 Good morning, everyone. Good morning and good afternoon and good early evening, for some of you. Welcome to the conference. After concrete materials and energy in the Anthropocene at Columbia University's Graduate School of Architecture, Planning, and Preservation. My name is Lucia Ale. I'm Forest Megers. And this is Forest Megers. I'm an associate professor of architectural history and theory at Columbia. And this is my co-host and co-conspirator, Forest Megers, who's assistant professor in the School of Architecture and the Adlinger Center at Princeton University, where he runs the appropriately named Chaos Lab. This is the second conference Forest and I have convened. The first took place in the fall at Princeton University. Today, we're being virtually hosted by GSAP at Columbia, for which we want to thank hardly the dean, Amal Andraous, as well as Laila Cadillier, the director of events, who is with us today and who will keep us on track. Please note two things, that our original date for the conference was a month ago. We were rescheduled out of consideration for the demands of the Graduate Student Workers Union at Columbia University. The strike has now been suspended, although the negotiations continue. And we encourage our audience to educate themselves on those negotiations. I'd also like to say that Forest and I are joining you from Brooklyn and Princeton in the United States land, which has been unseeded by native communities. The Lenny Lenape people, and even more pertinent to our topic today, we want to recognize the massive amounts of energy of coal, which are being extracted from the ground, in and around Navajo lands in the West, in order to make the energy that makes it possible for us to run this conference on Zoom. So by way of introduction to the conference, I want to introduce the conference by saying that, by repeating a statement of disciplinary humility that Forest and I have, which is that neither one of us is a concrete specialist. I'm not a historian of concrete. He is not a material scientist or engineer. And yet, concrete is unavoidable for thinking across our disciplines. And concrete has been our kind of lengua franca as we've worked together as a technologist and an engineer and a historian. Arguably, concrete makes possible thinking how we know the built environment across disciplines today. So I just want to take a small detour just to get us in the mood. There's a beautiful story of etymological origins of the word materials that's often repeated by scholars of material, whether in the history of architecture, the history of art, also the history of science and technology. And it's said the word for matter and materials share a common Latin root, which is mater, a root that both means mother, therefore connoting a kind of human creative power and that refers to wood, more specifically to matrix, the core of a tree, which is fibrous and therefore ideal for making. So the kinship between these words is usually told to urge us to think materially or concretely about the slide from specific knowledge to generic knowledge and general knowledge in any knowledge production. So it's not only that specific materials somehow, that materials are a specific instance of something that we call matter, which is more abstract and more general, but that the abstract notion of matter, the thing that subtends all of the natural environment around us, always in some sense presupposes a tree and a particular tree and a logger's attitude to that tree. So it seems to me, I'm telling you this story because it seems to me that today concrete performs that conceptual function in much of academic discourse. It helps people across all sorts of fields with technical fields and academic fields think between the general and the specific in the same way as you, as would use to perform that function in that story of etymological origin. Concrete today is a paradigm of something that seems given in the environment and also provides a matrix for thinking about all human making in a kind of technologically intense age. Concrete looks like natural stone, but it's human made and it continues to affect the environment through CO2 emissions long after it has been set and performs as a building. It's technologically sophisticated and yet easy to use and apparently locally made. Unlike wood in Roman times, but very much like any given tree today, concrete forces us to think about the role of labor, about temporality and energy in the built environment today. So concrete is inherently interdisciplinary. And yet the conversation about concrete itself is seldom interdisciplinary. And this is why this is the gap that force and I have been exploring for now, I guess six years. And in these two conferences, we are bringing more people into the discussion. Our first conference brought people who could tell us a little bit and we'll tell you in a little while about our own collaboration, our own research paper. But for now, just to make a distinction between the two conferences, we had a conference where we brought people who helped us think more specifically about how concrete something that is as made. And today we seek broader connections about concrete effects all making. So forest. Yeah, so the first conference and was extremely engaging. And I think the best part was the interdisciplinarity of the participants. And we hope to achieve that again today. But first I thought it'd be useful to lay out a little bit of the takeaways from that first conference to set up our paper that does focus as Lucia said, a little bit more on how concrete itself and the cement inside it is made. And today we'll pivot a little bit more toward what concrete is used to make. So in the first conference, we brought together experts that looked at the detailed aspects of concrete all the way down to the atoms inside it and how exactly it functions in the environment. The focus being on the fact that generally between both historians and engineers, we treat concrete largely as a relatively static thing in our environment once it's cured and set in place. But even once it's cured and set in place, there are dynamics going on inside that concrete that haven't really been given the importance that Lucia and I thought was relevant. And that's what the paper we'll start off again with today our sort of polemic around the lifespan of concrete being related to this phenomenon called carbonation and how that places a fundamental limit on concrete that's not really appreciated either by historians of architecture and what that means for our built environment and its longevity, as well as to engineers who sort of set the standards and decide how long concrete should last and analyze the properties of its fundamental chemical structure. So that sounds very detailed but in fact, the conference was not about the details it was about the conversations between experts and one domain of the concrete itself like researchers from ECH who's actually corrected Lucia and I and some of our science as well as historians that helped us to expose narratives around longevity and obsolescence. That conference is online. Feel free to revisit it if you like. Today we're going to try and shift a little bit more toward one of the polemical statements we'll come to at the end of our paper around concrete's larger role now not just in carbonation of itself but in the carbonation arguably of our whole atmosphere in our current moment of the Anthropocene. So the paper you, Forrest and I have been working on is about the carbonation of concrete and some of you may have heard us present this in the past. It is the provocation we gave to our speakers and so we thought we would quickly run over it kind of abridging the beginning but getting to the kind of provocation at the end which is about the Anthropocene. So, okay. So our paper which is sort of imminently going to be published is titled concrete is 100 years old and it concerns one equation, the carbonation which defines the conditions under which any concrete reinforced structure so any concrete structure which has also reinforcing steel in it fails through carbonation. The equation is here. It says that the time to failure is related to the depth of the steel away from the edge of the concrete. Now, if you plug into this equation the standard specifications for any standard reinforced concrete structure today you will get the results that concrete fails in about a hundred years. Now, before you protest that this is not exactly a hundred that there are many other mechanisms at play this is correct but even without many precisions and many ongoing refinements of this equation you get the surprisingly determined outcome that it takes about a hundred years for any reinforced concrete structure to fail through carbonation barring any other kind of failure such as demolition or other sort of environmental events. If you add to this the fact, the historical fact that concrete was invented about a hundred years ago. Again, it wasn't exactly a hundred but about a hundred years ago is when concrete became the dominant modernizing force for the built environment across the world ensuring that not only houses but also buildings and roads and bridges are built out of concrete. You get a surprising coincidence which is a kind of amazing image that a moving wall of obsolescence of physical failure has begin to rake through the built environment ensuring that much of what is built today is sure to fail in about a hundred years not only roads and bridges but infrastructure for energy and for many of the homes that people self-build around the world today. So we decided to research this equation and to render as an exercise a correct description of this equation both for historians and for engineers something that would be correct in both of our fields. So force is about to explain to you how this works. I'll just go to the wall. So one of the most important things we should recognize about concrete is that when we say concrete today we are almost always referring to reinforced concrete and obviously that was not always the case. The concrete that is a hundred years old is reinforced concrete and when we put reinforced concrete together we end up with steel buried under concrete and of course the failure mechanism is the resting of that steel. Now in early days people didn't know why the steel was resting and it was thought that it was just oxidizing because oxygen got into the concrete but in fact there's a much more interesting and long and slow process at play which is carbonation and the way that it enables the failure of concrete is through the diffusion of carbon dioxide through the pores of the concrete above this reinforcing steel. Remember the steel is there allowing all of the concrete structures we see that span long distances to be able to span and hold their weight and tension and so when the carbon dioxide is diffusing into the concrete and carbonating it the carbonation changes the pH of the concrete. The high pH of concrete is actually what prevents rust from occurring on the reinforcement. So having high pH does not allow oxidation to occur but carbonation reduces that pH and that is actually what allows the initiation of rusting and that what we call delamination of the reinforcement from the concrete thereby eliminating its structural tensile strength. And the equation then obviously has several components and what we did is we did set up interactive website. If you want to stop screen sharing momentarily I will show everybody their hard work. We worked with a web designer to put together an interactive system that you can change the thickness of concrete. I can put it at sort of a typical depth here and then you will see the sort of simulation of the slow moving carbon dioxide here at the bottom. You can see the longevity gets added into a histogram here where you can look at the previous results. We sort of start with some standard depths for different scenarios. And then that coefficient that you saw in the equation is represented by what properties the concrete has. In this case, talking about your low porosity will make the concrete have a much shorter lifespan or a low porosity will make it have a much higher lifespan because the CO2 can't go through the pores as fast versus the high porosity. And then Hamada will come to momentarily sort of the first number coefficient which is relevant because the history of this equation is one that wasn't really appreciated because it was such a long time in development and it has a very interesting relationship to material science. So if you give me back, I'll go back. So one of the things we looked into is why the science behind this equation has been known for quite a while. Experiments were done on the carbonation of concrete early in the teens in Japan. The first time this equation was proposed by a Japanese scientist Minoru Hamada in 1928. It wasn't published internationally until 1968 in English and then was re-tested by a Swedish researcher in the 1980s and eventually has become a kind of a subfield of material science. But the question we asked ourselves was why did this equation not make a bigger impact? One of the answers is that concrete was entirely bound up with the centennial culture of the early part of the 20th century when concrete's novelty, its secularism, its abstraction, its capacity to be molded into any form was announced with incredible amounts of historical hubris and indeed this was, and being able to announce that concrete will last a century that it was the material for a new century was integral to its seemingly lasting forever. So I'm showing you a patent that was first awarded the prize for the patent of the best invention of the 1900 World's Fair, which was for the NAB concrete system. Paradoxically, calling concrete secular and saying that it will last 100 was almost equivalent to saying that it was a permanent material and that it was secular and calling it 100 made it seem metrical. It was kind of bounded up with the tendency to count up history in multiples of 100 rather than let's say kingdoms or fiefdoms. Now this has affected, we did a study of the lifetime, the lifespan that were given in various countries over the world over the years. So in 1911, for example, the UK said, researchers in the UK had said that reinforced concrete could last between 75 and 900 years. 