Why aren’t we using Aerblock when we build?

Aerblock as an ecological building material like pumice or laterite

Why aren’t we using building materials like Aerblock instead of wood? Habitat Forum 1976 alumni Michael Baron is involved in manufacturing this safe, lightweight, storm-proof, insulating, healthy-air concrete material that mimics ancient pumice building blocks.

Aerblocks are so light they float, yet they are strong enough to withstand major natural disasters. Their application is almost universal—from disaster reconstruction in Haiti and Jamaica to full-scale luxury housing and large building projects.

Construction lobbies have helped thwart the adoption of this material in North America, but it is used in many other parts of the world. Why does North America lag so far behind? The only North American region to have adopted it in any significant way so far is Florida, only thanks to a hurricane problem that is so severe it has overridden the efforts of business to block it.

In other parts of the world, it’s argued that adoping Aerblock would aid in health and community development. Not only does it protect from heat, mold, insects and other threats to health, it is a simple and intuitive material to build with. Its interlocking blocks fit together so simply that untrained and uneducated builders can put together a decent shelter with the aid of pictorial instructions. Because Aerblock doesn’t require grout, which requires training to apply and is a major a source of failure, it’s more likely to be adopted while buildings are less prone to collapse either from quakes, storms or disrepair. The foam block mimics an ancient style of building with pumice blocks. It’s worth noting that there are ancient pumice buildings still standing today, including the pantheon in Rome.  

Baron contacted me in relation to my book research on Habitat Forum ’76, and then went on to tell me about his work with Aerblock. I asked if this material would work in a rainy, cool climate like Vancouver, and he said that contrary to popular assumption it would be ideal here. He had in fact been attempting to set up a small manufacturing plant in the Lower mainland as a result of his long ties with Vancouver. Asked why it hasn’t been adopted in construction, apart from the deterrent effects of the wood lobby, he pointed to something I’ve witnessed myself in my own attempt to salvage my building. There is a great deal of inertia in the construction industry. It’s easier to go on doing the same old thing than to invest in something requiring reeducation, new tools, etc.—even when the materials are ultimately cheaper or when they clearly benefit the homeowner. I myself have had to battle subcontractors and suppliers over choosing newer, more sustainable methods and materials.

It’s interesting how many alumni of the groundbreaking Habitat ’76 conference are still working on sustainable architecture and appropriate technology 37 years later. Why are we right back where we started when we first began to talk about these things? Rhetorical question.


“Our Mission: We strive to play a crucial role in furthering the advancement of aerated, lightweight cementitious technologies here in the US and around the world, as a legacy building material, for generations to come!”

Below: Vlack Temple in Colorado, constructed with Aerblock; Haiti reconstruction; fully modern, large-scale house;

Aerblock - church in Colorado

Aerblock Haiti

Aerblock - adobe-style mansion


Here are some chunks of the transcript of my interview with Michael Baron—all of the sections relevant to Aerblock/AAC:

I was just down in Haiti recently helping to set up a lightweight concrete shop down there where Haitians could rebuild in lighter weight block rather than the heavy block that had been pressing down on their heads. And all these things lead back to the discussions that went on back there at Habitat ’76…

..All people need their shelter. They need to have their little 10×12 space for safety and security and a place to get out of the heat, a place to get away from the cold. And we in the West live in these gigantic homes, these very large homes that most of the world does not live in. Most of the world lives in very small spaces, the whole family lives there though they might camp outdoors… But there’s a huge discrepancy in the world between what we do and the rest of the world is doing. And I guess what came out of Habitat ’76 and now I continue it, is working with buildings materials that to me are better for people. They’re safer, they’re quieter, they’re more insulative and they last for hundreds of years instead of going away in fires or being blown down in storms etc…

Me: Can I ask  more about Aerblock—that’s what you were doing in Haiti?

