Understand why watertight, properly supported formwork is critical for UHPC and how to prepare forms to handle hydrostatic pressure.
Good formwork is essential to a smooth experience with ultra-high performance concrete. Fresh UHPC is very fluid and needs to be treated as such until it has a chance to set and cure. Forms need to be more carefully installed than with traditional concrete.
Formwork should be installed to be watertight, and a water test is recommended before casting UHPC to identify any gaps in coverage. If the water can find a leak, the UHPC will too.
Forms also need to be able to withstand the hydrostatic pressure of the fresh UHPC, which is around 155 pounds per cubic foot. Formwork material and connections need to be considered to withstand this force.
The best way to ensure easy installation and appropriately tight connection of forms to prefabricated bridge elements is to collaborate with the precaster. They can help provide installation points for the formwork, such as threaded rod sockets, to improve watertightness and structural integrity.