1975 in India, in India, it was 30 years. Still in 1986, you can find a textbook that says that if you build something out of reinforced concrete it will last indefinitely. A second factor we have found for why the carbonation equation did not make a bigger impact was because it was couched and siloed into various research enterprises. So Minur Hamada, whose research is shown here was a very international figure. He had done part of his research based on the failure of reinforced concrete buildings in the San Francisco earthquake of early part of the 20th century. And yet he was also involved in a number of other research enterprises. He was testing concrete for failure against fire, war, et cetera. And so it didn't seem particularly necessary to globally question the validity of concrete. Similarly, Kyocituti, the Swedish researcher who took the equation and verified it by using, feeding it with data from the Swedish built environment was very much invested in the validity of the modernist paradigm, buildings of reinforced concrete that were being built since the after World War II all over Sweden. And indeed once the equation itself, the carbonation equation that we've been talking about which is the one that explains this universal failure mechanism of reinforced concrete. Once it was brought into the material science and engineering discipline, which was sort of becoming big in the 1960s and 70s, it also didn't make a big splash because material science and engineering was a kind of discipline invented precisely to host this kind of equation, but not in order to critically reflect upon how buildings had been built or how materials have been made, but rather to invent new materials. And so we arrived at this paradox by the end of the 20th century that the carbonation equation is known and it becomes obvious before it seemed to have become important. So back to first. And the real challenge was thinking about how in the timeframe of carbonation, what other things are important. And at that moment when material science was investigating the equation, at the same time we were becoming much more aware of a different form of carbon, which is carbon emissions. And it was not yet tied up to concrete in the same way. And so when we think about the timescale now of 100 years, all of a sudden today, that's become much more relevant on the news every morning. We hear something about various agreements on the order of 50 to 100 years to mitigate carbon emissions. And so today what we want to argue is that we need to start thinking again about 100 years. In the first conference we talked more about how relevant that is to our infrastructure and to the fundamental aspects of concrete and the history of this equation. And today I think we're gonna try and focus more on how looking at atmospheric carbon relates to the fundamental carbonation process of concrete itself. If we look at the timeframe of what's happening, it's very conveniently aligned with this challenge over the last 100 years of the increased carbon in the atmosphere, slowly warming the planets. And at the same time, somewhat coincidentally or somewhat problematically, the emissions of CO2 from concrete, concrete now being the largest industrial sector of emissions of five to 8% of global emissions, just being from making the cement to make concrete. Those CO2 emissions now feedback on that process itself. So we've increased the concentration of CO2 in the atmosphere. We've changed the climate, temperatures and weather. Those things feedback directly on that process of carbonation in the concrete itself. And thinking about the sensitivity of that process and closing that loop in a more broad context as well, seeing how those things are related and how we need to step back and understand how the dynamics of our seemingly static materials play out globally across infrastructure, society and systems is something that I think we wanna dive into today to investigate really how are our broader challenges around materials and their impacts characterized in longer timeframes that we can have a healthy conversation historically and technically using sort of concrete as this hinge to investigate and set up this interdisciplinary discussion. Okay, so these are the people we wanna thank for who's been working on the research with us. So concrete feeds its own failure and we've invited a very exciting group of people to help us think about that. Two notes about the panels. We have a panel filled with scholars and then followed by a panel filled with a technologist and then a keynote by a scholar of technology. We don't really mean it to be so dichotomous and disciplinarily bound. We are actually trying to create a narrative arc as you'll see, we'll end with Dan Stangart who is at the heart of sort of most recent thinking on energy storage. And we begin with Nimod Ben Zev who's telling us a history of 100 years of construction and labor in Jerusalem. So the way it's gonna work is that I'm going to introduce the first panel. I will give everybody a very short bio but we encourage you to go to our website and click on people's bios. They have fascinating achievements and they're fascinating people that we are very happy to have brought together. After each presentation, which will be quite short, we've asked people to make short presentations that don't shy away from technical specificity but also give a broader understanding of what the main point is. After each presentation we'll have one or two minutes for immediate questions, urgent clarifications about what they've just talked about. And then after each panel, we have a large chunk of time for broad Q&A and we encourage everybody to put their questions in the Q&A. We hope to invite anybody with fantastic questions to join us as panelists. Yes, if you'd like to. And be as engaging as possible. We want to, the last conference was extremely dynamic and we want to bring that dynamicism back. If you ask the right question, we may just ask you to ask if you would like to be elevated to the panelists so that we can see your face and have you live. Okay, so I'll start with our, we're a little bit behind but hopefully Lila does not present us too much for it. Our first panel presents ongoing research on environmental, economic and technoscientific agency that circulates in the built environment and hopefully helps question what is an architectural scale? What is building life? What is the formal concept of progressivism and how that's connected to concrete? So our speakers will be in order. The first one will be Nimrod Benzif who's a post-doctoral fellow at the Polonsky Academy of the Van Lier Institute in Jerusalem. Our second speaker will be Gabriel Lee who is a Cassius Marcellus Clay Fellow in the Department of History at Yale University. Our third speaker is my colleague Atiyah Korkiwala who is an assistant professor in architectural history and theory at Columbia GISA. And our fourth speaker will be Sophia Roost an anthropologist who is currently a Coleman Fellow at the New York Public Library. And with that, I will hand it over to Nimrod. So thank you very much, Muji and Forrest for inviting me, thank you to Lila and Lucy for making this conference happen despite all the global and local challenges encountered along the way. I think we were all sort of on edge when the conference was last scheduled to happen. And I think I'm sure most of us, if not all of us are very happy that we could contribute in some way at least to the Columbia student graduate workers union strike. So I'll just get started. And I'll say that beyond the sort of scholarly, architectural and environmental questions which make this event and the preceding one which Muji and Forrest mentioned that happened in Princeton in the fall, very welcome and very timely. I cannot personal note add and I imagine that there are other speakers here whom this might apply that I'm actually quite excited to be taking part in an event after which for once I will most likely not be remembered as the cement person and during which there's a significantly lesser risk of my being the sole perpetrator or a victim of puns about things being or being made more concrete. So now that I've got that out of the way, what I'd like to do today inspired in part by Lucia and Forrest instigating paper on the lifespan of reinforced concrete is to partake a bit in what that paper refers to as centennial fever. And with it in the notion that concrete is 100 years old. In the following presentation, I will be wed in this approximation of reinforced concrete's age and structural architectural lifespan to another approximate centennial with the eminent Palestinian American historian also of Columbia University, Rashid Kharedi has recently described as the 100 years war on Palestine. That is to say what I'll be doing is I'll be narrating roughly the past 100 years of Palestine, Israel's history through the history of cement and concrete in the land during this period. Now this narration is made possible because of the dynamics of cement and concrete's material and cultural spread during this century or so. And specifically their capacity to colonize the built environment and perceptions of it. This capacity has meant as Palestinian architects Yara Sharif and Fatina Biksuvedet have shown that even though concrete was reintroduced to Palestine as a colonial material in the late 19th century driven and clean primarily by separate populations in its initial decades, it quickly spilled over becoming an integral part of anti-colonial nationalism as well as more quotidian modes of struggle, survival and resistance. So what I'm arguing essentially is that cement and concrete have been integral in varying ways to how the history of 20th and 21st century Israel Palestine has unfolded. They were foundational ideologically and in practice to the Palestinian and Zionist nation-building projects in the first half of the 20th century and served as indexical of notions both of modernity, independence and power on the level of political economy and of racialized notions of civilization at the level of the individual body and the community. Now with the 1948 war, the establishment of the state of Israel and the Palestinian Nakba or catastrophe within the newly founded Israeli state even as these materials maintain the same associations with the modernizing developmental state indeed with Zionist ideology going so far as being called a Jewish or Hebrew material. They also found their way into the hands and homes of the state's most marginalized and oppressed populations becoming part of their means of recovery from the devastation of 1948. Now there's a further shift that occurs in this triangular relationship between Zionism, Palestinians and concrete and cement after 1967 which I'll be discussing as well. Essentially what happens as the West Bank and Gaza Strip are incorporated into Israel or occupied rather. Palestinians from the territories become the predominant force in construction work. More specifically they become the predominant population that engages in wet work that is concrete and cement work. What this essentially means is that there's a reversal that happens in terms of who is thought of or who is associated with these materials and work with them. Now in the Jewish popular imagination the association of Palestinians with construction work becomes the bedrock of their cultural representation beginning in the late 70s and early 80s. When they were not portrayed as terrorists they're frequently portrayed as construction workers. And for a meeting point of sorts between the two we also see the various stories of what we might call chemical acts of resistance and sabotage which I'll talk about a bit. Finally I'll end by juxtaposing the monumental reinforced concrete of Israel's separation wall in the West Bank with the ash and rubble-based green cake bricks pioneered in Gaza by two young Palestinian civil engineers Majd Maskarawi