CoatingsPro Magazine

MAR 2015

CoatingsPro offers an in-depth look at coatings based on case studies, successful business operation, new products, industry news, and the safe and profitable use of coatings and equipment.

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COATINGSPRO MARCH 2015 51 equipment in a matter of seconds." Te team fred up their Graco Reactor plural component sprayer and began laying down the GEO-TEK 4950. Te nozzle man worked in 20- by 30-foot (6 m by 9 m) grids and simply sprayed as much as he could in a single day. "He worked in a cross hatch pattern fashion w ith roughly three-foot [0.9 m] sweeps: two horizontal and two vertical," Faltus said. " T he goal was to keep the tip about two feet [0.6 m] from the concrete and aim the nozzle straight dow n (per pendicu- lar to the substrate) as much as possible to let it build. If you tr y to build 100 mils [2,540 microns] in one sweep, you're not going to be as accurate as if you do it in four crosshatches. T he poly urea sets quick ly, so overspray was not an issue." GEO-TEK 4950's fast-setting properties helped in another way. On this project, the CUI crew didn't have the luxury of waiting for the entire land bridge to be covered by polyurea prior to installation of Creative Polymers' PLIA-THANE 4975. So part of the crew splintered of and hooked up a Graco XP 70 plural component 2:1 pump to a ⅜-inch (1 cm) "B" compo- nent line, a ¼-inch (0.6 cm) "A" line, mixing block, two static mixers, a 20-foot (6 m) whip, another static mixer, and an 8-foot (2 m) whip. Te whip led to a Graco XP 7 gun armed with a 535 tip. Te crew fred up the rig, and soon a second nozzle man was spraying polyurethane while the frst sprayed polyurea. Little did they know, they had a hidden audience. "I rode up the Gateway A rch and shot a v ideo one af ter noon," Jarboe said. " T he neat thing about this combination is that as the poly urea is being laid dow n, sometimes w ithin 30 to 45 minutes, they were putting dow n poly ure - thane. Usua l ly you put dow n your basecoat and have to wait over night. It was ama zing to see both applications going dow n nearly simu ltaneously. T his a l lows an entire section to be 100 percent completed on the same day in a coord inated fashion. T hat helps productiv it y." To build the PLI A-TH A NE 4975 to 50 mils (1,270 microns) (approximate DFT), the nozzle man aimed the gun straight dow n and kept the tip less than a foot (0.3 m) from the substrate. T his helped control overspray, too. As soon as the nozzle man achieved the specified mil thickness, other crewmen went behind and laid dow n five-foot-w ide (1.5 m) swaths of US Fabrics' eight-ounce (227 g ) geotextile fabric w ith si x-inch (15 cm) overlaps. Other crewmen used nine- and eighteen-inch (23 cm and 46 cm) rollers w ith half-inch (1 cm) nap covers to press the fabric into the still-wet poly urethane. " You have to make sure you get the fabric completely saturated," said Faltus. "It's pretty apparent if you don't because you're going to see bubbles. You have a bit of time so you can always roll again if needed. If you go back later and find that a bubbled area has set up, you just slice it up w ith a knife, load the section w ith more poly urethane, put a fabric patch on top of it, and wet it again." Monumental Land Bridge Th e c rew s p ray - a p p l i e d a 1 0 0 - m i l ( 2 , 5 4 0 microns) pass (approximate DFT) of fast-setting polyurea. The applicator worked in 20- by 30-foot (6 m by 9 m) grids with quite the 630-foot-tall (192 m) backdrop!

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