's most likely limestone or a derivative of it (such as marble, which is metamorphosed limestone). From limestone you can make slaked lime cement, which isn't the best but certainly works - take the limestone, break it into small pieces, roast it (you need to hit 825 degrees Celsius) to produce lime, mix with water (slaking it) to produce calcium hydroxide, and once all the excess water evaporates, the calcium hydroxide will start to be carbonated by carbon dioxide in the atmosphere back into calcite (calcium carbonate). Won't harden in water, though - but if you can get your hands on some aluminium oxide silicate material (which isn't uncommon - if you can find kaolinite, you can heat it to form metakaolin, or you can use certain rocks like pumice or tuff, or even industrial by-products like fly ash), you can mix it in to produce a cement that *will* set underwater. This is, notably, what the Romans and Greeks used.
You say it'd be easy to confirm it's limestone via using hydrochloric acid- but what if you lack easy access to supplies of the stuff? How would you confirm it at that point?
While it's not too hard to get your hands on (it's often sold as a cleaning agent as Muriatic acid), there are a few other identifiers (if not as definitive). Depends on the type, of course. Fossiliferous limestone will, as the name implies, often have fossil imprints or even full-on fossilized remains in it. Oolitic limestone has a distinctive texture (being comprised of tiny ooids, or spherical grains). Travertine has very distinct layering and banding along with a crystalline structure. Micritic is probably the hardest to identify without acid, if only because it shares a lot of properties with other fine-grained sedimentary rocks - I suppose you could resort to hardness testing (limestone won't scratch a steel blade, but a quartz-based rock will). Possibly one identifying feature you could use to tell an entire bed at a glance is weathering patterns - limestone is very easily weathered, giving crumbly, pitted outcrops.
I suppose a geology field guide might be added to the list of books and reference materials you might want during a zombie apocalypse.
We're talking about in a post-apocalyptic scenario here; obtaining hydrochloric acid won't be as simple as walking down to your local hardware store. First part of Mark's question, after all: "so, going primitive... let’s say humanity falls (zombie apocalypse, nuclear war, basic Armageddon)..." thus the query. I'm quite familiar with hydrochloric acid in use for cleaning, myself.
dude on primitive technology made cement from snail shells. a lot of big limestone deposits are formed from ancient seabeds covered in shells. basically you cook them in a hot furnace and then crush it up. fly ash is pretty simple to make, it's the ash that flies up from a coal fire, chemically different from bottom ash which you could use to make soap. if you can make an electrostatic doohickey you can collect it while you bake your shells, or raid an abandoned coal power plant. mix those together and you got cement.
I am super confused how the driest samples were the strongest ... yet you mention earlier how insufficient water can screw up the mix, and underwater curing can provide stronger concrete? Fascinating video nonetheless, great job.
Right! I'm also very confused on what to do should I do a few water and dry cure it or just right water and wet cure it I don't get it
As someone who is certified in the concrete industry, great explanation, just like every video of yours ive watched. Man, i could have used your help back when i was trying to learn this stuff. Great job, sir!
I finally had to subscribe because I won't be able to binge all the concrete episodes at once.
"Here in my garage with my brand new concrete"
Fun to build with up in the Hollywood Hills
OMG I died at "we need to deal with it" and the hydraulic press. Thank's for that!!
RIP Rory
Hey Grady! Just wanted to thank you for making this amazing yet informative video really helped me out, cheers.
Love the Hydraulic Press Channel reference! And I now know the difference between concrete and cement, Thank you! Please keep posting videos!!
“Welcome to Hÿÿÿÿÿÿÿÿÿdráulic Press Channel...”
Nice little easter-egg! :P
I am sad there was no "extra content" at the end.
But in general, this was a very good demonstration of why you should not add more water to make the thing flow into form easier.
"You dont build structures from pure cement the same way you dont build furniture exclusively out of wood glue"
Holy shit that is the best way to describe the purpose of the rocks and pebbles...
I hear concrete called "cement" from the same peeps who call ammo "bullets"
@@charlesbeall9453 They're also the same people who call furnite wood glue.
