Cement grade in Nepal

 

The Nepal Bureau of Standards and Metrology (NBSM) has introduced a new grading system in OPC cement. In this grading system, cements are categorized into 33 grade cement, 43 grade cement and 53 grade cement. In the past, cement manufacturers could not label their products higher than 33 grade. But now cement manufacturers can get 43 grade and 53 grade certifications after meeting the quality parameters set by NBSM. Please consult your engineers before purchasing the cements. They will tell you which cement is suitable for your projects.

33 Grade Cement

33 grade OPC cement is the lowest grade OPC cement in Nepal. 33 grade is written on the cement bag.

It is the lowest compressive strength OPC cement.

Physical Requirements of 33 grade OPC cement

• Compressive strength in 3 days :- 16 MPa
• Compressive strength in 7 days :- 22 MPa
• Compressive strength in 28 days :- 33-48 MPa
• Specific surface (Blain method) :- 225 m (Minimum)
• Soundness test value by Le Chatelier's method :- 10mm (Maximum)
• Soundness test value by Auto Clave method :- 0.8% (Maximum)
• Initial setting time :- 30 minute (Minimum)
• Final setting time :- 600 minute (Maximum)

Chemical Requirements of 33 grade OPC cement

• Lime saturation factor (Ratio of percentage of lime to percentage of silica, alumina and iron oxide) :- 0.66-1.02
• Ratio of percentage of alumina to that if iron oxide :- 0.66 (Minimum)
• Insoluble residue, percent by mass :- 4 (Maximum)
• Magnesia, percent by mass :- 6 (Maximum)
• Loss on ignition, percent by mass :-  4 (Maximum)

43 Grade Cement

43 grade cement is the medium grade OPC cement in Nepal. Single stripe of 05-10 centimeter is made on the middle of bag of 43 grade cement. 43 grade is printed on the cement bag. 43 grade cement has higher compressive strength than 33 grade cement.

Physical Requirements of 43 grade OPC cement

• Compressive strength in 3 days :- 23 MPa
• Compressive strength in 7 days :- 33 MPa
• Compressive strength in 28 days :- 43-58 MPa
• Specific surface (Blain method) :- 225 m (Minimum)
• Soundness test value by Le Chatelier's method :- 10mm (Maximum)
• Soundness test value by Auto Clave method :- 0.8% (Maximum)
• Initial setting time :- 30 minute (Minimum)
• Final setting time :- 600 minute (Maximum)

Chemical Requirements of 43 grade OPC cement

• Lime saturation factor (Ratio of percentage of lime to percentage of silica, alumina and iron oxide) :- 0.66-1.02
• Ratio of percentage of alumina to that if iron oxide :- 0.66 (Minimum)
• Insoluble residue, percent by mass :- 2 (Maximum)
• Magnesia, percent by mass :- 5 (Maximum)
• Loss on ignition, percent by mass :-  4 (Maximum)

53 Grade Cement

53 grade cement is the highest grade OPC cement found in Nepali market. Double stripe of 05-10 centimeter is made on 1/3rd part of bag of 53 grade cement. 53 grade is printed on the cement bag. 53 grade cement has the highest compressive strength.

Physical Requirements of 53 grade OPC cement

• Compressive strength in 3 days :- 27 MPa
• Compressive strength in 7 days :- 37 MPa
• Compressive strength in 28 days :- 53 MPa
• Specific surface (Blain method) :- 225 m (Minimum)
• Soundness test value by Le Chatelier's method :- 10mm (Maximum)
• Soundness test value by Auto Clave method :- 0.8% (Maximum)
• Initial setting time :- 30 minute (Minimum)
• Final setting time :- 600 minute (Maximum)

Chemical Requirements of 53 grade OPC cement

• Lime saturation factor (Ratio of percentage of lime to percentage of silica, alumina and iron oxide) :- 0.80-1.02
• Ratio of percentage of alumina to that if iron oxide :- 0.66 (Minimum)
• Insoluble residue, percent by mass :- 2 (Maximum)
• Magnesia, percent by mass :- 5 (Maximum)
• Loss on ignition, percent by mass :-  4 (Maximum)

Source: National Bureau of Standards and Metrology