Laser grading, moisture meters and infrared repair

The truck has three things on it that were not there when I started: a laser, a moisture meter and an infrared thermometer. None of them does the work. Each of them prevents a mistake that used to cost a season. Here is what each one is for, and the fourth tool, an infrared heater, that changed how a pothole is fixed.

The laser, for the plane

A court is one plane with a fall of 0.83 to 1 percent, and the construction guides allow no depression deeper than about a sixteenth to an eighth of an inch under a ten-foot straightedge. For most of the trade's history that plane was set with a transit, string lines and a straightedge, and checked with a hose. A rotating laser level sets the plane once, from a tripod at the edge of the pad, and a receiver on a grade rod tells the operator at any point on the court whether the stone is high or low and by how much. On a new court the base goes in to the laser, lift by lift; on a laser-guided grader or box blade the machine holds the plane itself. The result is a base that is right before the asphalt covers it, which is the only time it is cheap to fix. We still flood-test after paving and after the resurfacer, because the laser checks the plane and water checks the court.

The moisture meter, for the slab

Acrylic coatings bond to a dry surface, and asphalt and concrete both hold water that you cannot see. A coat over a damp slab blisters as the water tries to leave through it. The old test was a square of plastic taped to the surface overnight: condensation under it meant wait. A pinless moisture meter gives the same answer in a second, at twenty points across the court, and a number to write on the day's sheet. On new concrete, which can hold water for weeks after it looks dry, it is the difference between a surface that lasts and one we strip off the next spring. The same meter tells us when a pressure-washed court is dry enough for the resurfacer, which on a humid August morning is not when it looks dry.

The infrared thermometer, for the day

Every coating has a minimum: the surface and the air at 50 °F and rising for acrylics and sealers, with a ceiling too, because a coat on a 140 °F court flashes off before it levels. Air temperature is on the radio; surface temperature is not, and a dark court in April sun can be twenty degrees warmer than the air, while a shaded court in October can be ten degrees colder. A point-and-read infrared thermometer settles it in a second and settles arguments: the number goes on the sheet with the time, and if a coat is applied, it was applied inside the maker's range. In the shoulder weeks of May and October, this is the tool that decides whether the crew works.

Infrared repair, for the pothole

A conventional pothole patch is a cut-out: square the hole, compact the base, fill with hot mix, roll. It works, and it leaves a seam all the way around for water to find. Infrared repair heats the existing asphalt with a panel until it is workable to a depth of an inch or two, rakes it, blends in fresh mix and a rejuvenator, and compacts the whole area as one piece. No seam, no cut, no haul-off, and the patch is open to traffic in an hour. It is the right tool for potholes, utility cuts, catch-basin collars and the raised edges where a plow has caught; it is the wrong tool for an area whose base has failed, because heating the surface does nothing for what is under it. On a lot kept on the sealcoating cycle, infrared handles nearly every spring repair.

What they add up to

None of this is visible on the finished court. What they change is the number of surfaces that fail for reasons that were avoidable: a low spot that should have been caught at the base, a coat over a damp slab, a coat applied on a cold surface, a patch that let the water back in. Thirty years ago those were a share of every contractor's callbacks, including ours. The instruments took most of them away, and the day sheets with the numbers on them are what we show an owner who asks why the coat went on Tuesday and not Monday.