A　design　for　optimum　proportioning　is　presented　using　a　test　for　low　quality　high　volume　fly　ash　concrete　pavement　used　in　light　to　medium　traffic　levels.　On　this　foundation,　the　main　mechanical　properties,　axial　compressive　strength,　flexural　strength,　elastic　modulus　and　fatigue　are　experimentally　investigated.　The　effect　of　age　on　low　quality　high　volume　fly　ash　concrete　strength　is　discussed,　and　a　formula　for　calculating　low　quality　fly　ash　concrete　strength　is　proposed.　Due　to　its　pozzolanic　reactivity,　fly　ash　has　been　widely　used　in　civil　engineering　structures,　especially　in　pavement　structures　under　light　to　medium　traffic　loads.　Utilizing　appropriate　fly　ash　replacements　for　cement　in　concrete　not　only　helps　to　protect　the　environment　and　save　energy,　but　also　can　greatly　reduce　the　production　cost　of　the　concrete.　As　far　as　current　production　and　application　are　concerned,　low　quality　fly　ash　concrete　accounts　for　the　vast　majority　of　its　total　output.　However,　its　application　in　structural　concrete　members　(GBJ　1991;　JTG　2003)　has　been　slow-going　due　to　the　lack　of　early　strength　in　fly　ash　concrete　and　disagreements　on　what　the　highest　allowable　replacement　level　should　be.　The　development　of　fly　ash　concrete　is　largely　inhibited　due　to　these　reasons.　To　solve　this　problem,　research　on　the　performance　of　fly　ash　concrete　structures　influenced　by　the　volume　of　fly　ash　and　quality　(Vandewalle　1992,　Galeota　1995,　Swamy　1998,　Xujian.　2004,　Chao　2005　and　Jie　2005)　has　been　conducted　by　researchers　all　over　the　world.　Research　shows　that　low　quality　fly　ash　concrete　can　meet　the　requirements　of　engineering　applications　by　using　a　rational　proportioning　design　and　specific　curing　practices.　In　this　paper,　mix　proportioning　and　the　main　mechanical　properties　of　high-volume　(≥20)　low　quality　fly　ash　concrete　are　discussed　for　concrete　pavements.　©　2011　ASCE.