Need assistance with Air-crete Making

  • I applied for hosting a work-shop next October, but in the meantime I have been playing with making Air-crete. I bought the plans for the foam generator. So far I'm pretty sure my Air-crete is not like the blocks I see in the videos. You can stick your fingers into the top. Perhaps, the air bubbles are to big?

    Finger poked block

    alt text

    I used large pot scrubbers in the foam generator instead of stainless wool. Dawn 2X is the foam agent.

    I did not weigh the foam. Using a sheet I found I made a spreadsheet to give me a mix based on cubic feet I want to mix. For 5 gallons (0.668403 cubic feet) I used 10 cups of cement, 13.2 cups water, and 55 cups foam(not measured but mixed in until bucket was full).

    alt text

    Can anyone assist me in getting the concrete right? Was my mix wrong? Are my bubbles to big?
    Block after simple wipe-off
    Weak Block
    Close View of Block after simply wiping the top with hand

  • First I would recommend ditching the dish soap and buying Drexel. Its worth it, check out Talyn71's video comparison for a great visual.
    Second you need to verify density of foam. You need to control the variables to see what the problems are. Different foam densities with produce different results at the same volume.
    Third remember that the more foam you add the more aircrete you get. However you also get less compression strength and shift to a more insulating quality. So determine what you want to use aircrete for then dial in your recipe for that project.
    Once you get your foam density figured out post results and we might be able to help assist with your recipe. Happy experimenting :-)

  • I made another test block. It collapsed some what after pouring and the bottom looks terrible.


    Bad block bottom

    Top fell in

    I used the mixer on high, was the mixing to vigorous?

    Was the bucket to tall for making blocks?

    Foam density was ~2.8 ounces per quart using seventh generation soap at 1:40 ratio

    It looks like the bubble size was to large at the bottom of the block.

    I have ordered Drexel foam agent, but besides that any suggestions?0_1507479459939_IMG_20171008_103114.jpg

  • Check out this video I think it will help you.

    Youtube Video

    Youtube Video

  • Looks to like you might have had large air pockets trapped in the bottom. How does the block feel in the middle where it looks more solid? Is it really crumbly and easy to compress? I had really brittle aircrete when I mixed to little water with my cement. What was you water/cement ratio? Your foam was on the low end of the density recommended but should not have been the issue.

  • @Von-Vest the bottom was wet. There were large bubbles top and bottom, but none when poured. The middle is firm, but I can push my finger into the middle.

  • I ordered Drexel foam. Is the water to Drexel ratio 40:1? Or 160:1 ?

  • Not sure. For a 5 gallon bucket i used 1 cup of Drexel. Good luck

  • Water to Drexel is recommended at 160:1 dilution. That being said you can add as much as you want to form a stronger concentrated mix. I have not experimented with a different ratio then the recommended 160:1 which comes out to be 4oz to 5gallons water.

  • Alright, I made five changes and have major changes in results.

    1. I remade the foam wand using fine stainless steel wool.

    2. I used Drexel diluted 160:1

    3. I did not wipe mold with oil as release agent.

    4. I injected foam only at bottom of bucket into mixer.

    5. I put an air solenoid on the regulator and wired it to a switch with the water pump allowing the foam to be produced with consistently and be switched off. Foam. Density was 88 grams per liter.

    **Results: @ 5 days cure, 156 pounds on a 1.49 inch round rod, Wich puts failure at 89 PSI **

    Failure is when as weight is slowly added there is no longer an increase in weight measured. This seems to coincidence with cracking.

    Unfortunately I did not make test batches between changes. Which is most likely to have cause foam to work? The Drexel, no oil, the fine wool in foamer, mixing foam at bottom??

    Also, I noticed the previous bad batches have gotten very hard now.

    my foamer


    my foamer


    Surface of Slab

    Structure inside slab when broken

    Testing Failure

    Failed Test Piece



    0_1511722358855_Failed Peice.jpg

  • **Results: @ 10 days cure, 173 pounds on a 1.49 inch round rod, Wich puts failure at 116 PSI **

  • I would think its a combination using finer steel mess and the solenoid to control foam creation are the key followed by the drexel. Glad it worked out for you. What are you planning to build?

  • @Von-Vest next year I will be building three 20 foot dome and one 16' dome. This winter I am going to build a small square solar green house to test the insulation properties of air-crete.

  • **Results: @ 15 days cure, 180 pounds on a 1.49 inch round rod, Wich puts failure at 120 PSI **

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