I wonder how easy this would be to knock up as a hobbyist ...

https://www.msn.com/en-gb/travel/news/the-secret-ingredient-in-roman-
concrete-that-means-buildings-can-last-for-millennia/ar-AA163dEr

The durability of Roman concrete, which has allowed structures such as
the Pantheon in Rome to remain standing for nearly 2,000 years, has long
baffled experts.

But scientists now believe they have rediscovered a secret ingredient in
the ancient recipe that makes the building material self-healing –
quicklime.

Experts at MIT and Harvard have found that adding quicklime to the mix
creates a super-hot chemical reaction that leaves calcium deposits
peppered throughout the concrete.

Crucially, if cracks begin to appear at a later stage and water seeps
through, it causes these calcium deposits to recrystallise into calcium
carbonate, filling in the gaps. The reactions take place spontaneously,
healing the cracks before they spread further and compromise the
integrity of a structure.
It explains how the world’s largest unreinforced concrete dome in the
Pantheon, which was dedicated in 128AD, is still intact, while many
modern concrete structures crumble after a few decades.

Some ancient concrete aqueducts still supply Rome with water, while large
parts of Hadrian’s Wall, its core bolstered by ancient concrete, survive.

Pliny the Elder, writing in Naturalis Historia in 79AD, noted that
concrete structures in harbours “become a single stone mass, impregnable
to the waves, and every day stronger” despite being battered by seawater.

Fullscreen button
Hadrian’s Wall - Peter Mulligan/Getty Images Contributor
Hadrian’s Wall - Peter Mulligan/Getty Images Contributor
© Provided by The Telegraph
The new finding could enable modern engineers to build structures that
can last millennia. It was made after experts started studying calcium
deposits, known as lime clasts, in the ancient concrete. They had
previously been disregarded as a product of sloppy mixing practices.

“The idea that the presence of these lime clasts was simply attributed to
low quality control always bothered me,” said Admir Masic, a professor of
civil and environmental engineering.

“If the Romans put so much effort into making an outstanding construction
material, following all of the detailed recipes that had been optimised
over the course of many centuries, why would they put so little effort
into ensuring the production of a well-mixed final product? There has to
be more to this story.”

To prove that the lime clasts were responsible for the durability, the
team produced samples of hot-mixed concrete that incorporated both
ancient and modern formulations, deliberately cracked them and then ran
water through the cracks.

Within two weeks the cracks had completely healed and the water could no
longer flow. An identical chunk of concrete made without quicklime never
healed, and the water kept flowing through the sample.

The team is working to bring Roman concrete back as a commercial product.

“It’s exciting to think about how these more durable concrete
formulations could expand not only the service life of these materials,
but also how it could improve the durability of 3D-printed concrete
formulations,” said Prof Masic.

The research was published in Science Advances.

On Wed, 13 Dec 2023 07:40:32 -0000 (UTC), Jethro_uk
<jethro_uk@hotmailbin.com> wrote:

