The influence of compaction method and density on the strength and modulus of cementitiously stabilised pavement materials

Australian practice is moving towards the utilisation of gyratory compacted samples tested by indirect diametrical tensile testing for determination of both modulus and fatigue life of cementitiously stabilised pavement materials. At the same time, conformance testing is expected to remain an unconfined compressive strength and density based assessment. The influence of material density on the strength and modulus of these materials is important as differing densities are achieved in the laboratory and the field. The effect of compaction method, where different test methods are used for characterisation and conformance testing, is also important. An investigation was undertaken to determine the influence of both dry density and compaction method on the strength and modulus of reclaimed pavement material stabilised with a slag-lime binder. As a prelude, the influence of compaction method and the addition of binder to the host material on the optimum moisture content and maximum dry density were also determined. The gyratory compactor protocol required to achieve densities equivalent to Standard Proctor compaction was determined and the influence of the addition of binder to a host material was found to be material specific. Whilst the compaction method (at the same dry density) had no significant influence on the strength and modulus of these materials, the density had a significant impact on both strength and modulus.