Recycled and alternative materials for transport infrastructure

The land transport system is heavily resource dependent, with raw materials, fossil fuels and energy all being consumed in large quantities. Recycling material reduces impacts on the environment because we don’t need to source as much raw material and can reduce the amount being sent to landfills.

Recycled and alternative materials allowed by Waka Kotahi

The tables below outline the recycled surface and pavement materials currently allowed on Waka Kotahi projects, according to the relevant specifications. The tables also provide limitations by volume of mass and relevant comments about the use of materials.

Sub-base aggregate

Sub-base aggregate guidance

Material type	Allowed	% by mass	Comment
Various	Yes	No restriction	This Sub-base aggregate guidance provides guidance on developing a local specification for sub-base aggregates. Generally, there is no upper limit for recycled material content. Local specification using recycled material other than glass will need to be approved by the appropriate regional council.

Material type

Allowed

% by mass

Comment

Various

Yes

No restriction

This Sub-base aggregate guidance provides guidance on developing a local specification for sub-base aggregates.

Generally, there is no upper limit for recycled material content.

Local specification using recycled material other than glass will need to be approved by the appropriate regional council.

Basecourse aggregate

M4 Specification for basecourse aggregate

Material type	Allowed	% by mass	Comment
Recycled crushed concrete (RCC)	Yes	No restriction	RCC use must be approved by the appropriate regional council.
Glenbrook melter slag	Yes	No restriction	Slag use must be approved by the appropriate regional council.
Reclaimed glass	Yes	5%	Proportions of reclaimed glass in excess of 5% may be used at the discretion of Waka Kotahi, provided that the requirements of the T15 Specification for repeated load triaxial (RLT) testing for pavement materials have been satisfied. T15 Specification for repeated load triaxial (RLT) testing for pavement materials

Sealing chip

M6 Specification for sealing chip

Material type	Allowed	% by mass	Comment
Glenbrook melter slag	Yes	No restriction

Dense graded asphaltic concrete

M10 Specification for dense graded asphaltic concrete

Material type	Allowed	% by mass	Comment
Recycled asphalt pavement (RAP)	Yes	<15%	No restrictions.
		15% - 30%	Needs to meet mixed design requirements.
		>30%	Requires approval of the National Pavements Manager (Waka Kotahi NZ Transport Agency).
Coarse recycled aggregate material	Yes	No restriction	Subject to the engineer's approval (includes slag or glass, or other materials approved by the engineer).