For the Haiti Challenge, the Architecture for Humanity team provided on-the-ground reports from Haiti.
A drop test is the simplest way to test the strength of a building block: if the block survives a 6-ft fall, it is strong enough to go into a building. This is true for concrete blocks, fired bricks and unfired earth blocks that are seizing a lot of attention in Haiti at the moment. Specifically: stabilized earth blocks that incorporate a bit of cement to secure the already-adhesive qualities of clay.
The Rebuilding Center has been sending teams to visit some earth block manufacturers exploring alternative masonry units in a country with strikingly few natural resources. Weekend demonstrations at these ad hoc manufacturing plants typically walk visitors through the block ingredients, the machine that combines them, the rate of output and persons needed to run it, and a test wall. Inadvertently, the teams return with mementos, that, on a Saturday when the drivers are late for the pick-up, become subject of thorough scrutiny:
Darren (the “dropper”) later assesses what went wrong. “Design and ingredients.”
On the one hand, this smithereened block was likely not compressed enough. The tested block had a compressive strength of about half what the minimum standard is for concrete block (although the properties are different, this particular earth block still, ACHEM, fell short).
On the ingredient front, this block was missing any form of sand which would have bonded the cement and the clay together. Fortunately, sand isn’t the hardest thing to find in Haiti (though cleaning it is harder than you’d think), so perhaps a bit of retooling in the kitchen is all these manufacturers need for fall-proof earth block.
