Four distinct patterns of cracking were found. Temperature cracks are transverse and occur at intervals of about 15 to 88 feet. Roller-induced cracking has been made apparent by weather and erosion. Longitudinal cracking is usually at the edges of the wheel paths where rutting is prominent. Map cracking or checkering in the wheel paths is caused by the maximum shear stresses occurring at a depth equal to 1/3rd the radius of the loaded area (tire print). This cracking penetrated about 2.5 inches. This cracking and weakness was found only in the all-gravel asphaltic concrete. No stripping was found, but evidences of weakness were discernible. Where gravels (partially crushed) were blended with crushed limestone, these defects in performance were not found.

Overlay requirements were determined by analysis of Road Rater deflect ions.

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