AS NZS 2425:2015 Bar chairs in reinforced concrete— Product requirements and test methods
3.4 Cover
The distance between the outside of the reinforcement and the nearest permanent surface of the element excluding any external finish.
NOTES:
1 Cover is typically specified by the structural designer on the structural design drawings.
2 Unless otherwise noted, the tolerance on position of reinforcement and tendons given in the relevant design Standard will apply.
3.5 Durability
Ability of a structure and its component members to perform the functions for which they have been designed, over a specified period of time, when exposed to their environment.
3.6 Height of chair
The distance from the underside of the reinforcement to the base surface of the concrete,when placed in the supporting surface of the bar chair.
3.7 Singular bar chair
The bar chairs that are used to support reinforcing at a single location.
3.8 Spacer
A non-vertical loadbearing chair used to maintain the position and cover of steel reinforcement during construction to ensure durability, strength and serviceability of the as-built elements, in accordance with the design specification.
3.9 Unit of manufacture (pack)
A quantity of product (typically 50 or 100) of the same nominal geometry and strength characteristics, which is typically in the form as delivered to the customer.
4 PRODUCT REQUIREMENTS
4.1 General requirements
When sampled and tested in accordance with Clause 6, batches shall be deemed to comply with the requirements of this Standard, provided all samples meet the requirements of Table 1.
4.2 Protective-tipped wire bar chairs
Protective-tipped wire bar chairs shall be examined after cessation of load test. The bar chair shall not exhibit evidence of penetration of wire end through the protective plastic coating or sleeve under the tip of the wire legs.
4.3 Plastic chairs
The chair design shall allow a nominal 20 mm aggregate concrete to readily penetrate the chair openings to minimize the risk of voids occurring in concrete placement.
4.4 Spacers
Spacers shall comply with the requirements of strength grade 60.
4.5 Concrete bar chairs
Concrete bar chairs shall have a minimum concrete compressive strength of 60 MPa.When type tested in accordance with ASTM C1202, with specimens prepared and results adjusted in accordance with Appendix A, concrete bar chairs shall have a maximum RCPT (rapid chloride permeability test) expressed in coulombs, appropriate to the chloride permeability class set out in Table 2.
NOTE: See Note 1 of Table 1.