>I wonder how easy this would be to knock up as a hobbyist ...
>
>https://www.msn.com/en-gb/travel/news/the-secret-ingredient-in-roman-
>concrete-that-means-buildings-can-last-for-millennia/ar-AA163dEr
>
>
>The durability of Roman concrete, which has allowed structures such as
>the Pantheon in Rome to remain standing for nearly 2,000 years, has long
>baffled experts.
>
>But scientists now believe they have rediscovered a secret ingredient in
>the ancient recipe that makes the building material self-healing –
>quicklime.
>
>Experts at MIT and Harvard have found that adding quicklime to the mix
>creates a super-hot chemical reaction that leaves calcium deposits
>peppered throughout the concrete.
>
>Crucially, if cracks begin to appear at a later stage and water seeps
>through, it causes these calcium deposits to recrystallise into calcium
>carbonate, filling in the gaps. The reactions take place spontaneously,
>healing the cracks before they spread further and compromise the
>integrity of a structure.
>It explains how the world’s largest unreinforced concrete dome in the
>Pantheon, which was dedicated in 128AD, is still intact, while many
>modern concrete structures crumble after a few decades.
>
>Some ancient concrete aqueducts still supply Rome with water, while large
>parts of Hadrian’s Wall, its core bolstered by ancient concrete, survive.
>
>Pliny the Elder, writing in Naturalis Historia in 79AD, noted that
>concrete structures in harbours “become a single stone mass, impregnable
>to the waves, and every day stronger” despite being battered by seawater.
>
>Fullscreen button
>Hadrian’s Wall - Peter Mulligan/Getty Images Contributor
>Hadrian’s Wall - Peter Mulligan/Getty Images Contributor
>© Provided by The Telegraph
>The new finding could enable modern engineers to build structures that
>can last millennia. It was made after experts started studying calcium
>deposits, known as lime clasts, in the ancient concrete. They had
>previously been disregarded as a product of sloppy mixing practices.
>
>“The idea that the presence of these lime clasts was simply attributed to
>low quality control always bothered me,” said Admir Masic, a professor of
>civil and environmental engineering.
>
>“If the Romans put so much effort into making an outstanding construction
>material, following all of the detailed recipes that had been optimised
>over the course of many centuries, why would they put so little effort
>into ensuring the production of a well-mixed final product? There has to
>be more to this story.”
>
>To prove that the lime clasts were responsible for the durability, the
>team produced samples of hot-mixed concrete that incorporated both
>ancient and modern formulations, deliberately cracked them and then ran
>water through the cracks.
>
>Within two weeks the cracks had completely healed and the water could no
>longer flow. An identical chunk of concrete made without quicklime never
>healed, and the water kept flowing through the sample.
>
>The team is working to bring Roman concrete back as a commercial product.
>
>“It’s exciting to think about how these more durable concrete
>formulations could expand not only the service life of these materials,
>but also how it could improve the durability of 3D-printed concrete
>formulations,” said Prof Masic.
>
>The research was published in Science Advances.

This is nothing new. The use of volcanic ash in concrete by the Romans
has been known for a long time. The ash comes under the general name
of a pozzolan. Other pozzolans are available.

See also
https://www.google.com/search?client=firefox-b-d&q=volcanic+ash+in+concrete#ip=1
and
https://www.google.com/search?client=firefox-b-d&q=pozzolan

--
Chris

On 13/12/2023 08:53, Chris Hogg wrote:
> On Wed, 13 Dec 2023 07:40:32 -0000 (UTC), Jethro_uk
> <jethro_uk@hotmailbin.com> wrote:
>
>> I wonder how easy this would be to knock up as a hobbyist ...
>>
>> https://www.msn.com/en-gb/travel/news/the-secret-ingredient-in-roman-
>> concrete-that-means-buildings-can-last-for-millennia/ar-AA163dEr
>>
>>
>> The durability of Roman concrete, which has allowed structures such as
>> the Pantheon in Rome to remain standing for nearly 2,000 years, has long
>> baffled experts.
>>
>> But scientists now believe they have rediscovered a secret ingredient in
>> the ancient recipe that makes the building material self-healing –
>> quicklime.
>>
<snip>

>>

>
> This is nothing new. The use of volcanic ash in concrete by the Romans
> has been known for a long time. The ash comes under the general name
> of a pozzolan. Other pozzolans are available.
>
> See also
> https://www.google.com/search?client=firefox-b-d&q=volcanic+ash+in+concrete#ip=1
> and
> https://www.google.com/search?client=firefox-b-d&q=pozzolan
>

Quicklime is not a pozzolan. The proposition is that the Romans used
quicklime to give something over and above the effects of pozzolanic
reactions. Clearer in the original paper[1] which includes the results
of their modern mixing.

As for the OP's question, I've no hands-on experience but hot mixing
with quicklime is still done by hand to make mortar for heritage
buildings. But needs care.