MB: Well I’ve always been interested in different kinds of building materials. I’ve tried for a long time to find something that is universal, something that anybody can work in, and that is very fluid in terms of design and what you can do with it. My wife is from Germany, and on our 9th wedding anniversary we went out into this little village in the middle of nowhere up on a hill. And after our lunch and things we came out and here was this building sending there that I hadn’t noticed when we walked in, it was all white, about 2 storeys, and they had just finished the blockwork, and the site was very clean—in Germany everything is cleaned up and they don’t leave a lot of rubbish around—but I found one little piece of material that this building was made out of. I picked it up and it was light as a feather. I thought “wow! This budding is built out of extremely lightweight stuff!” whatever this was. And I started asking around and her father said oh, that’s “eton”—and I thought I’d never heard of this, what is this eton. So my wife and I started driving all around near Stuttgart, up in the hills, through the town, and I started noticing buildings everywhere built out of this, and I thought it was unbelievable. When I got back to the States I thought I have to learn about this. And it turns out there were two  factories in Florida making it. So I flew down and I went through these factories that make it. I had this deal where I had this friend of mine who was sending hay down to Florida by big semi trucks and getting good money for his hay, but he had nothing to haul back, so I said listen Bernie, haul this lightweight block back for me. And so for 5 years he would back haul me this beautiful lightweight block and I got to work building buildings all through the high mountains of Colorado, up into Utah, Arizona, even some in Vancouver. I sent a couple of trucks up to Vancouver. Out to California. So I’ve been building with this for about 13 years. And it’s a lightweight material that you find everywhere in the world. It was developed in Sweden as a replacement for wood because towns were burning down, and back in 1924 the King of Sweden said ‘please come up with a material that doesn’t burn and that carpenters can build with.’ And this guy up there figured out how to make this material that he foamed up. He basically takes cement, very little cement in sand, and he uses a little bit of aluminum powder, and what this is it’s like putting yeast in bread which creates co2. So this guy did he takes a little sprinkle of very fine aluminum powder. And aluminum reacts with the cement which creates hydrogen gas. The hydrogen then provices the sand and cement this bubble matrix that rises up like Wonderbread—not that I eat Wonderbread, but it’s that kind of structure. And then it solidifies and then they open the mould up, just like a bread mould, and take out this material that’s like bread. They call it cake. And then they cut it up with wires, and it’s all wire cut into precision block, and then after there it goes into like a pressure cooker. And they put heat and pressure on the material for about 12 hours. And the material forms into a natural mineral called tobermorite which is completely inert. It is the healthiest building material you can live in. It does not off-gas, it’s a natural mineral, and you can build any kind of architecture with it.

Me: Why haven’t we heard about this more?

MB: We’re like old school pioneers, we live in wood houses. We have lots of wood, we’re blessed with forests of wood unlike the rest of the world. Germany has beautiful forests but they keep it for furniture and windows and doors. They don’t tear their forests down like we do, especially in the Northwest. So up comes this factory in Sweden, and then Finland and Germany and Norway and Siberia—at one point Russia had most of the factories in the world making it. And Germany has over 25 state-of-the-art factories and has been producing it for the last 70 years. And in this country we have just one, in Florida. And I tell people, “you know 40 years ago we went to the moon and at the end of it we played golf. And figured you know, we made it.” Things have not continued in that innovative spirit as much as they could have, in some of the other arts. I mean of course we have our iPhones, and things like this that have come along, but in terms of the buildings arts… You know, Europe is so far ahead in their use of materials, their use of solar energy, wind energy. All these things are so intense, so strong there that you feel like you’re on another world when you go visit these days. When you travel through Germany you think “why aren’t we doing this?” Germany doesn’t necessarily have a sunny climate like the Southwest here. It’s more like Vancouver. Yet they have, on every barn, every apartment, on houses on everywhere you go, they have solar panels. Anything facing south is trying to catch the sun. You have wind towers and wind generators all over the whole country, thousands and thousands of these things scattered everywhere. And it’s pretty shocking to see that. So I saw the evidence of their building materials, and I got going with this and I have been working with it ever since.

