Yesterday I poured half of the concrete floor. I started out with a formula for concrete I found online: 1 - 2 - 3. That is, one part Portland cement, two parts sand, three parts coarse aggregate. I was using the large gravel I have on hand rather than the pea gravel I've seen in bags of concrete mix, and ended by mixing 1 - 2 - 2, which made it easier to smooth. Having jumped the gun and not even made a footing for this structure, I dug out from under the walls and shoved concrete under there as well so that the papercrete isn't setting directly on the ground. I got to use my Harbor Freight cement mixer, which is still hard work but easdier than mixing so much concrete in a wheelbarrow with a hoe. I used coffee cans to measure my ingredients. Mixing it 2 - 4 - 4, it took four batches to pour half the floor. I'm hoping I can pour the other half Friday.