Cement 42.5 Specification: ordinary grey portland cement 42.5 ren 197-1/2000 and british standards bs12/96 Ordinary portland cement Specification sheet Construction grade 42, 5 Colour grey Minimum standards to be met:according to british standards 12/1996 or Astm c-150 , en û 197 û 1/2000 Chemical composition Aluminium oxideal2o35.30 Calcium oxidecao65.60 Dicalcium silicatec2s15.00 Ferric oxidefe2o33.30 Loss of ignitionloi0.9 Magnesium oxidemgo1.10 Silicon dioxidesio221.00 Sulphur trioxideso32.70 Tricalcium aluminatec3a8.05 Tricalcium alumino ferricec4af9.76 Tricalcium silicatec3s60.00 Physical and mechanical roperties Blain cm2/gr3.250 Autoclave expansion0.02 Initial setting time (vicat)105 minutes Final setting time (vicat)135 minutes Compressive strength @ 3 days230kg/cm2 Compressive strength @ 7 days305kg/cm2 Compressive strength @ 28 days420kg/cm2 50 kgm bags