Changes to VicRoads Aggregate for Sprayed Bituminous Sealing Specification

BRUCE McCLURE General Manager of the CMPA comments on the recently released changes to the Standard Section 831 Aggregate for Sprayed Bituminous Surfacing.

A revised version of Standard Section 831 (Aggregate for Sprayed Bituminous Surfacing) has been recently released and is now available on the VicRoads website.

The extractive industry is generally aware of the changes and has been actively involved in the revision process providing a number of valuable comments and suggested changes.

VicRoads anticipates that a period of transition (quarry production wise) will be necessary from the old Standard Section to the new one. Quarries may still have some stockpiles of sealing aggregates which conform to the previous version of Standard Section 831.

Most of the 2012/2013 municipal sealing aggregate contracts are likely to contain the old 831 specification and this may also provide an opportunity to reduce quantities of existing sealing aggregate stocks.

VicRoads also anticipates that the quarry industry will, beyond existing stockpiles, proceed to produce materials in accordance with the new Standard Section 831 specification, as soon as practical.

Sealing Aggregate Contracts advertised prior to the end of July 2012 are likely include the old version of the Standard Section 831 specification.

In tendering or supplying for sealing aggregate contracts, suppliers are encouraged to review the actual contract documents to ascertain which version of Section 831 is applicable to that particular contract.

If suppliers wish to provide sealing aggregates to the new Section 831 requirements, for contracts already advertised and awarded (which include the old Section 831), suppliers will need to seek approval (via principal contractor) from the VicRoads Superintendent for that particular contract.

Amendments have been made to Code of Practice 500.09 (Testing of Sealing Aggregates) and Code of Practice 500.16 (Selection of Test Methods etc) in line with the changes to Section 831 and these amended Codes of Practice will be issued shortly.

The recent changes to Standard Section 831 are significant and are briefly outlined below:

• A Hold Point has been included to ensure that the results of all required testing are provided to the Superintendent prior to delivery.
• There is now only a single grading envelope for each aggregate size, previous oversize and undersize tables have been removed.
• A minimum Average Least Dimension (ALD) is now specified for all aggregate sizes (20, 14, 10, and 7 mm) except 5mm aggregate.
• The limits for Flakiness Index (FI) and Unsound Rock Content have been tightened in line with Type H and Type N asphalt products.
• A single test only is now required for Unsound Rock Content, grading, ALD and FI per 350 tonne lot of aggregate.

It is important that all relevant personnel and quarry managers are made aware of this specification change to Standard Section 831 and the relevant Code of Practices 500.09 and 500.16. It is essential to visit the VicRoads website to view and obtain copies of the entire documents.

These specification changes will have cost implications for most sites as they will generally result in screen and crusher setting changes, reduced tonnage, more energy usage and more byproducts produced.

The CMPA will comment on the likely cost implications in more detail in the next issue of Sand & Stone.

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