and Rwana Pulatif as an alternative construction material for the reconstruction of the bombarded and cement starved Gaza Strip. Cement and concrete I argue continue to both foreclose and to constitute the horizon of possibility in Palestine-Israel. Port and cement likely appeared in Palestine first in the late or in the 1890s through Jaffa's burgeoning port. A cement product industry quickly developed producing tiles and other rudimentary building products and concrete began to be used as a structural material in Palestine, in autumn in Palestine roughly in the end of the first decade of 1900s and into the second decade of the 1910s. The introduction of these novel building materials was roughly in parallel with the first few waves of Zionist settlement in Palestine which began in 1881, 1882. And this coterminous arrival inspired some Zionists to bind cement and concrete to the Zionist project. The notion that port and cement understood as a quintessentially modern building material would serve as a foundational role in the similarly modern Jewish national rejuvenation in Palestine can be traced to a variety of leading Zionist thinkers. Alongside such fanciful notions of modernity, writ large, there were also those who quickly saw a considerably more pragmatic utility to these materials. The ability to bypass local materials such as the coastal areas, Kourkar sandstone, and indigenous expertise in utilizing them. Now, the photo you see here are the first lots of Huzad-e-Bait, the neighborhood that became Tel Aviv, which was founded in 1909, actually captures one of the first locales where we see this claiming of cement and concrete as a material that could substitute local stone and local expertise. The idea was, and it was pioneered by Kiva Yevais, one of the architects, well, actually a hobbyist in architecture, but an architect in the colloquial meaning of the term, one of the architects of Huzad-Bait assumed that if they were to introduce large-scale production of concrete bricks, which were not at that point yet produced in Palestine, and use only those in the construction of the neighborhood, they would be able to circumvent the local Palestinian stone masons and builders entirely and rely on Jewish labor. Now, while cement and concrete blocks did gain a foothold in Tel Aviv's construction during the subsequent decade, even if they did not revolutionize the industry quite as much as their proponents envisioned, Palestinian construction workers were consistently employed in the building of Tel Aviv during the 1910s and beyond. However, the underlying logic of the initiative, that logic of replacement, will actually continue to resonate strongly even as in practice, the introduction of the specific bricks tended to fail. Between 1918 and 1948, under British rule, the idea of Jewish workers expertise, indeed near monopoly over concrete construction, especially in reinforced concrete, was reiterated time and again in the Hebrew press and in the internal discussions of the Jewish General Federation of Trade Unions. As socialist-leaning labor Zionism grew in prominence in the settler community and its institutions cement concrete and the claim for exclusive Jewish expertise in them became wedded to narratives of Hebrew labor of the Daivite and building the land, Binana Aritz. Concrete structures built by Palestinian Arabs in contrast were constantly portrayed as always already falling apart and Jewish workers frequently called upon to rebuild them. So here you see sort of the archetypal Jewish construction workers with their iron bars and the concrete structures behind them. And on the right you see labor, decidedly modern form of labor in a quarry, but nonetheless the sort of work that Palestinians were imagined to be more naturally inclined to. Now the British actually very much went along with this sort of classification, placing it in a one could say typical British racial logic of dividing labor in the land between the true groups according to their racial properties or tendencies, Jewish greater intelligence as a sort of John Robert Chancellor who was high commissioner of Palestine between 1928 to 1931 said, made them inclined to work in machinery, reinforced concrete and electrical work, whereas Palestinian brute force and sort of physical strength oriented them to other forms of labor and in this racial sort of typology. And obviously there's actually very little to be said for the veracity of this narrative in terms of the labor itself as has been demonstrated and discussed in much of the literature about the history of concrete concrete is not only regarded but was prized for its ability to be a de-skilling material. So in that sense, the first half of the Zionist narrative is accurate. It did allow to dispossess or exclude stone masonry and traditional building crafts. And I imagine Gabriel who is speaking next is able to say quite a bit about that and the US context of the resistance of masons to the introduction of these new materials. However, the second part of the narrative that of the expertise of the laborers themselves in working with concrete seems to be very much a sleight of hand. In the sense that construction work certainly during the 1920s and 1930s in Palestine was the reserve of newly arrived Jewish settlers, immigrants, most of them without any experience and what we likely really have or the story that we're actually seeing unfold is one of engineering expertise as with concrete elsewhere. And importantly, also one of economic power and that layer of economic power has a lot to do with this factory that you see in the picture. The Nestor cement factory, which was founded in 1925 and which remained a monopoly in Palestine over cement production until the end of the British mandate in 1948 and then periodically with some interruptions basically is still a monopoly to this day. In contrast to that, there was never a successful Palestinian, sorry, Palestinian attempt at establishing a competing cement factory. And this is not for lack of trying. Since the late 1920s, there have been repeated attempts either thwarted by British authorities or simply unsuccessful due to the extinguishes or the extinguishes of Palestinian history which has been tumultuous to say the least for obvious reasons. But nonetheless concrete seemed to capture, cement and concrete seemed to capture the national imagination of both Zionists and Palestinians as a liberatory constitutive material which could essentially bring the nation forward and which was actually crucial to doing so. Now, as we move on into 1948, the civil war that erupts Palestinian Nakba or catastrophe and Israeli independence, we enter a new phase of the uses of concrete. For the Israeli state that is absorbing immense numbers of immigrants at this period, massive construction projects are the order of the day. And the demand for cement and concrete rises exponentially in the late 40s and early 50s as does demand for labor. And the laborers, ironically perhaps or not, end up arriving primarily from the most marginalized populations of Palestine Israel or of Israel at the time. Palestinian citizens who have remained in the state and Mizrahi Jews, Middle Eastern and African Jews who have immigrated to it. Concrete continues to have this sheen of a modernizing material on the backdrop of this ethnic division of labor. In fact, here we have this booklet published by the Ministry of Labor's Housing Division in Israel in 1960, which, as the title says, encapsulates their refugee rehabilitation happening 11 years after. Refugeehood, mind you, as a sort of modernizing push by the state to grant appropriate conditions, appropriate living standards to its Palestinian inhabitants, moving them, as the title says, from an earth hut to a real home. And in parallel to this sort of more lofty, and it's not accidental that this was published in English and in French, but I have not found any evidence of this publication either in Hebrew or in Arabic for that matter. There's also a reality of mass exploitation that emerges in these very same decades of that population, which is being given these homes and rehabilitated. One aspect of this is migrant labor, internal migrant labor of Palestinian workers. Here we see the conditions in one temporary workers camp that they have set up outside Tel Aviv. These are all Palestinian citizens of Israel who are working in the tens of thousands in Tel Aviv and the area at the time, sleeping in fields, et cetera, and mainly being employed with concrete and cement, so in wet work. And on the opposite side of that, we see immense restrictions or very stringent restrictions on construction for Palestinian citizens within Israel. And here concrete does or allows these Palestinians to invoke a sort of reversal. While they were being employed working in the Jewish cities, building structures for new Jewish inhabitants or immigrants, they were also learning the techniques of construction in concrete. They were obtaining some of the tools increasingly and they were able, in spite of restrictions on construction, to actually build their own homes. Here we have a photo of Ibrahim Shamshoom who's in the center being sort of hugged by a friend who told me his story of rebuilding his home despite the army coming to destroy it three times and the cement mixer is clearly a hero or a central figure in this sort of group photo. The final shift that I'd like to sort of capture and I'm sorry that I'm rushing through this, I realize that I'm also out of time is what happens after the 1967 war when the West Bank and Gaza Strip are occupied. And as I mentioned earlier, what happens essentially is that several years after 1967 and the occupation, Palestinians become increasingly the predominant workforce in the construction industry. And along that predominance, they are, along with that predominance, they're on the one hand made invisible as they're moving through Israeli space, oftentimes illegally, but also hyper-visible as a threat. You start hearing rumors in Israeli sort of public discourse about how they mix the cement in the wrong way as a matter of sabotage. And here we have a quote from Suweta Miri's I'm gonna lose but your life about a Palestinian worker who actually admits to that sort of work with the duality that's involved with that. And we also have their increased representation as workers. The most iconic representation of concrete at the moment in Israel-Palestine is undoubtedly the separation barrier in the West Bank which we see here. These massive slabs of concrete which separate in this case within Jerusalem itself, Palestinian neighborhoods from Jewish neighborhoods and run along the West line, with the one within the West Bank along the Green Line and not quite along it. So this is a very sort of monumental icon of state oppression. I'll skip the song although it's great. There's another aspect to cement and concrete at the present moment which has to do with Gaza. Cement is considered a dual use material according to the Israelis and is not allowed into the Gaza Strip. It can be made use in military applications as well is the claim. So this young materials engineer, civil engineer Mach Mach Harawi developed green cake which is the brick you see in the photo, a cement and concrete substitute which relies on a much lower ratio of cement on the rubble of Palestinian destroyed buildings in Gaza of which there is an abundance and on wood ashes. Also on the coal, essentially the ashes that are burnt in Gaza to produce energy and other matter. The question that I'd like to end on is as optimistic as a person like Mach Harawi's being, what do we do with the material that relies on rubble, on destruction, again on coal and again on cement to imagine Gaza after concrete or Palestine and Israel after concrete. And that's the question that I'd like to open to everyone. I'm sorry I rushed through this and thank you all very much. Thanks so much Nimran, that was fantastic. I think it's the perfect place to end and it really sets up some amazing arguments to be debated and reflects very wonderfully some of the things we talked about in the last conference too were just like Claire White talking about alternative cement mixtures and having someone innovate within Gaza. It's really amazing. And then also the earthen house to the concrete house and later in this afternoon, later we'll have Lola Benelon talking about going from concrete back to the earthen house. So thank you so much. I think you set us up very nicely. If anybody has any on the panel while Gabriel sets up and maybe starts sharing, if anybody has pressing questions of Nimrod, a specific clarification we have, we invite you to do so. If not, we will allow Gabriel Lee to lead us into the next paper. All right, thank you, Eric. I am unmuted, correct? Yes, okay, good. Yes, thank you, Lucia and Forrest for inviting me to speak today. And I also appreciated Nimrod's opening in that I, you know, when I chose concrete as my dissertation topic, I told my advisor at the time that I'd open myself up to a decade's worth of bad puns. So I definitely commiserate there. I am calling my talk today, The Culture