 our future and think so quite. I'm your host, Brittany Zimmerman. And I'm your co-host, Richard Ha. And joining us today is our guest, Kevin McDowell. Today, we're going to do a deep dive into another sea invention. Welcome to the show. How you doing, Richard? Oh, pretty good. Boy, it's raining cats and dogs as they say. Yeah, hearing he low, that seems to be the norm. And welcome, Kevin. How can you do it? I'm doing well. Thank you. Thanks for asking a little bit of a drier area here in the Geographic Center of North America, sort of the anti-Hawaii, as it were, in that it's about as far away as you can get in the United States from an ocean. Wonderful. Well, we're super glad to have you with us today. Our second sea letter invention, we just had so many in the sea category. We decided to do two, is cement and concrete. So, Kevin, you may know a thing or two about cement and concrete. So a little anyway. Please tell us a bit about you, your relationship to cement and concrete, and anything else you feel like sharing right off the go. Well, sure. I'm my name is Kevin MacDonald. I run a consulting engineering firm and I'm a professor at the University of Wisconsin, a stout in construction management, where I teach concrete as a material, reinforced concrete design and heavy equipment operations. I've been working in the concrete industry in various roles since the late 1980s in structural inspection and evaluation of existing structures and consulting, both in terms of plastic and hardened concrete. In fact, I spent 12 years manufacturing or involved in the manufacture of concrete. My previous employer would point out that I actually never did anything, but I told lots of people how they could do it much better. And then I went back into the consulting business. And my education is in chemical engineering, which is sort of an odd place to find someone living in the concrete end of the cement and concrete industry. But I first got into it into concrete as an exploration of the corrosion of reinforcing steel and concrete. And of course, the manufacturer of this synthetic stone, this concrete, is the largest chemical reaction that we run as human beings on earth. And so it's the logical place for chemical engineers. Awesome. I mean, that is super exciting. And we have Richard with us. Richard, do you have any major questions about cement and concrete or anything there related to kick us off with Kevin? Yeah, maybe I'm just a farmer. Yeah. So isn't cement and concrete the same thing? No, no, it's not. But it's a very common thing to look at. Now, concrete is a material that really defines our modern life. And it's very easy not to know anything about it. But cement is to concrete as flour is to cake. It's one of the necessary ingredients. And the cement is a powdery material that will react with water. Portland cement is to form a calcium silicate glue. And then it glues the rocks and other constituents of the concrete together. So the concrete is a material that is made of cement, but also includes mineral or synthetic aggregates or other materials that are bound together to form an artificial rock. And it's a fascinating material because it comes to the point where it is going to be used in the unfinished state. You can pour it into a mold and whatever mold you pour it into, it will eventually set and take on the shape of that mold. And so you can use concrete for making floors, for beans, for columns for all sorts of structures. So that that's the big difference between cement and concrete. The cement is a powder that mixed together with water becomes a glue. And it's a portion of what it is. In fact, it less than about 30 percent of the concrete by volume is cement and water. The rest of it is minerals, crushed rocks, that sort of thing on practically anything that that you can find. And unfortunately, not frequently enough recycled concrete. You know, I'm curious about. I've heard that the stuff you folks make is less a longer, less longer, you can use it quicker. What? Why? Why is that? So, you know, concrete is a very durable material. There are concrete structures in in Europe that are well over all over twenty five hundred years old constructed by the Romans, who had a similar, but not the same technology that we have. You may as concrete is a material that relies not on Portland cement, but on a different cementitious binder. And one of the advantages of that cementitious binder is that it reacts very quickly and it gains strength very quickly. And then it fills in the spaces. I hate the analogy, but if you can think of concrete as a hardened sponge, water can move through the concrete the same way it moves through the the voids or the pores in a sponge. And the humane material has a secondary reaction that plugs those holes and makes the sponge much more watertight. And really, water is the most destructive material on earth, right? It's amphoteric in that it will attack bases and acids. It it is the universal solvent, so it will dissolve many things and it can carry in chemicals that will cause problems in the concrete. Two of those chemicals that are very serious for Hawaii are sulfates and chlorides, both of which are found in the seawater. Sulfate will attack the illuminate phases in the cement, causing an expansion and a general disintegration of the paste. And the chlorides will penetrate in and cause the corrosion will cause any reinforcing steel to corrode. And it's really searching through that particular corrosion problem is how I started getting involved in concrete, because I was curious as to how we could stop that electrochemistry problem. In order to do that, you solve a corrosion problem. You need to understand the system where that corrosion is taking place. And after looking at that, the system was much more interesting than just the corrosion problem. But that's the reason that it is stronger at early