[1] https://www.science.org/doi/10.1126/sciadv.add1602

--
Robin
reply-to address is (intended to be) valid

On 2023-12-13, Robin <rbw@outlook.com> wrote:
> On 13/12/2023 08:53, Chris Hogg wrote:
>> On Wed, 13 Dec 2023 07:40:32 -0000 (UTC), Jethro_uk
>> <jethro_uk@hotmailbin.com> wrote:
>>
>>> I wonder how easy this would be to knock up as a hobbyist ...
>>>
>>> https://www.msn.com/en-gb/travel/news/the-secret-ingredient-in-roman-
>>> concrete-that-means-buildings-can-last-for-millennia/ar-AA163dEr
>>>
>>>
>>> The durability of Roman concrete, which has allowed structures such as
>>> the Pantheon in Rome to remain standing for nearly 2,000 years, has long
>>> baffled experts.
>>>
>>> But scientists now believe they have rediscovered a secret ingredient in
>>> the ancient recipe that makes the building material self-healing –
>>> quicklime.
>>>
><snip>
>
>>>
>
>>
>> This is nothing new. The use of volcanic ash in concrete by the Romans
>> has been known for a long time. The ash comes under the general name
>> of a pozzolan. Other pozzolans are available.
>>
>> See also
>> https://www.google.com/search?client=firefox-b-d&q=volcanic+ash+in+concrete#ip=1
>> and
>> https://www.google.com/search?client=firefox-b-d&q=pozzolan
>>
>
> Quicklime is not a pozzolan. The proposition is that the Romans used
> quicklime to give something over and above the effects of pozzolanic
> reactions. Clearer in the original paper[1] which includes the results
> of their modern mixing.
>
> As for the OP's question, I've no hands-on experience but hot mixing
> with quicklime is still done by hand to make mortar for heritage
> buildings. But needs care.
>
>
> [1] https://www.science.org/doi/10.1126/sciadv.add1602
>
>
>
>

It has been pointed out that the cathederals we see now are the
remainders of those that were built, the rest collapsed over the years.
The builders that built them were specialists, and very skilled. One
church that I know (C of I, at the moment ) had its outside wall, as a monument, been
repaired years ago and promptly collapsed, upon which is was noticed
that the construction was a lot more complicated than was noticed
before, At the moment the nearby round tower in being `repaired' God
Help US.

--
greymausg@mail.com
Death to the Influencers, hung, drawn and quartered is more than they deserve.
BringBack(Bonking)Boris..

On 13/12/2023 11:38, maus wrote:

> It has been pointed out that the cathederals we see now are the
> remainders of those that were built, the rest collapsed over the years.

There are periods in UK history where religious building and castles
were actively destroyed. They didn't necessarily fall down by themselves.

Afterwards the material was robbed out and often can be seen in half the
houses of a nearby village.

--
mailto : news {at} admac {dot} myzen {dot} co {dot} uk

On Wed, 13 Dec 2023 10:05:22 +0000, Robin <rbw@outlook.com> wrote:

>On 13/12/2023 08:53, Chris Hogg wrote:

>>
>> This is nothing new. The use of volcanic ash in concrete by the Romans
>> has been known for a long time. The ash comes under the general name
>> of a pozzolan. Other pozzolans are available.
>>
>> See also
>> https://www.google.com/search?client=firefox-b-d&q=volcanic+ash+in+concrete#ip=1
>> and
>> https://www.google.com/search?client=firefox-b-d&q=pozzolan
>>
>
>Quicklime is not a pozzolan. The proposition is that the Romans used
>quicklime to give something over and above the effects of pozzolanic
>reactions. Clearer in the original paper[1] which includes the results
>of their modern mixing.
>
>As for the OP's question, I've no hands-on experience but hot mixing
>with quicklime is still done by hand to make mortar for heritage
>buildings. But needs care.
>
>
>[1] https://www.science.org/doi/10.1126/sciadv.add1602

So basically what they're saying is that Roman concrete was a
quicklime-pozzolan-aggregate mix?

--
Chris

On 13/12/2023 15:46, Chris Hogg wrote:
> On Wed, 13 Dec 2023 10:05:22 +0000, Robin <rbw@outlook.com> wrote:
>
>> On 13/12/2023 08:53, Chris Hogg wrote:
>
>>>
>>> This is nothing new. The use of volcanic ash in concrete by the Romans
>>> has been known for a long time. The ash comes under the general name
>>> of a pozzolan. Other pozzolans are available.
>>>
>>> See also
>>> https://www.google.com/search?client=firefox-b-d&q=volcanic+ash+in+concrete#ip=1
>>> and
>>> https://www.google.com/search?client=firefox-b-d&q=pozzolan
>>>
>>
>> Quicklime is not a pozzolan. The proposition is that the Romans used
>> quicklime to give something over and above the effects of pozzolanic
>> reactions. Clearer in the original paper[1] which includes the results
>> of their modern mixing.
>>
>> As for the OP's question, I've no hands-on experience but hot mixing
>> with quicklime is still done by hand to make mortar for heritage
>> buildings. But needs care.
>>
>>
>> [1] https://www.science.org/doi/10.1126/sciadv.add1602
>
> So basically what they're saying is that Roman concrete was a
> quicklime-pozzolan-aggregate mix?
>

At the very least that needs "it is likely some" before "Roman".

