Exposed to salt-laden wind from the Atlantic Ocean and to the corrosive exhaust from spacecraft engines, the concrete cooling towers at the John F. Kennedy Space Center are providing good service life after treatment with a specialized admixture and repair material.
True, there are some examples of concrete structures with a service life of 2000 years. But it's highly improbable that even the Roman engineers could have ever considered the severe-duty challenges found in today's Space Age engineering community.
While there's a good deal of information on how the space program has spurred the development of computers, ceramics, and even airplane design, few know that there is a link between concrete and space travel. Concrete proves yet again to be the foundation of all things society deems important. So it's no surprise that the forward-thinking engineers at NASA would become concrete experts.
In fact, concrete is so important to service life, that NASA engineers study the effects of corrosion at its Materials Science Laboratory and Beach Corrosion test site at the John F. Kennedy Space Center in Cape Canaveral, Fla.
Engineers wanted to reduce any potential corrosion that could damage the rebar in important concrete structures located in the immediate vicinity of the launchpad. Since several space shuttles are launched each year from the site, the nearby structures are subject to highly corrosive exhaust fumes from the engines that propel the payload skyward.Launch pad test
In 2003, NASA structural engineers introduced a test specification on the cooling tower of space shuttle launch pad 39. Following the structural repairs, workers treated the concrete surfaces with a migratory concrete inhibitor. The project was established to be a field control evaluation of the product.
Early this year, engineers from Cortec Corp., the St. Paul, Minn., manufacturer of anticorrosive concrete admixtures and surface treatments that supplied the corrosive inhibitor, performed follow-up testing. Their goal was to determine what corrosion rates were now. Since testing was not done before application, there was no “control.”
The team used the Galvapulse test to determine the corrosion level on the tower's north and south walls. The results indicated that corrosion rates were low or moderate.
The test procedure allows for facility managers to be proactive. With periodic testing, they can continue to monitor the structure to see when rates would increase or get too high, and when they would need to apply more inhibitor.
Like other Space Age innovations, corrosion protection for concrete is becoming mainstream. The market for corrosion protection products, including admixtures, is growing, says Jessi Jackson Meyer, vice president of sales for Cortec. With owners requiring longer service life, they are more often willing to pay for the proper protection.
She points out that many engineers are now specifying Cortec's MCI 2000, an integrally added corrosion protection admixture, on many structures. The product has a proven track record, as it has been used on many precast and cast-in-place projects around the world.