And up in the mountains here, in the areas where the people that inhabited this land 1000 years ago, they cut out of the mountains the volcanic tuff. They cut out blocks very similar in density of this material and built their pueblos 1000 years ago that are still standing today. And that’s only 30 miles as the crow flies from here in Santa Fe. And so we have evidence of traditional people seeing right in front of themselves a material that worked for them. They made blocks, they lived in it, and then for whatever reason unrelated to architecture, these homes are abandoned. But they are still standing today.

So this is a material that really can help the world in creating housing that is earthquake proof. You can’t knock these buddings down in an earthquake, you can’t blow them down in windstorms. This is why we have a factory in Florida. And it doesn’t burn, it’s a perfect material for California and Texas and other places that are burning up. You could probably even resist some pretty strong tornados, not that anything is very tornado proof, but I think you could come up with pretty strong architecture that might hold up. Termites can’t get into it. It has the best energy performance of any material, which is why you find it up in Sweden, Norway and Siberia, very cold climates, because of the way that it holds energy you put into it. And it keeps you very cool in very hot climates. If you go to Kuwait you’ll find 4 factories in tiny little Kuwait that would fit between Santa Fe and Albuquerque—4 state-of-the-art factories. Because it reduces your air conditioning and cooling costs. And what we thought in Haiti was that this material could completely transform Haitian architecture. This would have been a great thing to have talked about those years ago at Jericho: the tyranny of concrete block that is spread around the world like a deadly virus. And people that build out of it suffer when there are earthquakes. You look at the young people trapped in Pakistan, in China in these concrete block schools that fall down in earthquakes. Haiti—Haiti was demolished. All the concrete block fell down. Everybody knew somebody who was killed by falling concrete block. So we went down there with the idea of making blocks because that’s what they know, they understand blocks, and we went down there and said “what if we provide a way that you could make your own lightweight block, and it takes very little cement to make them, and what we do is we mix in a foam in this cement, so we mix mix the cement, put a bit of sand in it, and then we mix up this surfactant foam like detergent, but it’s a plant protein or sometimes a synthetic protein and it’s simply like detergent but very strong bubbles. And it has the consistency of shaving cream, so it’s the same kind of foam you’d shave with on your skin.

And they got it. They thought it was wonderful and strange but it made sense. First we had to clear the whole site of rubble because everything had fallen down and people were killed in the yard where we constructed the demonstration building. The whole yard was cleared up, and then they found an old cement mixer and brought that in. And then we had this little foam machine that we had put together and brought down there. And we mixed up foam, we mixed up cement, we blended the two together, we poured this mix into—it was like chocolate mousse but with cement, and you pour this in a mould. The next day it’s strong so you can take the moulds apart and a few days later we had these lightweight blocks—t floats on water, that’s how light it is. And they’re interlocking blocks which means the mortar that traditionally you put blocks together with, they used so little cement that the mortar turned into sand and all the bricks fell down because they didn’t put enough cement in their mortar.

So now no mortar, we just interlock the blocks, and they connect up together like lego blocks.

I went over to Jamaica a few years before that to talk to the Jamaican gov’t about this type of material— they got it in a heartbeat. Even the taxi driver said

“you know this is amazing, what you’re showing me is amazing, our people are sick all the time from the heat, we can’t afford air conditioning, and we build these concrete houses where there’s no escape form the heat. And we have to put these hurricane roofs on, we cast four inches of concrete on our roofs so the roof doesn’t blow away in the wind, but then we have to seal them so they put black tar on the roofs and the black tar gets hot, and the concrete gets hot, and people are hot at midnight, there’s no escape from the heat.”

The the tyranny of concrete blocking and concrete roofs! And they’re always not feeling well, they’re feeling tired and worn out from the heat. And when I showed him samples of this block you should have seen this taxi driver, he was absolutely amazed that cement could be made that light. This would be their solution for cooler housing.

