Final Building Foundation Pour

We completed the fourth and final building foundation pour yesterday, and the crew worked quickly today to disassemble the forms on the interior walls and columns, so that the excavation contractor can start importing fill material tomorrow morning. We used around 25 cubic meters of concrete, but it was a time  consuming pour because it was all in small, constrained spaces as you can see from the photos below.

(forms and steel reinforcement are ready)

(crew standing on the forms waiting for the cement pump hose to get within reach) 

(guiding the pump truck hose along the wall forms, while crew on the ground gets forms wet)

(pouring the walls for the elevator shaft and the stairwell)

The building is starting to take shape as the exterior wall location gets defined and the elevator / stairwell area becomes more clear as well. After tomorrow, the fill material will be imported, compacted and rolled, and brought to within 10 centimeters of the future slab on grade elevation. Then we will excavate for the Ground Beams that tie the columns together, lay the steel in the trenches, place the wire mesh / grid on top of the compacted fill, and pour the slab and the Ground Beams at the same time.

(pouring the column necks to within 10 cm of the slab on grade) 

(concrete and water oozing from the forms immediately after the pour)

While the excavation contractor is doing his thing over the next 4 days, the crew will be working on the reinforced concrete retaining wall that will separate the site from the future street along the north (front) elevation. The total height of the wall will be 5.5 meters (~18 feet) with a footing that's 2.6 meters (~8.5 feet) wide. Here's a picture of the crew clearing the area for the foundation steel, while two others start setting the forms to hold in the concrete from the next pour for the retaining wall foundation. More on this to come in the next couple of posts.

(cleaning and setting forms for retaining wall footing)

Second Foundation Pour

The second foundation pour took place a couple of days ago, and everything went smoothly. We should have one more pour that includes the stair case and elevator shaft foundation, before starting to form the columns and prepare for the fill material to be placed below the slab on grade.

Below are a few photos of the rudimentary methods used in preparing and erecting the timber forms, which I continue to find strikingly old fashioned and ingenious at the same time:

(short footing edge formed with dirt and rocks)

(braces for the forms anchored with boulders)

The main element of support the crew needs during this stage is ensuring that the column and wall centers are accurate compared to the axis given to us by the surveyors, that the spacing and proper thickness of steel reinforcement bars are used, and that the layout of the steel for the column necks is correct. 

(close up view of one of the footing forms, still missing steel)

(forms completed)

(calculating steel reinforcement beam spacing and locations)

We calculated that we would need around 45 cubic meters of B300 concrete, placed the order and called the geotechnical engineer to schedule the testing crew again. They showed up a few minutes before the mixers arrived and took a sample from each mixer batch to test. After the 5 footings were poured, we ended up using 42 cubic meters of concrete.

(steel in place, concrete pump arrives with the fog from the valley)

(crews directing the pour, vibrating the concrete already placed, and smoothing the surface)

The next few days will bring the forming and steel setup for the stairwell and elevator shaft, the final foundation footing pour, the forming of the column necks, and preparation for construction of the 5.5 meter tall concrete retaining wall between the building and the street. 

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.