The fact that it doesn't have any rebar in it is probably why it's still standing. Sure rebar lets you do stupid shit like put concrete in tension, but your structure will only last 100 years tops before it starts rusting and breaking the concrete.
a solution is to use post tensioned slabs.
Instead of rebar, you use pass steel cables through a hole, and in principle you can adjust the tension or replace them if they rust
post tensioning eh? thats what they used on that bridge at florida university right, the one that collapsed and killed people before it was even opened?
> The National Transportation Safety Board (NTSB) determines that the probable cause of the Florida International University (FIU) pedestrian bridge collapse was the load and capacity calculation errors made by FIGG Bridge Engineers, Inc., (FIGG) in its design of the main span truss member 11/12 nodal region and connection to the bridge deck. Contributing to the collapse was the inadequate peer review performed by Louis Berger,
> The National Transportation Safety Board (NTSB) determines that the probable cause of the Florida International University (FIU) pedestrian bridge collapse was the load and capacity calculation errors made by FIGG Bridge Engineers, Inc., (FIGG) in its design of the main span truss member 11/12 nodal region and connection to the bridge deck. Contributing to the collapse was the inadequate peer review performed by Louis Berger, which failed to detect the calculation errors in the bridge design. Further contributing to the collapse was the failure of the FIGG engineer of record to identify the significance of the structural cracking observed in this node before the collapse and to obtain an independent peer review of the remedial plan to address the cracking. Contributing to the severity of the collapse outcome was the failure of MCM; FIGG; Bolton, Perez and Associates Consulting Engineers; FIU;
>and the Florida Department of Transportation to cease bridge work when the structure cracking reached unacceptable levels and to take appropriate action to close SW 8th Street as necessary to protect public safety.
~~*snopes*~~ lmfao nta but I'm glad that was early in your post. You may as well delete it unless it was a joke I dont even have to read it to know there's nothing of value there.
The foundations of the pantheon had footers 15ft wide and 25 feet deep. Jesus frick dude imagine being this stupid. The entire thing is engineered to be under compression. UNLIKE A SLAB.
The people who designed and built the Pantheon (or the three versions of it) understood compression. The vault is build of lighter grades of concrete, over massive pillars and walls, and even built a structure in the back of the building, the grottoni, to spread the pressure and to keep the curtain wall from falling over. Then they capped the dome at the oculus with a brick and bronze ring to keep the compression under control.
And none of that stopped the building from cracking over time, and needing repairs over the centuries. If it wasn't a building that has been maintained at high cost all these years, it probably would have collapsed by now, just from cracks and the sheer grind of pressure over 2000 years.
But morons here think how it was built is superior, lol.
>If it wasn't a building that has been maintained at high cost all these years
Its a building that might see 2-3 expensive repairs a century.
The maintenance on the Pantheon is cheaper than a lot of middle medieval cathedrals, where the wood has a finite lifespan and require extensive scaffolding just to replace the partially load bearing structure.
Rebar isnt to stop it from cracking its to make it a slow process over time instead of a single catastrophic event.
That isn't even what rebar is used for.
Rebar is used so you can use less concrete and build more vertically.
You're a moron. One, they made several attempts to make the Pantheon, two, it's got cracks in it, because it has no rebar, and three, if they'd had access to rebar or had discovered it, they would have used it. There's a ring of brick and bronze in the oculus, that is there to mitigate the pressures on the dome, which they wouldn't have needed with rebar.
I know it's PrepHole, and it's just NEETs and incels taking contrarian positions to neckbeard the hours away, but you're more moronic than they are.
>WA
You didnt give thickness.
If you're putting the rebar down yourself.
I'm just going to assume you're hiring outside out. For an eight inch slab of 3200 SQ FT, you're looking up to eighteen grand.