Concrete block by the way has cores so wherever there’s a core you put some steel in, because you have to really anchor these stones down or they will blow away, but you use the least amount of steel, and that steel goes from the foundation all the way up through the block, like threads through cloth. They go through the block into a bonding, and into that bonding we then have another system of trusses, lightweight trusses. This is a system you find in Europe; you don’t find it in Canada or US at all. It’s not practiced here at all. But in Europe and all through the world you find what are called triangular lattice trusses, and these are like very lightweight steel frames, steel frames,  zigzag trusses, triangular, and the bottom has very thin pieces of rebar. They’re actually very affordable all through the world. And what you do is you take a little form and you pour a cement plank on the ground, it’s like a 2×6 or 2×8, and you drop this triangular truss into it, so its little feet are stuck in the cement and the rest of it sticks up. Once this hardens and dries, now you’ve got a truss that’s say 15’ long, so that it spans the width of a house, maybe the house is 10’ or 12’ wide but now you have a little overhang.

Now what you do is you set up on top of the bonding every 2’—now you take the same block that you made for the walls and you cast pieces that are 8” by 8” by 24” and those pieces are set in between those trusses that span the roof. And these are very lightweight which means they don’t heat up all day long. They insulate the house from the heat. And these are then mortared together. They connected up with a bond beam that they tie down, and then you can come up with your whitewash, lime wash, lime on that slanted roof now. Now you can collect the water—nobody collects the water down there (because of the tar roofs). Now you can collect your own drinking water instead of hauling it from half a mile away. Collect your water, run it through your sand filter, now you’ve got your own water. Your water!

They get this in a heartbeat down there. Cool roofs, cooler sides, it can withstand the hurricane and everybody was looking into the sky for decades, looking at the sky, and hurricanes come and go. But nobody was looking down at their feet. Everybody forgot that 200 yrs ago, not only in Haiti but in Jamaica too, I think around 1804, they had a terrific earthquake and the entire city of Port Royale which is right outside of Kingston sank via liquefaction. A city as big as the city of Boston disappeared and everybody forgot about it until about the 1920s divers were diving around and began seeing the extent of the ruins of this city that had sunk during a forgotten earthquake. Earthquakes are a reality out there. And now we’ve got a solution for earthquakes, for hurricanes and for climate. And they don’t harbour bugs! And they’re very strong. And people for the first time can have homes that they can afford, they can build the block, they can build the houses, and they all work together down there. And they get what this material is about.


But try to get NGOs on board with this, and they look as if you’re crazy. You have to bring in tin, you have to bring in 2x4s, you have to bring in foam walls, you have to bring in all this crap from the States. And the millions and millions of dollars that are raised by these NGOs so that they can live lavish lifestyles down there is skimpily put out to the kinds of technologies that we were bringing down there. So we managed to get a little bit of grant money to get this started, but then they would say let’s build 40 of these buildings. And then they cut the budget down, and at the last minute say we only have enough budget for you to do 10 of these. And so it’s very sad that you come up with something that has so much potential to help so many people, and the people get it, but those that could fund it don’t have the mental capacity to get out of their own box and put some of the money they raise in the name of Haitian sorrow and Haitian injury, hundreds of millions of dollars that just sit in offshore banks and places. Those dollars are not really out there for the Haitians to utilize. Very little has really trickled down to the Haitian people. But the fundraising certainly makes good press, so these people can go back and raise more money so they can live in these compounds and drive all these SUVs that cost $90K dollars and have people wait on them, and in the meantime the Haitians pick up, they clean the rubble and they get on with their lives and it’s just such an upside down world… But the Haitians carry on. I’ve never seen such people as the Haitians, they are to be commended. They have their problems but they have a spirit that, again, so many of us in the West are afraid of.

..As for adoption of this material here, people in the West… It’s like talking to martians. So hard to get this going here, even in Santa Fe here in this kind of vernacular that suits it. It’s hard.

Me: Is this due to the startup cost? Is it because wood has been too cheap?

