In order for a pavement to have long life, it must be durable. The term ‘durability’ includes several different phenomena which are interrelated and time dependant, but two of the primary mechanisms to which an asphalt pavement is subjected in service are ageing and water damage. The Saturation Ageing Tensile Stiffness (SATS) test is the first protocol of its kind to combine these two mechanisms in a single laboratory test. However, the procedure is aggressive, and for lower stiffness materials where there is a risk of irreversible damage in the standard SATS conditions, an alternative approach was required to widen the applicability of the procedure. Accordingly, parameters of pressure, temperature and duration were altered either one at a time or in combination to try to arrive at a suitable combination for testing less stiff (40/60 pen) material. The requirements were that the revised conditions should give a similar relative reduction in retained stiffness as the standard conditions give for 10/20 pen bitumen specimens, while still being harsh enough to distinguish a ‘poor’ aggregate in terms of moisture susceptibility. A suitable parameter combination for a SATS test for specimens made from 40/60 pen bitumen was found to be 85°C temperature, 0.5 MPa pressure and 24 h duration.

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