Generically known as green or water board (due to its green paper facing), green board is a common reference in the industry to water- and moisture-resistant gypsum wallboard (used typically as a substrate for ceramic tile applications). Nowadays, the term green board has a dual meaning. Due to its environmental or green benefits, synthetic gypsum--created as a byproduct of the electric power generation process--has also become known as green board.
New heights
The mineral rock gypsum (calcium sulfate) has been used as a building material since ancient times. Created over millions of years as the result of salt water evaporation (salt water has a high concentration of calcium sulfate), gypsum deposits are found in abundance throughout the world. Two events in the 20th century revolutionized the use of gypsum as a building material: the war and the airplane.Needing a material that was a dry application and fire-resistant, gypsum board panels were first introduced during World World I for the construction of army barracks. After the war, gypsum panels lost favor to traditional lath and plaster because there was no efficiency in the installation of the panels.
Howard Hughes, the industrialist and aviation pioneer inadvertently changed all that when he set out to build the world's largest airplane in the 1930s, the "Spruce Goose."
Made of spruce plywood, Hughes' engineers had to come up with a method of attaching the plywood panels to the airframe in a quick, efficient and secure manner. This led to the invention of the screw gun. Not only did this invention make possible the construction and one-time flight of the Spruce Goose, it was adapted as a fast and easy way to screw-attach gypsum board panels to framing members. This made gypsum drywall efficient to install and a cost-effective alternative to lath and plaster.
The city of Paris, France, is built on a foundation of gypsum rock. It was the construction of the famous sewer system in Paris that generated the displacement of thousands of tons of virgin gypsum rock. As the main ingredient for making gypsum plaster--and with it in such abundance--gypsum plaster came to be known as Plaster of Paris.
In the United States today, 21 million tons of natural (mined) gypsum are consumed each year. Of this total, 75 percent is directed toward gypsum panel production.
As lucky can be
Synthetic gypsum has existed since the 1980s, but its boost in use came as a result of federal legislation. In an effort to reduce sulfur-dioxide emissions (the prime cause of acid rain), in the 1990s Congress mandated that power plants burning high-sulfur-content coal spray a combination of powdered limestone and water mist in their chimney stacks. When combined with the flu gases from the coal fired furnace, the resulting byproduct is calcium sulfate: gypsum. This process is referred to as flu gas desulfurization. It reduces sulfur emissions into the atmosphere by more than 96 percent.Beyond the benefits of scrubbing pollutants and preventing them from being discharged into the environment, the construction industry gained a new and, in many ways, superior form of gypsum. It is the purest form of gypsum with smaller, more consistent particle size than mined gypsum--without the burden of additional cost. Of course, it also reduces significantly the need for mined gypsum providing an alternative, continuously available and abundant source of raw material. Inclusive of shipping, synthetic gypsum costs about $11 a ton. Compare that to mined gypsum which costs about $23 a ton--more than twice the cost.
The green--in the form of reduced costs--has been an important component in the adaptation of synthetic gypsum core products by major manufacturers.
Gypsum board plays a key role as a barometer of the relative health of the domestic construction industry. With the construction boom of the 1990s, gypsum wallboard was often in short supply and prices were at all-time highs. Now, with the economy in the doldrums, sales have leveled off, as have prices, and the supply-demand equilibrium is in balance once again. Gypsum wallboard is perhaps the most widely used building product. As such, the increasing use and availability of synthetically produced gypsum plays an important, fundamental role in stabilizing and augmenting the supply of gypsum as a raw material for the manufacture of gypsum-board panels.
At the core
Since the 1960s, Temple (a subsidiary of Temple-Inland Corp.) has been producing gypsum wallboard panels with natural gypsum quarried from its mine in Oklahoma. Starting in the mid-1980s, Temple has been integrating the use of synthetically produced gypsum (made from recycled materials) as the core for it's line of gypsum panels. In 1984, the company began to add a blend of 10-percent synthetic gypsum to its mined gypsum.In 1997, Temple began producing gypsum panels with a 100-percent-synthetic-gypsum core at its West Memphis, Ark., plant. Following that success, it commissioned a new gypsum panel production plant in Cumberland City, Tenn., adjoining the Tennessee Valley Authority's coal-burning (fossil) plant (the source of their synthetic gypsum). This plant, which opened in 1999, was created for the exclusive production of gypsum panels with a synthetic gypsum core. Production capacity for this plant alone is in excess of 700 million square feet of gypsum wallboard panels per year--enough to construct 70,000 average size homes.
Between its two on-line plants, Temple has the capacity to produce more than 1 billion square feet of synthetic core gypsum panels annually. At present, of its total production capacity, 60 percent of its production output uses synthetic gypsum; the company goal is 80 percent. The Cumberland City plant is strategically located and services the entire eastern United States.
On a dry-weight basis, dependent on the type of core, between 95 and 95 percent of the gypsum core of its panels are made from recycled material. Add to this the fact that the paper facing of its panels are made from 100-percent-post-consumer recycled paper products and you have a building product produced from nearly 100-percent-recycled material--a very friendly combination for the environment. The Cumberland City/TVA plant annually removes 1.2 million tons of material from the waste stream--material previously destined for landfills.
In 2000, Temple received third-party certification for all its wallboard products manufactured with a synthetic gypsum core from Scientific Certification Systems.
Strategic locations
United States Gypsum is the world's largest producer of gypsum products, with 27 production plants throughout the continental United States. Of the total amount of energy required to produce and distribute gypsum board panels, 10 percent is required for transporting it from plant to site. Thus, each plant is situated so as to minimize this distance.Seven paper mills produce the paper face(s) for USG's gypsum panels from 600,000 tons of recycled newspaper, boxes and phone books. At the same time, each mill saves between 4 million and 6 million gallons of water per day (90 to 98 percent) by recycling wastewater used in the manufacturing process.
Currently, USG produces 25 percent (2.75 million tons per year) of its total production capacity with synthetic gypsum cores. A good case study of the transformation from mined to synthetic gypsum is its plant in East Chicago, Ind. This plant now receives its supply of synthetic gypsum from local and regional electric power plants. For the previous 60 years of operation, mined gypsum was supplied to the plant via Lake Michigan from a quarry 500 miles distant--three days' journey by bulk freighter.
Renewable agricultural products such as wheat and corn starches are also used by USG as binders in the manufacturing process for gypsum board panels. As a founding member of the U.S. Green Building Council, an organization devoted to improving the built environment through innovation and pro-activism on environmental issues concerning the construction industry, USG remains a leader in the gypsum building products industry.