MB: No, it’s way above that. You’re dealing with politics, you’re dealing with lobbies, you’re dealing with huge corporate institutional interests that have no interest in other materials coming in that would threaten their market. If you think about the wood industry, I mean look up there in Vancouver, look at Washington State, all these Northern areas. I lived there for 10 years at that border. I know the installation companies, the sheetrock companies, all these groups that have a vested interest in the status quo. And they do not want things to change because they’ve got their formula. And others that don’t have all this stuff (southern nations/regions who don’t have a local wood supply)? It doesn’t serve them to bring in this crap to their areas, because you know what, the termites eat the wood that they bring in. And the foam blows away in the first windstorm. And besides that, they’re not carpenters; they’re blocklayers. They know their block, they love building with block even though it’s what falls on heads in earthquakes, slides and storms. They’re very good at building with it because it’s what they’ve had. And if you give them a better block, that goes together quicker, and is cooler and stronger, they get it in a second. It does take a little bit for equipment to start things up. They have a  lot of cement in the Caribbean. Jamaica has some of the finest limestone in the world. It’s fine enough that you can make toothpaste out of it. And the island is made out of it. They have barely scratched one little mountain to make cement for their limestone. And this material takes very little cement to make. So it is a technology that I feel could have great value all throughout the so-called Third World because people get it and it’s just a matter of a little bit of startup capital for some of the equipment that once you get going they can keep it repaired. It’s not like repairing a cellphone today – it can be done.

…AAC is very like any kind of volcanic pumice. I mean it’s all over the world. Under the city of Naples—it’s all built on volcanic pumice and the pantheon in Rome is all built of pumice and dash from the volcanoes. The Romans made their own cement back then, taking lime and mixing it from the volcanic ash and you have cement that lasts 2,000 years. This has been understood for a long long time throughout the world and for some reason it hasn’t been brought back. What we’re looking at it simplifying, simplifying, simplifying until we have the least amount of material, least amount of equipment, and the most simplified processes to give people the most benefit at the best price. This is my goal.

LB: If you came up and gave a talk on this in Vancouver I think people would be really interested. What would the startup cost be in a place like this?

MB: I would say there’s different levels of startup. I’ve recently been talking to a German company because they’re very advanced in this kind of technology. You can start in a laboratory with a very small little mixer that sits on your lab bench all the way up to a small factory that puts out millions of cubic feet of material. All aerated cement just like pumice made in blocks. I could build the city of Vancouver out of this material. Some of the tallest buildings in the world are made of this material. You know the high towers in Malaysia, those two double towers. They brought an AAC factory in there for all the infill. So if you have a tall building, all that material on those Malaysian towers is AAC. So if you have a steel or concrete superstructure, in between the walls you want them to be lightweight, you want them to be soundproof, you want them to go together in modules and be fireproof, and so this is the future of certainly high-rise construction. But it’s also the future of everything in between. By the way I was pushing Soleri on this, saying stop using heavy material for Arcosanti! And I was talking to a gentleman up in Vancouver up until about 2012 who had a lot to do with setting up the apartments and dormitories in the Mexican Olympics down there in ‘68, and he used European eton materials to do that. And he was trying to see if there was any way we could afford to get a plant up in Vancouver for the Vancouver Olympics, and we tried to figure out how to do that. But unfortunately the economy was just in the garbage pail after the ’08 crash, and these factories that had been built were expensive. So what’s happened recently is that now there’s a group, a very smart group in Germany that has figured out a way to make these materials without autoclaving, which takes a certain amount of steam energy to make. Now it’s possible to make it just by foaming cement and cutting everything up with wires and letting it simply cure like cement does, and now we end up with wonderful aerated cement. It hardens because it’s cement itself. If you mix it properly—if you understand how cement works at a microscopic level—you mix it very very strongly so all the tiny little cement particles get hydrated and if you do that properly then there’s no wasted cement. Now if you’re mixing in a wheelbarrow or a cement mixer there’s tremendous waste of cement powder, because people don’t mix it right and it’s rarely properly hydrated…

But it would be very possible to do something like this up in Vancouver. You could start out with a small plant. It would cost perhaps a quarter million, maybe $300K dollars to do something that would put out a vast amount of material. You could also go up to, say, $2m and produce even more material and that could be scaled up even more and exported. There’s various levels that you could do this at. But in Haiti it was way down the line, a base level, and we made it work.

