Now that I am
retired, I can look back with fondness … or amusement … or embarrassment at
some of the jobs that I have had. Some have been interesting, but I have had my
share of spectacular failures.
The summer after
my sophomore year in college, I scored a great summer job as a concrete inspector. A
twenty year old kid, pretty wet behind the ears, I would drive sometimes 60
miles to a construction site to perform a simple test, called a “slump test,”
on the concrete from each truck before it was poured. I would get a pail of
concrete from the truck, and fill a slightly cone-shaped foot-high tin cylinder.
Then I would slowly lift the cylinder, leaving the pile of concrete unsupported.
If the pile saged three inches, the concrete was good to go. If it didn’t sag
enough, the driver would add more water into the truck, then I would test it
again.
A brief discussion
of concrete and water: water is essential to a good concrete mix. Too little
water, and some of the cement is not dissolved, leaving dry cement powder and
weak spots. Too much water, and the cement paste becomes runny. The sand and
gravel start to separate from the paste and settle out. When the cement truck
is initially loaded at the plant, the right amount of water is added. But as
the concrete is turned in the big round tub on the back of the truck, water is
lost due to the heat of the sun and chemical reactions in the cement. So the
driver often needs to add more water at the job site. Also, the concrete workers
much prefer wet concrete that will flow easily into the forms. So there is a constant
tension between the need for water so that the concrete flows well, and the
need to keep excessive water out so that the concrete is stiff and strong.
So I would perform
my test. If the concrete was dry, more water was added. If, however, the
concrete sagged too much, the concrete in the truck is too wet, and there is no
way to dry it out. I got to tell the driver, the foreman, and anyone else who
cared, that the truckload is rejected and has to be sent back. Picture a cement
truck driver. Picture a construction site foreman. You can imagine how well
that goes over.
One hot summer day
I was sent out to a construction site, an addition to the library in Lynn
Massachusetts. Nine foot high plywood forms for a new wall were baking in the
sun, waiting for the concrete. I tested the first truck that pulled up. The
slump test passed: good stiff concrete. They maneuvered the chute over the
forms and started pouring.
Almost immediately
the foreman stopped the pour. “We’re going to have to add more water.”
“Can’t,” I
replied. “the concrete is perfect right now.”
The foreman paused
for a minute. “The forms are so hot,” he said. “The moisture will evaporate as
soon as it hits the walls. We’re going to get bubbles unless we add more
water.”
I had been a “concrete
inspector” for all of two months. Judgment calls were out of the question. I
had done my test, and that was that. “Can’t add any more water,” I repeated.
“Ooooh Kaaay,” the
foreman said slowly. “Let’s pour it,” he hollered up to the truck driver. The
big drum turned, and the concrete poured out into the tall forms.
A week later when
I called in for my daily assignment, my boss at the testing lab told me to meet
him the next morning at the library. As I parked across the street I could see
the wall. They had pulled the forms off the day before, and even from a
distance I could see that the surface of the wall was covered with bubbles and
pockets, some of them as big as a fist. There standing in front of the wall was
my boss and the same foreman from the week before.
“What happened?”
my boss asked. I explained that the concrete had tested perfect. Something told
me that it was also important to explain that the foreman had predicted
problems if they didn’t add more water, and that I had refused to allow it. My
boss just nodded his head a bit as I spoke. “Well,” he said finally, “better
get on to the next job,” and he gave me the address. As I turned to go, the
foreman said “It’s OK, kid. You did what you had to do.”
I walked to the
car, feeling like a failure, but also feeling like I had passed some other test
that I couldn’t quite explain.
Frank Kearns
May 2015
