We talked about concrete going into the construction of the footings and the walls. In these pictures, we see it is also used for the driveway. In the first picture, the concrete truck is dumping the mixed concrete into a concrete buggy. This buggy is then driven to the specific area that needs to be built.
But how does the concrete get to this stage? The concrete truck goes to the plant and gets filled with a mixture of Portland cement and aggregate, comprised of both sand and gravel. The ratio of cement to aggregate is determined by the required compressive strength of the concrete. This is mixed in the drum of the truck which is the circular gray section you see to the left of the picture. The fins inside this drum are what is used to help mix the concrete. There is a limited time from adding the water, to mixing, to pouring the concrete. If it is done too soon, the concrete will not be properly mixed. If it is done too late the concrete will be too hard to pour.
The picture to the right shows the concrete buggy is going to the workers who are actually shaping the driveway. They put in the forms for the edges. Then a gravel base was laid. Upon this base is poured the concrete. The workers spread the concrete to the required depth and use a strike off to pull out any bubbles and smooth the concrete.
After that section is completed, you see how more concrete is poured behind the workers. They shovel it onto the edge to develop the curbs. They use a wood darby to shape the curb.
The concrete must set for a minimum of seven days before it is able to be used and does not reach full strength for 28 days. Water should only be added when it can be thoroughly mixed, rain on top must be removed and the concrete re-floated. There can be too much rain and then the pour would have to be removed. To help prevent this burlap and plastic was put on top when the rain was predicted. Timing is everything in construction and having the correct weather helps. As it happened, we only received about two tenths of an inch of rain and the driveway could cure.
Here is a picture of the finished driveway.