There's a new paper out exploring some of the chemical mechanisms at work in Roman concrete. As per usual, it’s triggered a round of enthusiastic discussion of Roman concrete, and how its ability to last for millennia puts modern concrete (which often fails after a few decades) to shame.
Residential sidewalks, excluding driveways, shouldn't need reinforcement. Better self-healing of cracks would be valuable. My city has a huge backlog of sidewalk repairs.
Thanks for writing about this. I happened to be in Rome when the paper came out and it was fun to visit the Pantheon with it in mind! Do you have any thoughts about fiber reinforcing and its effect on longevity?
Are we faced with such a binary choice? Could we not incorporate Calcium Oxide into reinforced concrete? I am no chemist, so I do not know what kind of reaction steel would have to this. Unless adding Calcium Oxide drastically alters the curing process (perhaps by slowing it down to an unacceptable degree, by modern standards), why could we not see it incorporated as an admixture in the future?
Thanks for writing this up. When I saw that tweet, my first thought was, "But this doesn't seem to address reinforcement corrosion directly?" This article saved me the time of having to dig around myself to make sure I wasn't crazy that this is still pretty far away from a practical improvement.
It'll be interesting to see if this has an effect on chloride/CO2 intrusion and consequent loss of reinforcement passivation. I don't recall that microcracking was a huge driver of that compared to porosity, but that's not something I've done much reading on in the last 20 years or so so I might be misremembering.
If steel is that much stronger, why use concrete at all? Just cost?
Something as simple as painting metal (or if you're feeling more advanced, plating with a corrosion resistant coating) can often reduce corrosion when the metal is bare. Has this been looked at for reinforced
Particularly enjoy posts like this that bring some relevant news to those of us that otherwise might miss it and tie in a whole bunch of other informative context as well. I know far more about concrete reinforcement than I did 30 mins ago.
I just think it’s amazing that without modern analytic tools, that they were able to figure out how to make, and use, such long lasting concrete. I think our powers of observation have atrophied.
I recently read a similar article on Roman concrete that said something completely different - that it was the high temperature it was mixed at that resulted in stronger chemical properties (nothing to do with rebar). The article didn't say how it was heated or how hot it was, just that its molecular composition was extraordinary.
Residential sidewalks, excluding driveways, shouldn't need reinforcement. Better self-healing of cracks would be valuable. My city has a huge backlog of sidewalk repairs.
Thanks for writing about this. I happened to be in Rome when the paper came out and it was fun to visit the Pantheon with it in mind! Do you have any thoughts about fiber reinforcing and its effect on longevity?
I wonder if it's a good thing that so many buildings will fall apart after 50 years because it lets you put something new in its place.
Are we faced with such a binary choice? Could we not incorporate Calcium Oxide into reinforced concrete? I am no chemist, so I do not know what kind of reaction steel would have to this. Unless adding Calcium Oxide drastically alters the curing process (perhaps by slowing it down to an unacceptable degree, by modern standards), why could we not see it incorporated as an admixture in the future?
Thanks for writing this up. When I saw that tweet, my first thought was, "But this doesn't seem to address reinforcement corrosion directly?" This article saved me the time of having to dig around myself to make sure I wasn't crazy that this is still pretty far away from a practical improvement.
It'll be interesting to see if this has an effect on chloride/CO2 intrusion and consequent loss of reinforcement passivation. I don't recall that microcracking was a huge driver of that compared to porosity, but that's not something I've done much reading on in the last 20 years or so so I might be misremembering.
If steel is that much stronger, why use concrete at all? Just cost?
Something as simple as painting metal (or if you're feeling more advanced, plating with a corrosion resistant coating) can often reduce corrosion when the metal is bare. Has this been looked at for reinforced
Thank you for the professional take on the issue.
Particularly enjoy posts like this that bring some relevant news to those of us that otherwise might miss it and tie in a whole bunch of other informative context as well. I know far more about concrete reinforcement than I did 30 mins ago.
I just think it’s amazing that without modern analytic tools, that they were able to figure out how to make, and use, such long lasting concrete. I think our powers of observation have atrophied.
I recently read a similar article on Roman concrete that said something completely different - that it was the high temperature it was mixed at that resulted in stronger chemical properties (nothing to do with rebar). The article didn't say how it was heated or how hot it was, just that its molecular composition was extraordinary.
https://www.foxnews.com/science/research-uncover-secret-made-ancient-roman-concrete-durable.amp