of Permanence and I'm responding to one part of Lucia and Forrest provocation, this idea that concrete is this permanent material as was expressed in mid-century in their paper. And that this kind of idea of permanence is linked to these arbitrary timescales and is subverted by the reality of impermanence through carbonation. But what I wanna do is suggest a much broader political implication for the discourse of permanence historically. Especially as it ties to the concrete built environment. So my work is on the U.S. I'm an Americanist by training. And in the U.S. context, in the early 20th century, concrete and permanence became synonymous. So the Portland cement association slogan for around 50 years was concrete for permanence. Permanence even entered the legal language of contracts, particularly for road building. So you'd see a contract very commonly that mandated a road to be built that Chevy permanent character and that just meant concrete. They were utterly synonymous. But the discourse of permanence was much broader than just concrete and pertaining to the built environment into the kind of progressive ideal of creating a template for modernity at the time. And so that's what I'm going to discuss today in this broader context of the idea of permanence. So there were two routes to the discourse of permanence and building materials in the 19th century and both of them contrasted to a materiality that was either impermanent or in other ways problematic. So this is an example of permanence and structural building material, which is the first route. And this is the permanent bridge in Philadelphia built in 1905. It replaced, it was a masonry structure that replaced a series of wooden bridges at this site that had burned down and indicates the idea of permanent construction at the time. Permanence contrasted in particular to wood. Wood was impermanent, not simply because it rotted but most importantly because it burned. And urban conflagration, the susceptibility to burning was the main problem of urban management in the 19th century. This is also in a society that was built over the 19th century on territorial expansion and building quickly, cheaply, often with wood in a country that had abundant cheap timber supplies. So permanence in the 19th century meant masonry construction for the first half of the century and then added an iron and then in the late 19th century steel and concrete. And by the 1910s, concrete had really become the material, the permanent material par excellence. The second route of the 19th century idea of permanence and materiality comes from road building. So for the, in a context of roads, permanence contrasted with dirt roads and through the late 19th century into the early 20th century into the 1910s. Anyways, permanent highways meant macadam highways. Macadam is a elaborate form of gravel construction and permanence here meant in part that macadam highways would last say 20 or 30 years was the idea with maintenance afterwards that could last in perpetuity but permanence also implicated something else which was that macadam highways built for wagon travel would allow farmers to go to market at any regardless of the season so that they would have a road all year round, permanent macadam highways would not be subject to spring rains and mud holes and washouts. You could take your product to market at any time you wanted. And so you had a road that was there regardless of the seasonal context. That was the idea of permanence that remained in kind of highway politics until the 1910s when automobility and then especially trucking particularly during World War I destroyed macadam highways all over the country. So afterwards concrete became as the office of public roads director called it the real permanent highway and for two decades through the 1920s and 1930s permanent hard surface highways were synonymous with concrete. And this is the moment in which the Portland cement association adopted their slogan concrete for permanence in 1916 and it lasted until the 1960s. This is just a couple of images showing the use of this slogan in advertising and also cement companies used it in their letterheads at the bottom of the letterheads. Importantly permanence in the 19th century did not mean that these materials will last forever. It meant that they were simply longer lasting and more apt than other materials. By the progressive era, the language of permanence became tied to larger social political discourses as uses of concrete enacted a number of built environment reforms is included urban sanitation and fireproofing, industrial architecture, particularly the daylight factory, automobile highways and hydroelectric and irrigation dams. And permanence became a way of articulating progressive politics in two different ways. First, permanence was tied to civilization and building a new modernity. There was this prevalent discourse of moving from a pioneering stage of development moving from wood to masonry and steel and contrasting the American built environment with that of Europe that were moving toward a kind of European model. But with concrete, there were also these comparisons to Rome to building civilization in stone. And so just like the Romans built stone roads and stone waterworks, we were building stone roads and stone waterworks if with this new novel industrial material. This is a commemoration of the Hetch-Hetchy Water System which the Polgis Water Temple is itself stone but it's commemorating this larger concrete hydraulic network. So in the case of concrete, Rome had other significance as well. People boosting concrete compared it to the standing Roman concrete and you start to get this idea through that that concrete was actually permanent that it could last forever. Boosters began to make unreasonable claims as early as the 1870s. In 1877, a contributor to the American architect and building news wrote that those who adopt concrete will find a material which will in a few weeks give a strength greater than has been attained even after enduring for 2000 years by the imperishable mortars of ancient Rome. And these kinds of claims became very common the idea that looking at Roman concrete, concrete will last forever. This is an argument that Thomas Edison made for example when he introduced his cast house for the working class, he pointed to standing Roman concrete and said that this concrete will offer quote, a home that will last centuries. And this just became a common conflation over the 1910s and 20s. That conflation exacerbated in the 1930s with the prevalence of large scale dam building. There were dams were commonly described as especially in the American West as becoming one with becoming part of the everlasting granite of the canyon in which they were built. Dams were described as the pyramids of the modern age. And this was captured well by a novelist named Robert Norman Case, speaking, writing of the Grand Coulee in 1938. He wrote that 5,000 years from now, archeologists and anthropologists intent upon seeking new clues to a vanished race will come upon a vast waterfall. The dam being anchored to granite that has survived millenniums will still stand. So concrete structures would build a new modernity and provide the lasting legacy of American civilization. The permanence also progressed progressive ideals in a second way in the ideal of building a managerial administrative state. The language of permanence was common in the kind of language of bureaucratic expansion. So you talked about adding new permanent agencies or new permanent bureaus to the federal government. And the same people who were advocating for new permanent highway systems were also advocating for new permanent agencies to build them, oversee them, manage them, et cetera. If you look at some of the new bureaucracies founded in the early 20th century, especially conservation bureaucracies, which are most familiar to me, you find the language of permanence really prevalent. So I'm thinking of the reclamation service in the U.S. Forest Service in particular. The Frederick Newell, the first director of the reclamation service wrote that irrigation would establish, quote, permanently improved agriculture regions in the arid west. And by subverting urban radicalism, these irrigation regions would assure the quote, permanence and stability of the commonwealth. The Forest Service, which was founded in response to a perceived temper crisis, they adopted sustained yield management that they said would produce, quote, permanent forests that could produce timber and perpetuity. And for both of these agencies, not incidentally concrete was part of their overall vision. And the reclamation service, they were building dams of unprecedented scale and concrete and also innovating uses of concrete to line irrigation canals. For the U.S. Forest Service, material substitutions became part of the project of sustained yield management, reducing demands on timber supplies through material substitutions. And concrete was singled out as a material that had an endless supply of raw materials, lime, clay and sand and gravel. So permanence was, in brief, a way of expressing the progressive ideals of overcoming nature, of building civilization and a new modernity, of building a bureaucratic managerial state and of making all of them lasting interventions that would be the progressive reform era's ultimate legacy. And this context is the precursor to post-World War II global developmental politics in which concrete became the material of modernity. This is true in the politics of international modernization which centered on large scale infrastructure, especially modern highways and developmental dams, which we're seeing as civilizing and often linking democracy to what were state-centered projects. And these were intended to be lasting social and economic transformations. And it's also, these progressive values are also present in the social politics of architectural concrete, predominantly the modernist and brutalist post-war housing and public buildings. This is a very common, you know, a very well-known example, Boston City Hall. And the language of permanence remained salient and the post-war decades. It's Michael McKinnell, one of the premier architects in designing this building, said the brutalist form, quote, symbolized longevity, it symbolized permanence. In this same moment, environmentalism really, really, you know, became a strong movement in pushing back against this model of modernity. And within environmentalism, however, permanence remained the frame. So there was the, you know, environmentalists argued that the geologic timescale of ecological relationships and hydraulic structures and so on created a baseline of value. And that modern engineering and modern nation states could disrupt those structures, could disrupt those relationships within a few years. And this became essential to the critique of the built environment among environmentalists in the 1960s and 70s. Fast forward to the present and environmental concerns have compounded but now they are largely pointing to concrete's fundamental and permanence. So there is the issue of climate change, not only cements CO2 contributions to the atmosphere, but the fact that concrete infrastructure supports energy intensive economies around the world. There's the issue of crumbling infrastructure and carbonation as Lachie and Forrest have discussed. And then there was also the issue of peak sand, this idea that there is not enough natural sand left on earth to reproduce all of the concrete that we've already poured, even if we wanted to. And yet we seem to be unable to think outside of this framework of permanence. 