What to expect on pour day

The crew shows up early, usually at first light in summer, because concrete has a working time and the day is planned around it. The first hour is checking. Forms are verified for line, height and slope so water runs off the slab and away from the house. The base is walked and compacted again where it needs it. Reinforcement is placed on chairs so it sits in the middle of the slab. In hot weather the base is wetted so it does not pull water out of the fresh mix. The concrete order was placed the day before for a specific time, and the crew is ready before it arrives.

If something is wrong at this stage, a soft spot in the base, a form that moved, a forecast that changed overnight, the pour is fixed or moved. It is far cheaper to delay a truck than to pour over a problem.

A mixer truck holds a set amount, and a driveway may take more than one. The driver backs to the forms where access allows, and the crew places concrete straight from the chute, working from the far end toward the truck. Where the truck cannot reach, a pump or motorized buggy carries the mix, which is why access is discussed at the site walk. As concrete goes in, the crew spreads it, consolidates it, and screeds the surface to the top of the forms. The pour is loud, muddy and fast, because the mix starts to set from the moment it leaves the truck.

Once the slab is screeded, the crew bull-floats it to bring paste to the surface and close it up. Then they wait. Finishing too early traps water in the surface and weakens it, so the crew reads the concrete and works it when it is ready, which changes with the weather. Edges are tooled, the surface is floated again, and the final finish goes on: broom for a driveway, a trowel and stamp for decorative work, a wash for exposed aggregate.

Control joints are cut with a saw as soon as the slab has hardened enough to cut cleanly, with temperature setting when that is, or tooled in during finishing. They are placed on a grid so the slab cracks in a straight line inside the joint rather than across a panel. Joint spacing is set by the thickness of the slab and is part of the plan before pour day.

The crew washes tools and the chute well away from the slab and the storm drain, pulls stakes, and leaves the forms in place until the concrete can hold its edge, then strips them and cleans up. Before they leave, they tell you when you can walk on the slab and when you can park on it, and weather changes those dates.

For the first several days the slab is curing. Depending on the weather the crew may leave a curing compound on it, keep it damp or cover it with blankets. Leave whatever they set up in place. Full strength comes near 28 days in mild weather, and the maintenance article linked below covers what to do after that.

A few things on your side make the day go smoothly and protect the new slab.

• Move every vehicle off the drive and out of the way of the truck the evening before.
• Turn irrigation and sprinklers off for the day of the pour and the day after, and keep them off the slab for the first week.
• Keep pets and children inside while the crew is working and off the slab until it is hard. Paw prints are permanent.
• Clear the path the truck and the crew will use, including low branches over the drive.
• Tell the crew about anything buried near the work: irrigation lines, invisible fences, low voltage lighting, septic lines.
• Plan to park on the street until the date the crew gives you, and tell deliveries to do the same.