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How Has Roman Concrete Lasted for Millennia? 1,900-Year-Old Latrine Offers Clues

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Re: How Has Roman Concrete Lasted for Millennia? 1,900-Year-Old Latrine Offers Clues

#111

Post by iknownothow »

meindnoch wrote: post #97
iknownothow wrote: post #74

For those not familiar, the secret ingredients are to do with the Lime Cycle [1]: 1) Quicklime/Slakedlime (Calcium Oxide, CaO) 2) Lime (Calcium Hydroxide, CaOH2) 3) Limestone (Calcium Carbonate, CaCO3) To keep it simple, typically you start with Quicklime (CaO) and after construction you end up with some mix of all three and after hundreds of years, the masonry transitions to mostly Limestone with microscopic traces…

>Cement/Concrete (based on Portland cement) is water proof That's patently untrue. Otherwise we wouldn't need concrete sealants.

You are correct.

I'm not sure why I remember cement to be water proof. Its possible I infered from how its been used around me. I have seen cement very often used where water contact is expected (bathrooms etc). I have also seen brick walls plastered with an extra layer of cement as putty considered to be rain proof and any leaks were thought of as poor workmanship rather than poor material choice.

P.S. I'm not a builder. I've taken an interest in the topic a few months ago.

Re: How Has Roman Concrete Lasted for Millennia? 1,900-Year-Old Latrine Offers Clues

#112

Post by dnemmers »

amszmidt wrote: post #100
meindnoch wrote: post #97

Earlier quoted context omitted.

>Cement/Concrete (based on Portland cement) is water proof That's patently untrue. Otherwise we wouldn't need concrete sealants.

The key here is “based on Portland cement”, which is generally has water repellent added to it making it water proof. Normal cement, concrete .. Is a different story.

I'm not sure exactly what you're saying is correct.

'Concrete' is a combination of sand, cement, water and aggregate, that cures together to form.

When the water migrates away from the curing concrete, it leaves open pores behind that future moisture can move through.

https://en.wikipedia.org/wiki/Portland_cement

Re: How Has Roman Concrete Lasted for Millennia? 1,900-Year-Old Latrine Offers Clues

#113

Post by tpm »

carlmr wrote: post #94
iknownothow wrote: post #74

For those not familiar, the secret ingredients are to do with the Lime Cycle [1]: 1) Quicklime/Slakedlime (Calcium Oxide, CaO) 2) Lime (Calcium Hydroxide, CaOH2) 3) Limestone (Calcium Carbonate, CaCO3) To keep it simple, typically you start with Quicklime (CaO) and after construction you end up with some mix of all three and after hundreds of years, the masonry transitions to mostly Limestone with microscopic traces…

>Fun fact! Lime putty is anti-mold even in humid conditions because upon exposure to moisture, CaOH2 + H20 becomes too basic for mold to grow on. Can we use this instead of grout in the bathroom somehow?

it's not waterproof

Re: How Has Roman Concrete Lasted for Millennia? 1,900-Year-Old Latrine Offers Clues

#114

Post by boringg »

yorwba wrote: post #101
Animats wrote: post #54

Earlier quoted context omitted.

Stainless steel rebar is a thing. It's expensive, but structures built with it last much longer. Washington State now has a policy that bridges over salt water will be built with stainless steel rebar. Stainless steel costs much more, but total project cost goes up less than 10%. Epoxy coated rebar looked promising for a while, but it's on the way out. Water gets in at cuts and joints. So all field joints have to hav…

> Two piers were built in the 1940s, side by side As far as I can tell, only one pier was built (using stainless steel rebar) and the presentation is comparing it to a hypothetical alternative as a theoretical exercise: "What if the Progreso Pier was built using carbon steel rebar?"

I think that was the prior pier maybe in the picture? The main pier only has one - it’s massive and goes forever. Pretty beefy construction too given that it takes a lot of heavy trucks.

Progreso - great pier and a great kiteboarding spot.

Re: How Has Roman Concrete Lasted for Millennia? 1,900-Year-Old Latrine Offers Clues

#115

Post by matheusmoreira »

dev_l1x_be wrote: post #34
matheusmoreira wrote: post #28

Earlier quoted context omitted.

Nobody is going to tear down old bridges and rebuild them at enormous costs just because technology changed. Some things can't or won't be redone and so it's worth it to build it to last and getting it right on the first try.

This is exactly what we did with houses, buildings. We had perfectly functional 100+ years old fully functional, gorgeous buildings and we replaced those with brutalist concrete/glass barely functional garbage.

Those are houses though, private property. Not government infrastructure.

Re: How Has Roman Concrete Lasted for Millennia? 1,900-Year-Old Latrine Offers Clues

#116

Post by gravypod »

tpm wrote: post #113
carlmr wrote: post #94

Earlier quoted context omitted.

