Roman concrete

[DBS]

https://news.mit.edu/2023/roman-concrete-durability-lime-casts-0106

Very interesting new research.

[Jim Webster]

https://news.mit.edu/2023/roman-concrete-durability-lime-casts-0106

Very interesting new research.

You beat me to posting it, very interesting

[Imperial Dave]

Could do with some of this...!

[Ian61]

Great find. There will be real interest in this by the industry.
Health and safety at work becomes a real issue though. Dropping cold quicklime (calcium oxide) into cold water can rapidly bring the water temperature to boiling. Temperature to one side even modern concrete can give chemical burns to skin (sweat adds to problem) through the alkali/basic nature of the slaked like (calcium hydroxide). Quicklime is much nastier and you would not want it on your skin. I suspect that accidents were common but of course would not be happening to anyone who mattered so we're not recorded.

[Ian61]

Sorry some up in might with one of those 'but that's wrong' moments. I got carried away thinking of all the times I have demonstrated the reactions to make quicklime and some reactions you can do with it. I had a sudden vision of a cement kiln and thought 'but that makes quicklime as a component not slaked lime' , even an a quick check online confirms this the reaction to make concrete in my notes from 90s indicates the reaction that makes cement go hard is principally CaO + SiO2 > CaSiO3 (damn can't subscript on my tablet but I think that is still clear). In ,other words something not quite right here. Carefully rereading suggests they may be adding extra quicklime as they do the final mix.

[Jim Webster]

Sorry some up in might with one of those 'but that's wrong' moments. I got carried away thinking of all the times I have demonstrated the reactions to make quicklime and some reactions you can do with it. I had a sudden vision of a cement kiln and thought 'but that makes quicklime as a component not slaked lime' , even an a quick check online confirms this the reaction to make concrete in my notes from 90s indicates the reaction that makes cement go hard is principally CaO + SiO2 > CaSiO3 (damn can't subscript on my tablet but I think that is still clear). In ,other words something not quite right here. Carefully rereading suggests they may be adding extra quicklime as they do the final mix.

I must admit I was hoping somebody would come up with the ingredients, proportions and method 

[Ian61]

Sorry some up in might with one of those 'but that's wrong' moments. I got carried away thinking of all the times I have demonstrated the reactions to make quicklime and some reactions you can do with it. I had a sudden vision of a cement kiln and thought 'but that makes quicklime as a component not slaked lime' , even an a quick check online confirms this the reaction to make concrete in my notes from 90s indicates the reaction that makes cement go hard is principally CaO + SiO2 > CaSiO3 (damn can't subscript on my tablet but I think that is still clear). In ,other words something not quite right here. Carefully rereading suggests they may be adding extra quicklime as they do the final mix.

I must admit I was hoping somebody would come up with the ingredients, proportions and method 

My new tablet has an autochanger that I haven't got on top of yet I definitely typed 'Sorry woke up in night...'.
The cement powder that is the glue that holds cement together is quite a complex mix but the idea is that crystals of calcium silicate (SiO₃) grow and stick the solid components of sand/gravel together as they form (each silicon atom forms 4 bonds going in different directions so ideal for this).