Findlay, Ohio July 9, 2001 -- The idea of using reinforcement in concrete can actually be traced back to an experiment conducted in 1850, when a Frenchman by the name of Jean-Louis Lambot built a concrete boat with imbedded iron bars. It floated and caused people to look at concrete in a whole new way. By 1884, two German engineers, Wayss and Bauchinger published a paper on steel reinforcement, based on the patent rights they had purchased from another French inventor Joseph Monier, who had patented reinforced concrete garden tubs. Wayss' and Bauchinger's paper is credited by many for launching the idea of reinforced concrete as a proper material for buildings, railroad structures and public works.

The first recorded American application of steel reinforcement took place in Portchester, New York in 1872. New York businessman W.E. Ward had been burned out of three houses and was looking for a way to "fireproof" a new home. In 1872, he used reinforced concrete to build a new home that was so fireproof that he regularly built bonfires on the floors to demonstrate!

"Up until 1885, the only way to reinforce concrete was by using bars of iron and tying them together," says Bob Richardson, historian and consultant for the Wire Reinforcement Institute, the trade organization that supports and researches Welded Wire Reinforcement. "But that changed when a man by the name of Elihu Thomson discovered while experimenting with a battery and a spark coil that he could fuse two 1/4" steel rods together. Thomson later became President of MIT and his discovery paved the way for a new way to reinforce concrete: welded wire reinforcement (WWR)."

One hundred years ago this year in 1901, patent papers were filed by Massachusetts inventor John Perry for a machine that was able to weld together wires in sheet form. While his initial idea was to use these welded wire sheets as fences, by 1906 catalogues were advertising these sheets as reinforcement for concrete.

Instead of long rods of steel, sheets of wire consisted of cold-drawn steel wire held together at regular intervals to form a crosshatch pattern (early wrapped wire came in triangular patterns but square welded patterns won out in the long run). Unlike the bars of iron, welded wire arrived at the job site already formed as a sheet. There was no need to tie wire together. This reduced construction time and lowered labor costs.

"In 1908, we saw the first major application of wire reinforcement in the form of the Long Island Parkway," says Richardson. "While it was only a lightweight mesh reinforcement weighing only 0.2 lbs per sq/ft, it was a step forward. From 1908 until the start of World War I, many eastern states specified wire reinforcement in pavement, eventually increasing to weights of about 0.65 lbs/sq ft."

It's not clear when welded wire was first used with portland cement for concrete pavement. Between 1910 and 1915, stretches of pavement in DeKalb, Illinois, California and Forest Park, Maryland were poured using WWR. However, the DuPont Road in Delaware, also shares honors. The road was the forerunner of all superhighways and was built with a variety of reinforcing materials, including welded wire reinforcement. While it was built using specs that we know today are not conducive to long life, it was another major development in the viability of WWR.

The biggest "proof" of the viability of welded wire took place in 1922 in Bates, Illinois, where a test took place studying 78 different types of road pavement. The best performing type of pavement would be used to construct several thousands of miles of highway in Illinois, so the stakes were high. The welded wire producers were able to persuade the project's chief engineer to apply welded wire to one of the sections. At the end of the test, one engineer observed that the section with the welded wire was "...the only one of the sections which was in sufficiently suitable condition after the final heavy traffic test." The results convinced a number of states to specify welded wire reinforcement in their roads.

"While welded wire had proven itself for road usage, there were still some who still questioned its viability for construction of buildings," says Richardson. "However, WWR was catching on in New York City, because it offered the perfect proving ground for welded wire. Major fires plagued the city before the turn of the century so city authorities looked for ways to fireproof buildings. The answer came in the form of WWR in flooring slabs that were made using waste product from the city's many coal burning generating plants. This 'cinder-arch concrete floor system' was key in the development of a number of the skyscrapers that grace the Manhattan's skyline including the groundbreaking Empire State Building. To this day, many of the buildings have been stripped to slab and frame and renovated, but the early wire reinforced floors are still in use."

Because WWR worked so well in New York, other cities started seeing WWR as a viable form of concrete reinforcement. If fact, welded wire reinforcement was so successful for building reinforcement that you can draw up a virtual "who's who" of major buildings in America over the past 100 years that have used welded wire reinforcement:

• Grand Central Terminal, New York
• Empire State Building, New York
• Merchandise Mart, Chicago
• Chicago Tribune Towers, Chicago
• World Trade Center, New York
• Sears Tower, Chicago
• Hancock Tower, Chicago
• Rio Vegas Hotel, Las Vegas
• Pacific Park Plaza, San Francisco Area
• Mariott Hotel-Rivercenter, Covington, KY
• Hyatt Regency, San Francisco
• Columbia Center, Seattle
• Continental Plaza Building, Seattle
• One Peachtree Office Tower, Atlanta
• Harbor Place Tower, Long Beach, California

 

An interesting note about the Pacific Park Plaza Building is that structural WWR played a siginificant role in its weathering the Loma Prieta earthquake. In a report published by the Concrete Reinforcing Steel Institute in 1990, well-respected engineer Dr. S. K. Ghosh said "The Pacific Park Plaza was undamaged after experiencing significantly strong ground shaking" and WWR was used in all the beam and column joints as shear reinforcement in that building.

