Behaviour of rubberised cement-bound aggregate mixtures containing different stabilisation levels under static and cyclic flexural loading

An investigation has been undertaken to investigate the influence of rubber inclusion at different levels of stabilisation on the behaviour of cemented granular mixtures, under static and cyclic flexural testing, and to compare this with mixtures without rubber. Both are intended to be used as base courses of semi-rigid pavement structure. 3%, 5%, and 7% of cement by dry weight of aggregate were used for stabilisation purposes. Rubberisation of cemented aggregate was conducted by replacing 30% of the aggregate of the 6 mm fraction size by an equivalent rubber volume. The investigated properties were flexural strength, static and dynamic stiffness moduli, toughness and fatigue life. Damage due to cyclic loading was evaluated in terms of stiffness degradation and permanent deformation accumulation. Flexural-induced cracking behaviour was also investigated. Results reveal that the rate of flexural strength increase is higher for the reference cemented mixtures. As stabiliser quantity increase, both static and dynamic stiffness moduli increased while rubberisation mitigated these two parameters at all stabiliser contents. Toughness and fatigue life were improved due to rubber modification at investigated stabiliser contents. Flexural-induced cracks always tend to propagate through rubber aggregate regardless of the quantity of cement.