--
Robin
reply-to address is (intended to be) valid

On 13/12/2023 07:40, Jethro_uk wrote:
> I wonder how easy this would be to knock up as a hobbyist ...
>
> https://www.msn.com/en-gb/travel/news/the-secret-ingredient-in-roman-
> concrete-that-means-buildings-can-last-for-millennia/ar-AA163dEr

> The durability of Roman concrete, which has allowed structures such as
> the Pantheon in Rome to remain standing for nearly 2,000 years, has long
> baffled experts.

One reason Roman concrete has lasted is that they didn't use steel
reinforcement that rusts eventually.

--
Max Demian

On 13/12/2023 11:38, maus wrote:
> On 2023-12-13, Robin <rbw@outlook.com> wrote:
>> On 13/12/2023 08:53, Chris Hogg wrote:
>>> On Wed, 13 Dec 2023 07:40:32 -0000 (UTC), Jethro_uk
>>> <jethro_uk@hotmailbin.com> wrote:
>>>
>>>> I wonder how easy this would be to knock up as a hobbyist ...
>>>>
>>>> https://www.msn.com/en-gb/travel/news/the-secret-ingredient-in-roman-
>>>> concrete-that-means-buildings-can-last-for-millennia/ar-AA163dEr
>>>>
>>>>
>>>> The durability of Roman concrete, which has allowed structures such as
>>>> the Pantheon in Rome to remain standing for nearly 2,000 years, has long
>>>> baffled experts.
>>>>
>>>> But scientists now believe they have rediscovered a secret ingredient in
>>>> the ancient recipe that makes the building material self-healing –
>>>> quicklime.
>>>>
>> <snip>
>>
>>>>
>>
>>>
>>> This is nothing new. The use of volcanic ash in concrete by the Romans
>>> has been known for a long time. The ash comes under the general name
>>> of a pozzolan. Other pozzolans are available.
>>>
>>> See also
>>> https://www.google.com/search?client=firefox-b-d&q=volcanic+ash+in+concrete#ip=1
>>> and
>>> https://www.google.com/search?client=firefox-b-d&q=pozzolan
>>>
>>
>> Quicklime is not a pozzolan. The proposition is that the Romans used
>> quicklime to give something over and above the effects of pozzolanic
>> reactions. Clearer in the original paper[1] which includes the results
>> of their modern mixing.
>>
>> As for the OP's question, I've no hands-on experience but hot mixing
>> with quicklime is still done by hand to make mortar for heritage
>> buildings. But needs care.
>>
>>
>> [1] https://www.science.org/doi/10.1126/sciadv.add1602
>>
>>
>>
>>
>
> It has been pointed out that the cathederals we see now are the
> remainders of those that were built, the rest collapsed over the years.
> The builders that built them were specialists, and very skilled. One
> church that I know (C of I, at the moment ) had its outside wall, as a monument, been
> repaired years ago and promptly collapsed, upon which is was noticed
> that the construction was a lot more complicated than was noticed
> before, At the moment the nearby round tower in being `repaired' God
> Help US.
>
>

The victorians rebuilt parts of the white tower at the
tower of London using some utter shit materials which are
now having to be rebuilt.

Stonehenge was rebuilt back in the 1930's ? and the
well-meaning idiots used concrete there too (maybe that's
why the public are kept back in case awkward questions are
asked).

On 13/12/2023 18:22, Max Demian wrote:
> On 13/12/2023 07:40, Jethro_uk wrote:
>> I wonder how easy this would be to knock up as a hobbyist ...
>>
>> https://www.msn.com/en-gb/travel/news/the-secret-ingredient-in-roman-
>> concrete-that-means-buildings-can-last-for-millennia/ar-AA163dEr
>
>> The durability of Roman concrete, which has allowed structures such as
>> the Pantheon in Rome to remain standing for nearly 2,000 years, has long
>> baffled experts.
>
> One reason Roman concrete has lasted is that they didn't use steel
> reinforcement that rusts eventually.
>

Do they get hard frosts in southern europe and north
africa ?

