Concrete Tracker

Block 9 consists of an 18-story, 235’ tall mixed-use building, 8-story parking garage and plaza. The building itself is 283,161 SF. There is one level of parking below grade. Levels 1-5 will be the new corporate headquarters for the R.D. Offutt Companies, and the main lobby, restaurant, and ballroom for the 4-star Jasper Hotel. Levels 6-8 are leasable office space; levels 9-14 will contain 126 hotel rooms; six condos will be built on levels 15-17, and floor 18 is the mechanical penthouse. The building is combination of structural concrete and structural steel. The exterior is a mixture of precast concrete elements and glazing. The building sits on 285, 18” auger cast pile drilled to 95’ below grade. The footings, foundation walls and pile cap are made of 489 CY of concrete with an additional 694 CY of slab on grade. The superstructure of taller tower portion of the building is all concrete. The elevators and stairs are in the 50’x40’ structural core running the entire height of the building which contains 1,783 CY of concrete. Twenty, 18-24” concrete columns support the building at the perimeter consisting of 473 CY of concrete. The floors are a mixture of mildly reinforced slabs and post tension slabs comprised of 6,075 CY of concrete. Outside of the footprint of the tower, the lower wider portion of the building is a steel structure with a lightweight concrete slab on metal deck, which added an additional 1,033 CY to the building. In total there is 12,294 CY of cast in place concrete on the building with 1,497 tons of reinforcing. The adjacent parking ramp is an 8-story, 350-stall precast concrete structure. It sits on 75, 18” auger cast pile. It has a cast in place foundation with a tunnel connection to the basement of the tower. The foundation is made up of 1,186 CY of concrete. The slab on grade in the ground level contains 338 CY of concrete and the crossovers and curbs were made up of another 144 CY. Construction on the building started in September of 2018, with construction wrapping up in December 2020. Concrete placement started in October of 2018 and continued nonstop until November 14th, 2019 when the building topped out. Exceptional cold weather concrete practices had to be put into place to support the winter concrete construction in 2019. To ensure that ACI 306R temperatures were maintained, McGough tracked temperatures 24 hours a day during the heart of winter by utilizing the thermal probes placed by the testing agency. A 7-day work week was maintained for most of the concrete work done in 2019, during which a 12-day cycle per floor average was achieved. Construction was aided by two Liebherr 316 tower cranes which stood as tall as 320’ over downtown Fargo. Above level 4, the concrete was pumped to a 38-meter self-climbing placing boom. Due to the schedule and logistics of the project, no space was left for a staging area. The project utilized just-in-time deliveries and offsite storage to meet those challenges. Reinforcing for the columns and beams was tied at an offsite yard and shipped to downtown Fargo where it was hoisted up on the building at scheduled time slot. Similarly, all formwork for the columns and core was brought in by truck when it was needed, then stripped and sent back to the offsite yard for cleaning and storage until it was needed again. The rebar mats for the core wall were too large to be transported, so the top deck of the recently completed parking garage was utilized to for assembling the large mats. This allowed them to be hoisted directly into place because this area was within reach of the tower crane. The decks were cast primarily on formwork tables. Total stations and lasers were used for layout and maintaining control of the building. Over 1,500 sleeves were cast in with just one sleeve being misplaced 7/8”. Drones flew over the project prior to each placement to photograph PT tendon locations with high resolution. The decks were placed using wet screeds with floor flatness levels in the upper 60’s being achieved. In total, more than 73,000 manhours were expended for the cast in place concrete on the building.