What is Concrete?

What's the difference between concrete and cement?
Concrete is the most important construction material on earth and foundation of our modern society. At first glance it seems rudimentary, but there is a tremendous amount of complexity involved in every part of designing and placing concrete. This video is meant to be a bare-bones introduction to the topic, with a cool demonstration of concrete strength using a hydraulic press.
Watch this video and the entire Practical Engineering catalog ad-free on Nebula: go.nebula.tv/p...
-Patreon: / practicalengineering
-Website: practical.engin...
Marxist Arrow by Twin Musicom is licensed under a Creative Commons Attribution License
Source: • Marxist Arrow - Twin M...
Tonic and Energy by Elexive is licensed under a Creative Commons Attribution License
Source: • Elexive - Tonic and En...
This video is sponsored by Brilliant.

[@sn1p4m4n]

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.

[@arthas640]

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_

[@GewelReal]

@@arthas640 lmao

[@malcolmparkins1935]

NoobCanoe yes

[@arthas640]

@@malcolmparkins1935 no

[@UmarFarooq-mo7no]

Hilarious

[@andrebartels1690]

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!

[@gobdeep]

André Bartels 5:41 “Aaaand here we go!”

[@MattH-wg7ou]

Heooooodlrawlik plress. Aaaand heere ve go!

[@craigskotnicki9994]

Recognized it right away! Jumped out of my seat! Nice nod to a fellow KZbinr

[@pmashtx]

Thought it sounded familiar

[@interestingstories1838]

Holy sheet!

[@shannonkaplan5007]

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

[@wynwehmeyer8230]

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.

[@nickdabaca]

you got a job?

[@Paladin.Krieger2287]

*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

[@kuolettavaVids]

So that's what the kids are calling it these days?

[@matak99]

The kids are alright

[@l0remipsum991]

studying human anatomy, the miracle of life and fluid dynamics

[@destroyer2496]

You're lucky that your parents closed the door man. Mine just leaves with the door wide open

[@soup5344]

"Hello, 911?"

[@doctorbobstone]

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 KZbin crowd by constructing a solid foundation of knowledge. So, steel yourself for the road ahead. 👷

[@messman10]

He who'd pun would pick a pocket! Rebar and curing double entendre; I love it!

[@maxpower892]

*no pun intended*

[@messman10]

Max Power : So, we're not being "pun-nished?"

[@joonasfi]

Awwww daymm, nice puns son :)

[@najrenchelf2751]

Chris Sloan, DU-BUP-PSH!

[@joonasfi]

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 :)

[@octour]

Joonas Loppi I'd paused at the same moment, to look for reference for this channel in comments)

[@En1Gm4A]

Hahaha that reference to the hydraulic press channel :-) Kind of ironic xD love it.

[@Der_Arathok]

and its just for the insiders! :D

[@4IN14094]

I mean, WOT DA F***!?

[@Chris-jo1zr]

Stoked about the reference!

[@1845scott]

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.

[@zackstewart4109]

"You don't build furniture completely out of wood glue." You know what I want to do now.

[@mc3123456]

Don't worry, we're almost there. It's called OSB.

[@981porsche3]

Not make furniture completely out of wood glue? lol

[@Omlet221]

Are you on that yt video rn

[@brotherfredrick]

Epoxy furniture.

[@austintaylor7117]

the king of random-lets do it

[@SithLord2066]

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.

[@mantis0427]

OMG if I had such a "Gun" I would have fun for the rest of my life... And everything would be covered in concrete... ;)

[@brianwyters2150]

You know how in cartoons characters get covered head to toe in something like paint or melted chocolate? Now they stay in place.

[@afc8981]

I believe it's used in tunnel construction as well.

[@gazs4015]

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.

[@gazs4015]

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.

[@ensoniq2k]

Welcome to the manually operated press channel ;-)

[@spyderindustries8247]

ensoniq2k It was a really good nod to them honestly XD

[@fadetounforgiven]

Now you need to say that again in heavy Finnish accent :D *Edited.

