✓ Cement is a mixture of         Calcareous and Argillaceous material.

✓ It is invented by Joseph Aspdin in 1824.

✓ A cement is a binder, a substance used for construction that sets, hardens, and adheres to other materials to bind them together. 

✓ Components of cements are as follows -

1. Silica ( 18-22% ) - it provides strength and plasticity. Excess of Silica causes delayed in strength
2. Iron oxide ( 1-3 % ) - It provides colour. Excess of iron oxide gives red colour to cement.
3. Lime ( 60-65 % ) - It provides soundness and strength to cement. Excess of lime causes expansion.
4. Magnesia ( 3-5 % ) - It provides colour and hardness to cement. Excess of Magnesia causes expansion.
5. Alumina ( 5-6% ) - It gives quick setting time to cement. Excess of alumina causes cracks and Shrinkage
6. Alkalies ( <1% ) - Alkalies does not gives any benefit to cement. Excess of Alkalies causes efflorance.

✓ Both Calcareous and Argillaceous materials burnt in kiln at 1300°C to 1500° C 

✓ At the time of grinding 2-3% of gypsum is added to prevent flash setting.

✓ The following tests are conducted on cement in the laboratory are as follows:

1. Fineness Test - The fineness of cement is responsible for the rate of hydration, rate of evolution of heat and the rate of gain of strength. The fineness of cement can be determined by Sieve Test or Air Permeability test. In sieve analysis The residue left on the sieve is weighed, and it should not exceed 10% for ordinary cement. In air permeability test surface are should not exceed 2250 cmsq/ gm.
2. Consistency test - This test is conducted to find the setting times of cement using a standard consistency test apparatus, Vicat's apparatus.
3. Soundness test of cement - This test is conducted in Le Chatelier's apparatus to detect the presence of uncombined lime and magnesia in cement.
4. Tensile Strength of Cement -  This test is carried out using a cement-mortar briquette in a tensile testing machine. A 1:3 cement-sand mortar with the water content of 8% is mixed and moulded into a briquette in the mould.
5. Chemical Composition Test - Lime Saturation Factor (LSF), i.e., the ratio of the percentage to that of alumina, iron oxide and silica should not be less than 0.66 and not be greater than 1.02. Total loss on ignition should not be greater than 4%. Total sulphur content should not be greater than 2.75%. Weight of insoluble residue should not be greater than 1.50%. Weight of magnesia should not be greater than 5%.