Clockwise from top R: concrete truck outside the Custom House; deteriorated subcellar walls; and pouring self-consolidating concrete.

Recently, the Alexander Hamilton US Custom House saw its first pour of self-consolidating concrete (SCC). The century-old masonry apron in the building’s subcellar is being restored with the application of new waterproofing, as part of a $55 million restoration of the landmark building.

The apron wall functions as a downward counterweight to the pressure slab below, resisting uplift from ground water pressure. The wall, including embedded steel members, exhibited extensive corrosion and exfoliation. In the underpinning approach devised by SUPERSTRUCTURES, the masonry mass is being replaced in a specific sequence, leaving three bays intact between the bays being restored.

The owner (the General Services Administration or GSA) has prioritized the procurement of American-made, low-embodied-carbon concrete, steel, and asphalt. The goal is to minimize embodied carbon in the manufacture of the reinforced concrete while promoting cleaner American manufacturing supply chains.

SUPERSTRUCTURES is the Engineer of Record, Pullman is the subcontractor performing work under Consigli, and Turner & Townsend Heery is the Construction Manager acting as Advisor for this project.