The building project at the Carrington site is actually taking shape. After the tunnel was done the concrete company moved onto the walls of the containment area. In the picture below you can see the forms for the footings. The footings are the base for the wall to sit on. They are one foot thick and reinforced with re-bar.
The crew had set all the forms so they would be able to pour concrete the next day and it rained again! Rain has been an ongoing issue with this project. Jared Volk our Site Supervisor in Carrington has lived in North Dakota for quite some time and he keeps telling me “this year is not normal”.
I am making a big leap here but as you can see in the picture below the footing forms did get concrete put in them. Also in this picture you can see the form panels are installed for the inside of the containment wall.
Next is the installation of the reinforcing re-bar for the interior of the walls. When the re-bar is installed in the footing the installers will leave a 1 to 2 foot piece sticking straight up out of the footing so they can attach the wall re-bar to it. The strips of metal sticking out from the wall panels are called breakback wall ties. After the outside panels are installed these strips of metal help keep the two panels from separating.
Now it is time for concrete!
The gentleman in the center of the picture is installing the concrete in the wall from the boom truck and the other two are vibrating the concrete in the wall. Vibrations cause the mixture to liquefy, reducing the internal friction of the mix components of cement, aggregate, and water. Thus allowing the mix to move around more easily in whatever form you are placing the concrete. This helps to ensure that enough concrete gets into every little nook and cranny and eliminate voids. Furthermore, the vibrations and liquification help to allow air bubbles to escape. There’s a lot of air in the mix when installed, and too much air in the mix allows for a less dense mixture and therefore can lead to failures and blemishes. The vibrations help to bring those air bubbles to the surface where they escape.
After the concrete has time to set the panels can be removed. As you can see the breakback wall ties are sticking out of the wall. You can strike them in a downward motion and they will break off back in the wall so nothing is sticking out.
Next up is the containment floor!