DIAMOND GRINDING: QUIETER ROADS, BETTER SKID RESISTANCE AND LONGER LIFE

Low noise diamond ground pavement surfaces deliver high-performance on Australia’s newest major motorway

The recently opened M12 Motorway, 45 km west of Sydney Central Business District, allows high-speed traffic to travel from the M7 Motorway to The Northern Road in the western suburbs in a growing area of Sydney. More importantly, it is a vital gateway to the new 24-hour Western Sydney International Airport.

The motorway consists of two carriageways with two 3.5 m-wide lanes, a

2.5 m-wide shoulder, and large breakdown areas typical of modern New South Wales (NSW) motorways. In addition, a shared path follows the motorway route, allowing people to cycle to the new airport and the proposed Western Sydney Aerotropolis.

The pavement chosen for M12 is a 250 mm continuously reinforced concrete pavement (CRCP) base supported on a 150 mm lean-mix concrete subbase and 300 mm-thick durable selected material zone. The Environmental Impact Statement noted that the pavement surface required a low-noise finish. Rather than placing a two-layer open-graded asphalt and dense-graded asphalt surface over the CRCP, which would be similar to the existing nearby M7 Motorway and would add another 75 mm of material to the pavement structure, Transport for NSW decided to use their low noise diamond grinding (LNDG) technique on the surface of the CRCP. The LNDG surface texture is inspired by and similar to the properties of NGCS (next generation concrete surface), minus the mandated use of the flush grind. 

When employing LNDG, a hessian turf drag is used during concrete placement, followed by longitudinal safety grooving. In the event the required smoothness is not achieved, conventional bump grinding is used to correct any ride quality issues, a flush grind is applied to any area with a conventional bump grind, and longitudinal safety grooving is performed on the entire pavement area. This is the fourth site in Australia to use the LNDG surface finish, showcasing the growing popularity of the texture. 

One of the three contractors involved in the M12 project, IGGA member Dowsing Group, provided large-scale diamond grinding and grooving treatments across the project pavement. 

Ride quality (smoothness) of the CRCP varied after placement. In areas where the target International Roughness Index (IRI) of 1.2 m/km (75 in/mile) was not achieved, conventional diamond grinding and flush grinding were performed before grooving took place. Areas that met the required IRI did not require conventional or flush grinding before safety groove was applied. 

John Roberts at the IGGA offered expert and timely technical advice for this project while George Vorobieff, a semi-retired pavement engineer, provided further improvements to the Transport for New South Wales (TfNSW) construction specification R94 for the application of LNDG on

the concrete pavement. 

Reach out to learn how diamond saw cut surface textures can deliver a high-performance concrete pavement on your next project. https://www.igga.net/contact-us