The foundation was ready, the adobes were dry and the math was done… there was only one question to solve… which should be the orientation of the adobe joints, should they be vertical (1) or horizontal (2). The answer was not easy to find by researching. In the end the answer came from Architect Gernot Minke to whom we wrote with our doubt.
The answer: From a structural point of view the differences are negligible. So the selection criteria became only those related to the building process. And having vertical joints (1) is much better because you don’t need to fit in the adobes from a new section with those on a previous one.
Everything was ready to go.
From this first experiment we wanted to solve three main doubts:
1- Would the vault hold…
2- What would be deformation of the vault when lowering the formwork with a short drying time (we actually took it out only 20min after we finished the adobe laying; we needed short drying time to be able to build everything in the 7 days workshop coming up)…
3- How long and how many people would we need to build a section of the building…
And we got our answers:
1- There was no problem; everything went according to plan with no cracks or anomalies.
2- We actually tried to prevent this deformation by adding more sand (coarse) to the mix. Increasing coarseness gives more stability to the mix during the drying process. 24 hours after lowering the formwork we could measure a deformation in the center of the section of about 2cm downward and 3cm forward (in the direction of the last adobes to be laid). Because one of the ends of the section has a slightly shorter drying time, being laid with a small default, deformation is higher creating a “Pisa tower effect” (I just came up with it). This deformation wasn’t that important and we’ll be able to correct it in the next section.
3- Four guys, organized in two teams (one laying and the other “serving the adobes)could build a section of about 70cm (6 columns) in about 4 hours. But we could clearly spot an increase in speed as we got more experienced. I’m sure that experienced workers (and maybe a 5th guy helping around) could easily lay two metters (about 500adobes, 28 columns) in an 8 hours working day.
Latter we’ll publish the specific complexities of this task.