New Hampshire’s Toughest Tunnel Repair Completed in a Single Shift with Phoscrete F3-VO
156 kits. Vertical and overhead patches. One mobilization. Here’s what happened.
On June 24, 2025, the Phoscrete team completed what is now our largest single-day onsite spray application to date: 156 kits of Phoscrete F3-VO applied inside a highway tunnel beneath the Spaulding Turnpike in New Hampshire, covering both vertical and overhead concrete repair in a single mobilization.
This is the project in detail.
The Site
The tunnel at Spur Road and Bellamy Lane runs underneath the Spaulding Turnpike near Portsmouth, New Hampshire. It’s a low-clearance structure with limited staging space, and years of chloride infiltration had done their damage. Active rebar corrosion, concrete spalling, and delamination were visible on both the vertical tunnel walls and the overhead ceiling.
Some Phoscrete F1-VO from a prior installation in February 2025 was still present on the structure and completely intact. That wasn’t a surprise – it was confirmation.
For this phase, NHDOT needed to address vertical patches ranging from 4 to 6 inches in depth and overhead patches between 8 and 11 inches. The scale and geometry made hand-packing impractical. Forming and pouring wasn’t feasible. NHDOT selected Phoscrete F3-VO and the ShotPump for the repair.
The Crew
Six people on site: three mixers, one sprayer, two finishers. Each mixer is running an 8-gallon bucket and a Phoscrete paddle. The sprayer is managing the ShotPump nozzle. The finishers are working immediately behind the spray with large plastic float trowels.
The team also included Phoscrete Application Engineer Jorge Giro, Sales Engineer Kyle Bartfay, NHDOT Principal Engineer Levi Byers and colleague Keith Perkins, and Lorella Angelini from Angelini Consulting Services as the IDP consultant.
The Application
7:30 AM — Arrival: The crew arrived, set up equipment, and staged materials. The ambient temperature is approximately 85°F in the shaded tunnel environment.
7:45 AM — Rebar Coat Phoscrete Rebar Coat (RC) is mixed and applied to 5–6 spots with active rebar corrosion. RC wrapped up by 8:12 AM.
8:15 AM — Run 1 (39 kits) F3-VO mixing began immediately after RC. Three mixers working in rotation fed the ShotPump hopper in sequence. Run 1 targeted the vertical patches. The spray nozzle worked across repair zones in methodical passes; finishers troweled immediately behind.
8:41 AM — Troweling Begins The first vertical run was troweled smooth. The crew transitioned to overhead positioning.
9:08 AM — Run 2 (26 kits) Run 2 shifted focus to the first layer of overhead repair and some additional vertical touch-up. Material was applied upward at controlled pressure, holding against gravity without visible slump or rebound.
10:23 AM — Run 3 (91 kits) The largest single run of the day. All 91 kits applied overhead, building sections from 8 to 12 inches of material depth. The ShotPump handled it in one run.
11:15 AM — Complete final troweling done. The shot pump was cleaned and staged for transport. Site cleared. Four hours of active application time.
What the Numbers Say
156 total kits — Phoscrete’s record for a single-day onsite spray application.
- Run 1: 39 kits – vertical patches
- Run 2: 26 kits – first overhead layer + vertical finish
- Run 3: 91 kits – all overhead, 8–12″ build-up
Surface temperature during active curing reached 135°F, consistent with the exothermic reaction of MPC mortar. No delamination, no cracking, and no premature set were observed across any of the three runs.
Why It Worked
F3-VO’s material behavior. Magnesium phoscrete cement mortar sets differently than Portland cement-based products. It doesn’t shrink on cure. It bonds chemically to the substrate. And at the right application consistency, it behaves like a thick putty that holds vertical and overhead placement without slump – even at 11-inch depths.
The ShotPump’s throughput. The machine’s continuous-feed design lets a three-mixer crew maintain a consistent spray pace without stopping to hand-pack or reposition frequently. At this volume and complexity, hand-packing would have required more crew, more time, and likely a second mobilization.
MPC’s cold-joint advantage. Because F3-VO bonds to itself across pour sequences, the three-run approach was additive rather than fragmented. Run 2 bonded to Run 1. Run 3 bonded to both. The repair is monolithic.
Prior Work Still Holding
The Phoscrete F1-VO installed in February 2025 was still visible on-site and completely bonded to the substrate. No delamination, no edge separation, no surface scaling. After four months of winter, freeze-thaw cycles, and active traffic loads overhead, the material performed exactly as expected.
What’s Next
NHDOT now has a completed baseline for how F3-VO behaves in tunnel environments with vertical and overhead exposure. The 156-kit, three-run, single-day record represents a scalable model for similar structures where geometry restricts conventional repair methods.
Are you evaluating concrete repair for vertical or overhead applications? We’d be glad to walk through the specifics of this project.
📞 Call us at 561‑420‑0595 now. You can also use the live chat 💬 or submit the contact form on our website.
Phoscrete Corporation develops structural concrete repair products based on Magnesium Phosphate Cement (MPC) chemistry. Products are applied by certified contractors and trained installation teams.