3000 feet x 8 inches=60 cubic meters
About 150 tons of concrete and 12 tons of steel (assuming you reinforce at 2% steel). At $70 per tonne its $10.000 for concrete and $6000 for steel, just on raw materials. Humongous slab
form a footing 2x3, form a stair however you need. Fill with steel 2" from the perimeter of concrete and footing, fill with concrete wet enough to fill all voids-- morons do this all day long, you can too. I work with a multi billion dollar corporation and they still frick this up. So, be better.
This would work, just start at the first step, then when it dries move to the second and so on.
11 months ago
Anonymous
although there is a practical limit to how far up you can pour in one lift, you don't have to do it step by step. Having a multi-tiered pour like that done in one pour is common for both small staircases like that and footings etc that have to go up or down in elevation a few feet
>Don't you need a layer of gravel first for frost heaves or whatever?
The gravel doesn't really stop frost heave -- for that you have to go deep so that your concrete rests below the usual frost depth (around me it's about 42 inches down). It's meant to give a bit of extra structural support under the concrete and a more regular base. For most smaller slabs that are going to be subject to light foot traffic, you can often forego the gravel base.
https://i.imgur.com/cht9fZ6.jpg
This makes engineers seethe
>Engineering principles put into practice makes engineers seethe
If you say so.
11 months ago
Anonymous
Gravel provides little to no stability. It's entire purpose is to allow water to flow past the slab, and not pool under it.
The more rebar you put the stronger it gets. The slab acts like a beam in a way, it should keep its shape if the ground sinks in some places. If the ground is very strong you dont need rebar.
People build stone and wood houses for ages with a pure stone foundation. Its more prone to collapse, it all depends on local soil, earthquakes, erosion. There was this guy that built on a slope and a river washed away too much soil and the slab lost support and cracked.
Rebar mesh should be close to the bottom and top of the slab/beam, when the slab gets bent the crack starts at a surface (top or bottom) so reinforce there. Rebar at the center doesnt do much.
Good practice is to put 2-4% of rebar by volume of concrete. Its going to cost you as much as the concrete
Rebar is so fricking overrated. Your concrete is going to crack and fail over time regardless of what you do to strengthen it. You think your little 1/2 sticks of rebar in your slab are going to stop it cracking and sinking on one side when the ground shifts beneath it? No lol they're just going to bend because it's like 10 tones of concrete weighing down on it.
I've seen block walls with 5/8 rebar in them start to lean over time as well and when I've demoed them the concrete is all crumbling within the cells because the rebar corroded over time.
>The more rebar you put the stronger it gets
Lol no. Have you not seen how they're having to rebuild like every bridge in the country in a wet climate that is over 50 years old? Concrete is porous and the rebar rusts and then blows it out from the inside.
You're a moron. One, they made several attempts to make the Pantheon, two, it's got cracks in it, because it has no rebar, and three, if they'd had access to rebar or had discovered it, they would have used it. There's a ring of brick and bronze in the oculus, that is there to mitigate the pressures on the dome, which they wouldn't have needed with rebar.
I know it's PrepHole, and it's just NEETs and incels taking contrarian positions to neckbeard the hours away, but you're more moronic than they are.
>it's got cracks in it, because it has no rebar
Clearly you haven't got much experience with concrete.
>over 50 years old >wet climate >Bridge
Build something that can withstand constant stresses, water, and can be usable for 45 years. Frick cost because I want your magnum opus.
>over fast flowing white water river
Worst case you just dig a channel to detour the river, build and then block the channel
11 months ago
Anonymous
>just channel the entire river away bro
why do you need a bridge if you can just channel the water away
11 months ago
Anonymous
Try thinking about what you said for more than 10 seconds. Even if you divert part of the river a few dozen meters to the side, you'd still need a way to cross it.
You at least need enough rebar (usually in the form of wire mesh) to resist cracking from temperature/shrinkage - otherwise your nice pristine slab will be cracked and chipped to shit within a year.
>Do you need to put rebar in concrete
yes
frick
How much does it usually cost for rebar and to pour concrete? Any directional idea?
About tree fiddy.
