Warmer temps ensure concrete quality

By Avice Meehan

Two significant Norfolk projects that were put on hold because of below-zero temperatures this winter are expected to resume by mid-March: Reconstruction of two retaining walls along Route 44 and the construction of a new firehouse for the Norfolk Volunteer Fire Department.

Engineers for the state Department of Transportation (DOT) said the retaining walls are still expected to reach substantial completion by September with only “punch list” items remaining after that. As for the fire-house, First Selectman Henry Tirrell said the new building will be completed by the end of this year, although demolition of the current firehouse and completion of site work would extend the project timeline and affect full operation of the new structure.

The delays were all about the peculiar properties of concrete and the costs of ensuring that it stays warm enough to properly cure. “It all depends on the mix design. You can pour at almost any temperature as long as we heat it.  Everything that concrete comes in contact with needs to be at 70 degrees because you don’t want to suck the heat out of the concrete,” said Shawn Smith, the new DOT project engineer. He has taken over from Amy Hare, who has been promoted within the agency. The bottom line for both projects was the same: keeping everything at the right temperature became cost prohibitive and risked overall quality.

Hare said that following a two-week holiday break, K2 Infrastructure determined in early January that it made sense to pause construction. A skeleton crew has remained on site, and the $37 million project continues to run under budget.

Smith and Hare described the concrete pours as complex and large. Individual sections of the wall are upwards of 30-feet wide and specific crews first need to install the rebar framework before carpenters come in to build the bracing structure and install the form liner that creates the exterior pattern. “It’s a logistical dance for sure,” said Smith, explaining that the contractor will still be heating the rebar and the ground under each panel to maintain a consistent temperature. Temperatures are monitored by gauges inside the wall itself and attached outside.

Although pouring footings for the $10.4 million firehouse is a simpler task, Tirrell and the Firehouse Committee made the decision to pause construction in early February and to resume work in mid to late March. Costs associated with the delay are estimated at approximately $175,000 with an estimated $300,000 in other unplanned expenses; the budget includes a $700,00 contingency.

During the pause, Tirrell said the construction manager (Newfield Construction) and architects (Silver Petrocelli) have finetuned logistical plans involving subcontractors and also begun working with a commissioning agent hired by the town. The role of the agent, as discussed at the Feb. 2 meeting of the Board of Selectmen, is to ensure that all systems work properly once construction is complete.