Large　porosity　and　connected　porous　structure　enables　pervious　concrete　to　obtain　water　permeability,　but　significantly　decreases　its　strength.　It　is　still　a　critical　challenge　for　the　mix　design　of　pervious　concrete　to　well　balance　its　permeability　and　strength.　The　purpose　of　this　paper　is　to　study　the　strength　mechanism　of　pervious　concrete　and　propose　a　modified　mix　design　method　based　on　Mohr-Coulomb　failure　criterion.　Five　groups　of　samples　with　different　aggregate-cement　ratio　varied　from　5:1　to　4:1　were　prepared　(target　porosity　was　20%).　The　triaxial　tests　were　applied　to　investigate　the　axial　compression　of　these　pervious　concrete　samples　at　different　confining　pressure.　The　results　show　that　Mohr-Coulomb　failure　criterion　can　be　used　to　describe　the　behavior　of　pervious　concrete　with　compression.　With　the　decrease　of　the　thickness　of　cement　paste,　the　cohesion　first　increase,　and　then　decrease　slightly.　At　the　same　porosity,　the　cementitious　paste　thickness　was　largely　determined　by　aggregate　content　coefficient　(ACC).　A　modified　mix　design　method　based　on　Mohr-Coulomb　failure　criterion　was　put　forward　by　introducing　the　aggregate　content　coefficient　(ACC).　It　was　observed　that　ACC　had　little　influence　on　porosity,　pore　area　and　fractal　dimension　of　pervious　concrete,　and　pervious　concrete　with　different　ACC　had　similar　permeability.　The　strength　increased　with　the　decrease　of　ACC,　but　the　growth　rate　was　gradually　decreasing.　For　the　case　in　this　paper,　0.94　was　found　to　be　the　optimal　value　for　ACC.　By　the　modified　mix　design　method,　pervious　concrete　gained　a　similar　permeability　but　obviously　improved　strength　compared　to　the　pervious　concrete　designed　by　conventional　method.　(C)　2020　Elsevier　Ltd.　All　rights　reserved.