20th century modernization paradigm remains for the global south, as they're building new infrastructures for so-called developing nation states. And when we talk about rebuilding and strengthening our infrastructure, we're discussing how to exchange materials, but often making them even more permanent, making them longer lasting. So concrete structures has produced, in a sense of second nature, supporting modern society that as Barry LePattner put it has become too big to fall. So I just wanna close this brief talk with a question that in a bid to think beyond concrete, I wanna ask if we can think also beyond not only discourses of progress, but also beyond the paradigm of permanence. Permanence points to the life of structures, but implicitly denies their death. So can we design structures with structural death in mind that can be more consciously adapted to social and environmental change? And it strikes me that we'll need to be more adaptive to build environments, to respond to both rapidly changing climates and sea level rise, especially in coastal cities. And also as this history suggests, because social and environmental values that today went up necessarily and probably will not map very well onto the social and environmental concerns a few generations hence. And so I wanna just leave us with that question, can we think beyond permanence and what might that look like? Thank you so much, Gabriel, that was fantastic. I think again, yeah. I was gonna say, I do have a while Atia who is next sets up. I have an immediate clarification. Yeah. That's okay. I mean, first of all, wonderful narrative arc that as you go from permanence imposed upon rural, hardly navigable paths to Boston City Hall, but you did mention in passing that one idea of permanence was associated political stability against subverted forces of urban radicalism. What did that mean specifically? Like just give us an example of what that urban radicalism would have meant. Like I guess you were talking about the 1930s maybe. Yeah. Well, 1910s, yeah. So there were fears among a lot of leading liberals at the time that capitalism was creating the conditions for its own subversion through radicalism and socialism. And then these projects were answers to that, these kind of state centered projects where it's aligned with this kind of safety valve of the American West idea. But as long as we have open land in the American West, then we'll have allow for urban workers to have their own farms and so on. So it was a way of creating kind of social stability. That was the argument at the time anyways. So you're not moving persons away from cities. You're just providing, or are you? Are you de-urban in the imagination? What is the company, these major projects? Like how specifically does that help? Does that move persons away from the city or does it provide with them work? Yeah. So that was the idea that you would provide workers with cheap farms and that they could find, they could pursue the home-making dream in the American West by opening these new arid landscapes to family farming. Yeah. Great. Thank you for that. Okay. So it seems like we're at the end if you're ready to go. So good morning and good afternoon to everyone here today. And thank you Luchia and Forrest for inviting me to this panel. I look forward to contributing to this conversation on concrete, its history, energetics. Today I want to talk about a period in India in the 1960s and 1970s when civil engineers recommended shell structures, RCC shell structures and economists recommended RCC silos as a scientific storage for grain, largely wheat but also rice. Both wheat and cement in the story are key commodities within the developmental schema. Cement for building the nation, wheat for building the body. And in the story, I blur the lines a little bit between cement and RCC not only by thinking of cement as a synecdoche for RCC but also by considering cement as the key component of RCC. Finally, because most cement was headed towards becoming RCC I treat cement as a mobile form of concrete that flows from factory to site to become concrete. Eventually my interest is in the structures and the forms that concrete ends up in. Leaning on Luchia's and Forrest's provocation that RCC is 100 years old because of how the carbonation equation works my paper aims to show how our use of concrete has changed concrete as an epistemic object. So even as concrete is 100 years old we've always had a different concrete to deal with. And this builds on one of the insights from the last, from part one of the conference which is that concrete seems less a material and more a process and a set of social relations. So entangled is it in our everyday lives that civil engineers who wielded it talked about themselves as agents of social transformation. So take for instance a talk from 1958 at the 30th annual session of the institution of engineers held in the city of Lucknow. The institution which was established in 1921 in the aftermath of World War I aimed to standardize the burgeoning field of engineering education in India. And as such it acted as an umbrella for organizing emerging types of education and practices across the country. At the 1958th session the then president Tunjisha Kassad civil engineer by training gave the presidential address and tied together planning economics, democracy and the successes and failures to achieve developmental goals with the profession of engineering. Quote, a new period of history not only in science but of all human culture and scientific engineering knowledge has been assured as a result of strenuous efforts of scientists, engineers and technicians. So this speech 10 years and five plans sorry, two five year plans into independence addressed the successes and failures and hopes of engineering not only as a technical field but in the realm of social transformation. So in Kassad's framing engineers were portrayed as experts not only of material and structural things but also of the corporeal and experiential condition of post-colonialities. Quote, let us therefore as the followers of the great science of engineering in all its branches unite in a common cause of applying the forces of nature to the service of mankind and make life less laborious, more safe, more productive more effective and more happy. Kassad concluded his speech by saying that we have the glorious task of securing the country against famines of increasing the value of its resources by improved road and rail connections of harnessing rivers by building dams of turning material resources into finished products and of bringing contentment and plenty to our fellow men. So dam building, road design, resource management all of these make sense and they even fall under specific engineering disciplines but why is securing the country from famine and engineering project? This is the most general and vague of the projects that Kassad references. The ways in which agriculture intersects with engineering are numerous and within a decade of Kassad giving this address agricultural universities would begin instituting their own agricultural engineering schools. These departments' work would range from building crop harvesters to designing irrigation systems but this was not the kind of engineering that Kassad was alluding to. He was referencing a problem whose solution was specifically aligned with his own training as a civil engineer that India being short of grain had been importing grain from overproducers like the United States, a situation which had led to a massive shortage of grain storage of warehouses. And so Kassad's reported that grain storage the problem of grain storage had been satisfactorily solved by the barrel shell type of design for warehouses. The barrel shell type has the advantages of better flexibility, better lighting and the possibility of reducing space or the space required. Besides this, the new design is expected to save a colossal amount of structural steel. The Central Building Research Institute has started a special course for training engineers in the technique of designing it. So barrel shells for Kassad offered a technology that became a formal and physical analog to the economic concept of buffer stock. Buffer stock was an economic device by which governments could manipulate the price of wheat in a market. They could artificially raise the price of grain by buying and storing it in these barrel shells. And likewise, artificially lower prices by releasing grain. RCC shells quickly became a quick and efficient way to deploy concrete expertise towards making buffer stock a manageable reality. And so the concrete publicity machine started publishing numerous images, plans and sections for barrel shells by PWD engineers and architects. And here are some images of them. And in this moment, concrete shell roofs with the thin cross sections came to correspond with economy efficiency and flexibility and construction. The thin shell and the civil engineer who designed it was seen as a direct contributor to social change in Kassad's developmental schema. And this is in particular contrast to gravity dams which harness the massiveness of concrete rather than geometry. And of course the dam is the other major developmental civil engineering project connected to agriculture. So to reiterate my point about how different concrete forms relate to different political economies where the RCC dam was iconic of increased productivity, greater irrigation, more electricity, the shell actually references the stabilization of the market, enough stock to make sure market prices don't go haywire. Stabilizing the predictable and unpredictable variations in agricultural output was central to maintaining the flow of green into the market. So while civil and structural engineers addressed the question of how to quickly and cheaply build warehouses to store green, agricultural economists addressed this other question of how to make green flow like cash through the economy. I'm skipping over some of the details here. The conclusion of what the agricultural economists were hoping to do is of what they sort of ended up doing is that between 1958 and 1975 civil engines and bureaucrats moved from idealizing shell roofed warehouses to idealizing silos because they conceive of green as something that flows like cash. A construction technology that negotiated the shift from shell roof warehouses to concrete silos was that of slip-forming. This new transfer of technology from the United States to India, but generally from the West actually I should say, to India promised revolutionary speed in industrial concrete construction. Slip-forming had been around in the concrete literature for some time, yet its technology had not been accessible. The cylindrical shape of the concrete silo lent itself to the much publicized technique where concreting was performed in one continuous stretch by slipping the ring-shaped formwork upwards using, and you can see the device on the bottom right of the screen here, by slipping the ring-shaped formwork upwards using the set concrete below for support. So slip-form construction meant that these vertical structures could be erected with limited amounts of formwork with very quick turnaround times. In silos, bursting forces of granular material played the major role for which you had to design against and vertical seams in the material were particularly vulnerable to dehesions and needed to be eliminated. In the 1978 appraisal of their re-storage projects of silo building, the World Bank itself noted that slip-forming had not been the panacea they had hoped it would be. Instead, it had proved hard to find engineers to design and manage the projects given the shortage of expertise in slip-forming. Subheer Sarkar pointed out in his 1979 article in the Indian Concrete Journal that slip-forming grain silos across the country using the same formwork, you know, saving formwork, while that would be fast and economical, it would require standardization across different administrative bodies. And this was the far harder task of the post-dependence political project. So to design slip-formed silos, an equivalency had to be created between granular material and fluid. How do you understand granular material when it flows? In designing silo, structural engineers changed how they thought about granular loads inside of a silo. So in 1972 and 1973, R.M. Garg published a two-part essay on the maximum pressures of granular material in silos. The essay reviewed research done in different countries to estimate the pressure inside silos. This is the essay here. First, the calculation of loads in silos was usually done using two methods. One by the German engineer, H.A. Janssen, and the other by W.Arie. Janssen's 1895 method used to the idea that granular loads are held in the cylindrical form by friction. So what that means is that the bulk of the load of the silo is exerted on the walls, thus the bursting force, rather than on the hoppers at the bays. What that means is that the load isn't really taken by these structures here. Janssen's formula used the coefficient of friction, which is different for different granular materials to calculate these lateral pressures. Arie's 1897 formula, on the other hand, used the French military engineer, Charles Augustine de Colombe's lateral earth pressure theory that assumed soil to be granular and experienced strain resulting in a plane of failure that would then put lateral pressure on the silo wall to calculate that horizontal load. The theoretical and conceptual starting points of these calculations and the failures of some of these models are different from each other in fundamental ways. There's very different ways to think about the load and then therefore arrive at the thickness of the wall of the silo and how much reinforcement is needed. In ways that recalls the E.H. Brown quote, that quote, structural engineering is the art of molding materials we do not understand into shapes we cannot really analyze so as to withstand forces that we cannot really assess in such a way that the public really does not suspect. End quote. So the work of calculating stresses, one of the things that struck me about it was that it was done by analogy that granular materials behave as fluids or yeah. Anyway, in the case of the Garg essay, he argued Garg argued that multiple failures of silos out in the wild and in experimental settings where full size silos were constructed for testing in France, Germany and the UK challenged Janssen's theories as sufficiently understanding loads. The modification being that Janssen and Erie models of lateral loads in silos only considered granular