20M Rebar

Reference

The step up for real flexure: beam bottoms, grade beams and thick footings pick up 20M when 15M counts get out of hand.

19.5 mm diameter, 300 mm2, 2.355 kg per meter
Nominal diameter19.5 mm
Cross section area300 mm2
Mass per meter2.355 kg
Standard grade400W, 400 MPa yield
6 m stock barabout 14.1 kg
Bars per tonne, 6 m lengthsabout 70
Nearest US bar#6

Notes for design and site

Each 20M carries the area of one and a half 15M bars, so switching a congested 15M layout to 20M thins the bar count by a third without changing the steel area. That trade shows up constantly in beam bottoms and footing mats where spacing, not area, is the constraint.

Rough lap at 40 diameters is about 780 mm, and a 6 m bar at 14 kg is still a one person carry but no longer a one hand one. Hooks grow with the bar too: minimum bend diameters scale up, so a standard 90 degree hook on 20M needs noticeably more room in a beam cage than the same hook on 15M.

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