Wednesday, July 28, 1999Pouring the Slab
Wednesday, July 28, 1999(Click on any photo to see a larger version of the picture.)
This was a day to remember. T.B. and Don and the concrete crew arrived at 6 a.m. The pumping truck and the first concrete truck arrived at 7. The early start is imperative in the July heat, since the hotter the temperature the faster the concrete sets. Starting early gives the crew a little more time to properly finish the concrete before it's too late.
The concrete is poured from the truck into a pumping bin attached to another truck, and from there flows through a hose up to the slab. Lots of volume, lots of pressure, so several people hold the hose to make sure it stays under control and doesn't give everyone concrete showers.
The finishing crew steps into action as soon as the first cubic yard is poured. Wearing rubber boots, they wade right in, making sure that the concrete fills the forms and is level with the screed boards that mark the finished floor level.
The photo left shows the concrete contractor Joe Markie (green shirt) and two of his crew working the concrete as Leo the pumper (2nd from left) handles the hose end. In the right background, T.B. and Don hold the hose for Leo.
Once the concrete in one section is roughly leveled, the crew tamps it (see Reuben below left) to settle it into the bottom, and then smooths it with long-handled tools. The grid lines for the finished floor are drawn and pressed into the slab. All these processes are repeated, some many times over, as the concrete sets.
When the entire slab has been poured, tamped, leveled, smoothed, and grid lined, the finishers set out with hand tools to smooth the slab again and again. Some of the crew work from the edges; others (right) kneel on snowshoe-like sleds and skim slowly over the concrete as they work it.
When the concrete has set to the point where it can no longer be worked, the process is finished. The crew hoses off the tools and the owner (that's me) breaks out the sodas and beer for a little celebration. For a little while I get to pretend to be one of the guys, and we enjoy the river view and I marvel at the beautiful new slab.
For the finished slab is a thing of beauty. It is not perfect; some areas are slightly lower than others, there are trowel marks and unevennesses. But this is the nature of concrete -- it's not Corian --it would be virtually impossible to make it perfectly smooth. The marks and imperfections give it character; I see it aging gracefully, developing a patina from all the nicks, scratches, and stains that it will inevitably pick up over the years.
But I'm getting ahead of myself. First we have to care for the slab while it cures. To slow down the setting process (thereby lessening the likelihood of cracks), we need to keep it moist. "The more water the better," says my friend Roland, and T.B. agrees.
So I have a new job now, hosing down the concrete several times a day. It is the greatest job, and not just for the obvious joy of spraying water around on a hot day. I have determined that to do this job properly I must shed my shoes and walk around on the slab in my bare feet. The feel of the warm water puddling on the smooth slab brings back memories of walking through a large warm shallow wading pool when I was a child. It is a happy time for me. I am learning to love this slab.
The concrete will take 30 days to fully harden. In that time it can be easily scratched or nicked, so we don't allow anyone to walk on it with shoes. Even Sam is forbidden to walk on the slab, as her toenails could scratch it and her paws will track dirt and grit. We will put down cardboard as we work on the walls.
After it has cured, we will finish it with acid washes and stains -- a topic for another day's writing.