substances in their static condition. However, when silos were being emptied, they exerted dynamic loads on the walls which explained the failures of these silos. So what I'm trying to get at here is that there's a shift in how we think about silos. They don't store grain, rather they help grain flow to the market. There's some idea of energetics as a metaphor coming into play here in thinking about how grain will move through the body politic and arrive at the body. Simultaneously, there is a shift in how we design silos as something that manages a dynamic flowing load as opposed to a static load. And so I'm hypothesizing a connection here between how we use RCC and how we know it. And so by way of offering a really tentative conclusion here, grain in that sense shaped how we understand our RCC functions in certain design forms and what loads these designs are able to take. And the food economy shapes this structure. And this is what I mean when I say that concrete is an entangled epistemic substance. It comes into view in how we use it and also in how we theorize it. And so here we see an instance in which concrete has an ambiguity as a material and instead we can think of it as the set of societal and physical relations rather than a fixed material with fixed properties. Of course, the irony here and there are many ironies in the story is that silos never made food more accessible. That's not how the food economy ended up playing out the economy of the distribution of food. Food as fuel was denied to the body politic and that's something that was noted in this found poem. From 1972, to quote just a small bit from it has this buffer been built purely for the sake of form for quenching the inner coast for poetry in some hearts? And so that is my paper, thank you. Thanks, Attila. I have a quick clarification for you as Sophia sets up. I mean, first of all, that description of structural engineering, the art of not knowing anything and getting the public to still trust us. I think we should just use it as a mad lib and plug in description of any expertise whatsoever. My question was about calculation. It strikes me that the buffer stock is being calculated very precisely in some way, but earlier you mentioned that saving that somebody said, well, we will also save on steel. I'm wondering if that was ever also calculated or if it was just something that they said, or we will also save on steel. Well, the funny thing about that is that concrete is of course so tied into its sort of form as into its publicity that all of this sort of question of saving on structural steel by using RCC comes out of the concrete industry and the data doesn't, you know, line up. They're like, oh, it doesn't really save costs. We still use it. We still end up using a significant amount of steel, but still we must use concrete. So there are, you know, calculations that people are making. Okay, this is precisely how much structural steel we'll be saving if we use concrete instead of steel, but it's sort of, I mean, there is obviously many parts. The most famous project is of course, Roger Evoel's The Grid for the Hall of Nations in Delhi where he makes the entire thing out of concrete instead of steel. But that being said, what I found striking was that there were actually people doing calculations who came up with no answer, no good answer. And that calculation is not dynamic. It's not about the market. It's not about a buffer. It's a one-to-one replacement. Yeah, well, yeah, because just physically there was no steel, you'd have to buy it. And so buying it means using foreign exchange and that's just not available. Got it, great. Concrete can always be replaced by like some sort of local source. Fantastic. Yeah, I think maybe later we'll come back to how this relates very much to the contemporary 3D printing and concrete moment, sort of a similar new technology, non-known calculations, can you replace things with other things, a good after-concrete setup? All right, but moving on, thank you again so much, Etia, it's perfect. I'll see you. Sofia, Sofia, in a charming turn will not use slides that will just speak as herself. So if you're ready. Yeah, I'm ready. I'm not going to be talking about what Lucia told me to talk about. I was supposed to speak about mid-century energetics and the place of thermodynamics and vitalist thinking and the more I ruminated on the subject, the more I realized that I wanted to offer something a little bit different. So thank you to Lucia for us. You're welcome, we appreciate it. For bearing with me and for pushing me so far outside of my comfort zone. I'd like to organize my comments to address a few concerns that I see emerge from reinforced concrete and its various afterlives. And I suppose these comments are united in their concern for what it means to even speak of the life, the death and the afterlife of concrete. So coming to this topic from my perch in the anthropology of the life sciences and in science and technology studies or STS, I want to place a little bit of analytic and interpretive pressure on the quote-unquote life of concrete. And I'll try to do so in a few different ways. So first, simply as a question of metaphor or a kind of discursive vitalism that I see haunting architectural thinking. And again, I am way out of my depth on this point so these comments will be blessedly brief. And I'll next inquire into different ways of grappling with the ontology of reinforced concrete, introducing the possibility of a praxeography of concrete. Toward demonstrating what this approach might offer, I'll give one brief example of a partial ontology of concrete, one which concretizes, and I didn't mean to do that, which concretizes, so please don't chuckle, a partial ontology of concrete that renders explicit the earlier metaphor of concrete's vitality by looking to recent accounts of microbially induced concrete corrosion or what researchers are discussing using the acronym MICC. But first, the issue of metaphor. So why is it that when speaking of materials that change over time, we are prone to adopting vitalist or organicist language? I'm curious as to what the unforeseen effects of such rhetoric might be. Why is it that when we recognize that reinforced concrete has a built-in rate of degradation, it is conceived as not only organic, but also as organismic, as a coherent body, a living thing that is isolable in both time and place. An entity with a fixed lifespan that will necessarily age, decay, and die. An entity that, and this is quoting from Lucian Forrest-Paper, is mortal almost as soon as it was born. Now this problem is further complicated by the fact that in this litany, organic changeability and duration is contrasted to the presumptive permanence of stone, which is also a bit of a misnomer or at least a partial view from a necessarily human vantage of geological ethics. Now in much of my scholarship, I've been concerned with the relationship of life to time. And as such, my ears prick when something that is putatively inorganic and designed, an object of human manufacture like concrete architecture is spoken of in organismic and even in gerontological terms. So if following Mohsen Mostafavi and David Leatherbarrow, buildings have a quote, life in time. And also after Stephen Cairns and Jane Jacobs, quote, buildings must die. I'm curious what works such metaphors do, both symbolically and also with regard to political economy. Here I'm sympathetic to Daniel Abramson's argument that such language naturalizes mutability and decay in order to obscure the fact that planned obsolescence is never inevitable, but simply an artifact of architectural modernity under conditions of late capitalism. Okay, so with all of that in mind, I'd like to expand outward to think about the many partial ontologies of reinforced concrete. And I wanna ask whether what is necessary is truly a new narrative, again, to quote the provocation. Instead, I'd like to see what hay might be made by using a methodological approach that science studies scholar Anne-Marie Moll has termed praxeography. And the work that I'm talking about originates in this book, since I don't have slides, I'll just use physical things. So this is a book called The Body Multiple Ontology and Medical Practice. It's gonna seemingly be very orthogonal to what we're talking about today because it's an ethnography of atherosclerosis, hardening of the arteries in a Dutch hospital. But I think this is actually gonna work. So let me see if I can make it work. So Anne-Marie Moll talks about praxeography. As a, sorry, there's some ambulance going by. One entry point for this method would be through a question. How is reinforced concrete practically realized across multiple domains of expertise and among diverse practitioners who might include but are not limited to architects, historians, engineers, builders, materials scientists, chemists, ecologists, et cetera, et cetera. Rather than fixing or unifying disparate views of concrete as a certain sort of thing. So for example, and here again, I'm quoting from the provocation, either a highly messy, complex, unpredictable material environment or the most abundant anthropogenic sedimentary rock or aging infrastructure or defer utopia or even as a substance that is either like rock or like air could a praxeography of multiple partial concrete's plural allow us to reckon with how everyday routines and practices make reinforced concrete coalesce as a thing in the world. Further, would that give us some traction on how and why concretes are both materially and ontologically unstable? And perhaps also to follow up on what Atea just said, theoretically unstable. So as philosopher of science, Ian Hacking explains, and this isn't a piece introducing the notion of both the ontological turn and praxeography. He says, such an approach must necessarily recognize that material qualities and here he lists qualities such as durability and recalcitrance never precede social practice, rather they are social achievements. And as such, materiality is always a consequence rather than a starting point. So to give one example of what a praxeographic approach to concrete might add to the conversation, I'm gonna talk about kind of making explicit organic or vitalist language rather than finding and excising all organists or vitalist language from studies of reinforced concrete, what if we instead decided to double down on vitalism and think about it not as a metaphor, but instead as a partial ontology of reinforced concrete? In doing some research for this presentation, I found that there's a substantial contingent of environmental engineers and microbiologists who have begun to study and think about reinforced concrete in a new theoretical and experimental framework, not as rock nor as air, but instead as a complex, vital and evolving ecosystem, a sort of symbiotic entity in which the substrate of reinforced concrete hosts a diverse interactive assemblage of microbial communities. Bacteria, fungi, algae, protozoans and lichens living in and beneath concrete surface all concertedly catalyze reinforced concrete's degradation via either carbonation or corrosion. And this is particularly exciting to me because in my most recent research I've been looking at vitality of stone and rock. So, and I mean this in a very explicit way, the kinds of living things that either have solicified or lithified in rocks, think here of limestone, for example, but also the kind of extant microbial communities that form biofilms or thin sheens either on the surface of stone or in stone's interior. And they have very fascinating lifespans and life trajectories. So let me say a little bit about these ecosystems that are now recognized as living in and on reinforced concrete. You might ask, well, what difference does it make whether carbonation and corrosion are understood to be purely chemical reactions, right? Abiotic chemical, mechanical chemical reactions or processes that are catalyzed by constituent microbes. Should the endpoint either way be necessarily the same? Well, it turns out not quite. For one thing, attending to microbial life makes clear that a structure's environmental context is profoundly significant to figuring the reinforced concrete's lifespan because the kinds of organisms that live in and on concrete mediate and induce degradation and decay at variable rates. So for example, sulfur metabolizing microbial communities rain in concrete sewers. While clades of microbes that can in fact precipitate calcium carbonate have recently been shown to potentially play a role in repairing cracks in concrete. And here I'm definitely not interested in discussing self-healing concrete and its uses in synthetic biology because this seems to me like a relatively bespoke technology and I don't think it's useful here. But microbiologists have now demonstrated that microbial strain diversity shifts significantly between the surface and interior reinforced concrete and that different strains and ecosystem balances are maintained in different sorts of building environments. So these can range from CO2 heavy urban atmospheres to underground pipelines to structures at sea. They can