Geopolymer Concrete, Perfecting Roman Technology Today

For all the things Romans got wrong (lead pipes anyone?) did you know we’re still using a less advanced concrete than they did? Consider some of the massive structures in Rome that have passed the test of time, lasting for more than 2000 years. The typical concrete that we use in construction starts to degrade after only 50 years.

Researchers at Berkeley think they’ve finally figured it out with thanks to a sample that was removed from the Pozzuoli Bay near Naples, Italy. This could vastly improve the durability of modern concrete, and even reduce the carbon footprint from making it. The downside is a longer curing time, and resource allocation — it wouldn’t be possible to completely replace modern cement due to the limited supply of fly ash (an industrial waste product produced by burning coal). Their research can be found in a few articles, however they are both behind pay walls.

Lucky for us, and the open source community at large, someone from MIT has also been working on perfecting the formula — and he’s shared his results thus far.

So, who wants to give it a shot? Any material scientists in our midst?

48 thoughts on “Geopolymer Concrete, Perfecting Roman Technology Today

    1. The DC metro area was using lead pipes up until the 90’s when they went on a crusade to get rid of them. Well all the pipe owned by the utility. The last 10ft were up to the home owner. After this campaign child lead poisoning cases skyrocketed. The utilities made the (minor) problem worse (read: worst case scenario ‘worse’) by being cheap.

  1. I can vouch for fly ash making damn hard and durable concrete. I used to work in underground construction. We had to place fiber optic cable in Fergus Falls , MN. This town is home to Otter Tail Powers Hoot Lake power plant, which is coal fired. They mixed fly ash in with lots of the old concrete used for roads back in the day. We could barely get through it with saws, and broke multiple jackhammer bits. We found one spot, by the oldest hydroelectric dam in town, where they had used pure fly ash as fill. It took us 2 straight days to get a cable to the control junction there. That stuff had mixed with the clay and formed something akin to limestone.

  2. Make sure to offer many sacrifices next vulcanalia! Pagan engineers for the win.

    Our concrete is much more advanced than Roman and UHPC have compressive MPa up to 250 compared to Roman at 50 MPa but the formation of calcium hydroxide crystals degrade them more quickly. You could say our concretes are drastically under-lived compared to Roman but not under advanced.

    Thanks hackaday love the chemistry hacks!

  3. Hey what’s with the hatin’ on the Romans? They gave us the orgy! A great, great civilization!
    @IH8UKULELE – But you have to admit that finding out why Roman concrete lasted 2000 years could make modern concrete better, why can’t we have strong concrete that lasts longer than a frenchman’s underwear? Also if you need to make a sacrifice to Vulcan why not just raid the IT department, plenty of virgins there.

    1. Yah I do admit that it would be nice to make something last in this consumer culture.

      Concrete, pottery, military organization, mass pacification of plebs via gore and waterworks were about all the early Romans did well… unless you count a republic that existed because roughly 2/3rds of its populace were slaves.

      Rome was not great, it just was. They did come up with some slick things though.

    2. Nm f that, Rome was great.

      Let’s bring back gladiatorial games for violent criminals in lieu of life sentences and death sentences.
      And lets build a new coliseum with roman era concrete.

      1. Although it is not my field, I do like Roman history especially in the larger European context. What always strikes me as odd is that during various episodes in our western “civilization” many have aspired to mimic either the republic or the empire in some form or another, often very superficial, historically incorrect or romanticized(I know). I find this odd because the one thing we tend not to do is learn from this common ancestral history and try and avoid making similar mistakes.
        In many ways we are the continuation of Rome and we relish in repeating it’s history (especially the nasty bits)

        1. Possibly the desensitization or , what we feel is normal , will be another downfall repeated ,like ya say. Kinda thought concrete hardened over time , guess till the brittle point .

  4. volcanic ash + lime. Sodium silicate is gravy. as simple as that. My dad researched this for years, to no interest by anyone he could find. Remember why tramways got replaced by buses? same difference. I could tell more, but what’s the point?
    If Berkeley say they’ve “discovered” it and that there’s not enough of it to go around, wow amaze

    Oh, BTW, this cement in nearly 100% waterproof – meaning no cracks, meaning no degradation by water infiltration. Fly ash is merely artificial pozzolan. See here

    Taylorian, indeed, pozzolan keeps getting harder and harder with age

  5. I was under the impression the primary reason Roman concrete is so much stronger was due to desires for modern concrete to behave somewhat like a fluid. Bigger rocks make better concrete, but it’s hard to put in a truck and dump where you need it compared to the sand and gravel mix we use today.

    1. Look at the plasticizer ingredient in the MIT guy write up. Makes it easier to work with. It really wasn’t stronger it just lasts 2000 years and is impervious to sea water.

  6. It’s not the concrete itself that is the problem with modern day concrete. That will last practically forever.

    It’s the rebar that rusts to bits and undergoes other galvanic reactions like hydrogen embrittlement. The romans did not use concrete to build anything that had to bear tension – only compression – so they never put any rebar or equivalent in it. Or at least, no such structure has stood the test of time to our days.

    We make overhanging beams and platforms out of concrete and subject it to dynamic loads in suspension bridges and free standing structures, they just made short arches and supported their beams by many columns.