A bag of Portland cement costs roughly double the cost of concrete mix. The sand and gravel not only add strength, they are cheap fillers as well.
Ok you just blew my mind with the old throwback to the Finnish hydraulic press channel. Hilarious and only to be enjoyed by those who have spent sufficient time in this rabbit abode...
Working for a company that produces additives for concrete production has opened the world of concrete to me. I never knew how both simple and complex concrete production could be. Great video! :)
Never been this fascinated with concrete. My life changed.
This was a pretty solid video
Greatest weakness?? TENSILE STRENGTTHHHHH square root of Fc’!!!!
Also, please talk about the dynamics of concrete and steel! These videos are great!
hey! whats Fc ?
@@Yajurshridhar it's hard to write it on the Web and make it look right, but pronounced "f sub c prime" is the compressive strength of concrete, typically expressed in pounds per square inch (psi)
Videos like yours make learning way more enjoyable. My old schools could have learned a lot from your methods. Thank you for explaining the topics in a concise and fascinating manner.
You know, it's so great that an ordinary guy who is interested in all kinds of stuff can just go on youtube and quickly learn some stuff about concrete.
You explain it really well, imagine 15 years ago, you wanted to learn a little bit about concrete.
Thanks a lot.
Wonderful Video.
Could be 30min long... I would enjoy if for every second
"We need to deal with them. DUUNN da Dun-n Dun-n Dun-n Daaa Duh Da Dumm.." Nice!
Love your videos! Can you explain why submerged concrete "will set and harden just as well, or maybe even better, as if it were dry" yet demonstrates the greatest compressive strength with the smallest w/c ratio? Does it somehow not absorb as much water when the sample is completely submerged? Thanks!
Yes please! I was looking for a comment with this exact question. Sad to see there are no replies after two years. Great video otherwise besides leaving this contradiction hanging as a question mark.
I just yesterday came across this channel and do not regret it, the perfect mix if entertainment and knowledge!
I don't know if anyone else has mentioned this, but I loved the shout out to the Hydraulic Press Channel. I got a good laugh from that.
TH-cam has gotten pretty comfortable with two midroll ads...
Can you do tests with different types of additives (sawdust, fibrous materials, carbon, polymers, etc.) to show the difference of how they compare?
This. Is. A. Genius. Suggestion.
This might require more tests to show different real-world applications -- e.g. long-term wear and tear, what if with rebar, what if exposed to water, what if exposed to heat-cold cycles for how long, what if layered, what if sharp trauma, what if vibration trauma, etc
Yaa
I love that Hydraulic Press Channel inset ;)
This dude made a random question that just came into my head take up more of my interest than I expected. Great video, made concrete much more interesting and intriguing
Wow, this video provided such a fascinating and comprehensive explanation of what concrete truly is! I never realized the intricate process and ingredients involved in creating this versatile building material. It's amazing to think that something as simple as cement, combined with aggregates and water, can result in a substance with such incredible strength and durability.
Great makeshift cylinder molds.
cardboard tubes might work to :)
They would probably deteriorate in the water. Also, if the cylinders were not cured in water, a tube would allow the water to evaporate too quickly and not give a proper result for testing. However, masonry grout is actually tested in cardboard tubes for this reason. When you fill masonry walls with grout the masonry will absorb some of the water so the cardboard gives some sort of parallel to this affect.
These are some concreet answers
Richard Jorissen pretty solid
Hard to answer
Beat me by 12 minutes :'( its a concreet failure
First I didn't have STRENGTH to say this joke. But once I SET my fears a side. I had a SOLID feeling, that it would be a ground breaking joke.
That's a well constructed joke. It made me laugh pretty hard
3:41 you mention that aggregates can increase the strength of concrete. Are you sure about this? I'm a Civil Engineering student and have been told that aggregates are only used to save on costs, since the aggregates reduce the strength because the boundary between the aggrigate and the cement is always weaker than the cement itself.
