Winter weather makes temperature-sensitive work on construction sites extremely difficult, even impossible in some cases. Concrete curing and bridge surface priming are typical examples. The company Bickhardt Bau AG resolved the weather challenge with a portable hydronic heater from Wacker Neuson. The E 700M allowed Bickhardt Bau to continue work during the winter months on a bridge in the northern German town of Burgdorf.

Full speed ahead in winter

To ensure that bridges can safely withstand traffic for several decades, the sensitive concrete in the bridge superstructure must be protected against chemicals and the elements. This is achieved by sealing the surface with a dual-action epoxy resin before applying the protective and surface layers of road. The concrete temperature must be between 5 and 8°C (41 and 46˚ F) in order for the primer layer to cure, which is often a challenge during the middle of winter.

“In the past, we typically had to abandon work and take a winter break when the temperatures dropped too low,” explains Matthias Kohlhase, site manager at Bickhardt Bau AG. “Portable hydronic heaters from Wacker Neuson save us time and money by allowing us to work right through the winter months.”

Hydronic heaters more efficient than air heaters

In December 2008, Bickhardt Bau, specialist in roadwork, was working on a bridge that is part of the Burgdorf bypass in the northern German state of Lower Saxony. At 45 meters (148 ft) long, the bridge passes over a lane in the eastern part of the town. At temperatures around zero (32˚ F), the company was unable to apply the epoxy resin coating.

“Under normal circumstances, we would have had to wait until March or April for the temperature to rise to at least 8 degrees (46˚ F) and remain stable for a few days,” says Kohlhase. “But we didn’t have the time for that. At first, we tried enclosing a bridge section in a tent and using a normal air heater, but that didn’t work. The heat was not transferred from the air to the bridge.”

The E 700M is significantly more effective than conventional methods. Approximately 15 percent of the heat generated by a gas or oil heater in a tent or enclosure actually penetrates the target material. With the E 700M, however, up to 94 percent of the heat generated penetrates the concrete.

Versatile in deployment

Originally developed to thaw frozen ground and cure concrete, Wacker Neuson’s hydronic heating systems are delivering value across a much wider range of applications, essentially anywhere the work requires heat. The E 700M is powerful enough to heat large areas and allow work to continue, even in sub-zero temperatures. The unit runs on diesel and heats a mixture of water and glycol to over 80°C (176˚ F). This heated liquid is then pumped through a 700-meter (2,300-ft) hose laid on the area that requires heating.

An insulating blanket – such as the Wacker Neuson Red Wave blanket – is placed over the hose to prevent heat loss. The heat is thus transferred directly from the heater’s hose directly to the concrete surface, and the insulating blanket ensures that only a minimal volume of surrounding air is also heated. “We were able to heat the structure to around 15 degrees Celsius (59˚ F) within 2 days, so we could easily apply the protective coating and leave it to harden,” adds Kohlhase.

Bickhardt Bau successfully deployed the E 700 M on two other bridge projects that December. The company is extremely pleased with the results. “We would have come to a standstill without Wacker Neuson’s hydronic heater,” concludes Kohlhase. “We plan to use these heaters regularly in the future.”

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