Concrete reinforcement
A concrete reinforcement structure 100 for making a reinforced concrete foundation horizontal beam upright or vertical column comprises a square or rectangular helical coil 101 which is manufactured in a compacted length form and can be pulled out under tension to an extended length, secured within formwork or a trench, and supplemented with additional supporting bars or rods 102 - 105 prior to having concrete poured into the formwork to form a reinforced concrete foundation or horizontal beam structure. The reinforcement structure can be manufactured on site or can be pre-manufactured in a factory and transported to a construction site.
1 . A reinforcing member for a concrete structure, said reinforcing member comprising:
an elongate drawn wire formed into a four-sided tubular helical member;
said helical member having a number n of 360° 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 member comprising four lengths substantially in the form of a rectangle or a square;
wherein each single 360° turn of the helical member comprises a first upper member, a first side member, a lower member, and a second side member, wherein the first upper member is connected to the first side member by a first corner portion, the first side member is connected to the lower member by a second corner portion, the lower member is connected to the second side member by a third corner portion, and the second side member is connected to the second upper member by a fourth corner portion;
said helical member being manufactured in a first compacted state in which said plurality of turns are compacted along a main length axis of said helical member to a first overall length L1; and
said helical member being capable of adopting an expanded state in which said helical 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 by applying tension between a first turn of said reinforcing member located at or near a first end of said reinforcing member and a second turn of said reinforcing member located at or near a second end of said reinforcing member;
wherein in an expanded in-use condition, the pitch p between adjacent successive turns is in the distance range of 4 cm to 15 cm;
wherein the helical member forms a tunnel being square or rectangular at any location along the length of the tunnel looking in a direction tangential to a centreline; and
a radius of curvature of an innermost periphery of each corner portion of the helical member is in the range of 0.5 cm to 5 cm;
wherein the wire has a carbon content in the range of 0.04% to 0.20% by weight.
2 . The reinforcing member as claimed in claim 1 , wherein the ratio of the second width w2 to the first width w1 is in the range of 1 to 3 w2 to 1 w1.
3 . The reinforcing member as claimed in claim 1 , wherein, in an expanded in-use form of the helical member, the pitch p between successive turns is between 1 and 10 times the pitch p when the helical member is in a fully compacted state.
4 . The reinforcing member as claimed in claim 1 , wherein in an expanded in-use condition, the pitch between adjacent successive turns is in the distance range 5 cm to 10 cm.
5 . The reinforcing member as claimed in claim 1 , wherein the uniformity of pitch p of the helical member when held between first and second ends on a level surface is p + or −7%.
6 . The reinforcing member as claimed in claim 1 , wherein said wire comprises a smooth outer surface.
7 . The reinforcing member as claimed in claim 1 wherein, in a newly manufactured form, a pitch between adjacent successive turns of said member is in the range 0 to 3 times an outside diameter of said wire.
8 . The reinforcing member as claimed in claim 1 wherein, in an expanded in-use condition a pitch between adjacent successive turns of said member is in the range 1 to 30 times and outside diameter of said wire.
9 . The reinforcing member as claimed in claim 1 , wherein the radius of curvature of an inner most periphery of at least one of the corners of the helical member internal to the tunnel shaped coil is in the range of 1.0 cm to 3.0 cm.