The performance of in-situ stabilized marginal sandstone pavements

This report presents the results of an Austroads/industry-sponsored field and laboratory assessment of the performance of an unbound marginal sandstone material and the same material after it was stabilised insitu with bitumen/GP cement and granulated slag/hydrated lime blends. During the trial, nine field experiments were conducted under accelerated loading using the ALF, and about 600,000 cycles of both the 80 kN dual-wheel and 50 kN single-wheel loading were applied. This testing was supported by an extensive laboratory program conducted on pre-construction materials, samples collected during construction, and field cores. It was found that the modulus of both the bitumen/cement and slag/lime cores varied over the site and there was generally no clear difference between the trafficked and untrafficked sections of the pavement. A comparison of the relationship between resilient modulus and UCS of the bitumen/cement stabilised cores at the completion of trafficking with the relationships currently recommended by Austroads confirmed that the current relationships over-estimate the moduli of these materials. In general, the performance of both the bitumen/cement and slag/lime materials was satisfactory, with no fatigue cracking or subgrade deformation observed. The increased costs associated with the stabilisation of the unbound sandstone material with both binders were more than offset by the observed improvement in performance resulting from this stabilisation process. (a)