Chemical Composition:
The various tests are carried out to determine the chemical constituents of cement. Following are the chemical requirements of ordinary cement as per BIS 269-1975 :
(a) Ratio of percentage of alumina to that of iron oxide should not be less than 0.66.
(b) Ratio of percentage of lime to those of alumina, iron oxide or silica should not be less than 0.66 and it should not be bigger than 1.02, while calculated by the following formula.
CaO - 0.7 ⋅SO 3/2.8 SiO 2+ 1.2 Al2 O 3 + 0.65 Fe 2 O 3
(b) The whole loss on ignition should not be greater than 4 %.
(c) The whole sulphur content is calculated as SO3 and it should not be greater than 2.75 %.
(d) The weight of insoluble residue should not be bigger than 1.50 %.
(e) The weight of magnesia shall not exceed 5 %.