[@yourcurtainsareugly]

Just say vittu perkele saatana a few times and you should mostly know Finnish.

[@NearCry91]

fadetounforgiven *Finnish

[@benkim6969]

SUCH A GOOD TRIBUTE IT LOOKS VERY DANGEROUS AND IT MIGHT ATTACK AT ANY TIME

[@arduinoversusevil2025]

7:22 one little nugde and we would have seen full Civil Nerdgasm.

[@parkerbradshaw4122]

AvE hi AvE

[@patrik5123]

OMG AvE follows the same channels I do... omg omg omg... ok be cool be cool... Sup? **That was so stupid**

[@dominiquegobeil5831]

AvE always follow awesome channel!

[@arduinoversusevil2025]

Sup lads. What are the odds Grady tests self-cleaning titanium oxide concrete?

[@PracticalEngineeringChannel]

@AvE No way I'm wading into that mess. I have a license and employer, both of which I would like to keep ;)

[@drowningflamingo]

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.

[@johndix1820]

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.

[@majermike]

well said couldn't agree more

[@hhhuthhhjj5599]

@@johndix1820 where ?

[@66block84]

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.

[@paulharris493]

As a retired structural engineer, I found this to be extremely well presented. Well done.

[@clktlk]

I have sooo much tension waiting for the next video!

[@GGJChannel]

David exactly! Haha

[@ampar1010]

i see what you did there.

[@colonelstriker2519]

Did you just

[@oogrooq]

This video reinforced my love for concrete.

[@oedipus322]

David It shear is exciting to watch these vids as a Civil Eng'g student

[@Krawacik3d]

Finally some concrete science!

[@samalbury9183]

krawacik3 "proceeds to jump off cliff"

[@buddimalliyanapathirana1767]

Yeah Science !

[@peachville4383]

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

[@artworkbybernizzz2654]

2022, and this video still helps people (especially me as an engineering student) a lot. Clear and precise content. Thanks for making this!

[@RobertMilesAI]

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.

[@RobertMilesAI]

vavanade Yeah but try plotting a 4D graph on a 2D screen

[@gordonrichardson2972]

Its 5D if you add time as well...

[@barneylaurance1865]

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.

[@JasmineLindros]

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.

[@jessethomas7949]

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.

[@danielsestina6457]

Well done sir. As a concrete finisher of several years, I appreciate your common sense approach to explanation.

[@Made2hack]

The TI-89 has a battery protect function which prevents battery drain from uninformed comments.

[@red__guy]

Made 2 Hack Non US engineers/student use casio calculators

[@GeorgeMonet]

Sadly it doesn't have antitheft function which is how I lost my beloved Ti-89.

[@user-rd5nc1nb9f]

@@red__guy nope I am moroccan and use an Nspire

[@kvakerbillduck9500]

George, she left you for bigger nerd

[@yzrippin]

Im american we have smart phones in the usa noone has calculators anymore.

[@sluggo0202]

Grady's voice has a calming effect. He should be a hostage negotiator.

[@g0mhc]

It would be better without that annoying background musak. Why do they do it? Grrrrrrr

[@cheesebusiness]

“How strong concrete do you want for the hostage?”

[@zachrichardson5581]

"I have the money you requested, but more on the that later"

[@569139]

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

[@Qwerasd]

Nice hydraulic press channel reference.

[@KatherineClairmont]

AND HERE WE GO

[@Nitrxgen]

AY DAS PLITTY GUD

[@KatherineClairmont]

lol WAAAW. DIS AX EES AMAASINK

[@thatoneguyRyan1]

Such a strong solid subject

[@rorynicholson9164]

OMG I died at "we need to deal with it" and the hydraulic press. Thank's for that!!

[@derputydog5803]

RIP Rory

[@kamlstha36]

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.