ages and later ages and is more durable. Both have to do with the reduction of the amount of pores or space that's inside the hardened material. In certain instances, your maize concrete does not have to use rebars. Is that is that true? Yes, concrete, which is designed, say it's continuously soil supported, or it's always in an arching action or some other some footings as well, being soil supported can be designed in the code without any reinforcement at all. So you may could be used with other plain concretes can be used in that same situation. One of the advantages with the you may material is that we get very high strains as a consequence of the reaction that we're getting. And so when we have very high strains, it makes it means that not just the compress over the crushing strain, but also the tensile or the stretching strain is considerably higher. And where that's the case, we can build things that things without reinforcement in them, pavements, this is an arched structures of concrete floors that would not need any reinforcement in them whatsoever. And you can make them thinner. And the advantage of making them thinner, of course, is that you use considerably less material. Oh, yeah, go ahead, Richard, you go knock yourself out. OK, here in Hilo, there's a portion of road that's made out of cement. Yeah, so so it goes to the wharf and stops right there. And our experience in Hilo is, you know, as soon as you pave the road, it doesn't take very long before it starts to get bumpy and then, you know, and it starts to degrade and it doesn't seem like it lasts very long at all. Now, when I look at this cement and it's not the same thing that you folks do, but it's cement, yeah, so concrete that cement. I'm guessing it will last longer than the asphalt right next to it. And maybe your mazes is similar to that cement or different towards. Yeah, one of the significant problems you have in in the tropics is the amount of sunlight that you have and that sunlight will degrade asphalt cement, which is the binder in asphalt concrete and asphalt cement will degrade under ultraviolet light and that starts to cause it to crack. But there's another issue, which is the the different mechanisms in the materials of asphalt or asphalt to concrete is a material that is flexible. It it relies completely on the sub grade for support. Concrete pavements are rigid. So as long as they're properly designed, they can bridge over softer areas. Now, you don't get to have the excitement that that we do here in the mainland where they get a lot of frost in the winter. In fact, people run away to Hawaii to escape from that frost and a lot of a lot of people looking to do that in January, February. And so you don't have quite those problems, but flexible pavements are much more dependent on the soil conditions and the ultraviolet ages them quickly and they start to crack. Concrete pavements won't have that have that issue. They can be more expensive to construct initially. But if you look at a lifetime and that's made what we should be spending more time doing is look at what happens over a period of time that concrete pavements will pay themselves will pay back the initial investment many times over by the fact that they don't need to be as repaired. They won't be to be repaired as frequently and they certainly don't need to be replaced as quick. I remember you said at the start you didn't like to use the example of a sponge, but yes. But so water goes through this. Is that right? It can. Yeah. Most most sponges are the the the voids are not connected. So in but in the case of concrete, if we make it in a particular way, we'll have pores that are connected. In other words, you could walk through void space if you were sufficiently small through void space from one side of the concrete to the other. We measure its permeability, which is a measure of how easily water will flow under a given pressure gradient. And in those cases, we see water can move readily through the concrete. The way that we stop that is by densifying the concrete is filling in those spaces so that we either have no connected space or that the path that is taken instead of being a straight line, it's very circuitous, virtuous. It takes time to for the water to move under a given amount of pressure. There's more back pressure. There's a number of things that can be done. And it's absolutely crucial for concrete durability to do whatever you can to keep the water out. Awesome. And one of the things that I get most excited about is really the environmental impact and what we can achieve in that realm. So for the viewers who aren't as familiar with why concrete and cements are emissive in the first place and how we're looking at trying to solve some of the issues around emissivity and greenhouse gas release, can you walk us through why traditional materials and concretes are so emissive and what the big difference is here? Yeah, I'd be happy to because this is a this is one of the downsides or the detriments of using Portland cement, our particular binder. Portland cement is a is a is a material that is processed with heat. We we start with some limestone and some clays or source of source of iron, source of silica. And the first step that we take is we heat the material up, which takes energy and which is often associated with emissions. But the first chemical process that occurs is called calcination. And calcination is the process of taking limestone, which is calcium and a carbon and three oxygens. And driving off the carbon and two of the oxygens, the CO2, leaving us with calcium oxide. So not only have we have we emitted carbon dioxide by burning fuel in order to get us to the temperature of calcination, which we'll have to go beyond to the B bor fuel. But we also have a chemical process that is converting limestone back into calcium oxide and carbon dioxide. And I say back