How the actual frick can we know if you won't tell us where you are?
The Pantheon is 2000 years old and doesn't have any rebar. Explain that, Einstein.
The fact that it doesn't have any rebar in it is probably why it's still standing. Sure rebar lets you do stupid shit like put concrete in tension, but your structure will only last 100 years tops before it starts rusting and breaking the concrete.
a solution is to use post tensioned slabs.
Instead of rebar, you use pass steel cables through a hole, and in principle you can adjust the tension or replace them if they rust
post tensioning eh? thats what they used on that bridge at florida university right, the one that collapsed and killed people before it was even opened?
Yes
Yes but it failed because it was designed by alphabet women, not because post tensioning is a bad idea.
Hur dur
https://www.snopes.com/fact-check/was-all-female-responsible-bridge-collapse/
> The National Transportation Safety Board (NTSB) determines that the probable cause of the Florida International University (FIU) pedestrian bridge collapse was the load and capacity calculation errors made by FIGG Bridge Engineers, Inc., (FIGG) in its design of the main span truss member 11/12 nodal region and connection to the bridge deck. Contributing to the collapse was the inadequate peer review performed by Louis Berger,
> The National Transportation Safety Board (NTSB) determines that the probable cause of the Florida International University (FIU) pedestrian bridge collapse was the load and capacity calculation errors made by FIGG Bridge Engineers, Inc., (FIGG) in its design of the main span truss member 11/12 nodal region and connection to the bridge deck. Contributing to the collapse was the inadequate peer review performed by Louis Berger, which failed to detect the calculation errors in the bridge design. Further contributing to the collapse was the failure of the FIGG engineer of record to identify the significance of the structural cracking observed in this node before the collapse and to obtain an independent peer review of the remedial plan to address the cracking. Contributing to the severity of the collapse outcome was the failure of MCM; FIGG; Bolton, Perez and Associates Consulting Engineers; FIU;
>and the Florida Department of Transportation to cease bridge work when the structure cracking reached unacceptable levels and to take appropriate action to close SW 8th Street as necessary to protect public safety.
https://www.ntsb.gov/investigations/Pages/HWY18MH009.aspx
~~*snopes*~~ lmfao nta but I'm glad that was early in your post. You may as well delete it unless it was a joke I dont even have to read it to know there's nothing of value there.
The Pantheon has cracks in it, and has been in a constant state of repair for thousands of years, dummy.
So is the pantheon a 3200ft pre fab metal building?
Is OP as smart as the people back then?(we know this answer)
The Lascaux cave has been standing for millions of years with no rebar
>millions
6000 tops
The foundations of the pantheon had footers 15ft wide and 25 feet deep. Jesus frick dude imagine being this stupid. The entire thing is engineered to be under compression. UNLIKE A SLAB.
> Nah bro the romans just put it on a slab
The people who designed and built the Pantheon (or the three versions of it) understood compression. The vault is build of lighter grades of concrete, over massive pillars and walls, and even built a structure in the back of the building, the grottoni, to spread the pressure and to keep the curtain wall from falling over. Then they capped the dome at the oculus with a brick and bronze ring to keep the compression under control.
And none of that stopped the building from cracking over time, and needing repairs over the centuries. If it wasn't a building that has been maintained at high cost all these years, it probably would have collapsed by now, just from cracks and the sheer grind of pressure over 2000 years.
But morons here think how it was built is superior, lol.
>If it wasn't a building that has been maintained at high cost all these years
Its a building that might see 2-3 expensive repairs a century.
The maintenance on the Pantheon is cheaper than a lot of middle medieval cathedrals, where the wood has a finite lifespan and require extensive scaffolding just to replace the partially load bearing structure.
That isn't even what rebar is used for.
Rebar is used so you can use less concrete and build more vertically.
You're a moron. One, they made several attempts to make the Pantheon, two, it's got cracks in it, because it has no rebar, and three, if they'd had access to rebar or had discovered it, they would have used it. There's a ring of brick and bronze in the oculus, that is there to mitigate the pressures on the dome, which they wouldn't have needed with rebar.
