As part of the rehabilitation of an existing deteriorating bridge, the New York State Department of Transportation had decided to completely replace, remove, and install a new precast UHPC connection on a busy I-90 bridge over Fuller Rd, Albany, NY. Since it is a critical part of the New York State transportation network, this project was greenlit on a Sunday morning with a tight deadline of 24 hours. To accommodate the accelerated construction and still meet safety requirements, the project required a high early strength of 10,000 psi (70 MPa) in 10 hours and 12,000-14,000 PSI to open the bridge for work traffic.
Giatec’s SmartRock® was described as a crucial product that was used for the UHPC connection to determine when to remove the formwork as well as to know when the traffic could be allowed back on the bridge.
“As this was an accelerated bridge construction, we needed to track strength in real-time instead of waiting on the usual method of cylinder breaks or compression breaks to determine the strength of the bridge. We used the SmartRock sensors and the Maturity Method instead to get a better idea of real-time strength and temperature on the bridge” – Hiram Olvera, Technical Representative, ceEntek Inc. North America.
The I-90 over Fuller Road project was a rehabilitation of an existing bridge. The steel girders in the previous bridge were susceptible to water leaking off the bridge deck, which caused major deterioration. The new design would prevent the corrosion of steel beams and girders. Casting was scheduled for four weekends in June, and the bridge was split up into four different sections of 2-lanes that were replaced each weekend. Traffic was open on three sections while work was being done on the fourth.
High early strength was necessary to open the bridge to traffic in less than 24 hours after the placement of UHPC. Accelerated strength gain to 10,000 psi (~70 MPa) of ceEntek’s UHPC 2.0TM allowed stripping of formwork 8-10 hours after placement. The new structure was Precast Modular Units (PMU) with UHPC closure pours and UHPC link slabs using ceEntek’s ce200SF-GTM. The deck was grounded and grooved leaving a smooth surface and UHPC exposed.
SmartRock sensors were installed at the start and at the end of different connection castings to get real-time strength and temperature data. With the accelerated construction schedule, data needed to be gathered frequently throughout the day while workers were casting. Team members even came back at night to evaluate the progress made. This easy-to-use product was extended to contractors as well, who were given access to the sensor’s real-time results. The contractors were able to update the sensors while they were working on-site to collect more data and fast results.
Olivera says that SmartRock sensors made it convenient for the team to track, update and consult the real-time changes, even when they were off-site. Before Smartrock, the company used cylinder breaks and thermocouples. This obsolete method requires workers to be on the site taking temperature readings and using those to convert the maturity method. The sensors make it easier to collect data compared to being always on the site.
“We use SmartRock in every project we work with,” Olvera continues. “Without it, we simply would not have been able to meet our deadlines.”