Australian rigid pavement design methodology

The methodology covers the design of jointed (unreinforced and reinforced), continuously reinforced and fibre-reinforced concrete pavements. The case of pre-stressed rigid pavement 

Unlike UK rigid pavement design methodology, the CRCP with asphalt overlay is not enforced to be used in all new constructions. However, the use of lean concrete, cement-stabilised crushed aggregate or dense asphalt concrete as a sub-base material in moderate to heavily trafficked roads is necessary for lightly trafficked roads, unbound granular sub-base may also be used. 

The procedure for the determination of the thickness of rigid pavements, and of the concrete slabs in particular, is based on the USA 1984 Portland Cement Association method (Packard 1984). Additionally, the method assumes that the base and sub-base layers are not bonded. 

For the determination of the concrete slab thickness, two distress modes have been considered (a) the flexural fatigue cracking of the slab and (b) the subgrade/sub-base erosion arising from repeated deflections at joints and planned cracks. 

Source Austroads, Guide to PavementTechnology Part 2 Pavement Structural Design, Pubiication No. 

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However, in the Australian pavement design methodology for rigid pavements (Austroads 2012), the axle loads determined as in flexible pavement (using the equivalency law) are multiplied by a load safety factor (LSE). The ESP is related to project reliability, which varied from 80% to 97.5%. Eor a reliability of 95%, the LSE for an unreinforced slab is 1.3, while that for a doweled or continuously reinforced slab is 1.25. 

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