AASHTO TP 114-18 (2021) PDF Download

AASHTO TP 114-18 (2021) is a provisional standard method of test that outlines a procedure for determining the interlayer shear strength (ISS) of asphalt pavement layers. This test can be performed either on laboratory-prepared samples or core samples taken from in-service asphalt pavements. The standard specifies that the test can be conducted on specimens with diameters of either 150 mm (6 in.) or 100 mm (4 in.) and a maximum total thickness of 150 mm (6 in.).

The test is applicable when both the asphalt overlay layer and the base layer are 50 ± 5 mm (2.0 ± 0.2 in.) thick. If needed, the layers can be saw-cut to achieve the recommended thickness. The purpose of this test is to evaluate the interlayer shear strength, which is a measure of the bond between adjacent asphalt pavement layers. It provides information about the overall structural integrity and performance of the pavement system.