Some years ago I investigated some houses in New Mexico that were made with pumice based concrete. They were getting between R1.5 and R3 per inch and although the walls were thick it made a very comfortable house. Does anyone have any information on whether this technology has gone anywhere? thanks griz

I don't know if there are any commercial versions of any scale, but DIY versions have been popular among some folks for awhile, along with EPS-crete, reclaimed/scrap EPS beads as the aggregate in a non-structural concrete, which runs about R2+/inch, as well as perlite-aggregte concrete. eg:

http://norishouse.com/archives/582

http://www.greenconcreteus.com/epscrete.html

There is at least couple of commercial players in the EPS-crete biz:

http://foamliteconcrete.com/

http://www.rastra.com/ (Insulating concrete forms made of EPS-crete)

As well as commercial systems for structure-rated pumice-crete suitable for load bearing walls:

http://www.pumicecrete.com/

Dana,
Scott McHardy the fellow behind pumicecrete.com was the chap I went down to see in New Mexico. We talked about having him come North with his forms to do a house for me but it never came to pass. There was this recession thing. I did some experimentation and talked to a Lab about having testing done with pumice-crete. In the end it turned out to get it "officially blessed" by California building departments would take longer than I expect to live.
I did however make a number of test items and then forgot about them for a couple of years until it came time to break them up. The largest was a picnic table, about 10 feet long. It was an arched form with a regular concrete top. I put rebar in the concrete and wire mesh in the pumice - crete. To break it up I just smashed the regular concrete with a sledge cut the rebar. done. The pumice crete was just about immune to everything I tried. If you hit it with a hammer the surface would pulverise down about half an inch and that was it. It was easy enough to cut but you couldn't crack it for love or money. Parallel cut more than an inch apart could not be chipped out. It took all afternoon to cut it up in pieces big enough that I could just bury. Out here where everyone is worried about fires and earthquakes I would think it would be nearly perfect but I have not heard of a single commercial application.
If I ever get somewhere, where I can build a house without having to have it approved by a $%$#@#$ building department I am going to build one.
Griz

I backed my one-ton van into a garage wall made of low density concrete. Put a half inch dent in it. That was it. After researching various approaches, I decided that various methods of pouring lightweight concrete were not possible without an experienced contractor because of the difficulty of getting uniform distribution. My choice would have been foamed concrete if I could have found a contractor. I am no seismic engineer but I would expect that walls that can absorb shock will perform well in earthquakes.

Todd, I'm not entirely sure what your "one-ton van" test tells us about low density concrete and seismic resistance. Can you elaborate? Standard reinforced concrete performs well in earthquakes.

Gentlemen,
Reinforced concrete is great stuff but it doesn't insulate worth a hoot. Additionally because it is very heavy it requires forms that are very robust. I have no experience with anything other than the pumice-crete, but you can directly apply stucco or paint to the outside, drive nails into it, screw into it with standard screws (they need to be good and long too hold but it does work). I would think it would be a DIY dream come true. I heard from some people in Hawaii that used it and a few in new Zealand but other than McHardy no one here in the lower 48. I keep wondering why it hasen't caught on. Tod correct me if I am wrong but commercially prepared low density concrete is fairly expensive but pumice is cheap. So I remain as usual confused.
Griz

As I said, ICFhybrid, I'm no seismic engineer. Autoclaved aerated concrete dents (crushes) rather than cracks because it is 80 percent air and 20 percent concrete. I'm guessing its light weight and composition would dampen the whip-like shear forces transferred from moving ground in an earthquake better than reinforced concrete. I doubt that this would matter much in a building of a story or two on a small footprint. But in Kobe Japan and Mexico City, AAC apartment buildings were still standing while full strength concrete stuctures next door were not. http://www.hebel.co.nz/about/kobe_report.pdf But that's not likely to be apples and oranges either. In multistory buildings AAC panels are hung on a steel superstructure in curtain-wall fashion. At any rate, I believe the point of multistory earthquake design is a building that gives rather than breaks.

Griz, I paid about $3/square foot for AAC block shipped from Fla to Pa. My all-in cost for a half inch of cement stucco outside and a quarter inch of plaster inside was about $10/foot as semi DIY. (I hired a mason and plasterer and served as their helper.) Both my plasterer and stucco guy are artists with a trowel, though, so that would be a very, very well-spent $10/ft. I don't know anything about pumice so we're even. You couldn't pay me to blend perlite in a house-sized quantity of concrete.

Structural strength is different from impact resistance, and seismic resistance is something else. What makes sense in a given location will vary.

Wouldn't perlite concrete fit the bill here?

Toddm,
Did you lay up the AAC block yourself? Did you use a standard mortar or one of the more esoteric varieties? I have considered using it myself but as I have mentioned in other posts the building department here is unbelievably obstructionist.

Thanks Griz

Should have been clearer whirnot. At wind speeds above 1 mph, in my experience, perlite only goes where it doesn't belong.

Griz, you won't find much satisfaction with AAC in CA unless someone has spent some money in recent years, which is doubtful. http://www.cnn.com/2009/TECH/06/11/green.building.material/ (Note the UT prof/earthquake expert's blessing of ductile (flexible) AAC walls. Note also how easily regulation can be turned to the advantage of entrenched industries. FYI, pumice crete would also be ductile.)

Anyhoo, AAC block is set in eighth inch joints of polymer fortified thinset. The blocks are cut and surfaced after they're baked, so you can generally trust the manufacturers' claims that ithey have a sixteenth inch tolerance on the mating surfaces. As in all stacking systems, the key is to get an almost perfect first course, which is set with standard mortar. I hired a moonlighting mason with 50 years of experience and a drill sergeant's approach to his tender (me). I set maybe a quarter of the block. Once I got accustomed to truing up the block in three dimensions, I could more or less match my mason at half speed. The maddening thing about glue/thinset is that it has a memory. Place the block wrong and you're looking at some considerable wrestling. Woe be unto you if you have pry it out of the wall and start over.

toddm,

I just got around to reading the cnn post. I assure you california in general is bad, sacramento is unreal. I think most people will agree that steel framing is not exactly cutting edge. It is even used in commercial buildings in sacramento. About ten years ago a developer built a small subdivision with steel studs. Literally across the road from where a shopping mall was being built using steel. Despite this the residential inspector put a hold on the project because he was not "comfortable with steel construction" and would not allow the development to go ahead until he could acquaint himself with the product. It appears he was a slow learner because the project was stopped for more than a year until the developer ran out of money. In the ensuing legal fandango the bottom line was "it is at the inspectors discretion whether to allow a project to continue." The only reason the situation improved at all was a very large developer threatened the Mayors office that he would take all his investments out of sacramento and would not build another wall if something was not done about the building department. That and a couple of law suits have made for a slight improvement. But I do mean slight. My last house took 6 months for plan approval and all I was doing was adding an upstairs bedroom. My current project will incur building fees of just short of 40K for a medium sized residential home and the next county over it would have been almost 80k. 1376 days to retirement and good bye california.
griz

Elemix ExB is used as a constituent in low density concrete. Elemix is 1.4 lbs/CF.

Also, www.elemix.com

www.elemix.com