Evaluation of complex modulus and fatigue properties of cold recycled material mixtures using small-scale specimens

The laboratory mechanical characterisation of cold recycled materials mixtures is necessary to develop mechanistic-empirical design methods for cold recycled pavements. The present paper describes a laboratory experiment where small-scale specimens were used to characterise the complex modulus and fatigue properties of cement bitumen treated materials (CBTM) manufactured with bitumen emulsion and cement. In particular, CBTM specimens with diameter of 38 mm were tested and compared with two group of specimens with diameters of 100 and 75 mm. The complex modulus was measured by means of cyclic compression tests and then rheological modelling was applied. Fatigue tests were carried out in direct tension mode of loading. All tests were carried out at long-term curing conditions. Results and statistical analysis showed that the complex modulus values measured on large specimens (diameter of 100 and 75 mm), were not significantly different. On the other hand, the stiffness modulus values measured on small specimens (diameter of 38) were about 15% lower.