TY - JOUR
T1 - Impact of specimen configuration and characteristics on illinois flexibility index
AU - Rivera-Perez, Jose
AU - Ozer, Hasan
AU - Al-Qadi, Imad L.
PY - 2018/1/1
Y1 - 2018/1/1
N2 - The Illinois Department of Transportation adopted the Illinois Flexibility Index Test (I-FIT) to evaluate the cracking vulnerability of asphalt concrete (AC) mixtures that was often shown to increase with the addition of recycled materials such as reclaimed asphalt pavement and recycled asphalt shingles. The test consists of a semi-circular AC sample that has a notch, loaded along the symmetric axis. Fracture energy (FE), post-peak slope, and the flexibility index (FI) are computed from the load displacement curve. These results can be influenced by specimen geometry and test parameters such as loading rate, AC voids content, and so forth. Therefore, this study investigated the effect of notch length, specimen thickness, loading rate, and AC air void content on the I-FIT results. It was found that an increase in the specimen thickness or loading rate resulted in a steeper post-peak slope without affecting the FE. As a result, the FI decreased. An increase in the notch length or AC air void content resulted in a flatter post-peak slope, thus, increasing the FI. From the results, it was concluded that existing correction factors to address the variations caused by specimen thickness and air void content are appropriate. A correction factor to address notch length variations is proposed. A unique correction factor for loading rate could not be developed because of the varying rate dependency of each AC mixture.
AB - The Illinois Department of Transportation adopted the Illinois Flexibility Index Test (I-FIT) to evaluate the cracking vulnerability of asphalt concrete (AC) mixtures that was often shown to increase with the addition of recycled materials such as reclaimed asphalt pavement and recycled asphalt shingles. The test consists of a semi-circular AC sample that has a notch, loaded along the symmetric axis. Fracture energy (FE), post-peak slope, and the flexibility index (FI) are computed from the load displacement curve. These results can be influenced by specimen geometry and test parameters such as loading rate, AC voids content, and so forth. Therefore, this study investigated the effect of notch length, specimen thickness, loading rate, and AC air void content on the I-FIT results. It was found that an increase in the specimen thickness or loading rate resulted in a steeper post-peak slope without affecting the FE. As a result, the FI decreased. An increase in the notch length or AC air void content resulted in a flatter post-peak slope, thus, increasing the FI. From the results, it was concluded that existing correction factors to address the variations caused by specimen thickness and air void content are appropriate. A correction factor to address notch length variations is proposed. A unique correction factor for loading rate could not be developed because of the varying rate dependency of each AC mixture.
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U2 - 10.1177/0361198118792114
DO - 10.1177/0361198118792114
M3 - Article
AN - SCOPUS:85052588805
VL - 2672
SP - 383
EP - 393
JO - Transportation Research Record
JF - Transportation Research Record
SN - 0361-1981
IS - 28
ER -