On 13/12/2023 19:55, Andrew wrote:

> Do they get hard frosts in southern europe and north
> africa ?

It's common for the Sahara Desert to have a temperature change of 40+C
in a 24 hour period with the night time temperatures dropping below 0C.

--
mailto : news {at} admac {dot} myzen {dot} co {dot} uk

On 13/12/2023 07:40, Jethro_uk wrote:

<snip>

> “The idea that the presence of these lime clasts was simply attributed to
> low quality control always bothered me,” said Admir Masic, a professor of
> civil and environmental engineering.
>
> “If the Romans put so much effort into making an outstanding construction
> material, following all of the detailed recipes that had been optimised
> over the course of many centuries, why would they put so little effort
> into ensuring the production of a well-mixed final product? There has to
> be more to this story.”

I've been wondering about this. I'm aware that there are many structures
that have not stood the test of time[1], and it wouldn't surprise me if
there were many Roman structures that disappeared from view shortly
after build.

I'm also conscious that most of the issues with modern concrete is
associated with rebar, which allows tension in concrete structures. The
Roman's would have to rely on compression in concrete structures with no
allowable tension.

[1] I'm aware of whole terraces of houses and indeed the 'second' Bath
Royal Crescent that fell down and/or were demolished.

On Wed, 13 Dec 2023 18:22:04 +0000, Max Demian <max_demian@bigfoot.com> wrote:

>On 13/12/2023 07:40, Jethro_uk wrote:
>> I wonder how easy this would be to knock up as a hobbyist ...
>>
>> https://www.msn.com/en-gb/travel/news/the-secret-ingredient-in-roman-
>> concrete-that-means-buildings-can-last-for-millennia/ar-AA163dEr
>
>> The durability of Roman concrete, which has allowed structures such as
>> the Pantheon in Rome to remain standing for nearly 2,000 years, has long
>> baffled experts.
>
>One reason Roman concrete has lasted is that they didn't use steel
>reinforcement that rusts eventually.

They did use iron clamps between stone blocks (ISTR either wrapped in
pitch-soaked rags, or held in place with a bit to prevent rust and the
swelling/cracking associated with it.)

These clamps were then later stolen, leaving holes...

https://rome.us/ask-us/why-the-colosseum-has-holes.html

Thomas Prufer

On 13/12/2023 19:54, Andrew wrote:
> Stonehenge was rebuilt back in the 1930's ? and the
> well-meaning idiots used concrete there too

What????
Why would anyone use concrete at stone henge?

--
Future generations will wonder in bemused amazement that the early
twenty-first century’s developed world went into hysterical panic over a
globally average temperature increase of a few tenths of a degree, and,
on the basis of gross exaggerations of highly uncertain computer
projections combined into implausible chains of inference, proceeded to
contemplate a rollback of the industrial age.

Richard Lindzen

On 14/12/2023 09:58, The Natural Philosopher wrote:
> On 13/12/2023 19:54, Andrew wrote:
>> Stonehenge was rebuilt back in the 1930's ? and the
>> well-meaning idiots used concrete there too
>
> What????
> Why would anyone use concrete at stone henge?
>

Concrete was used repeatedly to set the stones and to fill cracks in
"restorations" from 1901 through to the 1960s at least.

--
Robin
reply-to address is (intended to be) valid

On 14/12/2023 10:11, Robin wrote:
> On 14/12/2023 09:58, The Natural Philosopher wrote:
>> On 13/12/2023 19:54, Andrew wrote:
>>> Stonehenge was rebuilt back in the 1930's ? and the
>>> well-meaning idiots used concrete there too
>>
>> What????
>> Why would anyone use concrete at stone henge?
>>
>
> Concrete was used repeatedly to set the stones and to fill cracks in
> "restorations" from 1901 through to the 1960s at least.
>
>
Any references to prove that?

I went there. I never saw any concrete anywhere.

>

--
To ban Christmas, simply give turkeys the vote.

The Natural Philosopher wrote:

> On 14/12/2023 10:11, Robin wrote:
>> On 14/12/2023 09:58, The Natural Philosopher wrote:
>>> On 13/12/2023 19:54, Andrew wrote:
>>>> Stonehenge was rebuilt back in the 1930's ? and the
>>>> well-meaning idiots used concrete there too
>>>
>>> What????
>>> Why would anyone use concrete at stone henge?

