Princeton Friends School Annex

Concrete Block Step Down Footing

2008-03-03T22:51:00.000-08:00

The beginning of the block work for the foundation walls began today. First though, the wooden forms needed to be stripped off of the concrete footings (photo 2).

To ensure that the footings were level, the corners square and the footprint of the building accurate, the footings were surveyed and the corners of the footings were pinned with steel markers. These markers created accurate points of reference for the block masons to lay out
their walls (photo 1).

Because of the change in elevation at the site, the footings at the west wall needed to be stepped down so that they would remain below the frost line. However, the concrete floor of the bottom level of the Annex will be poured to a height 4" above the top of the upper footings.
Therefore, this stepped down portion of the west footings needed to be raised up to the height of the rest of the footings. This was achieved by the installation of this portion of the block wall today (photos 3, 4, and 5).

Tomorrow, the block that was laid today will be grouted solid with concrete. This concrete will fill the hollow cores of the block while also surrounding the steel reinforcing bars which had been embedded into the concrete footings last Friday. This grouting will turn the hollow core blocks into a solid wall anchored to the footings by the steel re-bar. ~ DS

Photo 1 (all photos today are of the concrete block step down footing,
west wall, sw and nw corners)

Photo 2

Photo 3

Photo 4

Photo 5

Concrete

2008-02-29T19:45:00.001-08:00

Views of pouring the concrete for the footings and piers in the basement of the Annex building.

Details (image numbers in parentheses):
A conveyor truck was used to move the concrete from the ready mix trucks to the forms (010, 015). The conveyor truck driver uses a remote control device to maneuver the extension arm into the correct position over the wooden form. The workers in the foundation site guide the
rubber chute at the end of the arm and spread and level the concrete within the form (019, 024). Later steel reinforcing rods are set into the concrete to strengthen the walls that will be built on top of the footings. In each of the isolated piers, four anchor bolts are set. When the steel columns are erected, their bases are anchored down by these bolts with washers and nuts (027). Samples of concrete are taken and tested to ensure that the concrete mix is of the right consistency and will attain its specified strength at the end of its 28 day curing period (016, 021).

Monday, weather permitting, block work for the west, south and north walls will begin. Then later next week, the east wall will be formed up and concrete poured into the forms. In the following week the plumber and the electrician will install their pipes and cables before the
concrete floor of the lower level is poured. ~ DS

Concrete (Photo #10)

Concrete (Photo #15)

Concrete (Photo #16)

Concrete (Photo #19)

Concrete (Photo #21)

Concrete (Photo #24)

(Photo #27)

Details of Foundation Form Work

2008-02-28T21:38:00.000-08:00

The second day of form work is completed. Concrete is scheduled to be poured on Friday, Feb 29th.

~ DS

Postscript: Following are descriptions and details for those among us who are interested in how buildings are put together.

Details: Notice the steel reinforcing bars set within the wood forms. The re-bars sit above the stone base upon small metal frames called chairs (first two pictures). The chairs assure that when the concrete is poured into the forms, the concrete will flow around and under the re-bars. Re-bars are used to reinforce the concrete, reducing cracking and improving the distribution of the building loads. In the isolated piers (third picture) the re-bar is criss-crossed and wired together to form a mat which sits on the chairs. Again, the concrete when poured entirely surrounds the steel.

Side note for trivia addicts: For those of you who have traveled to Cape May, New Jersey, you may have seen the remains of the SS Atlantis, a concrete ship just off shore at Sunset Beach. It was one of twelve experimental concrete merchant ships built during the closing days of WWI, when steel was scarce. Eventually, it was decommissioned and was to be used as a break water at the Cape May ferry, but the Atlantis broke loose in a storm and ran aground. This ship was built using steel reinforced (ferro-cement) construction, much like the footing system seen in the photos below.

But sorry, our new building won't float.

Details of foundation form work of Annex building (east wall footing looking north from location of rm117)

Details of foundation form work of Annex building (looking NE from east wall of rm 105, exterior stairway surround)

Details of foundation form work of Annex building (isolated pier footing)

Details of foundation form work of Annex building (from NW corner looking west, exterior stair of rm 105 in foreground)

Details of foundation form work of Annex building (looking due south from foyer, rm 110, to pierD1, rm 113, west wall of rm 114, sw corner)

Forms for the Footings

2008-02-27T17:05:00.000-08:00

Today the form work for the concrete footings began. The footings support the walls of the lower level which in turn suport everything above them. Within the outline of the footings you will notice additional forms. These are for the concrete bases of the steel columns which will support the floors above. All of this work sits on top of the compacted stone base. Even though we have had rain and snow and the soil around the work site is a soft muddy muck which is hard even to walk in, the stone base remains dry and firm allowing work to continue. ~ DS

Shades of Mike Mulligan

2008-02-21T22:18:00.000-08:00

Views of the work on day three as the foundation excavation continues. There now is so much dirt removed from the hole that the excavator has to load it into a truck and dump it at the far end of the work area.

The track hoe (power excavator) has reached the north east corner of the foundation hole and is moving towards the north west corner. The south east and south west corners were reached Tuesday and Wednesday respectively.

Note the continuing placement of the geotextile fabric and the 16" layer of crushed stone placed on top of it.

Once this stage is completed, the concrete contractor can start his work pouring the footings.

~ DS

Postscript: Parents of young children might want to put Mike Mulligan and His Steam Shovel into the bedtime reading rotation about now.

A Hole Is To Dig

2008-02-19T18:10:00.000-08:00

We have a hole in the ground and a nice new sign to explain what it's for.

~ DS