By the close of World War II, WWR showed its strength overseas. Because it requires less labor and time, it was seen as the perfect reinforcing material to help Europe rebuild after the war, when time and labor were short. Because of the success of the post-war rebuilding effort, European builders, architects and engineers started to realize WWR's potential. In fact, WWR remains extremely popular in Europe; accounting for over 50% of all reinforced concrete projects. Because labor is still very expensive in Europe, builders are keen on keeping costs low and getting projects completed quicker. These are two things that WWR affords.

"In America, the post war years were very good for WWR," says Richardson. "In 1956, President Eisenhower signed the national highway act and the states started building our current system of superhighways. Just prior to World War II, Pennsylvania started work on its turnpike between Irwin and Carlisle. Other states followed Pennsylvania's lead and soon wire reinforcement was being used in the Ohio Turnpike, The New York Thruway, The Indiana Turnpike, The Oklahoma Turnpike and others. It is estimated that WWR producers in the US shipped enough product to those working on the interstate highway system in the late 1950s and 60s to pave over 69,000 two-lane miles. To put that in scale, picture a two-lane highway that can wrap 3 times around the Earth!"

WWR has also enjoyed great usage in other projects like airport runways (i.e. O'Hare Airport, George W. Bush Airport) and a number of architecturally groundbreaking buildings (i.e. PanAm World Airways Terminal, JFK Airport; the Eli Lilly Plant, Indianapolis; Habitat '67, Montreal). Much post-modern design requires thin and odd-shaped building sections and WWR allows for ultra-thin concrete sections with enormous strength. Because the wire can be pre-bent for customer order, prefabricators can cast geometric designs offsite and then the finished pieces can be assembled at the jobsite. A prime example is bent reinforcement for precast seating tiers in sports stadiums. Places like the Baltimore Ravens Stadium, Camden Yards, and the new Seattle Seahawks stadium, The Cleveland Brown's Stadium and others have used this technology. This quality has also lead to WWR being used for tilt-up wall panels as well as other architectural accents on buildings.

"Almost any place that contractors have been using rebar, WWR will do the job," says Roy Reiterman, technical director for WRI. "Because of the ability to shape and bend the wire and the potential for thin slabs, WWR has also been a large part of the concrete pipe and box culvert industries. In fact, welded wire accounts for nearly 80% of all concrete pipe reinforcement and is gaining momentum in the box culvert industry."

For bridge structures, WWR structural shear reinforcement is seeing its way into more precast/prestressed girders, beams, boxes and bulb-tees. When it comes to bridge construction, some bridges being built in the past 10 years that have precast/prestressed concrete spans of over 150 feet and most of the bridge components have WWR shear reinforcement the complete length of the spans. The NU 2000, 150-foot "I" girder, with a depth of 7 feet and a top flange width of four feet was developed at the University of Nebraska by Dr. Maher Tadros and his graduate students.

"Dr. Tadros' girder has over two tons of shear reinforcement in the web and flanges," says Reiterman. "Similar 'I' girders are being designed by the State of Nebraska and other states with spans to 200 feet. The typical cast in place bridge decks or precast/prestressed replacement deck panels can also utilize mats of WWR. With WWR manufacturing capability or WWR up to 3/4" diameter, typical bridge reinforcing can be substituted with WWR."

One of the greatest things to happen to WWR technology in the past few years has been the ever-increasing wire diameter and materials that manufacturers have been able to weld together. Not only are some manufacturers selling welded wire that is 3/4" in diameter, but there are also zinc-coated and epoxy-coated products available to resist corrosion. In addition, stainless steel welded wire reinforcement may soon come to the market. These advancements have allowed WWR to move from just road and slab reinforcement to structural components in bridges and buildings.

"It still amazes me that despite a 100 year history of the product, many in the construction industry still think of WWR in the terms of what it was 50 years ago," says Reiterman. "When I tell people that they don't need to tie rebar anymore and can use welded wire, they look at me like I have a third eye! They tell me wire isn't strong enough. I tell them that according to ACI codes, some WWR has yield strengths up to 80,000 psi, which means it can be stronger than rebar and you don't need to waste material, time and labor tying the grids together. Honestly, I think the biggest challenge that welded wire faces in its next 100 years is conquering an image problem. One way to solve the problem is to call WWR what it is: welded wire reinforcement for structural concrete construction. To paraphrase an old Oldsmobile ad, 'we're not your grandfather's wire!'"

To learn more about WWR, please visit WRI's website at www.wirereinforcementinstitute.org or call us at(800) 552-4WRI [4974]. WRI is the concrete construction industry's leading source for timely, objective and credible information on the uses and benefits of WWR and related products. WRI works closely with government agencies, allied industries and organizations to ensure the most accurate, up-to-date codes, standards, specifications and regulatory requirements. WRI works to promote the superior performance attributes of WWR products across the full range of reinforcement applications.