Precast concrete formwork, floor system and a method of construction

Formwork in accordance with any one of the preceding claims wherein an outer surface of the pre-cast concrete members in combination with the surface of the upwardly directed portion of the supporting joists positioned at opposite ends defines an in-use receiving portion for receiving wet concrete.

Formwork in accordance with any one of the preceding claims wherein the pre-cast concrete members comprises edge portions extending along a length of the pre-cast concrete members wherein preferably at least a first edge portion extends along a first lateral side of the pre-cast concrete member and at least a second edge portion extends a second lateral side of the pre-cast concrete member.

Formwork in accordance with any one of the preceding claims further comprising pre-cast concrete joists supported by a plurality of beams extending generally in a perpendicular direction relative to the general direction of the said pre-cast concrete joists.

Formwork in accordance with any one of the preceding claims further comprising:

• a first connecting mechanism for connecting a first joist positioned on a first lateral side of the beam with a second joist positioned on a second lateral side of the beam, said connecting mechanism being further adapted for preferably applying a negative bending force to the first and second joists during use;
• and
• a second connecting mechanism for connecting two adjacently located beams supported simultaneously on a column, the connector being provided for applying negative bending to said adjacently located beams.

Formwork in accordance with any one of the preceding claims further comprising one or more permanent formwork members for being positioned in between two spaced joists and wherein preferably the permanent formwork members comprise a substantially L-shaped or U-shaped cross section.

Formwork in accordance with any one of the preceding claims wherein the joists of the formwork further comprise one or more apertures for receiving reinforcing bars, the reinforcing bars extending in a transverse direction relative to the general direction of the joists, the reinforcing bars being adapted for being tensioned (by way of post-tensioning) after pouring concrete into the pre-cast concrete receiving members.

Formwork in accordance with any one of the preceding claims wherein at least one the pre-cast concrete members comprises a stepped configuration having an in-use upper portion and an in-use lower portion.

A pre-cast concrete joist comprising:

• a horizontal base portion;
• and an upwardly directed portion extending substantially along the length of the joist, the upwardly directed portion having spaced apart surfaces extending upwardly from the base wherein shelf portions of the base are located adjacent said upwardly directed portion, each of the shelf portions defining a seat for receiving a connecting portion of a pre-cast concrete pan member or a pre-cast concrete shell member wherein height of the upwardly directed portion is equal to or greater than vertical height of the said shelf portions.

A pre-cast concrete member for being positioned in between and supported spaced apart joists or beams, the precast member extending along a length of the joists or beams for receiving wet concrete, the precast member comprising a supporting arrangement to support opposite ends each of the pre-cast concrete members upon oppositely arranged joists or beams.