into it because the carbon cycle, there's a process whereby a little bit of carbon dioxide is dissolved in the water and eventually precipitates down and becomes calcium carbonate. So we're reversing that process. And we always we're very good at reversing the process much faster than the natural process is. And so we have a lot of carbon dioxide that's emitted from calcination and a lot more that is emitted from heating. And then when we're done, we end up with nodules, ash or clinker of the burnt material in the size of say, say, macadamia nuts, and then you would take those and grind them up. Macadamia is still with the shells on there with the fruit on it. You grind those up into a fine powder, and that takes a lot of energy as well. And so where that energy is occurring, there's there are emissions. And so when we say cement, we really mean Portland cement. Portland cement is this material we're talking about. And we can add other materials to reduce the amount of Portland cement that we need and thereby reduce the emissions associated with it. But there are always emissions associated with with the clinker. And so what we're looking to do is to have a concrete that does not use any clinker that gets its its grinding or its hydratable material from other processes so that that you're able to reduce the emissions. The difficulty and often at this point in an environmental discussion, someone says, well, why don't we just get rid of concrete? And it's a it's a good idea, except concrete has a cost of cents a pound made to order delivered to your door. And there is no building material that that we can replace volume of concrete. We use as human beings on earth, more concrete than anything else other than water, about three or four cubic yards per person on earth every year. And we use it to make lots of materials, not not just pavements, but the things that we don't see wastewater treatment plants, water treatment plants, hospitals, structures that define our modern life. And so coming up and having a simple solution of, well, let's just not have concrete anymore is not really a solution. You'll never be able to replace it with materials, with other construction materials. And as a consequence, we need to find ways of making concrete that has little or no or even better, a negative quantity of emission. Yeah. And the major inputs in the system being waste, right? Yeah. And here in Hawaii, in Hilo, Hawaii, as we're looking at building up to our major input is actually the waste, the effluent coming out of the wastewater treatment facility center. So providing a much needed solution to a problem that I think has been here for a very long period of time. And so actually being able to process these sludges and the treated effluent coming out of some of the facilities that are currently being ejected out into the bay and actually a substituting that is a main input into the system. So it's really a beautiful thing because, right, all of the inputs are waste, right? Every single part of it. We can do wastewater treatment processing. We can do solid processing of the garbages that are at the landfill. Traditionally, we can do seawater as the sea levels rise. And there's, you know, there's no additional inputs that are needed that are not waste streams, which is one of the really beautiful things of the systems and the technologies. And then, like Kevin's pointed out, the fact that we can do this in a way where we are replacing 100 percent of the Portland cement based product, which is the part that is highly emissive, within the tech, you know, within the concrete product itself allows us to be net negative, which is really, really exciting. Because I think, yeah, Kevin's right on in saying there is not utilizing concrete isn't really an option right now in the way that we're functionally living in society. So right now, the concrete being emissive is a detriment to us, right, in terms of environment and society. So finding a way to make the concrete part of the solution for carbon drawdown in a way where the carbon is being locked up or sequestered in a geological way, right, because it's carbonated for millennia instead of it being utilized in a way that's re-released back into the environment, I just think is. It's just so circular and beautiful. Yeah, in a way, I don't think we've seen before in the cement or concrete industry. Yeah, and it's very much the chemical engineering approach, which is we know what molecules we want and we know what molecules we have. And so we need to run a process that allows us to take what we have and make what we want. And if we can do that by sourcing our molecules from waste streams that otherwise are going into landfills or, you know, they hate to say it's not being dumped into the ocean. And then we are in, we're in very good shape if we can continue those things. I always thought one of the nice things about the UMA process is one of the one of the byproducts is is potable water. It all depends on how you look at it, whether you think the concrete is the goal or potable water is the goal or whatever. But from my concrete chair, it's nice to see potable water of which there is not an awful lot as being one of the waste product. Can I, you know, get this straight in my mind? In other words, the process you're using, you may be using results in less greenhouse gases going into the atmosphere and affecting the climate. Is that fair to say compared to Portland cement or other ways of making concrete? Absolutely. That is exactly what the case is, is that the material not not by sequestration or anything else, but by simple avoidance of the of clinker makes a significant contribution. If you look at other aspects of the production, you end up having fewer greenhouse gases or less quantity of greenhouse gas per carbon dioxide in particular at the end of the process. Then you did at the beginning