A Home Run

Crews weather- and stain-proofed almost 500,000 square feet of concrete in Dodger Stadium's seating area.
Crews weather- and stain-proofed almost 500,000 square feet of concrete in Dodger Stadium's seating area.

Olympic baseball has been played here. The Beatles, Bruce Springsteen, and Pavarotti have performed in the stadium. The late Pope John Paul II celebrated mass here in 1987.

And since Opening Day in 1962, more than 120 million spirited fans have bellowed for their beloved Dodgers here. In the process, they've spilled rivers of beer and pop, and truckloads of peanuts, cheesy nachos, and condiment-smothered hotdogs all over the concrete seating bowl of Emil Praeger-designed Dodger Stadium.

“In some places there was a ¼-inch of buildup,” says Jason Dunster, the project manager for Walker Restoration of Los Angeles.

Dunster was responsible for ensuring that the repair, cleaning, and weather- and stain-proofing of the concrete during Dodger Stadium's off-season renovation met Walker Restoration's specifications. This work was part of the $20 million second phase of a multi-phase, multi-year program of improvements. In this latest phase, along with the concrete work, the stadium gained modernized box seating, new seats throughout the bowl, and a new loge-level terrace for fan gatherings.

Walker Restoration's work actually began during the 2005 season as Dunster and his team assessed the condition of the seating bowl's concrete while the Dodgers were on the road.

After more than 40 years of use, the concrete was chipped, cracked, and spalled. Many concrete connections were near the end of their service lives. Workers replaced 80% of these connections by job's end, along with 15 miles of joint sealant.

And the concrete was grimy.

“I don't want to give the impression that there was a 1/8-inch of buildup everywhere, but it was dirty,” says Dunster. “The seating areas were swept and hosed down after every game, but I don't believe they were ever truly power-washed.”

Overall, the concrete performed well, considering the wear and tear. Weather, traffic, and contaminants from millions of people for more than four decades were bound to take their toll.

Even so, in some areas, the level of chloride buildup in the concrete surprised Dunster. High levels of corrosive salts in concrete normally occur in environments near the ocean or where surfaces are exposed to de-icing salts.

In this case, the salts came from salty foods, like peanuts spilled on the deck. Water from washing after games swept some of the food away, but it carried the salts from them into the concrete pores, where they contributed to surface cracking and spalling.

Dunster concluded that, in addition to cleaning and repair, the concrete needed future protection.

Workers from Contech Services, Santa Ana, Calif.; and John Rohrer Contracting Co., Denver, followed the repair and steam-cleaning crews section by section, applying PROSOCO's Stand Off SLX100 Water & Oil Repellent.

“We tested 12 products before settling on SLX,” says Dunster. He favored the product because it's 100% silane, it's a water- and stain-repellent, and it doesn't change the substrate appearance.

The crews applied the protective treatment provided by Smalley & Company, Fullerton, Calif., with pump-up sprayers and rollers. Chuck Dunscombe, Contech Services president, explains that they flood-coated the freshly steam-cleaned concrete at about 300 square feet per gallon and back-rolled it.

“It went on great,” says Dunscombe. “There was no pooling or residue. Any water spilled on it beaded right up. Everyone loved that.”

The companies divided the stadium. Contech Services worked the first base side. John Rohrer Contracting got the third-base side. The two companies were necessary because of the sheer immensity of the stadium, almost 500,000 square feet of concrete, and the abbreviated time to get it done—about four months from start to finish.

“The seating contractor was there at the same time, trying to get 50,000 new seats in,” says Dunscombe. “But we all worked together, and there were minimal conflicts.

“This is one of the original old stadiums,” Dunscombe adds. “It's nice to see the owner investing in it, and not tearing it down and building a new one.”

Gary Henry is a business communications specialist at PROSOCO, a Lawrence, Kan.-based manufacturer of products for cleaning, protecting and maintaining concrete, brick, and stone. Telephone 785-830-7343, or e-mailgary.henry@prosoco.com.

Stabilizing Concrete Structures

Although structurally sound, the Anclote Power Plant cooling towers had a lot of concrete spalling and corrosion that cost the company millions of dollars per year.
Although structurally sound, the Anclote Power Plant cooling towers had a lot of concrete spalling and corrosion that cost the company millions of dollars per year.

It's a fact of life for building owners and structural engineers: Embedded steel in concrete corrodes. But Innovative Engineering Technologies (IET), a Stuart, Fla.-based engineering company, developed PermaTreat, a patented product that eliminates demolishing reinforced concrete structures to remove rust from embedded reinforcing steel.

It also has received accolades from the Space Alliance Technology Outreach Program (SATOP), the private sector outreach program of NASA. Penn State University research verified what SATOP discovered in tests conducted on distressed concrete—an increase of more than 100% of the modulus of elasticity.

Oxygen and water react with embedded steel in reinforced concrete, forming corrosion byproducts that are greater in volume than the original steel. That internal expansion causes concrete to break. Steel is susceptible because chlorides penetrate the concrete and disable the passivating layer of alkaline concrete.

Used with VAPIS, a pressure injection system, PermaTreat's formulations are composed of mixtures of chemically reactive silicates that implement a variety of permanent chemical and physical changes in concrete, ultimately arresting corrosion. The product uses a formulation of reactive silicates to penetrate deteriorating concrete, permanently halting reinforcing steel corrosion and improving the strength and ductility of the concrete to levels higher than original construction.

Using PermaTreat, the average corrosion rate dropped from 328.55 micrometers/ year to 95.39 micrometers/year.
Using PermaTreat, the average corrosion rate dropped from 328.55 micrometers/ year to 95.39 micrometers/year.

The company tested the product at Anclote Power Plant near Tarpon Springs, Fla. Anclote is a fossil fuel power plant that operates 24 hours a day. Each 22-foot-diameter cooling tower has 12 32-foot-diameter fans and 400 hp motors. The 20-year-old plant has a lot of concrete spalling and corrosion.

“The concrete cooling towers have been patched and repaired many times using conventional approaches,” says Gordon Anderson, a consulting engineer at the plant. “IET offered a novel repair method.”

A pretest grid was laid out at 3x3 feet, with 10-inch spacing. After initial testing showed cracking and spalling on the surface area of one column, IET found that it had a high corrosion current, which could result in premature failure, with a peak measurement of 1198.61 micrometers/ year. The average for the area measured was 328.55 micrometers/year.

PermaTreat was injected directly into the concrete under 70 to 80 pounds of pressure. The chemical penetrated the entire depth of the 2-foot-thick structure. A post test revealed a measurement of 200.62 micrometers/year, with the average for the area measuring 95.39 micrometers/year, a dramatic reduction in corrosion current.

The product increased compressive and tensile strength, while reducing porosity and improving the building's resistance to acids. The chemical reactions are permanent, reducing future repair costs.

For more information, telephone IET at 800-460-2701, or visit the Web sitewww.ietpower.com.

Editor's Note: Technology is changing so rapidly that it can be difficult to keep up with what's new. We encourage you to let us know how you solved a field problem using an innovative product, technique, or service. Please send your contributions toconcretesurfaces@hanleywood.com.