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JOINTS

410 JOINTS GENERALLY
• Layout: All joints to be accurately located, straight and well aligned.
• Construction joints made at end of working day: Form as contraction joints.
• Modifications to joint design or location: Submit proposals.
• Temporary support: Prior to concreting, set formwork, dowel bars, tie bars, joint filler
boards, sealing groove fillets and the like rigidly in position and support to prevent
displacement. Maintain support until concrete has set.
• Keep clean:
- Do not allow concrete to enter any gaps or voids in formwork or to render
movement joints ineffective.
- Do not allow concrete to impregnate or penetrate materials used as
compressible joint fillers.

420 TIE BARS
• Standard: To BS 4449.
- Product form/ designation: Ribbed.
- Strength grade: site specific.
• Bar dimensions: site specific.
• Protection: site specific.
• Cleanliness: Free from corrosive pitting, loose millscale, loose rust and contaminants
which may adversely affect the tie bars, reinforcement, concrete, or bond
between the two.
• Location: Place tie bars centred on and perpendicular to line of joint, within middle
third of the slab depth.
- Centres: site specific.
- Cover below top crack inducer/ joint groove (minimum): site specific.

430 DOWEL BARS
• Standard: Material to BS 6744, other requirements to BS EN 13877-3.
- Material/ Designation: Carbon steel.
- Strength: site specific.
- Profile: Plain, round.
- Condition: Free from oil, dirt, loose rust and scale.
• Bar dimensions: site specific.
• Location: Place dowel bars in movement joints at mid depth of the slab ±20 mm,
centred on joint and at 300 mm centres. Bars to be parallel to longitudinal axis and
top surface of the slab.
- Misalignment tolerance per 300 mm length of dowel bar: Maximum of ±3 mm
with two thirds of bars within ±2 mm.
• Debonding of bars: Flexible plastics sleeve covering, not less than 0.6 mm thick.
• Bars in expansion joints: Provide 100 mm long plastics caps for free bar movement.
Before placing concrete, ensure there is a space between the end of the cap and
the end of the dowel bar 10 mm greater than the thickness of the joint filler board.

RotF generic (intermediate) NBS 2014 6118-AEW-XX-XX-NBS-A-01