There are two Australian Road Research Board (ARRB) reports dealing with predicting the life of sprayed seals. This one gives technical information on laboratory testing and the development of mathematical models, and is more suited to a specialist audience. The later report, which is intended for general readership, will deal with applications of the models, including Pavement Management Systems (PMS), and give seal life predictions for a number of locations in each state. This report first of all gives background information on the bitumen hardening process in sprayed seals and the ARRB Bitumen Durability Test. It then describes a previously published model which allows calculation of the rate at which the bitumen in a seal hardens in different areas of the country. While this information is important, it becomes much more valuable if the hardness level, at which seal distress occurs, can also be calculated. With this extra information the maximum life of seals in different climatic areas can be predicted and the effect of using a more or a less durable bitumen can be calculated. A description of the work undertaken to determine this seal distress hardness (or viscosity) level, forms the bulk of this report. Seals, which were just starting to show distress, were sampled and the bitumen (distress) viscosity measured. A data base of results for 27 seals was built up. A simple relationship was found between distress viscosity and the average minimum temperature at a location. This allows the prediction of the viscosity level at which seals will fail, because of bitumen ageing, in different parts of the country. The data base used to construct the model is quite small and the model which has been developed should be regarded as an interim one. Priority should be given to obtaining further data to extend it (A).


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Filing Info

  • Accession Number: 00606278
  • Record Type: Publication
  • Source Agency: Transport and Road Research Laboratory (TRRL)
  • ISBN: 0-86910-441-1
  • Files: ITRD, TRIS
  • Created Date: Mar 31 1991 12:00AM