This week construction crews are scheduled to begin the pouring of concrete through the rooftop hatch at the top of the Freret Street emergency stairwell and into the forms now built for the shear wall slab inside. For this, two big trucks carrying the concrete will need to be directed through the fenced construction zone's main gate and the concrete itself will be transported to the top of the roof (and into the forms) through a tube attached to a large “boom,” which looks sort of like a thin crane on wheels. The trucks should arrive on site Thursday afternoon and Friday morning; the boom will also need to be brought on site in advance of the pour.
A pump at the base of the boom that will force the concrete through the tube may make some noise outside the library building.
The pouring will take place in two stages. This week's first stage will pour the slab from the base of the 3rd floor to the base of the 4th floor within the emergency stairwell. The second stage will repeat the same operation near the end of the following week, but from the base of the 4th floor to the roof.
Once the shear wall is poured and the concrete sets, the contractor can then begin to finish the inside and outside of the stairwell, which should be returned to normal in a few weeks and on schedule. Indeed the stair cutting operation described in the previous post was completed in less than half the expected time frame.
The contractor will also very soon begin work on the the slab foundation that will be the materials ramp and base of the external elevator planned outside the library building in the fenced construction zone. The external elevator will be used to regularly transport crews and materials to the rooftop.
Meanwhile, work crews have already completed the rooftop handrails and grid-like safety lines that will allow for more workers to begin preparatory operations on the library roof, even in advance of the external elevator.
Eventually, and before the fall semester study and exam period that begins Dec. 6, the contractor will need to drive 55 piles, in a 20’ x 25’ space near the former main entrance to the library, for the foundation that will serve as the base for the construction crane. Because the piles will be driven in a relatively confined space, the time frame for this task is expected to be limited to a period of 4-5 days. About a dozen piles will also need to be driven in a smaller area between the library and Dixon Hall for a foundation that will eventually serve as a base for a permanent emergency generator for the building.