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Bridge‑deck overlay procedures and testing outlined by Devil’s Lake team
Summary
Devil’s Lake DOT staff reviewed survey and delamination measurement methods, removal techniques including hydro demolition and milling, overlay materials (AE5 mix, Type 1 LMS cement), testing cadence and curing requirements (double-layer wet burlap, five-day cure), and urged timely coordination with bridge engineers.
Devil’s Lake DOT staff walked attendees through bridge‑deck overlay preparation, delamination measurement, removal methods and overlay placing and curing during a DOT training segment.
Darren, a Devil’s Lake presenter, said the district is preparing for bridge‑deck overlay projects and described the team’s inspection and preparation workflow. Surveying and delamination measurement used a combination of conventional chain‑sound testing and modern survey methods: staff “chained” the deck to identify delaminated areas, collected GPS corner points and also flew a drone to create high‑resolution aerial photos that were scaled into MicroStation and Trimble Business Center to produce square‑yard areas for overlays. One example in the presentation showed a deck with 326.6 square yards and 13.5 square yards of delamination (about 4.2% of the deck area).
Removal and demolition methods: James Wren reviewed removal options and safety constraints. He described three principal approaches used in the field: milling for even removal to a specified depth; pneumatic hammers and controlled jackhammering when careful hand removal is required; and hydro demolition, which the presenters described as “considered to be the safest and most cost effective” for removing poorly bonded concrete without harming remaining rebar. Wren emphasized that removal must preserve remaining reinforcing steel and that engineers should inspect after each pass to determine whether additional removal is required.
Materials and acceptance testing: Brian Benes summarized overlay mix and testing requirements the group will use. The overlay uses an AE5 mixture with cement, coarse and fine aggregates, water, admixtures and air entrainment; cement was described as a Type 1 LMS (Portland‑limestone, moderate sulfate resistance). The DOT takes aggregate samples on site and performs acceptance testing; production testing includes slump, air, unit weight and cylinder breaks. Presenters said testing generally uses one set of cylinders per 50 cubic yards, a 28‑day compressive strength target of 4,000 psi and air entrainment in the 5–7% range.
Placing and curing: Presenters described placement using buggies or belt placers and the importance of continuous operation to avoid transverse joints across the overlay. Surface preparation includes sandblasting and cleaning of rebar and a grout/bonding coat applied immediately before overlay placement. Darren and peers emphasized curing for at least five days using a double layer of prewetted burlap kept continuously moist; they cautioned against using plastic covers over the burlap because plastic can trap heat and “cook” the overlay. Temperature guidance was to place when ambient is 45–80°F and to maintain a concrete temperature above 55°F during curing.
Coordination and oversight: Presenters urged teams to involve bridge (Bridal) engineers early when projects raise questions about crown, rebar floats or unusual profiles. One attendee recounted a prior overlay where additional concrete increased the permanent dead load and required coordination with bridge engineers; Darren summarized the recommendation: keep bridge engineers involved for any deviations. The session closed with an invitation for questions and a reminder to coordinate on drilling, testing and curing requirements before contract completion.
No formal votes or policy changes were made; the presentation is documentation of recommended field practice and quality‑control measures.
