1. Diamond grinding of concrete pavements
Geoff Ayton
Pavement Structures Section
Engineering Technology Branch
8 Sept 2008

2. Surface profiles
& water spray
Ride comfort

3. Surface treatments
Three treatments
Milling

4.     Background information: Surface profiles PIARC Roughness
Microtexture
There are 4 distinct surface profiles (as shown above). The first two are desirable but the third & fourth are undesirable.
Microtexture is the main contributor to friction (the sandpaper effect).
Macrotexture doesn't (of itself) provide friction but is responsible for dispersing water so that the tyre stays in contact with the microtexture, hence it indirectly contributes to wet-weather skid resistance. 
Macrotexture 
Megatexture 
Roughness

5. * * Roughness Ride comfort
Critical wavelengths change with traffic speed because of frequency influence. * *
Roughness
Ride comfort

6. Milling 15mm: coarse milling 8-9mm: fine milling 6mm: micro-milling
There are three different grades of "milling" depending on the spacing of the cutters.
15mm: coarse milling
8-9mm: fine milling
6mm: micro-milling

7. Cumberland Hwy, Wentworthville

8. Coarse milling
* strongly discouraged on concrete surfaces * harsh and noisy ride * unacceptable damage to joints

9. Diamond grinding

10. Grooving
Pacific Hwy - Wang Wauk

11. Diamond grinding

12. Diamond grinding
Door plane

13. Purposes Grinding of concrete pavement improved ride quality
* everyday treatment for decades
* ~100 grinders
* most commonly used as a rehabilitation treatment
* also sometimes used on new pavements
Purposes
improved ride quality
reduced tyre noise
reduced dynamic traffic impact
improved skid resistance

14. 1. Grinding, produces a completely new running surface, hence changing macrotexture and microtexture.
2. Sawblade spacing such that the concrete fins are snapped off thereby producing a new surface

15. 1. By comparison, grooving places sawcuts in the existing surface
2. After grooving, the tyre is still running on the old surface The macrotexture will be improved but not the microtexture

16. Grinding Grooving In summary  improves ride quality
 improves microtexture
 improves macrotexture (albeit longitudinal)
 reduces tyre noise
Grooving
 has no impact on ride quality
 has no impact on microtexture (hence no improvement in dry friction)
 improves macrotexture, hence improves water dispersion
 is likely to increase tyre noise

17. Summary
Distinctly different profiles
Milling

18. Road Noise dB(A)
Jeff Parnell. MEngSc thesis

19. Road Noise dB(A)
Dash, Bryce, Moran & Samuels. ARRB. Mar 2002

20. Grinding reduces tyre noise on concrete by removing those texture wavelengths which are responsible for generating the most annoying spectral frequencies.
1/12th Octave, 7.5m offset, F3 near Wyong
Jeff Parnell. MEngSc thesis

21. Grinding Megatexture in CRCP Transverse N12 @ 750 c/c
Megatexture in JRCP
Mesh SL82
* Grinding can remove both roughness and megatexture.
* These textures ~2-3 mm deep and so readily removed by grinding.

22. Grinding
Bridgedecks under headlights

23. Longitudinal grinding followed by transverse grooving.

24. California
Grinding on a major overpass.

25. Florida USA - 2001. An old JRCP after grinding.

26. USA. Traffic on a pavement during grinding operations.

27. Grinding in echelon.

28. Ziming Tu
Dr Hans Prem

29. Effect of grinding (on ride)
Enables evaluation of the benefits of targeted grinding on both the ride quality and the resulting incentive value