Jack Lime-Mortar should 'fizz' violently with 5% Hydrochloric Acid (which, of course, you will have a bottle of in your garage). Portland cement may 'fizz' a bit, depending on how much calcareous matter is in the sand used. You should also be able to scotch lime mortar with a copper coin. Cheers Kevin
On 15 May 2013, at 01:03, Jack Aubert <j...@chezaubert.net> wrote: > This is all fascinating stuff and I will either impress or bore people with > my bogus erudition on the subject. > > But Is there an easy way to distinguish lime mortar from Portland cement > mortar, like with one’s thumbnail? In America, the oldest brick buildings on > the East Coast are from the mid 18th century but they would generally have > been re-pointed with Portland cement. Last weekend I was checking mortar > joints in Alexandria, Virginia, where the oldest buildings date from that > period. They all seemed to have the same sandy consistency. I jokingly told > a homeowners that I was the “mortar inspector”. He replied “Finally! We’ve > been waiting forever!” > > Jack > > From: sundial [mailto:sundial-boun...@uni-koeln.de] On Behalf Of Kevin Karney > Sent: Monday, May 06, 2013 2:39 PM > To: Sundial > Subject: Re: Re quicklime > > A further point about lime mortar. It sets quite hard within a few weeks, but > continues to get harder & harder at an exponentially slower rate until the > carbon dioxide (as carbonic acid) in the atmosphere eventually converts it > back to its original calcium carbonate. So Roman mortar is very very hard and > totally inflexible…. Yes!, it can take thousands of years to re-convert - > this is one of the reasons why ancient buildings (as Roman aqueducts) last so > long. The conversion is quicker in cold climates since frost makes micro > cracks which allows the carbonic acid to percolate into the mortar. > > CaCO3 (limestone) ---heat---> CaO (quicklime)+ CO2 > CaO (quicklime)+ H20 ---> Ca(OH)2 (slaked lime) > CO2 + H2O --- in the atmosphere ---> H2CO3 (carbonic acid - very weak) > Ca(OH)2 (slaked lime) + H2CO3 + O2 ---- time ---> CaCO3 (limestone) + 2H20 > My chemistry is very rusty - so I hope the formulae are right > > All the best > Kevin > > On 6 May 2013, at 15:32, Frank Evans <frankev...@zooplankton.co.uk> wrote: > > > Greetings, fellow dialists, > I'm now clearer on the subject of lime production. After firing It seems the > quicklime was taken from the kiln in lumps, separated from the ash and moved > to a pit in the nearby slaking shed (cheaper than iron pots). The pit was > lined to hold water and the quicklime was (cautiously!) added. It was in > timer bailed out and sieved (large lumps might not be completely slaked and > could "blister" later as mortar, with damaging consequences. The resulting > slaked lime could now be safely transported. Each firing produced several > tons of lime and this was sometimes left to mature for many weeks. > > Thanks to all who replied. I hope to talk further on the subject with the > stonemason when he returns to Tynemouth in the summer to paint the dial. I > note he was careful to chose the correct colour of sand to mix with his lime > putty for the repairs. > Frank 55N 1W > --------------------------------------------------- > https://lists.uni-koeln.de/mailman/listinfo/sundial > > > > -- > This message has been scanned for viruses and > dangerous content by MailScanner, and is > believed to be clean. > > -- > This message has been scanned for viruses and > dangerous content by MailScanner, and is > believed to be clean.
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