I boggled at that too, simpler times I guess

>> Concrete was used repeatedly to set the stones and to fill cracks in
>> "restorations" from 1901 through to the 1960s at least.
>
> Any references to prove that?
>
> I went there. I never saw any concrete anywhere.

Presumably it's underground?

<https://www.newscientist.com/article/dn310-concrete-evidence/>

On 14/12/2023 10:29, Andy Burns wrote:
> The Natural Philosopher wrote:
>
>> On 14/12/2023 10:11, Robin wrote:
>>> On 14/12/2023 09:58, The Natural Philosopher wrote:
>>>> On 13/12/2023 19:54, Andrew wrote:
>>>>> Stonehenge was rebuilt back in the 1930's ? and the
>>>>> well-meaning idiots used concrete there too
>>>>
>>>> What????
>>>> Why would anyone use concrete at stone henge?
>
> I boggled at that too, simpler times I guess
>
>>> Concrete was used repeatedly to set the stones and to fill cracks in
>>> "restorations" from 1901 through to the 1960s at least.
>>
>> Any references to prove that?
>>
>> I went there. I never saw any concrete anywhere.
>
> Presumably it's underground?
>
> <https://www.newscientist.com/article/dn310-concrete-evidence/>

Well I hardly regard the chinese whispers of the New Marxist reporting a
post doctoral students witterings as authoritative. I do know some were
re-erected. But if concrete were used it has to be underground

--
The higher up the mountainside
The greener grows the grass.
The higher up the monkey climbs
The more he shows his arse.

Traditional

On 14/12/2023 10:25, The Natural Philosopher wrote:
> On 14/12/2023 10:11, Robin wrote:
>> On 14/12/2023 09:58, The Natural Philosopher wrote:
>>> On 13/12/2023 19:54, Andrew wrote:
>>>> Stonehenge was rebuilt back in the 1930's ? and the
>>>> well-meaning idiots used concrete there too
>>>
>>> What????
>>> Why would anyone use concrete at stone henge?
>>>
>>
>> Concrete was used repeatedly to set the stones and to fill cracks in
>> "restorations" from 1901 through to the 1960s at least.
>>
>>
> Any references to prove that?
>
> I went there. I never saw any concrete anywhere.
>

Under the restoration paragraph...

https://www.english-heritage.org.uk/visit/inspire-me/blog/blog-posts/excavation-restoration-stonehenge-1950s-60s/

--
mailto : news {at} admac {dot} myzen {dot} co {dot} uk

On 14/12/2023 10:40, alan_m wrote:
> On 14/12/2023 10:25, The Natural Philosopher wrote:
>> On 14/12/2023 10:11, Robin wrote:
>>> On 14/12/2023 09:58, The Natural Philosopher wrote:
>>>> On 13/12/2023 19:54, Andrew wrote:
>>>>> Stonehenge was rebuilt back in the 1930's ? and the
>>>>> well-meaning idiots used concrete there too
>>>>
>>>> What????
>>>> Why would anyone use concrete at stone henge?
>>>>
>>>
>>> Concrete was used repeatedly to set the stones and to fill cracks in
>>> "restorations" from 1901 through to the 1960s at least.
>>>
>>>
>> Any references to prove that?
>>
>> I went there. I never saw any concrete anywhere.
>>
>
> Under the restoration paragraph...
>
> https://www.english-heritage.org.uk/visit/inspire-me/blog/blog-posts/excavation-restoration-stonehenge-1950s-60s/
>
That is hardly 'rebuilding' which implies masonry work. That was
re-erecting using concrete to stabilise the stones, which is fair enough
really.

I think I was one of the last people to actually access the circle
before they made it off limits to visitors. I have color slides of the
winter solstice sunrise from inside the circle.

It was fucking cold.

--
“when things get difficult you just have to lie”

― Jean Claud Jüncker

On 14/12/2023 10:46, The Natural Philosopher wrote:
> On 14/12/2023 10:40, alan_m wrote:
>> On 14/12/2023 10:25, The Natural Philosopher wrote:
>>> On 14/12/2023 10:11, Robin wrote:
>>>> On 14/12/2023 09:58, The Natural Philosopher wrote:
>>>>> On 13/12/2023 19:54, Andrew wrote:
>>>>>> Stonehenge was rebuilt back in the 1930's ? and the
>>>>>> well-meaning idiots used concrete there too
>>>>>
>>>>> What????
>>>>> Why would anyone use concrete at stone henge?
>>>>>
>>>>
>>>> Concrete was used repeatedly to set the stones and to fill cracks in
>>>> "restorations" from 1901 through to the 1960s at least.
>>>>
>>>>
>>> Any references to prove that?