    1. The rebar issue is missing from just about ever article written on Roman concrete. As long as you are using rebar-based design and construction techniques you are not going to see any overall benefit from alternative concrete mixtures.

  7. In my experience there are a few factors as to why modern concrete is “weaker” than Roman concrete.

    Cost is probably the major one. Engineers specify the weakest concrete that will do the job as no one wants to pay for 80MPa concrete if a 25MPa mix will do. Concrete suppliers also design the concrete mix so that it reaches the required strength in accordance with the building codes and no more. In Australia, that is 28 days and if we are consistantly getting a lot more strength at 28 days than specified, the supplier will generally tweak the mix to reduce the cement content and bring the strength closer to spec.

    Design life is another one. I personally haven’t been involved in the construction of a building that has required a design life of more than 50 years. Hence high compressive strength concrete (and its associated reduced water permeability) is not required nor specified.

    My first experience with fly ash was that it was used to reduce costs by reducing the cement content. Fly ash is a waste product and used to be thrown away. This was around 10 years ago.
    More recent experience with fly ash is that it is still being used to reduce the cement content, although now it is in the name of sustainability and amazingly these mixes now cost the same or sometimes more than a standard mix with no fly ash!

    Another problem with fly ash is it that the more you put in the mix the longer it takes to cure. This affects its use in post-tensioned structures, as well as its abrasion resistance. For the important of abrasion resistance, think of tight corners in a multi-storey concrete car park and excessive fly ash in a mix will have the cars wearing the concrete away.

    1. Partial replacement of cement with fly ash is old news in the US as well. It improves early strength of concrete as well as cement fluidity. Geopolymers are a different system than portland cement with pozzolan additions.


    Material scientist here, although not one working in the cement field. If I recall correctly, the main economic issue right now is the energy needed to produce the large amounts of sodium silicate used in geopolymer cement. Also, most geopolymers have a strong sensitivity to feedstock crystallinity and can have severely reduced properties with even moderate levels of transition metal oxides. Fly ash composition and structure have a lot of variation depending on the coal used and different parameters at combustion, which makes it hard to find a stable raw material source.

    On the plus side, its fire resistance is absolutely outstanding. Very little to no spalling and a very slow strength loss compared to conventional cement.

  9. Fly ash is only one source. Silica aggregate mixed with silica flour makes for a concrete that is waterproof. The recipes for such are not a state secret. Go to an older library and take a look through the older volumes. Cross reference Hadrian’s Wall. If you limit yourself to the electronic articles of modern scholars behind a pay wall then you need to do your research. Where do you think they got their ideas from? Certainly their papers have references… The references for the information in a bibliography are a treasure trove.

      1. ? The Romans killed Christ on behalf of the Jewish people claiming he was a false prophet, and their religion doesn’t permit them to kill. So Pontius Pilate who had many near revolts gave the people what they wanted. Not only that but Nero hated Christians and would impale them like Vlad did, set them of fire, and laugh, all while in his back yard. The Romans hated Christians in every regard

        1. Some romans did, perhaps, at some time. But later it became the cool hip thing to be christian, and emperors converted to chistianity. Emperor Constantin I ordered the, which was one of the points in time were christian doctrine (canon) was changed.
          The roman form of christianity is the ancestor of almost all christian faiths so denouncing ‘romans’ as christian haters is very narrow minded.
          But then again, religious faith by itself is very narrow minded, I’m always amazed how religious people claim their religion to be the true everlasting one, but fail to acknowledge the ancestry of their own belief system (and draw some logical conclusions from that).

    1. Taught the world what it meant to conquer through “tolerance”. And taught the world that through moral relativism, the worst atrocities of human kind is possible. And whats the worst sins a person and society can make. And by failing so miserably as a society and culture how not to fail, etc.

      1. Are you suggesting the romans were more cruel than their contemporaries, and that the cause of that was their ‘moral relativism’? And that their ‘downfall’ was based on their society and culture being corrupt? You must have read a lot of latin manuscripts to come to such an astounding conclusion, where can we read the full thesis that you summarized here?
        If not, I fear you are quite bigoted, parroting some dogma by an organisation that declared one group of people X (or aspects of that group) inferior, so that they could claim themselves to be superior.

        The ‘real’ reasons for the points you mentioned is probably politics and technological progress.

  10. After learning what the sun has in store for us in the next 30 years from last night’s talk radio Coast to Coast, I would say burn more coal.
    It ain’t the unions just everyone wanting to get the gravy train to make a stop for themselves on a regular schedule.

  11. One application of geopolymers (or any cheap eco-friendly cement for that matter) is in 3D printing architecture. A mixture that could resist curing until it passed a hot nozzle, and then pre-set so you can built non-collapsing (overhanging?) structures with it.
    Portland cement production is producing way too much CO2 to keep using, so we need another cheap cement that can take its role in the buildings of the future.

    1. I have an idea, instead of burning coal to produce ash for concrete, let’s capture some of that heat in a chamber with walls lined with water pipes, as the water heats up and becomes steam, let’s take the pressure of the steam and use it to do mechanical work (force times distance) for use such as pushing a piston in a cylinder or turning some angled blades mounted on a shaft! As the steam condenses, let us use the residual heat to heat buildings such as the building climate change “scientists” and their government leaders dwell and “work” in!

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