>Fun fact! Lime putty is anti-mold even in humid conditions because upon exposure to moisture, CaOH2 + H20 becomes too basic for mold to grow on. Can we use this instead of grout in the bathroom somehow?

it's not waterproof

Neither is grout. Grout is water permiable. You shower is water proof from the water proof backing we install the tile on top of.

Cement board + roll on or something like kerdi system.

https://youtu.be/B5DVpruLygw?si=jD8eMHHGQoWG4hI2

Re: How Has Roman Concrete Lasted for Millennia? 1,900-Year-Old Latrine Offers Clues

#117

Post by world2vec »

Animats wrote: post #54
bombela wrote: post #15

> It turns out that another chemical reaction, known as carbonation, might also contribute to Roman concrete’s longevity. Roman concrete was made lime cement (calcium dioxide); which cures via carbonation (hardens with carbon oxide). And adding pozzolan to lime makes it hydrolic (hardens with water). Is it surprising that it can still carbonate some? Modern concrete has steel which rust and crack concrete. You can us…

Stainless steel rebar is a thing. It's expensive, but structures built with it last much longer. Washington State now has a policy that bridges over salt water will be built with stainless steel rebar. Stainless steel costs much more, but total project cost goes up less than 10%. Epoxy coated rebar looked promising for a while, but it's on the way out. Water gets in at cuts and joints. So all field joints have to hav…

There's also Glass Fiber Reinforced Polymer rebar but I don't know much about costs and how good it is vs stainless steel rebar.

Re: How Has Roman Concrete Lasted for Millennia? 1,900-Year-Old Latrine Offers Clues

#118

Post by iknownothow »

carlmr wrote: post #94
iknownothow wrote: post #74

For those not familiar, the secret ingredients are to do with the Lime Cycle [1]: 1) Quicklime/Slakedlime (Calcium Oxide, CaO) 2) Lime (Calcium Hydroxide, CaOH2) 3) Limestone (Calcium Carbonate, CaCO3) To keep it simple, typically you start with Quicklime (CaO) and after construction you end up with some mix of all three and after hundreds of years, the masonry transitions to mostly Limestone with microscopic traces…

>Fun fact! Lime putty is anti-mold even in humid conditions because upon exposure to moisture, CaOH2 + H20 becomes too basic for mold to grow on. Can we use this instead of grout in the bathroom somehow?

I'm not sure as I'm not a builder or plasterer and it does depend on the use case.

However I do know that some grout and some paints that say they are anti-mold contain Lime or calcium hydroxide as their primary anti-mold ingredient. I think pure Lime putty can be used as pointing material between bricks in humid basements. Lime plaster (lime mixed with sand) can also be used in bathrooms (with some considerations I am not familiar with). So, my best guess is that some mix of Lime can be used as grout. But I can't say for sure.

Something I plan on doing before this winter is to use Lime Wash. Take Lime (CaOH2 in powder form) and mix with water until it has milk like consistency and brush it on grout or on (white) bathroom walls. If it works, I expect it to be a yearly or quarterly ritual and not a one time solution.

EDIT: A fascinating historical material I recently learned about used in bathrooms is called Tadelakt [1] which uses Lime as one of its ingredients.

[1] https://en.wikipedia.org/wiki/Tadelakt

Re: How Has Roman Concrete Lasted for Millennia? 1,900-Year-Old Latrine Offers Clues

#119

Post by matheusmoreira »

gus_massa wrote: post #51
matheusmoreira wrote: post #28

Earlier quoted context omitted.

Nobody is going to tear down old bridges and rebuild them at enormous costs just because technology changed. Some things can't or won't be redone and so it's worth it to build it to last and getting it right on the first try.

Usually you need wider bridges, so the old bridge needs a replacement or a second bridge on the side.

If the bridge became a bottleneck, then there is an actual reason to replace it. People aren't doing it on a whim because technology changed.

Re: How Has Roman Concrete Lasted for Millennia? 1,900-Year-Old Latrine Offers Clues

#120

Post by dnemmers »

iknownothow wrote: post #111
meindnoch wrote: post #97

Earlier quoted context omitted.

>Cement/Concrete (based on Portland cement) is water proof That's patently untrue. Otherwise we wouldn't need concrete sealants.

You are correct. I'm not sure why I remember cement to be water proof. Its possible I infered from how its been used around me. I have seen cement very often used where water contact is expected (bathrooms etc). I have also seen brick walls plastered with an extra layer of cement as putty considered to be rain proof and any leaks were thought of as poor workmanship rather than poor material choice. P.S. I'm not a bui…

Hydraulic cement is made for some of those occasions:

https://www.quikrete.com/productlines/hydraulicwaterstopceme...

But I wouldn't want to make any sort of building that only relied on it for waterproofing.

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