-Get hard
-Turn gray
-Crack
My dad and I finished building the forms for the grade beam that sits atop the gravel trench and also for the footing that will support the wall separating the garage from the shop.
This is the form for the footing. It is roughly 2 feet wide and 10 inches deep. Notice the re bar placed at the bottom third of the trench. This will provide tension in the lower part of the concrete to keep the wall load from cracking the footing.
A detail shot of the footing where it hits the grade beam:
The next pictures are of the grade beam forms. The grade beam is 12" high and 14" wide with 2" of foam adhered to the inside edge. You can see there are two layers of re bar surrounded by a bent piece of re bar called a stirrup. All of this bar keeps the concrete stable in all directions,keeping the wall load from cracking the beam, but also keeping the beam from shifting in or out on the gravel trench. I did a back of envelope calculation one time and figured the weight of the walls, roof and snow load at roughly 75 tons, so all the re bar is a good thing. At spots in the wall where there will be floor level openings (also know as doors), we had to step the forms down. A lower band of concrete and one layer of re bar continue underneath the doors to keep the side-to-side integrity of the grade beam intact.
The forms:
A detail shot of the corner:
The step down and back up for the garage door:
A step down and back up for an access door:
Once we finished straightening and levelling all of the forms, we called in the concrete. Since I did not have enough room to pour directly from the concrete truck, I rented a pump:
The truck pours the concrete into this hopper:
And the machine pumps is out this very long (and very heavy) hose that is being unreeled by the pump owner:
Using the pump, we "sprayed" the concrete into the forms, leveled and smoothed it off at the tops, and covered it with tarps and plastic. I would like to say I have pictures of this pouring process, but my camera had an operator failure (if I cannot even operate a camera, should I be allowed to build a building?), and I did not manage to take pictures during the pour.Here is a picture of everything covered up with tarps:
Contrary to urban legend, concrete does not "dry" it "cures." The chemical reaction that makes concrete get hard and turn gray requires moisture and lasts, in this situation, about a week or so. So the tarps and plastic will stay in place for many days, allowing the grade beam and footing to become as hard and strong (and gray) as possible. Eventually, we will have to take the tarps off. At this point, the excess water in the concrete will evaporate and the third step will happen--the concrete will crack (assuming the crusty old contractor is right). Don't worry, the cracks will be small and most likely harmless...