Many readily available but start with

https://www.english-heritage.org.uk/visit/places/stonehenge/history-and-stories/history/conservation/

"In the 1960s, conservators used cement mortar to fill in cracks and
fractures on the horizontal stones that sit on top of the huge upright
stones.

Cement mortar isn’t breathable, and as it degrades, it leaves the stones
vulnerable to damage from trapped moisture. In September 2021,
conservators replaced this with lime mortar to keep water out as well as
to allow any water that does get in to escape."

....

Also mentions that in the 1958-9 project "One of the large sarsens of
the inner horseshoe was set in concrete and a large hollow at its base
infilled."

>>> I went there. I never saw any concrete anywhere.
>>>
>>
>> Under the restoration paragraph...
>>
>> https://www.english-heritage.org.uk/visit/inspire-me/blog/blog-posts/excavation-restoration-stonehenge-1950s-60s/
>>
> That is hardly 'rebuilding' which implies masonry work. That was
> re-erecting using concrete to stabilise the stones, which is fair enough
> really.
>

Do you have any references for that distinction between building and
erecting? I ask as it is at odds with OED where

"build" means "To construct, put up, erect (a house or other dwelling or
building).... and

"erect" means "To set up (a building, statue, framework, etc.); to rear,
build"

--
Robin
reply-to address is (intended to be) valid

On 14/12/2023 10:46, The Natural Philosopher wrote:
> On 14/12/2023 10:40, alan_m wrote:
>> On 14/12/2023 10:25, The Natural Philosopher wrote:
>>> On 14/12/2023 10:11, Robin wrote:
>>>> On 14/12/2023 09:58, The Natural Philosopher wrote:
>>>>> On 13/12/2023 19:54, Andrew wrote:
>>>>>> Stonehenge was rebuilt back in the 1930's ? and the
>>>>>> well-meaning idiots used concrete there too
>>>>>
>>>>> What????
>>>>> Why would anyone use concrete at stone henge?
>>>>>
>>>>
>>>> Concrete was used repeatedly to set the stones and to fill cracks in
>>>> "restorations" from 1901 through to the 1960s at least.
>>>>
>>>>
>>> Any references to prove that?
>>>
>>> I went there. I never saw any concrete anywhere.
>>>
>>
>> Under the restoration paragraph...
>>
>> https://www.english-heritage.org.uk/visit/inspire-me/blog/blog-posts/excavation-restoration-stonehenge-1950s-60s/
>>
> That is hardly 'rebuilding' which implies masonry work. That was
> re-erecting using concrete to stabilise the stones, which is fair enough
> really.
>
> I think I was one of the last people to actually access the circle
> before they made it off limits to visitors. I have color slides of the
> winter solstice sunrise from inside the circle.

I can remember when you could climb on top of the toppled ones.

They remarked that in the "old days" they hired out hammers and chisels
so people could take samples of the stones home.

Can you still access the West Kennett Long Barrow? There used to be a
finger-post indicating where you could walk up the hill and go inside it.

--
Max Demian

On 14/12/2023 06:36, Thomas Prufer wrote:
> On Wed, 13 Dec 2023 18:22:04 +0000, Max Demian <max_demian@bigfoot.com> wrote:
>
>> On 13/12/2023 07:40, Jethro_uk wrote:
>>> I wonder how easy this would be to knock up as a hobbyist ...
>>>
>>> https://www.msn.com/en-gb/travel/news/the-secret-ingredient-in-roman-
>>> concrete-that-means-buildings-can-last-for-millennia/ar-AA163dEr
>>
>>> The durability of Roman concrete, which has allowed structures such as
>>> the Pantheon in Rome to remain standing for nearly 2,000 years, has long
>>> baffled experts.
>>
>> One reason Roman concrete has lasted is that they didn't use steel
>> reinforcement that rusts eventually.
>
> They did use iron clamps between stone blocks (ISTR either wrapped in
> pitch-soaked rags, or held in place with a bit to prevent rust and the
> swelling/cracking associated with it.)
>
> These clamps were then later stolen, leaving holes...

