Building Materials | 2021 Update | Civil Knowledge |

 Building Materials : 

          It means the materials which are required during complete construction period of the building structure. 

• Materials 

1. Timber
2. Bricks
3. Sand 
4. Stones
5. Cement 
6. Lime 
7. Aluminium
8. Steel
9. Plastic

 ☆ Cement :

             A product obtained by burning and crushing of certain stones or mixture to a fine gray powder is called cement. 

 ☆ Manufacturing :

1. Cement : The clinker is cooled and ground to a required fineness with little addition of gypsum to retard the rate of its setting. The resulting fine powder is the cement.
2. Clinker : A mixture of siliceous, argillaceous and calcareous materials is burnt together in a definite proportion to a partial fusion in a rotary kiln at a temperature of about 1400℃ 

 ☆ Types of Cements :

• Normal Types of Cements :

1. Ordinary Portland Cements 
2. Low heat Cement
3. Pozzolanic Cement
4. Sulphate Resisting Cements
5. Rapid Hardening Cement
6. Slag cement
7. High Alumina Cement

• Special types of Cement :

1. White Cement
2. Expanding Cement
3. Refractory Cement
4. Hydrophobic or Waterproof Cement
5. Acid resistant Cement
6. Masonry Cement
7. Coloured Cement

 ☆ Properties of Cement :

1. Setting time 
2. Fineness
3. Hardening
4. Heat of Hydration
5. Soundness
6. Compressive Strength

More information

• Fineness :

                   It increases the quality of cement.

                   It affects properties of cement e.g. rate of setting and hardening, rate of heat production during hydration, cohesiveness, water demand and workability of concrete.

• Setting Time :

                  The time lapsed between addition of water to cement upto complete solidification of cement 

• Compressive Strength :

                    It is the ability of the cement to impart crushing strength to its mortars or concretes. It is tested after 7 days of hardening. It is given in Newtons/mmsq.

• Soundness :

                 Cement may contain free lime and crystalline magnesia. They produce excessive expansion and cracks in the cement. This is not desirable due to unsoundness. Minimum Cracks and low expansion produce soundness in the cement.

• Heat of Hydration :

              When water is added cement chemically reacts with water and produces heat. The heat generation is an advantage for small concrete work but it is harmful in mass concrete works.

• Hardening :

             High Percentage of C3S and low % of C2S produce rapid hardening of cement but evolve more heat and vice versa.