Question: Is there any satisfactory way of obtaining skid resistance in concrete pavements that is less expensive than diamond grooving?

Answer: The Federal Aviation Administration (FAA) has been conducting tests at its Naval Air Engineering Center in Lakehurst, New Jersey on a reflex percussive process. This technique is said to offer potentially reduced costs for runway grooving while optimizing aircraft braking efficiency on wet surfaces. It is reported to be faster than diamond grooving.This process involves a machine with tiny pneumatically driven hammers made of hardened tungsten carbide steel. The hammers striking the surface cause the material directly under the area of impact to pass through a rapid compression-tension cycle. Since concrete is weak in tension, it fractures in the localized area of impact. The advantage in this method of cutting is said to be its ability of not loosening the aggregate particles within the matrix or creating microfractures in the undamaged surrounding concrete.

The cutting heads are tilted at 13 degrees so that the reflex-percussive grooving machine produces nonsymmetrical V-shaped grooves. The cut is not as clean as a saw-cut groove, but groove dimensions can be held within tolerances already quoted in the FAA advisory circular AC-150/5320-12. Experimental percussive groove spacing as wide as 4 1/2 inches seems to equal the wet-surface braking performance of saw-cut grooves spaced 1 1/4 to 2 inches apart.