3 ms·

The follow up from this year (2019) https://rootsofprogress.org/cement-redux https://rootsofprogress.org/cement-redux is even more interesting. It also mentions

The follow up from this year (2019) https://rootsofprogress.org/cement-redux https://rootsofprogress.org/cement-redux is even more interesting. It also mentions the DARPA effort to re-discover the formula for Roman maritime cement which gets stronger in sea water rather than erodes in sea water. If we can figure that one out we could make concrete hulls for ocean going ships that would last many lifetimes.

samstave 7y ago
I thought I read recently that the 'secret' to Roman Cement - was that they were using volcanic ash, which changed the composition and resulted in a better ingredient. https://www.nature.com/news/seawater-is-the-secret-to-long-lasting-roman-concrete-1.22231 https://www.nature.com/news/seawater-is-the-secret-to-long-l...
- phinnaeus 7y ago
  Very recently indeed, this is mentioned in the linked 2018 article. I assume there is some other secret sauce or it wouldn't be so secret.
  - jasoncrawford 7y ago
    The fact that they were using volcanic ash is nothing new. I mean, Vitruvius basically wrote down that it was volcanic ash. The specific chemistry of how the specific silicates interact with seawater and how that forms new compounds is a new discovery.
    - RRWagner 7y ago
      This is all explained in the books of Joseph Davidovits.
- ChuckMcM 7y ago
  Yes and no. The linked article explains that the 'secret' was ash from Mt Vesuvius which added silicates. But the Romans had another cement called "Maritime Cement" which is mentioned in the second article (the follow up article that I linked) which says, "There does seem to be one particular application in which the Romans had a formula we would like to rediscover: maritime concrete, exposed to seawater. Normally, concrete in a pier or harbor erodes over time, both due to the salts and other minerals in the seawater, and due to the abrasion of sand and silt. However, some Roman marine structures have survived for 2,000 years. Geologists studying Roman concrete have recently discovered (2017) that the particular concrete formula used in those structures has a beneficial interaction with seawater, creating new crystals within the cementing matrix that actually increase strength. DARPA just announced that “Unlocking the Secrets of Roman Concrete” is one of many topics for exploration under a research awards program."
  - amluto 7y ago
    Is it substantially better than modern concrete with seawater-proof reinforcement? Stainless steel rebar, fiberglass rebar, and basalt rebar all exist. The latter sounds quite promising if you believe its manufacturers’ claims. (A major cause of failure of concrete near or in the sea is that the rebar corrodes and expands, cause the concrete to break.)
    - ChuckMcM 7y ago
      Yes it is substantially better because it grows in sea water. Which is to say that it is self healing with respect to erosion. They give examples of roman maritime concrete that is over 2000 years old and still functional. No existing concrete does this (hence the DARPA call for research topics). It is also why a concrete hulled boat using this stuff would not suffer hull erosion like the existing cement fleet did during world war II and afterwards. It isn't clear to me (but I've not found a good paper on Roman "maritime" concrete either :-)) how it interacts with barnacles and other marine life.
hartzell 7y ago
Thanks for reminding me of trips to See the Atlantus at Cape May when I was a kid.... :) https://en.wikipedia.org/wiki/SS_Atlantus https://en.wikipedia.org/wiki/SS_Atlantus (and horseshoe crabs and Cape May diamonds and ...)
dredmorbius 7y ago
There are concrete ships. Often these are barges, though traditional sail and powerboat designs are found (news to me as I wrote this comment, see Wikipedia link below). I don't know how well the Roman formula would hold up, but traditional concrete tends to spall badly in constant exposure to salt water. Reinforced concrete suffers from rusting of the steel rebar segments. Under dynamic stress, I doubt you'd get lifetimes of wear. Though several decades should be reasonably viable. https://en.wikipedia.org/wiki/Concrete_ship https://en.wikipedia.org/wiki/Concrete_ship

samstave 7y ago

I thought I read recently that the 'secret' to Roman Cement - was that they were using volcanic ash, which changed the composition and resulted in a better ingredient. https://www.nature.com/news/seawater-is-the-secret-to-long-lasting-roman-concrete-1.22231 https://www.nature.com/news/seawater-is-the-secret-to-long-l...

phinnaeus 7y ago
Very recently indeed, this is mentioned in the linked 2018 article. I assume there is some other secret sauce or it wouldn't be so secret.
- jasoncrawford 7y ago
  The fact that they were using volcanic ash is nothing new. I mean, Vitruvius basically wrote down that it was volcanic ash. The specific chemistry of how the specific silicates interact with seawater and how that forms new compounds is a new discovery.
  - RRWagner 7y ago
    This is all explained in the books of Joseph Davidovits.
ChuckMcM 7y ago
Yes and no. The linked article explains that the 'secret' was ash from Mt Vesuvius which added silicates. But the Romans had another cement called "Maritime Cement" which is mentioned in the second article (the follow up article that I linked) which says, "There does seem to be one particular application in which the Romans had a formula we would like to rediscover: maritime concrete, exposed to seawater. Normally, concrete in a pier or harbor erodes over time, both due to the salts and other minerals in the seawater, and due to the abrasion of sand and silt. However, some Roman marine structures have survived for 2,000 years. Geologists studying Roman concrete have recently discovered (2017) that the particular concrete formula used in those structures has a beneficial interaction with seawater, creating new crystals within the cementing matrix that actually increase strength. DARPA just announced that “Unlocking the Secrets of Roman Concrete” is one of many topics for exploration under a research awards program."
- amluto 7y ago
  Is it substantially better than modern concrete with seawater-proof reinforcement? Stainless steel rebar, fiberglass rebar, and basalt rebar all exist. The latter sounds quite promising if you believe its manufacturers’ claims. (A major cause of failure of concrete near or in the sea is that the rebar corrodes and expands, cause the concrete to break.)
  - ChuckMcM 7y ago
    Yes it is substantially better because it grows in sea water. Which is to say that it is self healing with respect to erosion. They give examples of roman maritime concrete that is over 2000 years old and still functional. No existing concrete does this (hence the DARPA call for research topics). It is also why a concrete hulled boat using this stuff would not suffer hull erosion like the existing cement fleet did during world war II and afterwards. It isn't clear to me (but I've not found a good paper on Roman "maritime" concrete either :-)) how it interacts with barnacles and other marine life.

hartzell 7y ago

Thanks for reminding me of trips to See the Atlantus at Cape May when I was a kid.... :) https://en.wikipedia.org/wiki/SS_Atlantus https://en.wikipedia.org/wiki/SS_Atlantus (and horseshoe crabs and Cape May diamonds and ...)

dredmorbius 7y ago

There are concrete ships. Often these are barges, though traditional sail and powerboat designs are found (news to me as I wrote this comment, see Wikipedia link below). I don't know how well the Roman formula would hold up, but traditional concrete tends to spall badly in constant exposure to salt water. Reinforced concrete suffers from rusting of the steel rebar segments. Under dynamic stress, I doubt you'd get lifetimes of wear. Though several decades should be reasonably viable. https://en.wikipedia.org/wiki/Concrete_ship https://en.wikipedia.org/wiki/Concrete_ship