1 INTRODUCTION In this paper the behaviour of two crushed materials of extended grading is analyzed, lime- stone and granite, used as unbound granular sub-base of road pavements in Portugal. The geo- technical characterization is achieved through tests such as the methylene blue or the micro- Deval and the characterization of the mechanical behaviour is performed through cyclic triaxial tests, performed according to the standard AASHTO TP 46 (AASHTO, 1994). Within a PhD thesis work, the aim was to contribute to the modelling of the behaviour of that type of material. 2 MATERIALS The materials used in these work were limestone and granite. The number of characterized samples for each material was: 5 of crushed limestone, from Pombal, centre of Portugal, and 3 of crushed granite, 2 of them outcrops near Celorico da Beira and the 3 rd one near Braga, inte- rior centre and north of Portugal (Figure 1 to Figure 3). All materials examined were used in granular sub-base of pavements constructed or under construction in Portugal, namely in the motorway A23, fragment of Castelo-Branco Sul - Fratel, centre of Portugal, where the limestone has been used. 3 GEOTHECNICAL CHARACTERIZATION The collected samples were subjected to a set of laboratory tests to evaluate their geotechni- cal characteristics: the Los Angeles test (LNEC, 1970), the micro-Deval test (IPQ, 2002), the sand equivalent test (LNEC, 1967b), the methylene blue test (AFNOR, 1990) and the California Bearing Ratio (CBR) test (LNEC, 1967a). Mechanical behaviour of UGM for Portuguese conditions R. C. Luzia Department of Civil Engineering of the Superior School of Technology of the Polytechnic Institute of Castelo Branco. Portugal L. Picado-Santos Department of Civil Engineering of the FCT of the University of Coimbra. Portugal ABSTRACT: Coarse aggregate is widely used in the unbound granular layers (UGM) of roads, in particular as granular sub-base and base. However, although various studies have been con- ducted on these materials, their mechanical behaviour has not been yet properly characterized, in Portuguese conditions. This has special importance for Portuguese pavement technology. In the attempt of contributing for a better knowledge of that behaviour, an experimental work was undertaken to access the structural performance and to establish behaviour models for crushed materials coming from different lithologies, namely limestone and granite, susceptible of being used as UGM. This paper describes the principal results obtained from this work pointing out the main directions that can be extracted from it, in terms of the global behaviour of a road pavement.