For this episode we talk with Dr. Marie Jackson a Research Professor in the Geology & Geophysics department here at the University of Utah. Dr. Jackson’s work is centered in mineralogy, pyroclastic volcanism, and material science, but she applies her work to the realms of engineering, archeology, and more. She’s done a lot of pioneering work on understanding ancient Roman concretes, their composition, structure and how they age over time. She has also fabricated a modern proxy of Roman marine concrete. Through production of self-sustaining, resilient concrete for coastal infrastructure her work will help to lessen carbon emissions and combat the environmental impacts that come with a changing climate. (Featured image: ROMACONS drilling at a marine structure in Portus Cosanus, Tuscany, 2003. Drilling is by permission of the Soprintendenza Archeologia per la Toscana.)
Listen to the Interview:
Transcript:
Ross Chambless
Well, Marie Jackson, welcome to our show. I’m Ross Chambless, co-host of this podcast here with Margaret Call. And I’m going to hand it off to Margaret for your first question.
Margaret Call
Yeah, we’re super excited to have you here to talk about your work! Would you mind kind of giving us an introduction to you, what you do, and your involvement here on campus?
Marie Jackson
Well, I am a research professor in the Department of Geology and Geophysics, and I work on three prominent topics, which seem different but are actually very similar, ancient Roman concretes, the fabrication of environmentally sustainable concretes for different marine applications, and the basalt of a very young oceanic island called Surtsey in Iceland.
Ross Chambless
Fascinating. Well, I’m already very intrigued. I’d love to hear. So how did you get into this topic? What was it in your background or your experience that brought you into this field of research?
Marie Jackson
My background was in volcanology and rock mechanics. I was once a real geologist. Quite a few years ago, I changed my focus to actually looking at geologic construction materials, and this led me to very interesting topics in ancient Roman building stones and concretes.
Ross Chambless
Interesting.
Margaret Call
Awesome. Yeah. So can you tell us a little bit, just for listeners that might not know what we’re talking about, but can you tell us a little bit about what Roman concrete is?
Marie Jackson
Roman concrete is a tremendously complex material that Romans developed probably over a couple of hundred years. They used pyroclastic volcanic rock, that’s rock that’s produced through explosive volcanic eruptions, from the landscape of Rome and the landscape of Naples to create extremely durable concretes both for architectural applications and also for seawater harbor applications around the Mediterranean.
Ross Chambless
Interesting. So, I mean, I think just to bring it around, I mean, I know that part of the reason we’re talking about this is… that my understanding is that Roman concrete has a much smaller environmental impact than compared to modern concrete or cement in some ways. And so maybe can we talk about it that a little bit?
Marie Jackson
Sure. Portland Cement concretes are made of cement. This is a material that is essentially burnt rock, rock burnt at 1450 degrees centigrade that is used to bind inert sand and gravel aggregates. It’s inexpensive to make in terms of money, but it has a very high carbon footprint in terms of both the fuel used to produce the cement and the CO2 released in that production. Roman concrete is about 85 volume percent rock. Rock aggregate that is produced either through volcanic eruptions or from limestone near the building site. And Romans developed a method to make that rock react over time, first with lime and then with interstitial fluids so that mineral cements are growing over thousands of years to build chemical and mechanical resilience in the structures.
Margaret Call
So they get stronger over time?
Marie Jackson
I wouldn’t say they necessarily get stronger. This is not a material that has a very high compressive strength. Instead, they get more resilient. Because they grow these mineral cements of different types, they have an ability to arrest the propagation of fractures. Fractures do form, but it’s hard for them to propagate. And when they do form different mineral cements keep growing and bonding the walls of the cracks back together. So both from the point of view of fracture as well as chemical resilience, these materials are truly extraordinary in the way that they become more resilient over time.
Ross Chambless
That is really fascinating. So it seems like you’re saying it’s almost kind of self-repairing material in some ways?
Marie Jackson
Well, I’m glad you use the word self-repairing. That’s a good word, and we use it. We can think of ancient Roman concrete as an environmentally sustainable building material. Great. And I have another perspective on it, and that is that these are self-sustaining materials. This material has the ability to sustain itself over time, especially the harbor concretes. This is very important because when we build in the sea, we want materials that will produce local environments that are ecologically and geomorphologically compatible with their surrounding environments. And that is what we are doing with a new grant from the Engineering with Nature program through the Army Corps of Engineers.
Ross Chambless
So I guess kind of what I’m wondering is why is, why are the Roman concrete methods and processes and the use of Roman concrete not more widely used today and in place of what we normally think of concrete as, you know, the Portland concrete. What happened to Roman concrete? Why did it sort of go out of style?
