That plastic bag from Target may end up being used to build part of the boardwalk at your favorite beach.

Trex Co., the Winchester, Va.-based manufacturer of wood-alternative decking and railing products, is suppling materials used to rebuild boardwalks at four East Coast beaches damaged by Hurricane Sandy.

The company, founded in 1996 by four Mobil Corp. executives, recycles about 1.3 billion plastic bags each year from Target, Wal-Mart and other big-box retailers and combines them with wood scraps and sawdust that would otherwise end up at landfills. The result is splinter-free, mold-resistent decking material, 95 percent of which is made from recycled products, that does not need staining or painting.

Trex materials are being used to reconstruct a 1.3-mile boardwalk at Belmar, N.J., and three other smaller boardwalks — at Point Pleasant Beach and Sea Girt in New Jersey and at Atlantic Beach in New York.

Rebuilding boardwalks is not something the company does frequently, since many boardwalks do not have to be replaced for 15 to 25 years, said Adam Zambanini, Trex’s vice president of marketing.

“There’s been more this year just because people are in the race to get [boardwalks] completed before summer,” he said.

The company’s regional sales representatives made product pitches to municipalities in the same way they pitch to homeowners looking to build their own decks and porches, Zambanini said.

“In Belmar, the largest boardwalk we installed, they wanted something high-performance and easy to clean up,” he said. “On boardwalks, ice cream, pretzels and cheese get spilled all the time.”

Trex, which sells its products at about 6,000 retail locations in the United States and Canada, started off as a division in Mobil that later spun off to become its own entity; it went public in 1999. The company started out in the commercial space, supplying materials used in Disney World exhibits and boardwalks. Today, the majority of the company’s sales are in the residential market, Zambanini said.

Like many industries tied to the housing market, Trex was hit by the economic downturn, and in 2009 its stock price dropped to an all-time low. The company said last month that it continues to receive and settle warranty claims stemming from flaking material produced at a Nevada factory prior to 2007.

More recently, its financial outlook has improved. Last month, Trex reported 2012 net sales of $307.4 million, up 15 percent from $266.8 million in 2011.

Trex’s chairman, president and chief executive, Ronald W. Kaplan, predicted a stronger year in 2013, “during which we expect to benefit from the growing momentum in the housing sector,” he said in a February news release announcing fourth-quarter sales results.

Kaplan is counting on two new products the company introduced in January that it hopes will help Trex grow in new markets — aluminum railing for multifamily homes, and a product called Trex Select that competes with PVC vinyl railing used in building houses.

“Aluminum railing gets us into multifamily operations,” Zambanini said. “That market alone is a $125 million market. That’s an opportunity for us. Trex Select, that’s the first time we’ve had something comparable with PVC on price. That’s a $189 million market.”