[@Tacsponge]

I finally had to subscribe because I won't be able to binge all the concrete episodes at once.

[@sayhellomonster4302]

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!

[@TizonaAmanthia]

I'm hoping you'll explore the ancient Roman concrete, as well, and perhaps even describe some other sources of the quicklime, like shells.

[@tommy-er6hh]

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.

[@deltib]

Primitive Technology recently uploaded a video where he made lime from snail shells.

[@TizonaAmanthia]

I watched it. as well as every other video he's ever published. [and about 5 other similar channels, but yeah!]

[@PhilBoswell]

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 ;-)

[@gordonrichardson2972]

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

[@geoffholmes7291]

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...

[@vaderdudenator1]

It’s sparks great joy when one KZbin channel I like references another one

[@IowasDirtyCivilian]

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.

[@PyroDesu]

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)

[@PyroDesu]

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.

[@KainYusanagi]

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?

[@PyroDesu]

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.

[@KainYusanagi]

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.

[@edstirling]

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.

[@Fred_uyz]

Concrete is domesticated rock, fight me

[@Bekindallways]

So then also is glass

[@Bekindallways]

🤛🤜

[@Alshevano]

I hate engineering’s basket on the scrusñ people who are 😊

[@lumberjackcharlie6154]

You're thinking of cultured stone.

[@texschuler]

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!

[@ClemmyGames]

Hi! Just wanted to say that I recently discovered your channel and am enjoying it! Great stuff!

[@Jonassoe]

Welcome to hand-cranked press channel

[@Kargoneth]

And here ve go!

[@NGC1433]

It still is hydraulic.

[@Jonassoe]

You're right. I didn't think about that.

[@F-Man]

“Welcome to Hÿÿÿÿÿÿÿÿÿdráulic Press Channel...” Nice little easter-egg! :P

[@LinkTheHero]

"Here in my garage with my brand new concrete"

[@Brave_SJ]

Fun to build with up in the Hollywood Hills

[@christopherjennings2830]

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.😅

[@charofamily4430]

Love the Hydraulic Press Channel reference! And I now know the difference between concrete and cement, Thank you! Please keep posting videos!!

[@emeryshurpit8656]

"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...

[@charlesbeall9453]

I hear concrete called "cement" from the same peeps who call ammo "bullets"

[@bitterlemonboy]

@@charlesbeall9453 They're also the same people who call furnite wood glue.

[@ralphbell1786]

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.

[@VladKine]

Never been this fascinated with concrete. My life changed.

[@martialmarshal]

Greatest weakness?? TENSILE STRENGTTHHHHH square root of Fc’!!!! Also, please talk about the dynamics of concrete and steel! These videos are great!

[@Yajurshridhar]

hey! whats Fc ?

[@scottrabinow2773]

@@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)

[@designtechdk]

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! :)

[@franklesser5655]

I like that you present concrete examples.

[@dawnofjustice4689]

Thanks a lot. Wonderful Video. Could be 30min long... I would enjoy if for every second

[@kingkirby8960]

This was a pretty solid video

[@qwerty25844]

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!

[@Nettle314]

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.

[@coryzipperle5627]

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.

[@tommy-gz4jr]

Hey Grady! Just wanted to thank you for making this amazing yet informative video really helped me out, cheers.

[@dberzins]

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.

[@WarrenGarabrandt]

"We need to deal with them. DUUNN da Dun-n Dun-n Dun-n Daaa Duh Da Dumm.." Nice!

[@teramasz]

I love that Hydraulic Press Channel inset ;)

[@janetpocsi1498]

Thanks!

[@EbenezerChristine]

I have apaper tomorrow and I can't express enough my gratitude to you. Thanks for this video❤. May you have a beautiful life..

[@73standard]

Great makeshift cylinder molds.

[@firefox5926]

cardboard tubes might work to :)

[@clee8768]

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.

