Rammed earth mixer


I build rammed earth dwellings. So trying to find ways of mixing my raw material, which in most cases is crushed limestone, is always on my mind. A while ago I built an attachment for my bobcat that would do just that. However, my assessment of the pressures involved on the end of the ‘paddles’ was a tad out. In the last few weeks I fixed that issues, but of course, other issues arose, right on cue as expected. Nevertheless, the adjustments to the mixer were actually successful, and today as I built a second wall in the current project, I used it for the first time, it worked very well, I was very pleased.

The next problem along the ‘issues chain’ is actually the chain. A third of a cube of crushed limestone is roughly 450kg dry weight, and that is a lot of stress on the chain, which at one point begins to jump. I get about a turn and a half before it decides to take a leap to the next tooth of the drive pulley, but that is enough for the material to mix with the cement and water. I have a 600mm helix set up around a 50mm 4140 shaft in a 1530mm bucket. The bobcat hydraulic pump is handling the load very well as is the main hydraulic motor on the mixer, but the chain is ‘a bitch’n.

Im thinking about installing a gear box of appropriate strength to handle a full 500kg load. But for now gently nursing the 5/8 chain is my only option.

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