Thursday, May 5, 2011

Foundations & Concrete

Work has been progressing relatively quickly at the site for the past week. Once the marks for the foundation axis were established, the crew went to work setting up forms for the foundations that will support the building columns. I find myself constantly impressed at how old-school the methods used to accomplish this work are: all the measurements (after the surveyors gave us the initial markings) are taken with a tape measure and the crew uses string, a level and spray paint to mark form locations, all the elevation levels are taken with a clear hose filled with water, then measured from the benchmark set by the surveyors on the 'bracelet' fence surrounding the site, wood boards are fastened together using metal wire and supported by large rocks and dirt on the outside edges.

Keep in mind there have been only 4 workers on the site this whole time, we only added a fifth two days ago to prepare for the pouring of the first layer of concrete (the Blinding, called 'nadaaf' in Arabic, or clean layer) which will allow us to set up our steel reinforcements on a uniform, horizontal surface.

Below are a few photos of the site over the past few days, showing various stages of development:

(workers and foreman discussing progress)

(setting a new mark for the edge of a concrete form using string and a level)

('bracelet' on the right and forms on the left, before cleaning the pour area)

(the forms taking shape)

(areas around the forms are getting cleared of debris)
In addition to the construction oversight, project budget management and scheduling, I've enjoyed learning (or remembering) how to perform some of the engineering calculations required for the ordering of materials and supplies. We had our first order of reinforcing steel arrive at the site today:

(delivery truck unloading steel)

(steel of various thicknesses and shapes, based on the foundation design)
After finalizing our price negotiations with the concrete plant yesterday, the time came to receive the first batch of concrete for the nadaaf areas that were ready. Based on the surface area we calculated and a 10 cm thickness, we ordered 15 cubic meters of concrete with +/- 2 cubic meters that were allowable for return if need be. The mixer trucks carry 9 cubic meters each, so we had two mixer trucks and a big (52 meter) pump truck come out to the site today:

(setting up for initial concrete pump, & spraying water on the ground underneath it)

(ready to go)

(pumping begins and the crew goes to work guiding, shaping and smoothing)

(each crew member knew what to do, worked very efficiently)

(tough job of guiding the erratic pump hose manually)

(foreman giving directions on depth)

(almost done)

(foundation base is in place)
We can't forget the floor of the new site bathroom (not quite portable), so that there's a flat surface to stack the concrete bricks on for bathroom walls:

(barrel with sawed opening in the middle)
And here's the site after the week's work was completed:

(1 week down, 76 to go)
The crew started right back up setting forms for the remainder of the foundations that will get poured with the next concrete order. We used 16 cubic meters this time around, quite close to the estimate we calculated. Next week should be more of the same, but we'll get closer to pouring the actual foundations and ground beam, which will allow us to set up the column necks then fill around them to get to the finished slab elevation for the bottom of the second basement floor.

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