[@thespeedycamel]

Can you do tests with different types of additives (sawdust, fibrous materials, carbon, polymers, etc.) to show the difference of how they compare?

[@ninomartin]

This. Is. A. Genius. Suggestion.

[@ayuchanayuko]

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

[@varadbidwai4489]

Yaa

[@ivantarnyagin]

KZbin has gotten pretty comfortable with two midroll ads...

[@alphabladelm2011]

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.

[@homierdawg]

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

[@scronx]

Thank you -- interesting. The last cylinder's surface resembles cinder block. Same recipe?

[@RCWolf]

This video cements the facts and has concrete proof to back it up :^

[@wierdalien1]

Gosh darn that HPC reference

[@concretestory3414]

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.

[@Mikki-Moo]

I like your dry delivery of the humor, makes it pretty funny!

[@kmg501]

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. :)

[@zachburke8906]

kmg501 hopefully this comes up in a video of the series.

[@rweissrock]

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.

[@MijnAfspeellijst1234]

These are some concreet answers

[@DanielGalllego]

Richard Jorissen pretty solid

[@cedric4928]

Hard to answer

[@eschel2155]

Beat me by 12 minutes :'( its a concreet failure

[@MijnAfspeellijst1234]

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.

[@bloodaid]

That's a well constructed joke. It made me laugh pretty hard

[@leonardkielland3263]

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.

[@euromicelli5970]

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.

[@WG55]

I hope that he describes post-tensioned concrete, the kind that failed in the recent Miami pedestrian bridge collapse.

[@vessmachineen193]

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.

[@4wheelwarrior]

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.

[@carlbenedictbais7422]

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

[@KyleLi]

You know how people talk about watching paint dry? I never expected to be this excited to watch concrete dry.

[@Bialy_1]

"concrete dry"? Maybe you should watch it again?

[@augustreigns9716]

i have a question. how come there are songs about cowboys, but no songs about cement finishers?

[@libertardsbeware4180]

Bob the Builder intro song

[@johndix1820]

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.

[@tubestick00]

@@johndix1820 concrete workers definately blow their wages on binges

[@jesselanting3931]

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.

[@skyr8449]

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?

[@chrissekely]

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.

[@FutureChaosTV]

I don't think concrete ever stops curing given that it retains enough moisture to keep going.

[@zlerj]

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.

[@gordonrichardson2972]

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.

[@romeohussain6564]

7:01 to 7:12 Such a cool shot. And I'm glad you're having fund with the neighbours and the kids with the concrete experiments.

[@AtomBomb420]

I just yesterday came across this channel and do not regret it, the perfect mix if entertainment and knowledge!

[@backstept]

So . . . Cement Mixer Trucks carry concrete, not cement? [edit] I was making a joke, guys.

[@georgegreen3470]

backstept technically both at once

[@ra4yu]

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)

[@aStiffSausage]

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.

[@seneca983]

I guess you can say that cement mixers mix the cement with aggregate and water.

[@Pasquali_Sergal]

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

[@oyiebhoy5884]

Sir, what will happen if you mix plastic to the concrete? Will it be strengthened or weakend?

[@xorgelopez4740]

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!

[@PiranOfficial]

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.

[@Painteagle]

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.

[@MrBrew4321]

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

[@hein27]

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.

[@MrBrew4321]

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.

[@frankw7266]

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.

[@PCHSwS]

Wow I just realized I wasn't even subbed to you channel. For like 3 years. Luckily KZbin knows what's good and always recommends your videos, but now you got your deserved sub :D

[@chrishanke9523]

I drive a mini concrete mixer truck and I am looking to learn everything possible that I can about concrete, so I found this video interesting as well as accurate. Nice job!!

[@ArkadiuszPL]

I made concrete canoe with special concrete that after 3 days had 110 MPa. :-)

[@richardhoekstra960]

Arek got any vids of that?

