8 ms·
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, CaO
by iknownothow 2mo ago
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 of the other two. The slow transition of the lime cycle upon exposure of the masonry to both air and water (rain) ends up making the structure "self healing" and "stronger over time".
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.
Cement/Concrete (based on Portland cement) is water proof but Lime by itself is not. But Roman Concrete, made from Lime and mixing with ash or broken pottery or ceramics makes it water proof [2]. I beleive Roman concrete was used whenever contact with water was expected. Both concrete and Roman concrete have the same underlying chemistry (Pozzolanic reaction) to make them water proof [3].
The fascinating thing is that Lime is everywhere in ancient masonry. Lime is more breathable, workable and sustainable. The only thing is, it requires maintainance, which is why Portland cement has taken over the world.
Modern cement/concrete is amazing for large structures. I hope Lime makes a comeback soon at least partly as putty and for building smaller homes.
[1] https://en.wikipedia.org/wiki/Lime_(material) https://en.wikipedia.org/wiki/Lime_(material)
[2] https://en.wikipedia.org/wiki/Roman_concrete https://en.wikipedia.org/wiki/Roman_concrete
[3] https://en.wikipedia.org/wiki/Pozzolanic_activity#Reaction https://en.wikipedia.org/wiki/Pozzolanic_activity#Reaction
- iknownothow 2mo agoI forgot another important reason why Portland cement is preferred over lime these days. Lime takes a while to set (a few days?), cement sets faster.
- aaron695 2mo ago[dead]
- _n_b_ 2mo ago> Lime takes a while to set (a few days?) Up to 30 days to set, and depending on the type of lime (hydraulic or non-hydraulic) and form/process (putty, hot mix, etc.) up to a year to reach full hardness.
- dnemmers 2mo agoCement will still take many days to reach full cure time (measured in increasing PSI ratings) https://www.ce.memphis.edu/1101/notes/concrete/section_3_properties.html https://www.ce.memphis.edu/1101/notes/concrete/section_3_pro...
- carlmr 2mo ago>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?
- tpm 2mo agoit's not waterproof
- gravypod 2mo agoNeither 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 https://youtu.be/B5DVpruLygw?si=jD8eMHHGQoWG4hI2
- tpm 2mo agoright, but lime will be washed away by the water if no waterproof layer is added
- iknownothow 2mo agoIt is not lime as in the fruit, it is lime as in the material (CaOH2). Lime the material is the binding agent in lime plasters. It is not likely to get washed away.
- tpm 2mo agocaoh2 is water soluble (slightly). the question was about anti-mold properties and it is commonly used for these properties in paint for example in cellars but it will lose these properties when too wet. so it's not used in bathrooms.
- iknownothow 2mo ago
- meindnoch 2mo ago>Cement/Concrete (based on Portland cement) is water proof That's patently untrue. Otherwise we wouldn't need concrete sealants.
- amszmidt 2mo agoThe 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.
- lazide 2mo agoConcrete is generally porous and definitely not micro-waterproof (aka lots of water vapor makes it’s way through). Including if using Portland cement. It is generally macro-waterproof, however, unless there are large cracks.
- dnemmers 2mo agoI'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 https://en.wikipedia.org/wiki/Portland_cement
- iknownothow 2mo agoYou 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.
- dnemmers 2mo agoHydraulic cement is made for some of those occasions: https://www.quikrete.com/productlines/hydraulicwaterstopcementpro.asp https://www.quikrete.com/productlines/hydraulicwaterstopceme... But I wouldn't want to make any sort of building that only relied on it for waterproofing.
- deleted 2mo ago[deleted]
- eleveriven 2mo agoThis makes me want to see lime used more in ordinary homes
- abdullahkhalids 2mo ago> Lime is more breathable, workable and sustainable. The only thing is, it requires maintainance What sort of maintenance does it need?
- Fizzadar 2mo agoIt wears down quicker than concrete (you can scratch it easily with a nail and minimal pressure). But we’re still talking 50+ years (before repointing brick, in my case). As long as maintained it’ll last forever (our home is 140 years old, I just re-did the pointing, should be good till I die).
- CGMthrowaway 2mo agoTLDR, use lime mortar not portland cement. And don't use rebar. Also- modern concrete is not waterproof... requires sealant
- Fizzadar 2mo agoVictorian brick houses are all lime based, pointing (mortar between bricks), render outside and internal plaster. (Ours is 140 years old ish). Lime is also more flexible (these houses have minimal to no foundation and constantly move), it’s breathable (no/less damp) and as such it also improves air quality indoors. It’s annoying to do because drying times are days/weeks not hours, but long run it’s a far superior material for small buildings. It does burn though if you accidentally get it on your skin!
- ln809 2mo agoSpain stone buildings too... common problem modern plaster on those stone walls, folk have forgotten the wall needs to breathe
- cogman10 2mo ago> The only thing is, it requires maintainance, which is why Portland cement has taken over the world. What kind of maintenance and why did roman cement survive without it? Or are we simply looking at ancient survivorship bias where the surviving roman concrete structures survived through the lime cycle without maintenance until it was no longer required?
- iknownothow 2mo agoI mentioned elsewhere that time taken for setting is also a major factor for why Portland cement is preferred. Maintenance is probably less of a factor but it also depends on the use case. Take what I have to say with a grain of salt. Lime is a living material that slowly converts lime to limestone. For some use cases, the lime needs to be replenished often through applying lime wash on the plaster of external walls or wet interior walls. As for load bearing walls or regular interior plaster walls I'm not sure there is much maintenance you can do and they are fairly durable. As far as I know Portland cement sets faster and is a stronger but has a life span of decades and does not lend itself to be repaired or replenished. I'd like to also convey some vibes I have about this topic as follows. Imagine having a 2 storey family home made of concrete that you want passed on for many generations. In 50-75 years, repairs/upgrades would require a lot of demolition as concrete with rebar is very strong. Much of the old material is trashed and hard to recycle. A similar house made of lime based products and some stone and wood would lend itself more easily for similar repairs and seamless upgrades and can maintain the same aesthetic look for longer. It feels like lime based products are appropriately strong and suitable for the smaller scale. The old material can be treated like any old dirt or rubble and is less polluting.
- poelzi 2mo agoThe trick was: Lime CHUNKS, proper volcanic fly ash, salt water + no steel. Self repairing and more flexible