SYMPOSIA PAPER Published: 01 January 1999

On the Study of Crack-Initiation Fracture Toughness of Fiber Glass Asphalt Shingles


The fracture behavior of fiber glass asphalt shingles was examined by measuring their J-integral fracture toughness at crack initiation. The corresponding fracture mechanisms were also studied by in situ fracture observation and by scanning electron microscopy. The applicability of using J-integral fracture toughness to characterize asphalt shingles was discussed and its relationships to other mechanical properties was established. The results indicated that the fracture toughness at crack initiation can be accurately measured for fiber glass shingles and the values may be used to characterize their cracking resistance. Fracture toughness measured from various shingle samples was found to correlate to the shingle's tensile toughness and to its tear strength. Preliminary results on fracture mechanisms suggested that failure in the asphalt coatings by micro-cavitation may be the controlling event leading to crack advance. The importance of the glass fiber mat on a shingle's resistance to fracture was also discussed.

Author Information

Shiao, ML
CertainTeed Corp., Blue Bell, PA
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Developed by Committee: D08
Pages: 132–151
DOI: 10.1520/STP13303S
ISBN-EB: 978-0-8031-5399-8
ISBN-13: 978-0-8031-2494-3