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This paper details findings from the New Zealand Transport Agency's research project by Henning and Roux (2008). It forms part of the overall New Zealand Long-term Pavement Performance (LTPP) programme. The paper documents the development of prediction models for dense-graded asphalt (AC) surfaces and open-graded porous asphalt (OGPA) surfaces. Two models were developed including crack initiation on AC surfaces and ravelling initiation on OGPA surfaces. Continuous probabilistic models were utilised for both crack and ravelling initiation in order to predict the probability of the defect occurring. Models developed during this research use data which is readily available on network level databases, and can therefore be applied to asset management applications such as the New Zealand (NZ) dTIMS system (NZ's nationally adopted pavement management system (PMS)). Although a crack initiation model was also developed, it was not as robust as the ravelling model. Further work required includes refining of the models based on the LTPP data which includes bitumen property data. Although the developments are solely based on NZ data, there are a number of aspects applicable to the South African context. Firstly it presents a novel way of modelling the performance of asphaltic surfaces. Secondly it demonstrates some practical implications of maintenance practices that are sometimes considered for South African conditions. [ABSTRACT FROM AUTHOR]

The impact of a water droplet on a glass surface is studied experimentally using a high-speed video camera which can catch up to 60,000 images per second with an exposure time of 10 micros. A wide range of impact velocities are studied by varying the fall height, showing different spreading regimes. Particular attention is given to the dynamics of the contact angle and its relation to the maximum expanding radius and capillary number. A linear relation between the contact line velocity and the impact velocity is found experimentally. Using acoustic analysis, an evaluation of the pressure at the contact line is given. We also confront predicted and experimental jetting times. This work shows that descriptions of drop impact based purely on conservation of energy are inadequate to describe the dynamics of the event. The different shapes taken by the drops between the initial impact and the maximum radius determine the final outcome.