Isn't it because aggregate holds itself better together than cement does? So it's basically lots of strong spots held together with weaker material in the "hope" that the strong spots take all the load. And "hope" in quotations because it's more of science than blind luck these days :D
The aggregate itself is stronger than the hydrated cement paste.
my buddy from high school did construction for awhile with his dad and I asked him about concrete awhile back. His answer to this was that "fence post concrete" excludes aggregates entirely and it's the weakest kind of ready-mix concrete you can buy. I'm not an engineer or physicist, but that's certainly a data point.
Part of the benefit of large aggregate is that cracks cannot take a direct route through the cement matrix. They have to divert around large particles, so must grow larger before the material fails. Think of them like wood dowels holding together two planks to stop them sliding past each other.
Rough aggregates (as opposed to smooth pebbles) are especially good because of friction at the grain boundaries.
(I'm speaking from geological training more than engineering.)
Motoko Urashima "aggregates entirely" would be like a bag of rocks with some cement on top. Hes not wrong but the type of aggregates you use can change the dynamics
I should recommend your video to our customers.
We are concrete block manufacturer company located in Turkey and our customers ask about concrete mixing ratio and other details. I will recommend your video from now on.
I have apaper tomorrow and I can't express enough my gratitude to you. Thanks for this video❤. May you have a beautiful life..
Here in New York City I observed highway builders use something like large canvas tarps and leaking hoses (hoses with many holes in the sides?) and they would leave them over fresh concrete pours for days at a time. Maybe two or three days/nights they would leave them. I figured it was part of the cure but I didn't know how till now. :)
kmg501 hopefully this comes up in a video of the series.
You nailed it, the idea is that drowning the surface with water protect the concrete from the weather and doesn't allow the water to evaporate, in some projects we build the forms 5 cm higher and fill that gap with water for 5 days.
Let me guess the topic of the next video! Concrete, while excellent under compression, is very weak to tension. This is why you often reinforce concrete with prestretched steel rods that ensure that the concrete is always under compression.
Leonard Kielland , yes but what matters are the steel rods themselves. The "stretching" part you mention (pre-stressing or pre-tensioning) are special high performance variants, but they're not essential to the principle. Often, the design just calls for rods to be placed at rest. Where you place the rods (and how much) is critical, though.
I hope that he describes post-tensioned concrete, the kind that failed in the recent Miami pedestrian bridge collapse.
Thank you -- interesting. The last cylinder's surface resembles cinder block. Same recipe?
Thanks!
*Portland cement* got its name from the similarity with Portland stone which was quarried on the Isle of Portland in Dorset, England.
I have a question. In the construction industry I’ve always heard that old concrete is harder/stronger than fresher stuff. The longer it sits the stronger I gets. Is this true. If so why? It seems that after the curing cycle it could only get weaker. Idk.
jesse lanting I heard it was stuff getting packed into it, idk how true it is. If it is true, the real question is why not add fibres to the mix?
I think it does start getting weaker after the curing cycle. I believe, though, that the curing cycle can take years(even decades) to fully complete. I'm sure it's not linear (ie. greatest effect on strength in the first days or weeks with diminishing effect tapering off as the cutting cycle completes over many years). I'm not an expert. This is just my best guess.
I don't think concrete ever stops curing given that it retains enough moisture to keep going.
Generally the concrete is designed with a warranty age, this means the concrete get it's 100% strength after this period (usually 28 days), but it's true, this doesn't mean after the warranty age the concrete strength stop growing, but it's grown is not the same. From 7 to 28 days the concrete increases from around 70% to 100% and from 28 to "x" days grow from 100% to 105 or 120% max. This tested on laboratory of course.
OK then why gets weaker? This is because external facts like weather (rain, wind) and of course time, the concrete is a formidable construction material but is not inmune to mother nature forces.
According to Wikipedia concrete strengthens with age due to absorbing CO2 gas from the atmosphere, and converting calcium hydroxide into calcium carbonate over several decades: en.wikipedia.org/wiki/Concrete#Curing
A rule of thumb is maximum strength around 75 years, by then the corrosion of rebar will be weakening the overall structure.
i have a question.
how come there are songs about cowboys,
but no songs about cement finishers?