I know it's PrepHole, and it's just NEETs and incels taking contrarian positions to neckbeard the hours away, but you're more moronic than they are.
>it's got cracks in it, because it has no rebar
The cracks are entirely due to earthquakes
All in compression moron
What dumb question is this.
Not dumb, if its less than 4 inch or so you can get away with wire mesh. But I wasn't buying it so asked
WA
At least $1000
That's way too cheap Black person. I don't think your number are coming from experience
>WA
You didnt give thickness.
If you're putting the rebar down yourself.
I'm just going to assume you're hiring outside out. For an eight inch slab of 3200 SQ FT, you're looking up to eighteen grand.
Is 8 inch necessary or 6 inch can do? What area do you usually operate in? Just trying to understand how pricing works around different areas.
Also, in the 18k. Does it include site prep and gravel work as well? Or just the rebar and pouring of cement?
3000 feet x 8 inches=60 cubic meters
About 150 tons of concrete and 12 tons of steel (assuming you reinforce at 2% steel). At $70 per tonne its $10.000 for concrete and $6000 for steel, just on raw materials. Humongous slab
Is scrap rebar a thing?
I want some to make some stairs in my backyard
lenth amd gauge don t matter but i dont want to pay a lot or at all
You chimps freak me out. Get off DIY and educate yourselves.
Where should I go then? This is the closest bulletin I could fine kek
form a footing 2x3, form a stair however you need. Fill with steel 2" from the perimeter of concrete and footing, fill with concrete wet enough to fill all voids-- morons do this all day long, you can too. I work with a multi billion dollar corporation and they still frick this up. So, be better.
This would work, just start at the first step, then when it dries move to the second and so on.
although there is a practical limit to how far up you can pour in one lift, you don't have to do it step by step. Having a multi-tiered pour like that done in one pour is common for both small staircases like that and footings etc that have to go up or down in elevation a few feet
kek thanks for the encouragement
How much does that one load of concrete truck mix cost?
In my area usually a few hundred dollars.
Could you share some instances where they fricked it up and how bad was it to fix it? Very curious since professionals are messing up on this too kek
So you just pour it directly on top of dirt? Don't you need a layer of gravel first for frost heaves or whatever?
>Don't you need a layer of gravel first for frost heaves or whatever?
The gravel doesn't really stop frost heave -- for that you have to go deep so that your concrete rests below the usual frost depth (around me it's about 42 inches down). It's meant to give a bit of extra structural support under the concrete and a more regular base. For most smaller slabs that are going to be subject to light foot traffic, you can often forego the gravel base.
>Engineering principles put into practice makes engineers seethe
If you say so.
Gravel provides little to no stability. It's entire purpose is to allow water to flow past the slab, and not pool under it.
Where can i get educated in the field of scrap rebar?
Is there a good textbook for building with concrete? Online calculators and following the manufacturer instructions are a pretty crappy way to learn.
China.
>Is scrap rebar a thing?
No.
Rebar is for walls. Floors support themselves.
You may also just want to use gravel to avoid some building code laws about permanent structures.
The more rebar you put the stronger it gets. The slab acts like a beam in a way, it should keep its shape if the ground sinks in some places. If the ground is very strong you dont need rebar.
People build stone and wood houses for ages with a pure stone foundation. Its more prone to collapse, it all depends on local soil, earthquakes, erosion. There was this guy that built on a slope and a river washed away too much soil and the slab lost support and cracked.
Rebar mesh should be close to the bottom and top of the slab/beam, when the slab gets bent the crack starts at a surface (top or bottom) so reinforce there. Rebar at the center doesnt do much.
Good practice is to put 2-4% of rebar by volume of concrete. Its going to cost you as much as the concrete
Very helpful
Any resources where I can find prices for concrete pouring along with rebar?
