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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

#191

Post by litoE »

pinkmuffinere wrote: post #50
litoE wrote: post #20

Earlier quoted context omitted.

As I understand it, concrete has excellent resistance to compression but fails easily on traction, while steel bars are exactly the opposite. That is why you put rebar in concrete: the steel handles the traction loads and the concrete handles the compression. This works well because both materials have similar coefficients of thermal expansion, so as the temperature changes they both expand and contract at the same r…

> Wouldn't your beams start cracking at the bottom, where they are subject to traction? You have a few mistakes here. I’m not trying to demean you, but I’m going to number them just for clarity, as it can get confusing when there are many misunderstandings. 1. You are intending to ask about tension (which the rebar helps with), not traction (the force your tires exert against a road). 2. Tension is not only experienc…

1.- My apologies for the terminology - I took one overview class on the subject in Spanish, and haven't looked at it in the last 60 years. 2.- Agreed - that's why rebar on horizontal beams (and slabs) sometimes goes on the top edge and shifts to the bottom edge. 3.- By beams I do mean horizontal beams. This also applies to horizontal slabs. However, vertical columns also need rebar, especially in earthquake-prone areas. If the ground moves horizontally in an earthquake, the (vertical) columns have to transmit the motion to the upper parts of the structure. This create huge tension stresses on one side of the columns so they need vertical rebar rods on their perimeter.

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

#192

Post by Moto7451 »

gravypod wrote: post #116
tpm wrote: post #113

Earlier quoted context omitted.

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

This is why you pay the premium for epoxy grout. When we redid our house we used only epoxy grout and cleaning it as as simple as using a foaming tile spray.

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

#193

Post by AngryData »

jaapz wrote: post #131
modo_mario wrote: post #58

Earlier quoted context omitted.

>cold in winter >in my region terribly humid You need to actually reduce draft a bit (often old houses like mine tend to accumulate flaws that the elderly living there before didn't fix anymore.) and use a heating sources that matches. Having a fireplace is fine. It could overheat the house whilst also keeping air dryer and it's essentially renewable (compared to the alternatives and houses made of more plastic insul…

Fireplace is extremely inefficient, and really bad for both your (exhaust fumes get into the room anyway), and your neighbors (the smoke doesn't just dissappear) health, though. I love the heat and smell of a good fire as much as the next guy, I'm just not sure it's worth the risk of cancer and respiratory diseases.

If efficiency is important, like if you are using wood for primary heat, you should at a minimum be using a sealed box stove which should be pretty efficient and have little to no smoke escaping.

Alternatly you could just use an outdoor stove that merely heat exchanges to the inside.

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

#194

Post by gravypod »

Moto7451 wrote: post #192
gravypod wrote: post #116

Earlier quoted context omitted.

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

This is why you pay the premium for epoxy grout. When we redid our house we used only epoxy grout and cleaning it as as simple as using a foaming tile spray.

This is not always a great idea. Especially if you have a water proofing membrane that allows drying out. You never want to trap moisture in a cavity. You want to be able to dry into the wet side.

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

#195

Post by Barbing »

beeforpork wrote: post #76
Barbing wrote: post #23

Earlier quoted context omitted.

Like the plate of food on the grass for the bees at the barbecue

Wasps, not bees. (Sorry, I'm a bit of a nerd. But I am sure you can cope with that.)

Retract my bee slander!!

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

#196

Post by PunchyHamster »

rkangel wrote: post #82
PunchyHamster wrote: post #79

Earlier quoted context omitted.

Or simpler: people don't exactly want a house layout that was popular 100 years ago. And definitely not the level of insulation it provided. Nor the fact putting any new wiring and piping thru concrete is PITA Tastes change and so do other requirements. but , if we actually built for longevity in use, we could build a very durable shell of a house and then use more perishable but easier to modify methods for inside.…

There are some downsides, but most people on the UK would prefer houses that were 100+ years old. In the village I live in the houses immediately around me are "only" 50 years old. Most of the ones on the main street are well over 100 years old. Housing tastes don't really change that much. Yes over the years we've had to fit things like double glazing and better insulation but that's a whole lot cheaper (and better…

I think there might be some survivorship bias there - the house that survived 100 years in state where people still want it probably was built well, the 100 years old ones that didn't were scrapped/rebuilt

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

#197

Post by dlubarov »

middayc wrote: post #86

Very interestin discussion below/above. I just want to say that building with hempcrete, which relies on lime and NHL (natural hydraulic lime) or Baumit Trassitplus whic is some version of roman "cement" relies on may of these principles and is a "modern building technique". It's also much more carbon neutral than many other methods, can produce good thermal dynamics and "breathable" walls. And is DIY friendly.

Compared to traditional concrete, isn't hempcrete much weaker and less rigid? It's an interesting material for sure, but I thought it was basically considered non-structural filler.

Autoclaved aerated concrete is worth a mention as well - it's also a decent insulator and somewhat environmentally friendly, while additionally being, light, easy to cut, and somewhat usable as a structural element.

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

#198

Post by happyopossum »

freedomben wrote: post #167
nly wrote: post #166

Earlier quoted context omitted.

Primairly because old houses are on bigger plots and allow for extensions and conversions.

ah interesting! That's quite different from the areas I've lived in the US. If you're in or near city lines the lots on older houses are small. It's not uncommon to see .15 acre lots. Newer houses aren't much better, but you can see .2 to .25 acres relatively commonly, though those are nearly always on the outer city or outside city lines so it could just be proximity to the city that's the factor there rather than a…

That is highly location dependent. Many cities had/have large lots in older neighborhoods and have transitioned to zero-lot-line construction or smaller lots in the past 30-40 years as demand for housing grew.

In fact in most of the western US that’s the norm…

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

#199

Post by CGMthrowaway »

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…

TLDR, use lime mortar not portland cement. And don't use rebar.

Also- modern concrete is not waterproof... requires sealant

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

#200

Post by [deleted] »

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?

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