I’m not a concrete expert, but a tonne of concrete is less than half a cubic metre.
A concrete truck carries 10 cubic yards, or nearly 18 metric tons of concrete.
If this “educational fact” is true, then that amount of sugar might cause an issue with a piece of sidewalk, but it’s unlikely to get noticed on anything being built with concrete, unless you bring a metric shit ton of sugar to the party.
As it happens, sugar appears to be added to concrete on purpose, specifically to increase the working time at the potential cost of weakening the structure, but research into that is ongoing.
There’s two broad categories of ways that concrete can get messed up: things that apparently ruin a batch on the spot, and things that compromise the resulting structural integrity in ways that might not be readily apparent.
The biggest things I can think of for the first category are water and time. More water means more “workability”, so it flows better, but it means the overall strength goes down. You basically want to use a minimal amount of water you can get away with. More water also means more time to set, so concrete workers will add water to the mix in the truck to slow it down if they need to. You can always add more water, but you can never take water out (or add more cement/aggregate on site). Concrete trucks have a water tank on board to add water, and also clean off equipment after pours because job sites often don’t have water. If enough water is added to the concrete in the truck, the batch is ruined. I’m sure there are compounds that could ruin a batch, but the water is right there.
Time also hurts because there is a ticking clock for getting the mix out of the truck once it has been made, particularly if the batch plant is far from the work site, and weather is hot. If the site is not completely prepped and ready to go when the truck gets there, enough delays will force the whole batch to be scapped before it ruins the truck. A lot of work goes into getting forms set properly and squared, and the underlying gravel compacted, so that is all delicate before the truck gets there.
The second category, things that compromise the integrity over time has a lot of potential, but there is no guarantee that strength will be compromised enough to cause failure, and there’s a lot of potential for collateral damage if it’s in a bridge, building, or something people could be on/in. The first things that come to mind here are stuff that will decay over time resulting in voids, like woodchips. I know there’s been research into woodchips as an intentional additive, but I’m sure there’s more science that goes into that than just tossing it it. Something that causes oxide jacking would also really increase failure rates. This is when a material like steel rusts and expands, splitting concrete apart. This happens often if rebar is not fully encased in concrete. This does happen eventually to any reinforced concrete, which is why modern concrete structures have design lifetimes unlike Roman concrete which lasts indefinitely, but has to be much more massive. Adding a bunch of nails or something like that to concrete would probably speed up the process, but enough nails/woodchips to make a difference would most likely be noticed by the people doing the pour (which could actually be a benefit).
If you wanted it to be unnoticeable, you would probably want to get a roll of rebar tying wire, and figure out a way to get it placed in the prepped site in such a way that it would be exposed to the elements after the final pour without being easily noticeable by the people doing the pour. Bonus points if the effort is focused on areas of stress concentration like corners or joints in the concrete.
There was an episode of MythBusters where they buried a couple pigs in concrete to see what decomposing bodies do in exactly that case. They indeed leave a gross hollow space.
According to the netflix series called High Tides that I watched the rich bury dead bodies in the buildings they build to hide them and Netflix would never lie to me
Well what you could do is put calcium chloride into the concrete and that’ll fuck up the chemical composition of Portlandcement and most steel reinforcements found in concrete.
My dad told me stories of him chucking a bag of sugar into mixers when pouring slabs if the first truck was taking too long and the next truck got going too early. So a fully loaded mixer is going to need more than one bag to fuck up the whole batch. Fortunately there’s a nice cone at the top which makes it easier to chuck stuff into the mixer, I’m sure you and maybe 5 of your close friends could take one or two bags each.
I don’t know, after reading through that AI slob of an article it says a good amount to add while still retaining sufficient strength after curing is between 0,1 to 0,5% sugar.
So let’s assume that more than 1% gets you into trouble, that’s still a lot, but sticking to your 18 tons concrete truck example - 180kg of sugar will ruin a whole truckload of concrete.
I think I could smuggle 180kg of sugar into a concrete truck without anyone noticing until it’s too late.
I’d say with enough people and dedication the story in the post could be true, not super likely but also not impossible.
Oh yeah, the numbers in the OP are probably off, I meant the story about anarchists using the method to disrupt construction of prisons is in the realm of possibilities.
I’m not a concrete expert, but a tonne of concrete is less than half a cubic metre.
A concrete truck carries 10 cubic yards, or nearly 18 metric tons of concrete.
If this “educational fact” is true, then that amount of sugar might cause an issue with a piece of sidewalk, but it’s unlikely to get noticed on anything being built with concrete, unless you bring a metric shit ton of sugar to the party.