> https://rome.us/ask-us/why-the-colosseum-has-holes.html

I think the Colosseum (and many other Roman buildings) is stone with a
concrete infill isn't it? The Pantheon is a rare example of concrete
cast in shutters.

They used the infill method for medieval cathedrals, but, in this case,
the infill would either be rubble or lime mortar concrete, which could
take literally centuries to harden completely, as this requires CO2 to
migrate in and change the Ca(OH)2 to CaCO3.

--
Max Demian

Am 14/12/2023 um 13:26 schrieb Max Demian:
> On 14/12/2023 06:36, Thomas Prufer wrote:
>> On Wed, 13 Dec 2023 18:22:04 +0000, Max Demian
>> <max_demian@bigfoot.com> wrote:
>>
>>> On 13/12/2023 07:40, Jethro_uk wrote:
>>>> I wonder how easy this would be to knock up as a hobbyist ...
>>>>
>>>> https://www.msn.com/en-gb/travel/news/the-secret-ingredient-in-roman-
>>>> concrete-that-means-buildings-can-last-for-millennia/ar-AA163dEr
>>>
>>>> The durability of Roman concrete, which has allowed structures such as
>>>> the Pantheon in Rome to remain standing for nearly 2,000 years, has
>>>> long
>>>> baffled experts.
>>>
>>> One reason Roman concrete has lasted is that they didn't use steel
>>> reinforcement that rusts eventually.
>>
>> They did use iron clamps between stone blocks (ISTR either wrapped in
>> pitch-soaked rags, or held in place with a bit  to prevent rust and the
>> swelling/cracking associated with it.)
>>
>> These clamps were then later stolen, leaving holes...
>
>> https://rome.us/ask-us/why-the-colosseum-has-holes.html
>
> I think the Colosseum (and many other Roman buildings) is stone with a
> concrete infill isn't it? The Pantheon is a rare example of concrete
> cast in shutters.
>
> They used the infill method for medieval cathedrals, but, in this case,
> the infill would either be rubble or lime mortar concrete, which could
> take literally centuries to harden completely, as this requires CO2 to
> migrate in and change the Ca(OH)2 to CaCO3.
>

Not a civil engineer, but we used to have a "geometra" (roughly =
chartered building surveyor) in the house.

I was told, when I was little, that "concrete" (in Italian "cemento" or
"cemento armato" or even better "calcestruzzo armato") is different from
"cement" ( = "calcestruzzo").

The name "concrete" is supposed to be used only for the mix of cement
and steel for XX century kind of high rise concrete buildings or bridges.

You can build a 1 or 2 floor house with cement and stones without steel
reinforcement.

I am sure civil engineers in UK and in Italy use different and possibly
confusing terminologies.

--
Ottavio Caruso

On 14/12/2023 14:22, Ottavio Caruso wrote:
> Am 14/12/2023 um 13:26 schrieb Max Demian:

>> I think the Colosseum (and many other Roman buildings) is stone with a
>> concrete infill isn't it? The Pantheon is a rare example of concrete
>> cast in shutters.
>>
>> They used the infill method for medieval cathedrals, but, in this
>> case, the infill would either be rubble or lime mortar concrete, which
>> could take literally centuries to harden completely, as this requires
>> CO2 to migrate in and change the Ca(OH)2 to CaCO3.
>>
>
> Not a civil engineer, but we used to have a "geometra" (roughly =
> chartered building surveyor) in the house.
>
> I was told, when I was little, that "concrete" (in Italian "cemento" or
> "cemento armato" or even better "calcestruzzo armato") is different from
> "cement" ( = "calcestruzzo").
>
> The name "concrete" is supposed to be used only for the mix of cement
> and steel for XX century kind of high rise concrete buildings or bridges.
>
> You can build a 1 or 2 floor house with cement and stones without steel
> reinforcement.
>
> I am sure civil engineers in UK and in Italy use different and possibly
> confusing terminologies.

Cement is the binding material, e.g. Portland cement which is supplied
as a fine powder. The word is also used for glues generally.

Concrete is cement plus aggregate, i.e. sand and stones of various
sizes, i.e. gravel. Coarse aggregate is also called ballast, from its
use to stabilise unladen ships.

--
Max Demian