Tendon-identifying, post tensioned concrete flat plate slab and method and apparatus for constructing same

For use with a temporary, box-like concrete slab formwork having a uniform flat bottom and arranged to support a plurality of post-tensioning uniform tendons in predetermined laterally spaced apart, longitudinally extending condition, a temporary concrete form panel member for placement on the flat bottom of the formwork inbetween laterally spaced apart tendons prior to introduction of concrete material into said box-like formwork for producing tendon-identifying, post-tensioned concrete slabs, the concrete form panel member comprising:

• a) a longitudinally elongated, substantially rectilinear panel member arranged with predetermined length, width and depth dimensions and having a closed top side, closed peripheral side walls, and a supporting bottom side arranged for disposition on the underlying flat bottom of the box-like formwork,
• b) said predetermined panel member width dimension being less than the distance between laterally spaced apart, adjacent uniform tendons supported in the box-like flat plate concrete formwork, and
• c) said predetermined panel member depth dimension being between 10% to 40% of the full thickness dimension of a concrete slab to be formed in the box-like flat plate slab formwork,
• d) for placement of a plurality of said concrete form panel members in longitudinally extending rows between each laterally spaced apart uniform tendon supported by the box-like formwork preliminary to introducing liquid concrete material into the formwork.

A method of constructing a tendon-identifying, post-tensioned concrete slab, the method including the steps of:

• a) providing a temporary, elevated, box-like concrete formwork having a substantially uniform flat bottom surface and enclosing upstanding peripheral walls forming an interior cavity for receiving and containing liquid concrete until it hardens,
• b) identifying on the formwork the positions for the placement of the opposite terminal ends of a plurality of individual, laterally spaced apart, longitudinally elongated uniform post-tensioned tendons to be supported in the formwork,
• c) providing a plurality of individual, substantially rectilinear longitudinally-elongated concrete form panel members each having a selected length and a predetermined width selected to be less than the distance identified on the formwork between adjacent, laterally spaced apart uniform tendons, said form panel members each having a predetermined depth selected to be in the range of 10% to 40% of the full thickness of the concrete slab being constructed,
• d) placing said individual concrete form panel members on the flat bottom of said box-like formwork in longitudinally extending rows centrally between the positions identified on the formwork for the placement of the opposite longitudinal terminal ends of the plurality of laterally spaced apart, longitudinally-elongated uniform tendons,
• e) installing a plurality of individual uniform tendons in the box-like formwork as previously identified on the formwork, for longitudinal extension of the individual tendons between and along adjacent rows of said concrete form panel members placed on the flat bottom of said formwork,
• f) introducing liquid concrete material into the interior cavity of said box-like formwork to a predetermined depth corresponding to the predetermined full thickness of the concrete slab being constructed,
• g) allowing the concrete material to harden,
• h) individually tensioning the post-tensioning tendons to a predetermined tension and securing the tendons in tension condition,
• i) removing said temporary box-like concrete formwork, and
• j) removing the temporary concrete form panel members from the bottom of the hardened concrete slab, revealing inwardly extending, longitudinally elongated recesses in the bottom of the concrete slab for identifying areas of the concrete slab inbetween individual, laterally spaced apart, longitudinally-extending adjacent post-tensioning tendons embedded in the concrete slab.