The　mix　proportion　of　manufactured　sand　concrete　(MSC)　was　designed　based　on　a　minimum　paste　theory,　where　microfines　was　added　to　replace　part　of　cement.　The　effect　of　microfines　content　on　the　workability　and　mechanical　properties　of　MSC　was　investigated.　The　study　reveals　that　the　microfines　can　be　used　as　an　ingredient　of　MSC　and　a　moderate　amount　of　microfines　can　improve　the　workability　of　MSC.　The　compressive　strength,　axial　compressive　strength,　splitting　tensile　strength　and　elasticity　modulus　of　MSC　increase　gradually　with　the　increasing　of　microfines.　However,　too　much　amount　of　microfines　makes　the　mechanical　properties　of　MSC　decrease.　Mixing　microfines　in　MSC　can　reduce　the　dosage　of　cement,　carbon　emission,　concrete　cost　and　benefit　from　environment　protection.　The　use　of　the　minimum　paste　theory　in　the　mix　proportion　design　of　MSC　is　expected　to　improve　the　volume　stability　and　cracking-resistant　performance　of　MSC.　(C)　2013　Elsevier　Ltd.　All　rights　reserved.