also vary significantly with regard to climate, something built in a desert versus an Arctic tundra is gonna have a very different kind of microbial community as well as a different kind of indigenous microbial ecosystem. Furthermore, just like other ecosystems, think for example, forests, which age across ecological neif successions over time, concrete can also host multiple dynamic ecological successions before arriving at an apex ecosystem. So over time, the concrete ecosystem will have different ecological moments, right, that age until it reaches a final, quote unquote form. Of course, new technologies of DNA extraction, amplification and sequencing now aid researchers in identifying, but they're calling the genome of concrete. Such research suggests an altogether different meeting of the lifespan or life cycle of reinforced concrete architecture. Thinking about concrete as a living ecosystem enrolls non-human actors like microbes into the project of architectural maintenance and ecosystemic sustainability. Moreover, it is one escape route out of the fallacy that rock and stone because they are relatively durable and should be understood as homogenous, immutable or inorganic. And as I said earlier, this is in fact not true. Anthropologist Anit Singh encourages scholars of the Anthropocene to shift our attention toward learning how to flourish in the ruins of industrial capitalism and to do so by attending to the ways in which humans are imbricated and entangled in much more complex interspecies landscapes and associations. So perhaps this partial ontology of reinforced concrete as microbial ecosystem can retune our analytic expectations to bring into simultaneous focus, right? A kind of stereoscopic awareness, how processes that are both below the scale of human attention because too small and beyond the scale of human attention because too protracted are newly consequential for modeling what kinds of architectures might buttress novel forms of ecological relation. This is definitively not an argument for new materialism in the vein of Jane Bennett's Fibrant Matter because I have no intention of arguing for a universal protean energetics that infuses all matter or specifically reinforced concrete. Much more modestly, what I'm trying to point to today is the fact that reinforced concrete as a material is the consequence of multiple framings and practices that have at various historical moments augured concrete's putative lifespan via thermodynamic principles, mathematical modeling, architectural obsolescence, engines of global capitalism, ecosystemic balance sheets and in the present example, also complex microbial ecosystems. And I'll leave it there. Thank you so much. Wow, that was awesome. I'm so excited about that term that we just took to think about life in concrete because we didn't really have that at all this year. I know, I'm so glad you didn't do what we asked, Sophia. Yeah. I don't know, I guess the clarification from my side, as we, in the next panel, we're gonna end up talking a lot about life cycle and maybe differentiating how, because I don't think it's that related though, maybe in the context of the praxeography as one of those processes at play. So maybe to help differentiate for the audience where life cycle maybe fits in or next to life, I guess, on a concrete wall. I don't know if that's clear, because I had a hard time. So you were arguing for considering all of the complex ecologies and organisms that are in the wall, but does that directly relate to this broader metaphor that engineers use to talk about complex life cycles of the material that are not organic, I guess, is what I'm kind of driving at. Maybe you can differentiate for us a little bit how that maybe relates to the differentiation that is a part of praxeography. I don't know, it's a new concept for me together. Yeah, right. It's complicated. And the reason why I ended by distancing myself from new materialism is I think one of the things that new materialism can sometimes do is fall into a kind of new reductionism. And I don't want to set this up and say, no, really you guys, concrete is an ecosystem. Rather, I wanna say, well, we have an earlier model where we're thinking about a lifespan and putative vitality. And there are other people who are thinking about lifespans as well. And what does it mean that in this current moment, there is a new kind of nature that is about microbes and the ways in which they can exceed human design or human intentionality. And if we bring that into this diverse constellation of different kinds of practices that generate meaning and the substance of concrete itself, what does that add to the conversation? With regard to things like durability, intentionality and temporality, does that clarify? Yeah, yeah, no, hopefully, yeah, that's... I really wanna try and bring that into the conversation in the next panel too. And to help inform, I guess, how we think about lifespan and permanence that we just sort of talked about too in relation to concrete's role in the broader context. Yeah, I mean, I think that what's amazing about the four papers and the arc that they outline is that all of you have brought us agents who are tied to concrete and whose agency is temporarily delimited. I mean, in the case of Gabriel, there's permanence, which is a kind of mandate. In the case of Nimrod, okay, you talked about the 100 years, but really there's a kind of dual parasitic relationship between one community and the other, both seeking to outlive each other. This is kind of what I heard. And I tell you, of course, we have stability as the foremost. It's a way of qualifying life. It's a way of saying it's a better life and therefore one that lasts longer. So I'm just really impressed by the number of historical agents that have been brought to the table and that are not either the maker of the concrete or the person kind of living in the concrete. You know what I mean? That there are these other agents. I would have one question for all maybe to start us off and we also have questions in the chat, but to what extent are these agents also being made to inhabit a kind of spectrum or a hierarchy of life where some distinctions of some lives being more and not necessarily human lives, but just some life being different, life no longer being one thing, right? So I mean, in the case of Nimrod, it's quite easy because there are two populations at stake, but also Atea, I wonder to what extent therefore certain norms about what a life worth working on or a life worth living or a life worth feeding, something like that. And certainly Gabriel, you have two kinds of lives. You have the urban potentially politically dangerous life and then you have the much more promising life on the frontier. So I'm wondering if you guys could, and Sofia of course, I wanna know whether these, what did you call them ecological communities? I'm sorry, micro-bacterial, microbial ecosystems. Yes, well, they went from being, the key ecosystem includes the concrete, but if you take away the concrete, you now have the microbial communities. To what extent could we even imagine that these are living with us and that we are somehow considering them in our system of values without being vibrant materialists, to what extent is there now, what does this do to our ability to either distinguish between lives or to on the contrary, elaborate A idea of life? That's the big question. Hi, Kio. I can say one thing, which is that like this entire story of the silo starts by actually treating green as chemical instead of biological, right? Like the point is to stop it from sprouting. And so there's this entire sort of new chemical, not ecosystem, the opposite of that, being created within these spaces by adding aluminum as a kind of pesticide, by sort of, you know, by blowing dry air through them, by doing all of these things to kind of stop any kinds of biological reactions from happening. And so I think that it's, I mean, and I'm also looking at this question here on water and concrete. And the water and concrete is, you know, modern water in the sense that it's a very specific form of water that is used. And so I think particularly in relation to stability, I think it speaks to these systems as responding to certain market needs for, you know, of like, of how do we, you need to keep things stable. Otherwise your market will go crazy and you will end up, and that has very profound effects, which means that someone will not be able to buy food because their labor will no longer have value. And so, you know, to imagine all of these things as unstable again, requires us to really reimagine that economy. So some particles are allowed to act biologically and others are not. Yeah. I think, so Norman, just to show we're serious about audience members joining as panelists. Norman Weiss, who is of course a concrete specialist, much more so than we are is joining us as well. Did you have a specific question you wanted to jump in? Let me jump in with a couple of basic points. I've been taking lots of notes because I found many of the presentations really interesting for their particular focus. Obviously I get fidgety when I hear about the significance of the Hamada equation, as I did last time when you addressed that, simply because it's a generalization based on lots of other generalizations. Its value originally is still its value, which is that it relates cover, the distance of bars from the surface to the process. But as a generalization, it only is good if we believe that concrete is a thing, that there is one thing called concrete. And that's something that really, it requires a much greater subtlety for us to understand it. For example, let me just sort of quick in the things. Nimrod, you started out with the concept that concrete somehow bypasses the use of local materials. But all of the literature up until at least the 1930s emphasizes that concrete uses local materials because most of what's in concrete is sand and gravel and broken stone, which is all used locally because it doesn't make sense to transport inexpensive materials like that, any great distance to produce concrete. So maybe that is not one of your most important tenets, but I think that's worth looking at again. Gabriel on permanence, I love the fact that you made a more finessed definition of permanence for us, which is really great, that permanence can have to do with being resistant to fire, being resistant to other things and so on. And I would just add to that, that two things that you've got to think about the significance worldwide of the publication of photos immediately after the 1906 earthquake and fire in San Francisco. This photograph spread within the engineering community through all sorts of journals in English and in other languages to say to us that look at this material, which we questioned, we questioned its value, we questioned its cost, we questioned its difficulty of construction, but it came through exceptionally well as compared to unreinforced, made traditional masonry structures. And also that that dam construction, those decades of it, that's a subject that fascinates me because it represents new technologies. It represents the application of concrete science, which was brewing since 1920 and by the early 30s was being applied in that whole field of dam construction. So it's really important to understand that concrete as a thing was changing, as a substance was changing. The grain storage stuff. I can just jump in real quick. The photograph we showed of a concrete structure, neoclassical concrete structure, which had failed, that was from the San Francisco earthquake. Yes, I understand that, but the numbers argue in the opposite direction. That's right. Just as the data that you showed on estimates of service life that varied so much from country to country argues against the concept that the Hamada equation gives us 100 years or that it's valuable as a generalization. So that, again, it's a question of finessing the information and saying, boy, this is a much more challenging field than it seems to be. Well, I think the semantics of service life is something we talked about in the last conference too, whether we're talking about service life or the sort of life of the material, more as the sort of metaphor for when does it get recycled or destroyed or fail on its own and sort of having an anthropomorphic life, the sort of the context that we arrived at at the end that this, you know, carbonation is more like the slow, you know, ultimate old age of something, right? Ageing, there's normal aging, this is like, right? But arguably people didn't take that factor into account that there's this permanence that Gabriel was talking about was sort of always talked about first and foremost. And I think thinking about that changing, I think. I think everybody brought up good context to where that concrete is significantly... Something that you're pointing out, Norman, and that Gabriel also pointed out, which is that it was especially in the early part and Nimrod said this too. Basically, the valuations of material was comparative. It was more permanent than something else. And reinforced concrete