The Wacker Neuson E 700M is fast becoming many bridge contractors’ most versatile and efficient pieces of equipment for winter restoration and construction projects in Germany. When temperatures drop below freezing and winter projects come to a standstill, contractors are abandoning inefficient conventional heating practices that take days to minimally raise the structure’s temperature. Rather, they are now choosing significantly more efficient hydronic heating systems to quickly bring heat to where it’s needed in order to keep projects on schedule.

During the winter of 2008, the Bickhardt Bau Company, Kirchheim, Germany, employed the portable E 700M hydronic heater on three separate bridge restoration projects when the ambient temperatures dropped to approximately 0° C (32° F). As the structure’s temperature dropped, projects were brought to a standstill until the crews could bring bridge deck temperatures back into a workable range.

Bickhardt Bau initially used the E 700M on a Siegen, Germany, jobsite when the 0° C (32° F) outdoor temperature dropped the bridge deck’s natural temperature to 3° C (37.4° F). The company was using a synthetic resin to restore the bridge deck and protect it from corrosion and erosion. “The make-up of the two-component resin requires a minimum temperature of 5° C (41° F) for the chemical reaction to take place,” says Robert Brauneis, product manager for utility at Wacker Neuson SE in Europe.  

With the restoration project at a standstill, Bickhardt Bau needed a quick solution to keep it on schedule. The solution came in the form of the E 700M, which was used to raise the bridge’s 5 by 45 m (16.4 by 147.6 ft) surface to a target 5° C (41° F), even with an outdoor temperature hovering at 0° C (32° F).

Crews laid the heater’s hoses directly onto the bridge deck surface. In sharp contrast to conventional systems that must heat the air surrounding the structure in addition to the surface, the E 700M heats the surface directly. With a standard 700 m (2,296 ft) length of hose, the E 700M can heat areas up to 409 m2/h (4,402 ft²/h) for restoration projects. Normal operating temperatures range from 38 to 82° C (100 to 179° F) for the hydronic heater, and it delivers a 74 kW (252,723 BTU/hr) heat output. A digital temperature controller affords quick temperature adjustments for heat transfer fluid output.

Within an hour, crews laid out the hose pattern over the 225 m² (2,422 ft²) area and began the heating process with the E 700M. The bridge’s structural element temperature was raised to 10° C (50° F) in about 16 hours, making it possible once more for crews to coat the surface. It was only by the use of the E 700M that the operation was successfully completed on schedule.

Top

Bridges of Burgdorf, Germany

Achieving success in Siegen, Bickhardt Bau again turned to the portable E 700M hydronic heater for two bridge restoration applications in Burgdorf. With ambient temperatures of 2° C (35.6° F) plummeting the BU 6 Bridge deck’s temperature to below 5° C (41° F), the chemical restoration process of the two-component coating had come to a standstill on the tent-covered bridge.

Initially, Bickhardt Bau’s crew members installed air heaters in an effort to continue the binding process. However with this method, the heaters not only heat the bridge surface but also the area enclosed by the tent. As a result, the heat penetrates the bridge surface at a very slow and extremely inefficient rate. As the heat rises, much of it is lost through the top of the enclosure.

“Conventional heating solutions of operating gas or oil heaters inside of a tent or enclosure allow as little as 15% of the heat to penetrate the ground,” says Brauneis. “In comparison, the E 700M delivers as much as 94% heat penetration to the surface, saving the contractor time, money and fuel.”

With the hydronic hoses carrying a glycol solution heated to between 38 to 82° C (100 to 179° F) laid directly on the ground, work crews covered the hoses with Red Wave thermal insulating blankets, which help to transmit the heat directly into the surface. The hydronic heating system was in place and operating within an hour. In less than 30 hours, the bridge’s surface was heated to the point to where work could continue. To achieve the same results with standard heaters, the process would have taken days.

After disassembling the equipment, work crews masked the sides of the bridge with tar roofing paper over a width of one meter and the formwork for the bridge’s crowns was erected. It was only by the use of the E 700M that the restoration job could be completed so quickly.

At the nearby BU 8 Bridge project, Bickhardt Bau’s crews had the bridge surface covered with a tent and were ready to apply the two-compound synthetic resin. However, outdoor temperatures of 1° C          (33.8° F) dropped the structure’s temperature to the point where it was not possible to continue.

At this jobsite, Bickhardt Bau skipped the step of trying to heat the structure by traditional means and, instead, went directly with the E 700M hydronic heater.  The heater’s hoses and insulating blankets were quickly set up on a Friday. Over the weekend, the structure’s temperature increased from 5° C to 15° C (41° to 59° F), allowing crews to apply the coating and keeping the restoration project on schedule.

Regardless of whether it’s concrete restoration, concrete curing, ground thawing or frost prevention, the portable E 700M Hydronic Heater from Wacker Neuson saves contractors time, money and fuel vs. traditional heating methods.

Top

Cost-effective Curing
In addition to warming concrete surfaces, as was the case with Bickhardt Bau, the Wacker Neuson E 700M hydronic heater cost effectively allows contractors to effectively cure concrete in subfreezing temperatures. As ambient temperatures dip below 5° C (41° F), pouring and curing concrete is adversely affected.

Concrete’s sensitivity to the cold presents several issues that can result in delays and additional costs for the contractor when placing and finishing concrete during the winter months. First, time for initial concrete set is extended. Second, early freezing permanently damages concrete. Finally, lower temperatures slow the rate of strength gain.

For years, the conventional approach to heating and curing concrete during the winter relied on air heaters. However, this inefficient tactic posed several shortcomings, including:

• Building costly enclosures
• As little as 15% of the heat penetrated the surface
• Uneven curing
• Noxious fumes
• Extremely high fuel bulls
• Curling and chalking of the concrete
• Open flame safety concern

The portable E 700M hydronic heater from Wacker Neuson represents a radically different approach to heating and curing concrete. The efficient system offers many advantages, including:

• No enclosure required
• As high as 94% heat penetration to the surface
• Uniform curing
• No noxious fumes
• Fuel less than € 50 ($70) per day
• Easy temperature control
• Quick and easy set up with no flames

Operating costs for the E 700M are less than half that of traditional air heaters, while it is significantly more efficient at heating. Click here to see a cost comparison of heating methods.

Top