This　paper　deals　with　the　mechanical　behaviour,　especially　the　permanent　deformation　and　resilient　deformation　of　an　unbound　granular　material　(UGM)　from　Brefauchet　quarry　which　is　used　as　base　layer　material　in　low　traffic　pavements　for　full-scale　tests　at　IFSTTAR　in　France.　Medium-scale　repeated　load　triaxial　tests　(RLTT)　are　carried　out　at　different　water　contents　and　the　results　show　that　both　permanent　and　resilient　deformations　increase　with　water　content.　Besides,　two　techniques　of　fixing　the　sensors　in　materials　with　large　particles　for　RLTTs　are　proposed　and　compared　with　each　other.　The　results　suggest　that　the　tube　method　is　more　suitable　for　the　UGM　for　an　accurate　measurement　and　a　good　adaptability　is　obtained　during　the　RLTT.　Based　on　the　test　results　of　UGM　Brefauchet,　the　modelling　work　is　performed　with　improved　models　used　previously　for　a　sandy　material.　It　appears　that　both　the　permanent　and　resilient　behaviours　of　different　unbound　granular　materials　can　be　well　captured　by　the　proposed　equations　considering　the　effects　of　water　content　and　anisotropy.　This　study　is　helpful　to　understand　the　evolution　of　permanent　and　resilient　deformation　in　different　granular　layers,　especially　for　the　base　layer,　in　low　traffic　pavements.　The　verified　models　can　be　used　for　other　similar　granular　materials　and　this　will　lead　to　reducing　the　number　of　tests　required　to　predict　the　deformation　behaviour　of　granular　materials.