Bob the Builder intro song
Because concrete finishers don’t generally isolate themselves for weeks at a time hanging with cattle, talking to no one then blow all their cash on drunken binges once they hit their destination. Somewhat like sailors except Cowboys’ charges get slaughtered intentionally at the end.
@@johndix1820 concrete workers definately blow their wages on binges
Gosh darn that HPC reference
This was fun to watch. Smooth and effective delivery of knowledge.
This is great! I appreciate your deep interest on this.
So next video is about concrete being strong only in compression?
Maciej Bator the one about sand is sort of about that as well
Yep, the wait can't take the tension.
You know how people talk about watching paint dry?
I never expected to be this excited to watch concrete dry.
"concrete dry"? Maybe you should watch it again?
This video cements the facts and has concrete proof to back it up
:^
I like your dry delivery of the humor, makes it pretty funny!
Good start to learning about concrete. First time I made concrete was at age 15 on a roadworks job. Since then, I have mostly worked for pay or at home with pre-mixed concrete delivered by truck. I loved both kinds of concrete and have studied the history of concrete from Roman times.I am an economist by profession and have not been employed in construction since age 17.
Sir, what will happen if you mix plastic to the concrete? Will it be strengthened or weakend?
Felipe Goleta plastic like water bottle plastic may not be a great idea. I know that fibers made from polymers are used in concrete mixes to increase strength!
When do you do 'Jet fuel melts steel beams' ?
I'd be careful with this "diving into concrete" thing :D I have a question though, Is'n the sand actually crucial to the curing of concrete? I remember from school it actualy takes part in the process as a substrate.
It's crucial to the strength, but it takes no part in the reaction. You can have small aggregate (sand's part in concrete) that does react, but silicate sand does not.
Overall sand is a bad thing for concrete, unless it is a low alkaline mix, or the sand is resistant to alkaline attack. But initially it is a good thing because the silica turns into a gel and hardens, and is actually a part of the cementing process. So in the short run increases the strength of the composite. Also much of the larger aggregate likely has a lot of silica because it is a common part of other minerals. The problems with sand come in the long term. Silica alkali reactions continue through the life of the concrete, and the gel volume of each original sand particle increases leading to intense internal hydrostatic pressure. That, along with potentially the rusting of the rebar, is why old concrete begins to spall. en.wikipedia.org/wiki/Alkali-silica_reaction
According to me sand and stone is just a "filler" the actual strength of the concrete is determined only by the cement water ratio. The sand however plays a big roll in the amount of water needed.
effyou128, this wouldn't surprise me since it's a very complex science. However since you don't give any reasons, and or links to back up claims.. that and the whole f***you name... and calling us retards..... hmmm.
This is why GGBFS (ground granulated blast furnace slag) is now popular as an additional pozzolan... not only does it mitigate ASR, but also assists in reducing permeability and heat generation.
I have been looking for such a video and for this type of information for over six months now. Thanks you for sharing this knowledge!
You are such a marvelous teacher and your programs are answering a lifetime of questions for me. Many thanks.
What herbs and spices are used?
Mainly gypsum I believe
Thyme and rosemary
correct. along with small amounts of iron sand
Don’t forget the lamb sauce
Bart Bols Gypsum
So I don't get it (maybe I have to watch the video again). How can the water be so important to curring (so that it can harden under water), but too much water is bad for compression strength? How does that mix up? I mean, how are birdge foundations made, if concrete with too much water is nearly useless?
That is a point i wish he had brought up during the video. But the short answer is that the amount of water used only matters during mixture; after concrete hardens (which could take from 15 minutes to 2 hours, depending on its characteristics and if any special chemicals were added), it should ideally stay submerged to prevent the water added during mixture from escaping. The reason for this is that the water added during mixture will increase the volume of concrete, increasing the spacing between the cement molecules and making it weaker, but after concrete has hardened, the spacing between molecules is somewhat fixed, so water is used for curing to ensure that hydration takes place properly (to ensure that cement has enough water to bind / react with so it gains strength continuously).