Me: I lived in Greece at one point in one of the Aegean white villages and I’d lie in bed in my 400 year-old stone house in the village—on an island that Japanese seismologists would visit every few years and warn the villagers is next in line for a big quake because it’s right by a fault—and I’d lie there and look at the slates overhead, held in place by dry beams that were simply trunks of saplings, and I would think “I am toast.”

MB: Places like that are catching on, there are a lot of factories being built in India right now, all through the mideast, Turkey has some of the largest factories in the world and of course they have issues with heat and energy but also earthquakes and so this material is the most lightweight material you can build out of in seismic areas.

Me: I lived in Greece at one point in one of the Aegean white villages and I’d lie in bed in my 400 year-old stone house in the village—on an island that Japanese seismologists would visit every few years and warn the villagers is next in line for a big quake because it’s right by a fault—and I’d lie there and look at the slates overhead, held in place by dry beams that were simply trunks of saplings, and I would think “I am toast.”

MB: That’s really interesting Lindsay, because the Japanese embraced AAC. They brought in about 10 plants in the mid-70s or something. Ten state-of-the-art German factories they brought in there. And the Japanese are masters of AAC panel construction. These are big panels that come 20’ long, 2’ wide, and 8, 10 and 12” thickness wide, and very lightweight. And they build buildings all over the place. It’s one of the biggest building materials used in Japan because it’s lightweight, it’s seismically structurally safe, it doesn’t burn when the quakes and fires happen. And when the big earthquake in Kobe happened it was really interesting because there were literally thousands of AAC buildings at the time back in 1984, and when that earthquake happened and buildings fell down all around these other buildings, the reason some AAC buildings were damaged was because other buildings fell on them. Or some actually walked off their foundations – they weren’t anchored down right. But most of the AAC buildings stood up beautifully in Kobe. And then the other thing that they noticed was when they had these horrendous fires—and Japan is famous like San Francisco for huge fires that happen after earthquakes—the fires came through and the AAC buildings served as firebreaks and stopped the fires in some areas… And they’re light so they stand up to the inertial forces of earthquakes. So not surprisingly Japan is one of the top users of AAC for a country of its size. China probably has 12 German state-of-the-art plants, the most advanced plants built today. Now China is moving so fast with this they’re designing their own equipment, they’ve got 100s of smaller plants that they built themselves, they are also using this other material that I’m getting into now called cellular lightweight concrete which is foam, and they will be building equipment for the rest of the world. And we here in the west are in the Stone Age when it comes to these materials. And it will be the Chinese that will bring it in here at some point. But yeah Japan understands seismic. And what we learn in Japan could be applied in California, it could be applied all the way up to Vancouver because I tell you because from Mexico all the way up to Alaska, we are all susceptible to seismic and out your way, out in Washington, I know that there are these faults out there in the ocean, not far offshore…

LB: All my adult life things seemed to go in reverse. Where are the solar panels from Habitat? The electric cars?

MB: I know. Remember Arco solar which at the time was creating amorphous crystal panels that didn’t require silicon, they could be done with silicon that was set to these panels with vacuum deposition and this is revolutionary. We wanted to build roofs out of this stuff at this conference centre in Colorado, so we could demonstrate collecting solar right off roof panels. They’re just like your corrugated sheet metal but these would be coated with this material and generating electricity. We followed that program and I came up and spoke about it, and many were talking about it, but somehow that got bought out or shut down, something happened, and to me I think it was all the result of oil interests that said ‘don’t get too far ahead here, guys, we still have a lot of oil to sell people, and as we run out of oil, we want to make sure that we’ve kind of got our hand on the meter here for any other kind of energy platforms, but we still have a lot of oil fields to pay off here so don’t get ahead.’


And today, Michael emailed me this: “I have shipped aerated autoclaved concrete (AAC) to Vancouver in the past, but the trucking is very expensive. We are currently setting up a test operation here in Santa Fe to produce a similar type material called LithoPore. It is cellular lightweight concrete (CLC) and we are able to produce it in blocks, panels or cast in-situ. If your colleague is interested, have a look at the website of our group in Germany for more information on the technology: Luca Industries. This kind of manufacturing system and products would go very well in Vancouver!”

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