Assessing Geometric Features Impact of Laboratory Specimens on ITS Variation

The research focuses on Indirect Tensile Strength variation by changing Height and Diameter of bituminous specimens related to AC16 dense-graded binder course with limestone aggregates and neat bitumen at 4.5% following SUPERPAVE procedure. 70 specimens were prepared by using gyratory compactor by fixing hmin/D ratio equals 0.68. A total of 20 specimens whose diameter is 100 mm were prepared and the other 50 specimens were made according to a 150 mm diameter. Then, 30 of 50 specimens with a 150 mm diameter were cut in two different ways: 10 specimens were cut from the centerline and 20 specimens were cut both from the bottom and upper part to obtain a final height falling a range of 35 and 75 mm in compliance with UNIEN12697-23. Then second step refers to H0 hypothesis test as follows: could ITS values resulting from specimens prepared with 150 mm in diameter and cut by using different procedures be equal to ITS values (mean 3.47 MPa) of specimens prepared with 100 mm in diameter and different height (mean height 69.5 mm) with a significance level of 0.05? The results showed that no statistical difference exists between the 100 mm in diameter specimens and 150 mm in diameter specimens that were cut both from the upper and bottom part. However, in the other scenarios statistical differences were founded. Overall, according to the results it can be concluded that 100 mm in diameter specimens can be used for ITS evaluation of AC specimens instead of 150 mm, which consequently resulted in less materials and simplified lab-scale asphalt manufacturing procedures.