How Tech Ticks
Rock out
by Richard Lovegrove
Photos by Logan Wallace • Video by J. Scott Parker
Virginia Tech has been operating a quarry of some sort since the 1800s (one quarry was where Derring and Cowgill halls now stand), blasting and cutting Chepultepec and Kingsport dolomite of various hues that are then laid out in an "ashlar" pattern to give campus buildings their distinctive style.
1. Shooter
The method that shooters at the quarry use to separate large slabs from the shelf of rock is a bit old-fashioned and traditional. Typically, they rely on black powder measured out in a Vienna sausage cup, though they'll employ dynamite when it appears a layer is going to result in useless scrap. Workers drill 20-25 holes with a 1 3/4 drill bit, run 250 feet of drop cord, then hook it all to a battery-powered detonator. They do yell "Fire in the hole!"
2. What about the colors?
Stone from the university quarry is primarily shades of pink and gray, but the façade on Hokie Stone buildings calls for 20 percent black rock. This comes from a quarry in Luster's Gate, about 600-700 tons a year. Called a "bull nose," stone on older buildings protrudes more than modern rock.
Rocks fall
Rocks collected
3. Stone blocks
Quarry workers prefer the largest blocks that can be fit on the saws, but if they're too large, they look for a good seam, drill into it, insert a hydraulic splitter, and slowly break the slab apart. A loud "pop" means good stone.
4. The saws
The stone slabs are then moved onto one of two enormous saws. The blade saw has 140 diamond teeth and is replaced every three months. The quarry also uses a wire saw made up of aircraft carrier cable (used to snag aircraft landing on ships) covered with plastic inserts and diamond-embedded metal joints. Both saws are run by computer, which notifies the quarry manager if they stop or jam.
5. The breaker
Quarrymen take blocks from the saw and feed them into a breaker that applies 3,000-3,500 pounds of pressure to crack them into predetermined sizes. The useable pieces are stacked on pallets that hold about 2,350 pounds. The quarry produces about 60 pallets per week. The order for Goodwin Hall required 3,200 pallets, or a little more than a year's work.
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