Friday, August 3, 2007

Fortress Update

Another day of fine progress on our safe-house! Davy (the mason) showed up bright and early, with two of his sons (Roberto and Alfredo). As usual for them, they worked hard, straight through the day – from about 8:00 am until about 4:30 pm, right through the hot part of the day (and it was darned hot today!

I learned today from Ruben (my contractor) that Davy has five sons – all of whom are budding masons – and one daughter. I've now met three of his sons, and my reaction could be summed up very simply: as far as I can tell, he's got every reason to be one proud papa. All three boys I've met are courteous, hard-working, and (especially considering their age) remarkably talented. It's a pleasure to watch them all work together; it reminds me of certain times in my childhood working with my father…

The work today, for the most part, was a straightforward continuation of the earlier masonry work I observed. Just a couple of new things to talk about.

Yesterday, as you know if you're following these events, we didn't have quite enough concrete on the truck to complete the grout lift. So this morning Alfredo and Roberto mixed several bags of concrete in a wheelbarrow, and lifted it up by hand about two gallons at a time in a bucket to finish the grout lift. It didn't take them long at all; just a half-hour or so.

Partway through today, Davy finished laying blocks on both sides of the doorway. The next row would go over the cutout for the doorway – so how do you lay blocks in mid-air?

He did it very simply, by building a temporary wooden support for the blocks (you can see it in the photo at right). Then he laid the next row of blocks right over the support. Over these “suspended” blocks, and for several block lengths on either side, several pieces of rebar (as called for in the plan) will be fit into notches. There are three more rows of block going over this one.

If you think about this from the perspective of a mechanical engineer, it's quite a complex system: horizontal rebar near the door cutout to handle the tension created from the weight on the blocks above the doorway (which will be considerable when the roof is poured!), vertical rebar to handle the much lower vertical tensions, and the block plus grout to handle the compressive loads. It would take me quite a while to figure out how to model this system, but with such a mix of materials I know it would be tough to calculate…

And now some photos from the day:

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