[@clee8768]

ASCE student competition? www.asce.org/event/2018/concrete-canoe/

[@ArkadiuszPL]

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

[@ArkadiuszPL]

facebook.com/BetonkanuRegatta/

[@luciferholmes7469]

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.

[@blakOrkk]

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

[@MorleyKert]

The aggregate itself is stronger than the hydrated cement paste.

[@Motoko_Urashima]

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.

[@SonOfFurzehatt]

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.)

[@WiscoDrinks]

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

[@StaryWymiatacz]

So next video is about concrete being strong only in compression?

[@dgnikon]

Maciej Bator the one about sand is sort of about that as well

[@zeroone8800]

Yep, the wait can't take the tension.

[@RoNiminal]

This was fun to watch. Smooth and effective delivery of knowledge.

[@Accumulator1]

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.

[@ashwadhwani]

When do you do 'Jet fuel melts steel beams' ?

[@BartJBols]

What herbs and spices are used?

[@PracticalEngineeringChannel]

Mainly gypsum I believe

[@WiscoDrinks]

Thyme and rosemary

[@enja001]

correct. along with small amounts of iron sand

[@QuantumApple]

Don’t forget the lamb sauce

[@rocky0982]

Bart Bols Gypsum

[@florichi]

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?

[@MurdocK-BR]

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).

[@florichi]

Oh Ok. Thanks for the answer

[@jay-tbl]

"How does that mix up?" Did you just

[@EnjoyCocaColaLight]

So, mix the concrete, wait for 15 minutes, and now it's still maleble?

[@midoelghawaby825]

@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

[@fwcolb]

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.

[@damionhooper408]

Kinda late watching the video but I recently got a ready as a mix truck driver and this video helped me get a better understanding of how concrete works

[@PaGrapes]

are you the how its made narrator?

[@thegamecracks1317]

you should have asked, "Are you 'How to Basic'?"

[@Der_Arathok]

apparently everyone is how to basic

[@Knight_Astolfo]

Are you Expert Village?

[@iagreebut6813]

"...then we beat the workers to a pulp.."

[@vincentgagnon8309]

Why is Roman concrete so hard? There are Roman aqueducts still standing that are more than 2,000 years old and concrete sea walls that have withstood pounding ocean waves for more than 2,000 years!

[@clee8768]

It isn't necessarily hardness. Concrete today can achieve strengths of 20,000 psi or more (3000-5000 is most commonly used). The reason the Roman structures are so durable is that they did not use reinforcing steel. Given enough time water intrusion through the smallest of cracks will corrode the reinforcing eventually which causes the steel to expand and spall the concrete (cause chunks to crack off). Since they don't have rebar this doesn't happen. So why do we use rebar then? For many reasons but the most basic is that by using rebar we can reduce the amount of concrete needed in a design by an enormous amount. If designed correctly the structure will last long enough for its anticipated use but also be way cheaper and more aesthetically pleasing as well.

[@vincentgagnon8309]

Thanks Lee for the explanation. It is very much appreciated! I did not think about that. I make sense that without reinforcing steel the Roman aqueduct are massive compared to modern structure, but are still standing after 2000 years. I also found a reference from the journal Nature (03 July 2017) explaining that mixing sea water, volcanic ash and lime to bind rock fragments made very hard concrete. Here is the reference: www.nature.com/news/seawater-is-the-secret-to-long-lasting-roman-concrete-1.22231

[@zeroone8800]

Steel is also used to add some tensile strength and stainless steel is very expensive. Chromium is several to to many times as expensive per kg than carbon steel, depending on the market.) Chromium makes up at least 10.5% of stainless steel. Sometimes, the chromium can be more expensive than the iron in stainless steel. Despite there being much more iron than chromium in it.

[@insertnamehere9180]

Me a Minecraft player: the ingredients are sand, gravel and any colour dye then put it in water and bing bam boom.

[@chrisdavis2683]

Three concrete videos in now.. You got me, KZbin Recommendations, I'm in