Modular concrete form

Claim 2

A form assembly comprising: form plates arranged in edge-to-edge contiguity, each of said plates having a pair of longitudinal sides and a pair of transverse sides; a fastening means provided along said longitudinal sides to fasten releasably said form plates; reinforcement channel pieces attached detachably to said form plates along said transverse sides; and trussed backing members extending longitudinally between said channel pieces, each of said trussed backing members having two opposite joint ends, said joint ends being detachably connected to said channel pieces, wherein each of said channel pieces includes a plate member, two opposite longitudinal backward flanges extending from two opposite sides of said plate member of said channel piece, one of said opposite longitudinal backward flanges abutting with said form plate for connection thereto, two opposite inward flanges respectively extending from said backward flanges and defining threaded holes therein, and opposite transverse backward flanges extending from said plate member of said channel pieces between said longitudinal backward flanges.

Claim 3

A form assembly as claimed in claim 1, wherein said fastening means includes a plurality of looped members projecting from each of said form plates adjacent to said longitudinal sides, said looped members of each of said form plates being respectively aligned with said looped members of an adjacent said form plate, each of said looped members having an engagement face spaced apart from said form plate and two spaced apart opposed side flanks connected securely to said form plate on two sides of said engagement face, the distance between said flanks being greater than that between said engagement face and said back face, and key members each having an insert rod portion to be inserted in at least two aligned said looped members and a handle rod portion which forms an angle with said insert rod portion, said insert rod portion having a pair of first opposed longitudinal faces, and a pair of second opposed longitudinal faces, the distance between said first opposed faces being smaller than said distance between said engagement face and said form plate so that said key rod portion can be inserted into aligned said looped members, the distance between said second opposed faces being greater than the distance between said first opposed faces, said second opposed faces being engaged with said engagement faces of said looped members and said form plate when said insert rod portion is turned an angle after being inserted.

Claim 4

A form assembly as claimed in claim 2, wherein said insert rod portion has a substantially rectangular cross-section, and said second opposed faces are convexed.

Claim 5

A form assembly as claimed in claim 1, wherein each of said trussed backing members is provided with two opposite transverse joint end plate members abutted with said inward flanges of said channel pieces.

Claim 6

A form assembly as claimed in claim 4, further comprising connecting pieces to interconnect said trussed backing members, said connecting pieces being detachably connected to said trussed backing members, wherein each of said connecting pieces is a one-piece member having two spaced parallel plate members and a transverse web interconnecting said spaced parallel plate members, said spaced parallel plate members being provided with opposite right-angled flanges abutting with said joint end plate members for connection thereto.