Oh Ok. Thanks for the answer
"How does that mix up?" Did you just
So, mix the concrete, wait for 15 minutes, and now it's still maleble?
@I know Cause I'm BatMan. Well yea. After it hardens the chemical reactions in the concrete cause heat and that leads to the water being evaporated which is bad as the mix is already hardened which leads to spaces formed between the particles and that lowers the strength of it due to cracks being formed. so it is best to submerge the concrete for a few days pervent that from happening
So . . . Cement Mixer Trucks carry concrete, not cement?
[edit] I was making a joke, guys.
backstept technically both at once
probably concrete, the applications of cement dont really require quantities that are more than what 1 person could mix by hand(or on site machine) for 5 or so people at once.(Cement often being used to describe mortar)
I'd say the name is same mistake as when people call concrete as cement, but yes, they carry concrete. Cement is often transported in a tanker truck where it is pumped in/from with air pressure. Concrete mixer trucks are the ones with the distinguishable rotating "cylinder", which is there to prevent the concrete from settling inside the cylinder. Especially relevant during extreme temperatures.
Source: Worked at a concrete plant for a few years, mixing concrete for construction sites and for use at element walls.
I guess you can say that cement mixers mix the cement with aggregate and water.
Concrete trucks carry everything already mixed including the cement. So if you're going by the terminology in this video then concrete trucks carry concrete. The only thing that is added in the truck is additional water
Wonderful and educational video. Really like the simple testing of the importance of water content vs strength testing.
I would like to see a video about concrete additives, like fiber material, plasticizers and bonding agents. Basic explanations of what they do, how to use them, and for what type of projects they would benefit.
That demonstration just confirmed all my doubts about water/cement ratio as it affects concrete strength. Now I will REALLY be careful with the hose and maybe start using plasticizers. Thanks a lot sir.
I made concrete canoe with special concrete that after 3 days had 110 MPa. :-)
Arek got any vids of that?
ASCE student competition? www.asce.org/event/2018/concrete-canoe/
I am from Poland and I made 2 canoes. First was for Beton Kano Race 2016 in Arnhem and second was for Concrete Canoe Regatta 2017 in Colonge. If you want to know what was the mix here it is (for 1m^3)
-1000kg of 52,5R cement
- 200kg of silica dust
- 200kg of H20
-300kg of 0,2mm sand
-500kg of 0,4mm sand
- and 60kg of some nasty chemical stuff (Superplasticizer etc.)
Test:
cube dimensions: 150x150x150mm
weight: 7521g
density: 2228kg/m3
destructive force: 2375kN
compressive strength: 105,6 MPa
I can say that these concrete canoes give so much fun. You can actucally make something with your own hands (make computer design and wooden formwork and ofc conrete). Only thing you need is 10 people, around 3 000 $ and free time :D I also took part in 7 bridge competitions (steel and wooden) and only thing I find more fun than this conrete canoe is building wooden bridge and than destroying it. :D
facebook.com/BetonkanuRegatta/
are you the how its made narrator?
you should have asked, "Are you 'How to Basic'?"
apparently everyone is how to basic
Are you Expert Village?
"...then we beat the workers to a pulp.."
But whyyy is the least water the strongest
Exp lane more please
Doug Reed I don’t quite understand what you are saying
It's a bit more complex than this, but here's a very basic explanation. When the cement particles encounter water, the hydration process begins.... in which case they begin growing "crystals" that bind & interlock with the crystals from other cement particles. Think of two cement particles as sawhorses, and lay a single 2x4 across them... the sawhorses are the cement particles, and the 2x4 is the crystal between them. If the sawhorses are very close together, and you push down on the 2x4, it will be very difficult to bend, let alone break... this is a low "water/cement ratio". Now, as you add more & more water, it takes up volume that pushes the cement particles farther & farther apart so those crystal bonds aren't nearly as strong... as you move the sawhorses farther apart, the 2x4 becomes easier & easier to flex until it becomes very easy to push down & break.
Frank W I think I get it thanks
Thank you for going to the work of making this video for us to instruct us in the science of concrete. We appreciate it. You would make a good school teacher.