of the process. And that's what net negative means is that it pulls carbon dioxide out of the system. And at the end of the day, it fixes it mineralogically in the same process that the earth has been doing for time in memorial, pulling carbon dioxide out of the out of the air and reacting it with calcium in the seawater to form limestone. It's pretty amazing. But why aren't we doing it right now? There's there's several reasons why I and this is where this is where the you may process for me is absolutely fascinating is that down at the concrete end, some of the waste byproducts of waste products, however you want to describe it, of the manufacture of the of among other things, potable water is a material. That currently and desalination is a brine that is put back into the ocean. Further processing of the brine results in an alkali type material that can be used to activate salacious materials. So the reason it's not being done right now is because that alkali material is very expensive and it's also a very energy intensive to manufacture. But because it comes out as a waste process, a waste product of the you may process, it's essentially without value and something you probably have to pay to get rid of. And instead, you take that material and you find another use for it. This is one of the my my personal belief is that, you know, we meet a lot of young people and my nieces and nephews among them and young people at the universities who think that the world is broken. And in fact, it is not broken. We just haven't solved the engineering problems that our current situation presents. We've had worse engineering problems that we have solved as societies and potable water and safe drinking water being one of them. Highway safety being a prime example as well. We'll continue to fix these problems so long as we apply our ingenuity so that we can solve the problems looking at not just what the problem is, but also the potential new problems that it may create. So I'm actually positive about fixing many of the challenges we have facing us in society and during the process, you make of large scales of hydrogen. Is that right? Just part of the process. Yeah, it's easy. Yeah, yeah, I'm talking too much. Don't get you it is wonderful. I love it a lot. Yeah, we do. We produce right now between 11 and 12 tons of green hydrogen as a byproduct in the facility that's planned for the heloside of the big high end. So it's pretty substantial in the amount of hydrogen that's produced. And that's at qualities that exceed what is needed for fuel cell utilization. So that's, you know, 99 point. It's over 99.99998 percent pure. So that's fantastic. Is that the right number of nine? So yeah, it's really nice to leave it on the energy side of things, right? Because we get to produce something that can actually help make another sector greener, right? We're really focused on how to do the carbon drawdown, right? And in the production of our concrete is where we're really sequestering our carbon dioxide, which is fantastic. But then we have these wonderful co-benefits in terms of the co-products that are produced, right? All of them being a valuable product and not having a stream of our own. That's produced, I think, is really one of the very exciting parts of the system solution. And hydrogen helps clean up the energy sector, right? As a sustainable alternative to some fossil fuels, right? It's an energy storage mechanism. And then we have our water, which we have our potable water as an output of the system, which is really exciting as well, because drinking water and need for that globally is an issue. And then we actually have our biochar, which is another carbon sink for us, where we keep our high-grade carbons that need to be introduced back into agriculture. And then we have our concrete, right? Which is, like Kevin was saying, the most utilized man-made material on the planet. So it's a cross-subsidized approach where all the waste coming in gets to feed grain solutions in different sectors. And that's one of my favorite parts about it. And the cement and concrete is a big part of that. Wonderful. Awesome. Well, I think we're just about out of time here. Were there any other last-minute questions or go-backs that you had, Richard? No, that's a lot to digest. But the bottom line is pretty clear. It's going to be good for the climate. And we're going to use our waste. We don't have to bring it all in. We'll just use what's on the island for a solution that's lasting longer, stronger. Holy smokes. And it's, even in the middle of it, it still seems fascinating. Holy smokes is the right thing to say. Awesome. Well, any last-minute go-backs from you or anything else you wanted to add in there, Kevin, before we wrap up? No, other than, you know, concrete is a requirement for our modern and safe world. In which we live. And we need to continue to find ways to provide it without the large emissions associated with the manufacturer of Portland cement. Absolutely. And thank you, Kevin. I know that a large portion of your career, you're one of the leading experts in the world in looking at how to, yeah, how to carbonize the cement and concrete industry. So thank you for everything that you've done in that sector and everything you continue to do. Well, thank you for the opportunity to talk to people about it. Yeah, yeah. Thank you. We loved having you on. Yeah. Yeah. Agreed. All right. Yeah, this is Inventing Our Future. I think Tech Hawaii. Thank you so much, Dr. Kevin McDonald, for joining us today. And thank you to you, our viewers, for watching. If you want to get on our email advisories to see a complete listing of all of our shows, you can sign up for them. I think Tech Hawaii.com. We will be back in two weeks. So please turn in to do a deep dive into our de-invention. We will dive into the de-invention this time. But until then, I'm great. Mahalo.