You are living in a delusion
>Any resources where I can find prices for concrete pouring along with rebar?
Have you looked in the phone book under concrete, or general contractor?
At this point, I am a little worried for you.
>Have you looked in the phone book...
Tell me you're a boomer without actually saying you're a boomer. What if he gets a busy signal when he calls the number he gets out of the phone book?
"dial a number"
"hang up"
ahh, such ancient terms. need to die along with all the boomerati.
I was going for sarcasm here you tart frick!
Rebar is so fricking overrated. Your concrete is going to crack and fail over time regardless of what you do to strengthen it. You think your little 1/2 sticks of rebar in your slab are going to stop it cracking and sinking on one side when the ground shifts beneath it? No lol they're just going to bend because it's like 10 tones of concrete weighing down on it.
I've seen block walls with 5/8 rebar in them start to lean over time as well and when I've demoed them the concrete is all crumbling within the cells because the rebar corroded over time.
>The more rebar you put the stronger it gets
Lol no. Have you not seen how they're having to rebuild like every bridge in the country in a wet climate that is over 50 years old? Concrete is porous and the rebar rusts and then blows it out from the inside.
>it's got cracks in it, because it has no rebar
Clearly you haven't got much experience with concrete.
>over 50 years old
>wet climate
>Bridge
Build something that can withstand constant stresses, water, and can be usable for 45 years. Frick cost because I want your magnum opus.
3 words: Epoxy Coated Rebar
This PhD fellow goes on the problems of epoxy rebar
Romans built bridges like that out of limestone blocks.
The way we do modern concrete is sweaty and autistic.
This makes engineers seethe
No it doesn't moron, because engineers designed it, in 1825.
designated seething engineer. Can't fathom how to make this without pla and 3d printing zoomie?
how do you build such a structure over fast flowing white water river
They built it before it was a river. THAT'S how old it is
rivers usually shape the landscape
>over fast flowing white water river
Worst case you just dig a channel to detour the river, build and then block the channel
>just channel the entire river away bro
why do you need a bridge if you can just channel the water away
Try thinking about what you said for more than 10 seconds. Even if you divert part of the river a few dozen meters to the side, you'd still need a way to cross it.
Bridge builders used to be men.
Rebar isnt to stop it from cracking its to make it a slow process over time instead of a single catastrophic event.
Threads like this seriously make me wonder if the shills are making slide threads on PrepHole now too.
The big rebar shills?
Shhh...the /misc/ tard wranglers will show up eventually to bring him back to the containment field....
>the shills
are the shills in the room with you now? because there aren't any here, nor on /misc/
Fiber mesh is better.
What if you were building a patio? It's not like there's gonna be any significant load on it.
Where im from sidewalks are built with flattened sand and then flat stones are laid on the sand. No binder
Grade it, put down a few inches of gravel and compact the shit out of it, should be fine without rebar
souless. what a dumb spot for a tree
It's like they want a fricked up patio in 5-10 years
You at least need enough rebar (usually in the form of wire mesh) to resist cracking from temperature/shrinkage - otherwise your nice pristine slab will be cracked and chipped to shit within a year.
wire mesh prevents concrete from cracking in extreme temps? isn't that an inherent problem with cement
biggest issue with concrete is its weakness in tension. If you have steel wire/rebar to take up said tension in the concrete, it won't split.
if on fill dirt, absolutely. if on excavated ground up to 6" concrete, wire mesh will do. be sure and pull the mesh off the bottom.
>erecting
Use fiberglass rebar
You're almost guaranteed to frick up steel if you aren't a concrete guy
>pour slab with rebar
>rebar rust expansion blows concrete out, fails in 30-50 years
>pour slab without rebar
>rain erodes concrete over 500-1000 years
>post on PrepHole
>oF CouRSe yUO NeEd RebAR!!!!
reinforcing concrete increases strength in modes other than compression.
you don't need it for a slab on any decent sub base.
Matthew 7:24-27
>Matthew 7:24-27
absolute unit