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My builder, Bob Emery, arrived at 0800 Monday morning to form up for the 6" slab and install the rebar.  We quickly realized that we had never discussed whether or not the slab was to be insulated; I decided that 2" Styrofoam insulation beneath the concrete was definitely the way to go, so Bob and his helper drove a short distance to the local lumberyard and picked up the necessary materials.

When they returned, they quickly set to work building the 2x8 formwork for the slab; concrete was due later in the week.  As soon as the form was built, however, a problem came to light:  the compacted slab base was nearly 6" out of level in the back corner, meaning the form was high above the earth when it was leveled.  Looking at the pad, it was easy to see the dip.  There was no way to continue work with the foam and rebar until this problem was taken care of, so I called Scott Dugas and left a message while Bob and his helper left for the day.  Dugas called back a few hours later, and promised to send someone over right away.  Within moments of hanging up the phone, it seemed, a small dump truck pulling my dream John Deere tractor pulled up.  Wow--great service.  Thanks, Scott!

The solution was relatively easy.  Just add some fill to the low spots and rake it out level.  The driver left in the dump truck and returned with a load of crushed rock, which he dumped inside the three remaining sides of the form (Bob had removed the front for access for this purpose) and then pushed into the back corner with the John Deere's bucket as needed.  After an hour or so of work, he was done, and  loaded up and departed.  The new fill leveled the back end of the slab base nicely, right up to the bottom of the formwork.  These sorts of issues are common enough in construction, but it's still a little demoralizing to have the work finally begin on a barn that's been in the planning stages since January, only to have work have to stop only an hour later because of something that was out of my, or anyone's, control.  The end result, however, is a success, and fortunately the concrete truck wasn't due later the same afternoon; that would have been more difficult to work around.  This was more of an inconvenience for  Bob, who lives 40 miles away.

The next day, Bob returned to finish preparations.  He and his helper laid down the 2" blue Styrofoam, then set up a grid of 1/2" rebar above, laced together with small wire ties.  The job took a few hours, after which they raised the grid up partway off the Styrofoam base, supported with pieces of broken bricks.  This will ensure that the rebar ends up more or less in the center of the concrete slab, not sunk to the bottom.  With the formwork in place, I got my first real idea of how big the barn was going to be.

Concrete day!

The house was inundated with pickups first thing in the morning, as Bob and his crew of concrete guys arrived to take care of last minute preparations before the load of concrete arrived.   This included completing a small section of the rebar (they ran out of wire ties and needed to secure a small section of the grid) and add a 1" spacer on top of the entire formwork to ensure that the minimum thickness of the slab would be between 5"-6".

Shortly thereafter, one concrete mixer arrived, but there seemed to be a problem of some sort--there was a flurry of cellphone calls, and then Bob left in his truck somewhere.  I think he had to head out to lead a second concrete truck to the site, since they apparently couldn't find there way here.  The whole crew stood around for 30 minutes looking ever so much like a state road crew.  Then a second truck arrived, and the pour began.  As things progressed, a third--and finally a fourth--truck arrived, and by 1000 the pour was complete and roughly smoothed out.  

Click here to see a series of photos from the concrete pour and the finished slab.

With the initial troweling complete, I stuck a cornerstone in the front corner near where the entry door will go.  I thought a bronze Pearson Triton plaque, stamped with the year of construction (2003) would be appropriate.  To protect the plaque during power troweling, I covered it in multiple layers of tape.

After an hour or so, the concrete was setting enough in the back corner to begin the finishing and smoothing process.  With a pair of power trowels, Bob and his crew started the long and laborious process of smoothing the concrete, forcing the aggregate down and bringing up the liquid cement, or "cream".  At first, the trowel seemed to only scuff up the surface and make it look worse, but as the material continued to cure, it burnished the surface to the smooth, hard finish that we associate with concrete.  After a few hours of on and off work, the job was complete.

 Click here to see a series of photos from the concrete pour and the finished slab.

Any large concrete slab has a tendency to crack over time--it's just one of those things.  To that end, Bob came down Saturday to cut some relief joints in the new slab.  The point is to either encourage cracking to begin in these joints, or to provide a stop so that any cracks that do form on the surface will only go as far as one of the joints, then stop.

With a circular saw and masonry blade, Bob cut about 1/2" into the slab, dividing it longitudinally into two sections and crosswise into three.  When the grooves were cut, he filled them with flexible concrete caulk to prevent junk from getting in there and becoming stuck.

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