29 September 2009

Time Cures All Ills and Concrete

Curing, in Construction vernacular, is when concrete transforms from the liquid state to a solid state (7 days = 70% strength and 28 days = 100% strength). We began prepping for the next phase (Foundation walls) the day after we poured the footing. Although the concrete had not completely cured, the surface was solid enough that one or two can walk on. Remember, concrete is an excellent material under compression. The guys tied the vertical and horizontal rebar grid (Spacing 12" x 12"), placed the bond breaker barrier (So out foundation wall doesn't attach itself to the neighbors) and then...

erected the form work. The form is the layer (Made out of plywood and steel angles) that one creates the negative space, and where the concrete will be pumped into to create the positive space. Notice how the forms are braced so the weight of the concrete does not blow them out (Diagonal wood members and horizontal 2" x 4" members along the form edge).

The guys are relaxing before the storm, aka the 12 yard concrete truck (12 yards = 11 actual yards because there is hard shell of concrete inside the drum). Notice more diagonal bracing and a platform where the guys can manage the pumps hose (The hose is in sections and lying on top of the form, clamped at every section). As the concrete is pumped to the farthest distance, a section of pumps hose is removed (And cleaned) and concrete is pumped to a closer section of the form.

Concrete goes into the pump..

and out of the hose and into the form. In this image, Jose is standing on the hose pump while Cigaro and Lucio are vibrating the concrete mix. The concrete vibrator is used to make sure that the concrete surrounds itself around the rebar and prevents honeycombing (Small pockets of cavities).

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