Experimental Study of Moisture Sensitivity of Aggregate-Bitumen Bonding Strength Using a New Pull-Off Test Jizhe Zhang, Alex K. Apeagyei, James Grenfell and Gordon D. Airey Abstract Moisture damage in asphalt mixtures is a complicated mode of pavement distress that results from the loss of interfacial adhesion between the aggregate and bitumen and/or the loss of cohesion within the bitumen. Both adhesive and cohe- sive strength of aggregate-bitumen bonds can be determined in the tensile testing mode. This paper presents the development of suitable procedure consisting of an innovative sample preparation, controlled moisture conditioning and new pull-off test set-up to characterise moisture damage resistance of the bonding strength of aggregate-bitumen samples that is sensitive to the mineralogical and physico- chemical properties of the aggregates as well as key bitumen physical properties. The test set-up consists of three main parts: a moisture conditioning step designed to ensure characteristic moisture diffusion into the aggregate-bitumen interface, accurate determination of bitumen film thickness using a modified dynamic shear rheometer and direct tension fixtures mounted on an Instron universal testing machine. The capability to vary loading rate, accurately control film thickness and ensure moisture diffusion to the aggregate-bitumen interface are an important improvement over most existing pull-off tests. The test was also found to be sen- sitive to moisture conditioning time, moisture uptake and the type of aggregate. All samples were subjected to the pull-off test to characterise their tensile strengths before and after moisture conditioning. The results show that the magnitude of the aggregate-bitumen bonding strength in the dry condition is mainly influenced by bitumen. However, the magnitude of the tensile strength after moisture conditioning was found to be influenced by mineralogical composition as well as the moisture J. Zhang (&)  A.K. Apeagyei  J. Grenfell  G.D. Airey Nottingham Transportation Engineering Centre, Department of Civil Engineering, University of Nottingham, University Park, Nottingham NG7 2RD, UK e-mail: evxjz3@nottingham.ac.uk A.K. Apeagyei e-mail: alex.apeagyei@nottingham.ac.uk J. Grenfell e-mail: james.grenfell@nottingham.ac.uk G.D. Airey e-mail: gordon.airey@nottingham.ac.uk © RILEM 2016 F. Canestrari and M.N. Partl (eds.), 8th RILEM International Symposium on Testing and Characterization of Sustainable and Innovative Bituminous Materials, RILEM Bookseries 11, DOI 10.1007/978-94-017-7342-3_58 719