Concrete reinforcement

A reinforcement structure for a concrete structure, said reinforcement structure comprising:

• a square or rectangular helical member;
• and
• one or a plurality of elongate rods or bars;
• said a square or rectangular helical member, having a plurality of 360° turns, said helical member capable of adopting a first compacted state in which said plurality of turns are compacted along a main length axis of said member to a first overall length L1;
• and
• said helical member being capable of adopting an expanded state in which said member expands in a direction along said main length axis of said member to a second length L2;
• said helical member having a resilient shape memory which causes the helical member to adopt a contracted, as manufactured state when said member is not under tension such that each turn lies in contact with an adjacent turn;
• wherein in an expanded in-use condition, the plurality of turns of the helical member automatically space out substantially equidistantly between adjacent turns with a substantially constant pitch p;
• wherein the wire has a carbon content in the range of 0.04% to 0.20%;
• and
• each said elongate rod or bar being connected to said helical member at least at a first turn and at a second turn of said helical member, so as to maintain said helical member in said expanded state.

A method of manufacture of a cast or poured concrete structure, said method comprising:

• assembling a formwork for containing said concrete structure;
• placing a reinforcing member into said formwork, said reinforcing member comprising:
• an elongate drawn wire formed into a four-sided helical coil;
• said helical coil having an overall length in which there are a number n turns;
• each turn having a first width w1 and a second width w2;
• each turn as viewed in a direction along a main central length axis of said helical coil comprising four sides;
• said helical member having a resilient shape memory which causes the helical member to adopt a contracted, as manufactured state when said member is not under tension such that each turn lies in contact with an adjacent turn;
• wherein in an expanded in-use condition, the plurality of turns of the helical coil automatically space out substantially equidistantly between adjacent turns with a substantially constant pitch p;
• wherein the wire has a carbon content in the range of 0.04% to 0.20%;
• expanding said helical coil lengthwise into an in-use condition in which adjacent successive turns of said coil automatically adopt a substantially evenly pitched spacing;
• inserting a plurality of rigid longitudinal members along a main length of said helical coil;
• securing said plurality of longitudinal members to at least a first turn of said helical coil and to at least at a second turn of said helical coil, to create a rigid reinforcing structure in which said helical coil is maintained in expanded lengthwise form;
• and
• pouring fluid concrete around said helical coil and said elongate longitudinal members of said reinforcing structure.

A method of preparing a reinforcing framework prior to forming a cast or poured concrete structure, said method comprising:

• expanding a helical reinforcing member in a lengthwise direction said helical reinforcing member comprising:
• an elongate drawn wire formed into a four-sided helix;
• said helix having an overall length in which there are a number n turns;
• each turn having a first width w1 and a second width w2;
• each turn as viewed in a direction along a main central length axis of said helix comprising four sides;
• said helical coil having a resilient shape memory which causes the helical member to adopt a contracted, as manufactured state when said member is not under tension such that each turn lies in contact with an adjacent turn;
• wherein in an expanded in-use condition, the plurality of turns of the helical coil automatically space out substantially equidistantly between adjacent turns with a substantially constant pitch p;
• wherein the wire has a carbon content in the range of 0.04% to 0.20%;
• expanding said reinforcing member into an in-use condition in which adjacent successive turns of said member automatically adopt a regular even pitch spacing, by applying tension between a first turn of said reinforcing member located at a first end of said reinforcing member and the second turn of said reinforcing member located at a second end of said reinforcing member;
• inserting a plurality of longitudinal reinforcement bars along a main length of said reinforcing member;
• securing said plurality of longitudinal reinforcement bars to at least said first turn at said first end of said reinforcing member and a second turn located at said second end of said reinforcing member, such that said reinforcing member remains in said in-use expanded condition.

A method of manufacture of a helical coil reinforcement for a concrete structure, said method comprising the stages of:

• providing a reel of round wire, wherein the wire has a carbon content in the range of 0.04% to 0.20%;
• drawing said wire from said reel;
• changing a direction of travel of said wire, in order to remove surface scale from said wire;
• drawing said wire through a die in order to reduce an external diameter of said wire;
• spooling said wire under tension on to a driven rotating former, having four corners to produce a four-sided helical coil on said former such that each turn lies in contact with an adjacent turn;
• and
• cutting said wire after a predetermined number of turns have been wound onto said rotating former.