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Cement-2

Properties of Cement 
  • Following are the properties of cement 
    • Physical properties 
    • Mechanical properties 
    • Chemical properties 
      Cement
      Physical properties
Physical Properties Of Cement 
  • following are the main physical properties of a good cement 
  • physical properties primaries depend upon its chemical composition thoroghness of during and finess of grinding
    • Fitness 
      • the finer the cement in grain size the better is its quality 
      • it is believed that in final grain size the cement particle react with the water more quickly and third reduce the time for hardening thereby producing a cement of high early strength
    • Soundness 
      • cement expand show some extent on setting 
      • this expansion is sometimes responsible for cracking of cement after setting 
      • sound as is the capacity of cement to from a non district grating hard and uniformly strong mask on  setting
    • Setting of cement 
      • it may be defined as the capacity of the cement to with stand loads without disintegrating or cracking 
      • the change from a plastic mass to a non plastic and rigid mass of cement may take time between few minutes to an hour or more 
    • Setting time 
      • some cement that quickly within a few minutes where as other may take more time between a few minutes to an hour or more
    • Some other properties of cement are
      • It acts as an excellent binding material 
      • it provides strength to the masonary 
      • it provides good plasticity 
      • It is early workable 
      • it stiffens for hardness early 
      • it offers good resistance to the moisture

Mechanical Properties Of Cement
  • compressive strength and tensile strength are the two important Mechanical properties of the cement 
    • the compressive strength at the end of three days should not be less than 115 kg / km² and that at the end of 7 days should not be less than 175 kg / cm²  
    • the tensile strength at the end of three days should not be less than 20 kg / cm² and that at the end of 7 days should not be less than 35 kg / cm²
      Cement
      Chemical properties
 Chemical Properties Of Cement 
  • the quality of portland cement depends to a great extent upon the ratio in which the major components are present in it specifically the lime silica iron and alumina 
    • Ratio of percentage of lime two percentage to silica aluminium and iron oxide should not be less than 0.66 and should not be more than 1.0
    • Ratio of percentage of alumina to iron oxide should not be less than 0.66
    • Weight of magnesia should not exceed 5%
    • Weight of insoluble residue should not exceed 1.5 %
    • Total sulphur content should not be more than 2.75 %
    • Total loss on ignition shall not exceed 4%
      Cement
      Grade of cement
 Grades Of Cement
  • Present practice of classification of cement is according to the grade
  • There are three basic type of cement grades available
  • These are
    • 33 grade cement
    • 43 grade cement
    • 53 grade cement
  • in this the figure 33 ,43 and 53 indicate the 28 days compressive strength of cement
  • If the 28 day strength is less than 33 N/mm², it is is called 33 grade cement and is normally used for all reinforced cement works
  • if the 28 day strength is not less than 43 N / mm² it is called of 43 grade cement and is used for general construction work
  • If the 28 days friend is not less than 53 N / mm² ,it is called of 53  grade cement and is used for high rise building, bridges, flyover, chimney and pre-stressed structure where high grade concrete is required
  • In market now a days cement are generally available according to the grade
Cement
Comprehensive strength in N/mm²
Grade
3 days
7 days
28 days
33 grade
16
22
43
43 grade
23
33
43
53 grade
27
37
53

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