Assessment of Bond between Asphalt Layers
Professor A. C. Collop (Formerly NTEC) - Supervisor
Muslich H Sutanto - Research Student
Sponsored by Nottingham Asphalt Research Consortium (NARC), Universities UK (ORS Award)
Background
Asphalt pavements usually constructed in a number of layers. At present, most of pavement design and evaluation techniques assume that adjacent layers are fully bonded together without any relative displacement. However, it seems that good bonding is not always achieved since a number of pavement failures have been linked with poor bond condition.
Bond is critical to transfer radial tensile and shear stress into the underlying layer and furthermore to the whole of pavement structure. To achieve the required pavement performance, good bonding is very important. However, up to the present, no specification limit exists related to the required and achievable shear strength of a range of UK road constructions and material combinations.
Aims and objectives
Thus, the main objective of this project is to provide guidance for assessing bond between layers, in order to facilitate the construction of roads with more assurance of achieving the design requirements. To achieve the main objective, several sub-objectives have been defined. These are:
- To develop a test to determine the bond strength and stiffness beneath ultra-thin surfacings (<30mm) under a more controlled condition;
- To develop a data base of bond strengths and stiffnesses for a wide range of UK material combinations (including ultra-thin surfacings) and bond conditions;
- To investigate the development of bond with trafficking;
- To determine specification limits for bond strength from the data obtained in Objectives 1 and 2;
Methods
- Modified Leutner test, torque test, Impulse Hammer Test.
- Small scale trafficking using the Slab Testing Facility (STF) and Medium scale trafficking using the Pavement Test Facility (PTF)
- Field investigation.