performed better than unreinforced concrete in the San Francisco earthquake. So Gabriel, I guess I was gonna aim a question at you. I mean, you can also respond to Norman's question, but you mentioned it's really great that you're bringing this data and this historical study of the road because it's studied an under-understood aspect of reinforced concrete. Somebody in the chat put the recent show at the MoMA about concrete modernism in Yugoslavia, which is of course very iconic and wonderfully suggested, but at the same time, not the dominant way in which concrete is spread around the world. And so my question to you is about the idea of obsolescence. How is it different in roads than it is in buildings? Danny Abramson has written this amazing book about obsolescence, which shows that most buildings are deemed to have a certain life that is determined by the market, by planned obsolescence. But that's very much a study that's based on real estate and buildings. Is there an equivalent kind of calculation that's being made in roads either today or in history where insofar as something is planned to be replaced or lose its value or something like that, a road, I mean, that that's calculated in some way or no. And you can answer that or any other questions that's been lobbed at you, maybe just to pass the mic to you. But you have to turn the mic on. Classic. It has to happen. Yeah, I mean, so over the 20s and 30s when concrete's coming in to road building, it is considered permanent in a real sense in that, I remember what convinces the Office of Public Roads to declare it the real permanent road, there are these reports that they get back that the maintenance costs for counties that have experimented with concrete roads is zero across $0 across a number of years. And so, I mean, the idea is that they might need maintenance far into the future, but that's gonna far exceed the kind of bonds that are gonna be issued to fund them. But there is also a sense that concrete roads last kind of indefinitely. I don't think that the same calculation is in with asphalt roads. So when you get into the late 30s, especially in the post war decades, most interstate highways become asphalt highways. And those certainly have an expected shelf life, but I don't know that kind of calculation exactly like what's expected of them, that they were cheaper to build but concrete is always seen as a longer lasting road, even if it's, so there are cost calculations. When the interstate highway system is implemented, states are required to pay for, they only pay 10% of the construction costs, but they pay for the maintenance. So they end up building much more in concrete than had been the case in the 1940s and otherwise in state highway building. But I don't really know what the calculation is as far as the lifespan, the kind of expected life of an asphalt road versus a concrete road, yeah. A lot of those numbers are actually out there now because this fight between the concrete highway guys and the asphalt highway guys is ongoing and it actually has kind of heated up in the last two or three years for some reason or other. So if you go to any of the newsletters and either of those industries, you're gonna find all the new numbers that they're throwing at each other to continue this struggle between the two materials. Okay, we need to have that paper also in the next iteration. Oh, and I see you have your hand up. Yeah, I mean, can you hear me? Yep, yeah. One thought on the asphalt versus concrete is that it's been going on since, I mean, in Palestine since the 1930s and it has to do with affiliation to Germany or to the US so it's not only a contestation of materials, but I have a different, I have one thought that I want to break to five parts. It's a connective thought and it stems Lucia from your proposition that the concrete replaces the tree, the matter. And I wonder if instead of replacing it, it's extending it or if concrete is post tree, post in the extending as well as in the breaking width. And that's relevant to each of the papers and also to another paper to the Pestracrabartis thesis that makes a distinction between biological life or by humans as biological agents and humans as geological agents, which we begin to problematize here. So it's relevant to each of the papers. In Nimrod's case, the other dual material or dual just material in that period is our nitrates that can be used in explosives and for agriculture. So and work is agricultural work initially. So agriculture as the kind of main setting to, or as a context to resituate your story is one theme or one question I would like to post to you. It's relevant in Gabriel's case because the discourse of permanence contrasts concrete with trees or with wood. But I wonder if along the kind of shock of the old argument if there's a real replacement here because in each of the images, we see trees. I'm sure wood is around in the scaffolding. Did we get rid of that? It's all right, the contrast of green and gray. And I wonder if concrete really does get rid of wood and trees or if it's a story of extension. A Tia's story, obviously, I mean, the industrial revolution in the British Isles is around textile production, but in the colonies, it's an agricultural industrial revolution. So it's the very context for engineering that anything from irrigation and all form of cultivation to grain storage would be a wedding of concrete and grain. In your story, I have multiple other questions that the applicability of William Cronin's grain elevator to the futurity of concrete, but that's maybe another story. And Sofia, you know, when I heard you, I said yes and absolutely doubling down on the organismic discourse, but then what could happen? And of course I'm thinking all these thoughts along the lines of my intervention in the evening or in my evening of the subterranean forest and of coal, obviously. So what happens is alongside the microbes, we would consider other kinds of ecologies, trees or humans or, I mean, how would that inflect the story? I have a quick, while people think of their answer. Oh, that's fantastic. When I was thinking about whether to, how far to take the concrete is performing today, what would the matrix of the wood did in that sort of somewhat mythical etymological origins. I was pitching it to forest who said, of course, because once upon a time we chiseled and now we pour. And I was debating how far to go with the pouring, but essentially we have a number of papers which have specifically talked about the liquidity gesture taking over, but in no way removing, I mean, in ATIA's case is the paradigmatic example. The pouring of concrete is a problem, a technical problem that engineers think about and the forms they make, that vault is arguably one that for fronts, the liquidity of concrete, the fact that it's molded and poured in place. And yet this in no way removes the older model of life as something that works for land, that is agricultural, that where you have to tear out trees or not all plant trees, et cetera. So definitely, I mean, agreement that there's an extension of the, it's not post trees, it's just that you have to think the tree differently in a different sort of universe. I don't know if anybody has a specific answer to own any more. I can answer really quickly. So yeah, there is this rhetoric about reducing timber supplies through permanent materials and including concrete. And but an irony with concrete that you might have suspected is concrete actually lets timber, let's wood back into urban cores because the early 20th century is the exclusion of what you're building codes. I'm trying to fireproof cities and urban cores become largely masonry and steel and some concrete. But when you get concrete buildings into urban centers, it actually through not just the scaffolding but the form work. The form work ends up being a way that carpenters and timber ends up having a prominent market in urban cities. There's actually almost as much like when building concrete houses, people argue there was as much timber in the form work as there would be in a wooden house. So yeah. Okay, just any more. Hopefully. So thank you, thank you everyone. Norman, just to your point, you're absolutely right that the ability to source materials locally was actually crucial to the success of this endeavor to introduce cement. What I should have clarified that these were specific local materials that could be circumvented. So stone as a building material rather than lime as something that is used in the process of creating cement, the specific sort of facets of quarrying that were being sidelined and stone masonry that were being sidelined that had to do with local materials and essentially repurposing much of the sort of the subterranean in Palestine so that it comes into cement and eventually into concrete rather than into building with stone itself. So thank you for that question. On about sort of the agricultural aspect. Yeah, you're right in the sense that I tell the story in a way that sidelines agriculture in many ways but increasingly I think of the two together for reasons that I think you and I have discussed in other opportunities. Agriculture and construction sort of emerge as these twin fields, twin economic fields in Palestine both in the ideological sense that they're aware the work of building the nation occurs and in the sense of the labor itself they are the ones that are to be conquered by Zionism they're the ones to be defended and sort of modernized by Palestinian entrepreneurship and they also interface in really interesting and important ways. So the forests for example and forest protection in Palestine is propelled forward by the British authorities in part through making lime kilns in forests illegal whereas lime kilns were the sort of a main force of mortar for Palestinian construction. Lime kilns that are burning forests down, et cetera and destroying forests become an object of forest regulation. Concrete irrigation is really important for citriculture in Palestine and sort of the revolutionizing of citriculture. So the intertwine and I was thinking Atea while you were speaking I was thinking of there's a set of silos for feed premix for animal feed premix in Israel in which one of the workers that I interviewed has this really remarkable story about working in the silo as these large forms sort of these moving forms move up around and one worker falling in but essentially what's so interesting is how this becomes an industry that is intimately tied not only to feeding humans but also feeding livestock and sort of the feeding process more broadly. Now I wanna congratulate several of you for bringing agriculture into the discussion here in a way that is really fantastic and significant. In the US specifically, I have always felt that by about 1930 a rural contractor, contractor working in a farm area knew more about handling concrete than their urban counterparts. And part of that was an emphasis on the part of the Portland Cement Association to put out booklet after booklet about the use of concrete to farm construction. I have myself collected these things over the years and there are other others that have been scanned out there in public collections and so on but that idea of concrete as something urban and modernistic and so on and so forth. Really it was concrete on the farm that moved the subject of concrete utilization forward especially in the 1920s which I think is and it's great that we're hearing so much about that. Yeah, thanks for that comment. I appreciate it as I grew up on a farm and actually did pour concrete. Yeah, when Frank Lloyd Wright had to replace the contractor at Fallingwater, he turned to one of the apprentices for advice and it was the apprentice in charge of the cows at the Taliesin where they kept lots of animals and so on and the cow apprentice, I've forgotten his name particularly, recommended a contractor that he knew of who could work in Western Pennsylvania and really had the expertise that the first contractor did not have. So there is this amazing intertwining of these relationships. Precisely, yeah, thanks Norman. I don't know if anybody has any last comments we're about 10 minutes over but we have built in some extra time at the end too. Are there any final parting thoughts as we transition to the second panel? We'll continue to address some of these questions going forward, certainly they're all relevant to the upcoming talks. Yeah, the conversation is, as I said, ongoing. I do wanna thank our speakers for absolutely incredible talks. Thank you so much. And there are a couple of questions in the Q&A which we're punting to the next. I'll try and address them as we introduce the speakers. I'll try to address them as well. And also thanks to Atea for answering questions specifically about the lifespan of concrete in India. Specifically mentioned that they're different. Not only are there people advocating for asphalt versus concrete, there's also people advocating lobbying for standards and people lobbying for use and those are two very different things. So yeah, let's maybe go to the next panel. Thank you guys. Thank you so much guys.