Day 2

It makes a big difference when you have a relatively steady supply of concrete. Even though Wednesday's 20,000-square-foot placement involved four different mixes, it went a good bit more smoothly than the first day. All the concrete was down by 3:30 and the power trowels were doing their best to finish it off.

Meanwhile the testing firm made several runs with the D Meter, provided by the Allen Face Companies. The device is similar to a Dipstick, but uses a somewhat different measuring protocol. The readings from the first section, bounded by column lines C/D and 3/4, gave an FF of 46.4 and an FL of 29.1.

Another crew also came in and scanned the previous day's slab, using a Trimble laser scanner. In addition to comparing this information with future scans, the plan is to share the collected data with the ACI 117 Tolerances committee as an example of real-world slab-on-grade placement.

Again it was clear that the vapor barrier, although puncture resistant, takes a beating as ready-mix back over it to deliver the early loads, especially as they turn their wheels to navigate around the tube steel columns. And how the crew deals with folds and other deformations is most interesting. Enough on that for now.

While the weather on Tuesday, the first day, was clear, sunny and breezy with near-record high temperatures in the 60-degree range, Wednesday brought dropping temperatures and it rained throughout the day - good concrete weather when you're inside a warehouse with the doors only partially open.

Thursday should be interesting, as it will include the stiffest, most high-fiber mixes. They tried placing one trial load of it this afternoon by one set loading docks. The way it hung in the rebar graphically demonstrated the effect of the fiber. Thursday should be interesting.