Removal of Falsework Supporting Wide Culvert Slab
Removal of Falsework Supporting Wide Culvert Slab
(OP)
Just wondering what the structural engineering group sees as the criterion (criteria) for removing falsework supporting a thick wide (10 m) culvert slab (one way steel). For instance, the Alberta Ministry of Transportation states:
Portion of Work Age or Minimum Strength
Arches and girders - 14 days (or 80% of 28-day strength)
Pier caps and beams - 5 days (or 50% of 28-day strength)
Columns - 1 to 3 days
Decks & Slabs - 5 days (or 50% of 28-day strength)
Vertical faces of supported elements - 12 to 24 hours
Walls over 3 m high - 2 days
I would think that these strengths are based on using OPC (ordinary Portland cement) concrete whereas today, in many cases the use of fly ash up to 50% are being used in concrete mixes which will delay the initial hydration potential of the concrete. Too, some specifications that use fly ash constituents in the 30 to 50% range will actually specify 90-day characteristic strength values rather than the more traditional 28-day values.
Your comments would be appreciated.
Portion of Work Age or Minimum Strength
Arches and girders - 14 days (or 80% of 28-day strength)
Pier caps and beams - 5 days (or 50% of 28-day strength)
Columns - 1 to 3 days
Decks & Slabs - 5 days (or 50% of 28-day strength)
Vertical faces of supported elements - 12 to 24 hours
Walls over 3 m high - 2 days
I would think that these strengths are based on using OPC (ordinary Portland cement) concrete whereas today, in many cases the use of fly ash up to 50% are being used in concrete mixes which will delay the initial hydration potential of the concrete. Too, some specifications that use fly ash constituents in the 30 to 50% range will actually specify 90-day characteristic strength values rather than the more traditional 28-day values.
Your comments would be appreciated.






RE: Removal of Falsework Supporting Wide Culvert Slab
Is there some pressing need for the falsework material elsewhere?
Mike Halloran
Pembroke Pines, FL, USA
RE: Removal of Falsework Supporting Wide Culvert Slab
RE: Removal of Falsework Supporting Wide Culvert Slab