Three thousand cubic yards of freshly placed concrete generates a lot of heat as it cures – enough to damage the material and permanently weaken its structural integrity. Devising a way to cool it sufficiently as it hardens, while ensuring a high-quality finished product, is a challenge common to many large-scale concrete construction projects. What varies is whether a contractor responds to the challenge with creativity, innovation and a commitment to unsurpassed quality.
That was the situation Sundt and a joint venture partner confronted as we constructed the $218 million Sellwood Bridge over the Willamette River in Portland, Oregon. While placing 3,000 cubic yards of 6,000-psi concrete for two of the bridge’s massive piers, the team had to find a way to carefully control the heat of hydration to avoid damage and ensure that precise quality standards were met.
Our solution was to design an internal water-cooling system to remove the excess heat from the concrete. Water pumps, manifolds, intake screens, valves, flow meters and thousands of feet of flexible plastic water tubing were carefully placed throughout the concrete formwork. After the concrete was placed at the piers, cool water was continuously pumped through the plastic tubes, which in turn carried away the excess heat from the concrete. Remote temperature sensors were also placed throughout the fresh concrete to collect temperature data. As the concrete cured, and the internal temperatures climbed, this data was constantly monitored to confirm the performance of the cooling system and to ensure a quality finished product.