As it happens, sugar appears to be added to concrete on purpose, specifically to increase the working time at the potential cost of weakening the structure, but research into that is ongoing.
Source: https://concretecaptain.com/what-does-sugar-do-to-concrete-mix/
In other words, this post is bollocks.
Can any concrete experts suggest another additive for us to avoid?
There’s two broad categories of ways that concrete can get messed up: things that apparently ruin a batch on the spot, and things that compromise the resulting structural integrity in ways that might not be readily apparent.
The biggest things I can think of for the first category are water and time. More water means more “workability”, so it flows better, but it means the overall strength goes down. You basically want to use a minimal amount of water you can get away with. More water also means more time to set, so concrete workers will add water to the mix in the truck to slow it down if they need to. You can always add more water, but you can never take water out (or add more cement/aggregate on site). Concrete trucks have a water tank on board to add water, and also clean off equipment after pours because job sites often don’t have water. If enough water is added to the concrete in the truck, the batch is ruined. I’m sure there are compounds that could ruin a batch, but the water is right there.
Time also hurts because there is a ticking clock for getting the mix out of the truck once it has been made, particularly if the batch plant is far from the work site, and weather is hot. If the site is not completely prepped and ready to go when the truck gets there, enough delays will force the whole batch to be scapped before it ruins the truck. A lot of work goes into getting forms set properly and squared, and the underlying gravel compacted, so that is all delicate before the truck gets there.
The second category, things that compromise the integrity over time has a lot of potential, but there is no guarantee that strength will be compromised enough to cause failure, and there’s a lot of potential for collateral damage if it’s in a bridge, building, or something people could be on/in. The first things that come to mind here are stuff that will decay over time resulting in voids, like woodchips. I know there’s been research into woodchips as an intentional additive, but I’m sure there’s more science that goes into that than just tossing it it. Something that causes oxide jacking would also really increase failure rates. This is when a material like steel rusts and expands, splitting concrete apart. This happens often if rebar is not fully encased in concrete. This does happen eventually to any reinforced concrete, which is why modern concrete structures have design lifetimes unlike Roman concrete which lasts indefinitely, but has to be much more massive. Adding a bunch of nails or something like that to concrete would probably speed up the process, but enough nails/woodchips to make a difference would most likely be noticed by the people doing the pour (which could actually be a benefit).
If you wanted it to be unnoticeable, you would probably want to get a roll of rebar tying wire, and figure out a way to get it placed in the prepped site in such a way that it would be exposed to the elements after the final pour without being easily noticeable by the people doing the pour. Bonus points if the effort is focused on areas of stress concentration like corners or joints in the concrete.
Not a concrete expert, but dead bodies. They decompose, can create pockets of pressurised gas, and leave a hollow cavity of no structural strength.
Source: Me. I made it up, but seems plausible.
There was an episode of MythBusters where they buried a couple pigs in concrete to see what decomposing bodies do in exactly that case. They indeed leave a gross hollow space.
I mean your username is literally “towerful” so I expect you to know something about towers that don’t collapse, I guess?
According to the netflix series called High Tides that I watched the rich bury dead bodies in the buildings they build to hide them and Netflix would never lie to me
Well what you could do is put calcium chloride into the concrete and that’ll fuck up the chemical composition of Portlandcement and most steel reinforcements found in concrete.
So instead of sugar, use salt.
My dad told me stories of him chucking a bag of sugar into mixers when pouring slabs if the first truck was taking too long and the next truck got going too early. So a fully loaded mixer is going to need more than one bag to fuck up the whole batch. Fortunately there’s a nice cone at the top which makes it easier to chuck stuff into the mixer, I’m sure you and maybe 5 of your close friends could take one or two bags each.
I don’t know, after reading through that AI slob of an article it says a good amount to add while still retaining sufficient strength after curing is between 0,1 to 0,5% sugar.
So let’s assume that more than 1% gets you into trouble, that’s still a lot, but sticking to your 18 tons concrete truck example - 180kg of sugar will ruin a whole truckload of concrete.
I think I could smuggle 180kg of sugar into a concrete truck without anyone noticing until it’s too late.
I’d say with enough people and dedication the story in the post could be true, not super likely but also not impossible.
2 pounds of sugar is not the same as 10 kg of sugar.
Oh yeah, the numbers in the OP are probably off, I meant the story about anarchists using the method to disrupt construction of prisons is in the realm of possibilities.