Marie Jackson
Well, Roman concrete has many different varieties through the Roman Empire. People used different materials in the concrete, although they used the same kinds of reactive processes and principles. In terms of Roman marine concrete, there came a time in the Roman Empire when huge, massive structures requiring tens of thousands of cubic meters of volcanic tephra from the coast of Italy transported around the Mediterranean were simply no longer needed. Either the infrastructure was in place or things had changed enough so that there wasn’t that same kind of maritime traffic. So Roman marine concrete probably was phased out because it wasn’t needed in the same way that architectural concrete was needed.
Ross Chambless
I see.
Margaret Call
Yeah. Earlier when you were talking about kind of the three projects that you’ve been working on, you mentioned like coastal resilience. Is there a way you want to expand more on that?
Marie Jackson
Sure. When we look at sea level rise, we know as geologists that seawalls are not an answer. We need to find solutions that are geomorphologically in tune with coastlines and have the ability to survive over time. If we make structures in Portland Cement concrete with steel reinforcement, you can imagine what those are going to look like in 200 years, much less 2000 years. We have already left big footprints of corroded steel concrete around coastlines around the world. Our process is to make concretes that are in equilibrium with the seawater environment, and the Romans were the masters of doing that.
Ross Chambless
That’s so fascinating! So talking about this, is the ancient Roman example really the only example of that kind of approach going on with marine cement that we can look at? Or are there other examples?
Marie Jackson
I really wouldn’t call it marine cement, because then you immediately go back to the world of Portland Cement. Yes, there are. In fact, as of a month ago, we have a new group in the American Concrete Institute for seawater concretes. There’s that much interest and importance being placed on these materials right now. So this is really a very new thing and we’re really excited to get to work on those topics as a collective community.
Ross Chambless
Yeah, well, I wanted to acknowledge that you brought in some visual aids, some samples to look at, and unfortunately it is an audio podcast. So perhaps later we can share a photo of these. But do you want to describe what you’ve brought in?
Marie Jackson
Yeah, I took a drill core of the platform at the Portus Claudius structure at the mouth of the Tiber River near Rome to show you how much volcanic rock is actually used in those materials. It looks like a very rustic, rough material. However, please note that this has remained intact as a kind of buttressing terrace around the port for 2000 years, and it is remarkably robust and compact. This smaller specimen is our reproduction of that mortar, which we’ve made with western United States volcanic rock, using exactly the same principles and seawater. So one of the important factors of what we are doing is using sea water to hydrate our concrete rather than the tremendously precious resource of fresh water. In addition, that builds a chemical system that’s ready to react beneficially with seawater. We know this concrete is going to react with seawater. We want to drive that reaction in a beneficial way so that new mineral cements form. And we are doing that with our analog.
Ross Chambless
Fascinating. Well so what is your perception of the potential for scaling this up, this approach to making this more resilient sort of Roman concrete going forward in the future? As far as new applications, obviously dealing with climate, you know, with the changing climate and rising sea levels and structures that may need to be built in in a more resilient way along coastal lands. You know what is the potential, is there enough resources available? Are there facilities that need to be built or infrastructure that needs to be built up to provide for that?
Marie Jackson
This is a material that fits within the current concrete infrastructure. It does not use cement, it needs a reactive glass. Whether that is a synthetic glass or a volcanic glass depends on the application. And we as part of our Engineering with Nature project, will be placing blocks of this concrete in different U.S. Army Corps of Engineers sites to look at its resilience over time. So that’s a first step.
Ross Chambless
Okay. Fascinating. Who else is working on this challenge, I guess your peers in academia or even in in the government level or, you know, it seems like it’s a pretty important space.
Marie Jackson
Well, we have a Mechanical Engineer who’s been working on this for quite a few years, Phillip Brune, who is very adept at looking at fracture processes and modeling. So, we have developed a new arc shaped bending test to actually measure that kind of resilience. And we want to start looking at different ways to measure concrete performance, not simply uniaxial compressive strength, but the actual ductility and the ability of the material to resist fracture and then repair itself after a fracture occurs. There are many different aspects of that, and we hope to be doing more of that in the future.
Ross Chambless
Interesting. I was going to ask what sort of materials are necessary for this approach? Well, I mean, obviously there’s different there seems to be different approaches to the Roman concrete recipe, I suppose. But it sounds like you mentioned seawater as a potential and also volcanic materials. What other minerals are essential for this?
Marie Jackson
Roman concrete is activated through lime. CaO. This is produced by burning limestone. Burning of limestone has been taking place for thousands and thousands of years. It occurs at a substantially lower temperature than Portland cement, 900 degrees centigrade. And what we need to remember about true Roman concrete is this is simply an activator. It’s called a pozzolanic reaction. We want to activate that pozzolanic reaction. And then we want to develop a system that reacts with interstitial waters over time. How do we know about that system? Well, volcanic rocks around the world grow similar mineral cements through the percolation of fluids, through the volcanic tephra. And this is why we have drilled, for one reason, the volcanic island of Surtsey in Iceland. Because Surtsey is growing the same mineral assemblage as Portus Claudius. We have several new publications that are describing those processes.
Ross Chambless
Oh, interesting. Well, with regard to the Iceland project, what are you hoping to learn? How far along is that project?
Marie Jackson
Oh, it’s very far along. In fact, the University of Utah has the “Surtsey at 50 Years” blog space. We’ve created that so that the general public can get a firsthand picture of what it’s like to have a scientific drilling project in an environmentally protected area. Surtsey is a UNESCO World Heritage site. We have posted our publications online with kind of common sense descriptions of the results, ranging from geochemistry to microbiology to geophysics to mechanical properties and lots of mineralogy.
Ross Chambless
Fascinating.
Margaret Call
Cool. Now that we’ve kind of gone into the weeds of everything that we’ve been talking about. What’s been your favorite part of the research you’ve been doing lately? Or the most exciting thing that you’ve found?
Marie Jackson
Hmm. Well, when I was a real geologist, I made geologic maps at the kilometer scale. And nowadays I make geologic maps at the micrometer scale. I’ve done a lot of work with X-ray microdiffraction at Beamline 12.3.2, of the Advanced Light Source, and what has been truly remarkable is to make maps that show the mineral evolution within these tiny areas. We are probing the materials that people made 2000 years ago in the Mediterranean Sea, and tracking how they’ve reacted over time by this very powerful tool, at the ALS.
Ross Chambless
Fascinating. So I was thinking about students, maybe students here at the U, students who are elsewhere who might be listening to this podcast. What sort of maybe advice do you have for students who are interested in this particular space dealing with sustainable concrete or with anything related to geology that might be in a similar focus or track that you’ve focused on. What advice might you have for them as far as what to explore and what how to approach that?
Marie Jackson
Well, research at its most profound level comes from curiosity. So, I would think that if students began to wonder about what they were curious about, they could start getting some ideas of what kind of questions they might ask. And when we ask questions and start to answer them, we get knowledge. Romans called knowledge “Scientia”. That means science. So, I would encourage students to look at what they’re interested in, what are they curious about? And start from there.
Margaret Call
Yeah. Kind of bouncing off of that. What would you say to someone who doesn’t know if they like environmental science or research at all? Like, how do they get involved in that? How do you start to see if that’s something you’d like to do?
Marie Jackson
They could go to this Surtsey@50years blog and look at some of our papers. This is the environment of a tiny oceanic volcano. The research goes in many, many different directions and gives a picture of how intertwined processes are among physical, chemical, and biological processes. And from then they could start looking in the areas for which they have the greatest curiosity.
Ross Chambless
Yeah, I think that’s great advice. I think maybe just a few more questions with this conversation. I’ll let you go. But I was just thinking something I find really amazing, what I’m really enjoying about this conversation and learning about the work you’re doing is that so much of the looking back at these ancient societies, ancient Roman societies and the techniques that they used for building structures and finding and seeing how we can pull important lessons for that for our own modern time looking into the future as far as how we can replicate some of that to address our own challenges for having resilient structures going forward. And I find that really beautiful or almost poetic a little bit. But I mean, do you sense that it must be really fascinating to be looking at the past, but also seeing how to apply it towards the future with this challenge?
Marie Jackson
Very much so. We are very fortunate that Romans left us some very valuable texts which of course have been copied and re-copied over the centuries. So, a big part of my early research was translating De Architectura, literally almost algebraically, to really understand what Vitruvius was conveying and then using geologic principles and engineering principles in translating that to what we know that Romans built during that exact period that he was writing de Architectura. These were people who didn’t have the same kinds of energy resources that we had. So, they made things in ways that were more sustainable, both in terms of the environment and in terms of the ability of the material to maintain itself. They couldn’t rebuild the Theatre of Marcellus every 30 years because the concrete failed. We have a throw away construction material mentality that I think is changing. And you’re absolutely right. The ideas of resilience that Roman texts have offered us, integrated with the buildings they made are very profound in how we can guide our own principles.
Ross Chambless
Yeah, well, I guess just last question. Where can folks go to learn more about your work or your research? Do you have a website or where would you recommend people go to learn more about this topic?
Marie Jackson
Well, we have a book called “Building for Eternity” on the drilling project that took place from 2002 to 2009 in eleven harbors around the Mediterranean. That is written for the general public. It’s scientific and archaeological, so that’s a good place. I think most of my papers are posted on my webpage here at the U. So that’s another good place.
Ross Chambless
Wonderful. Well, Marie Jackson, thank you so much for talking with us.
Marie Jackson
You’re very welcome. It was fun.
Margaret Call
Yeah. Thank you.
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