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(2) The main content of the revision of the six cement standards

1. Change the strength test method of cement mortar to GB/T 17671-1999 method

The six major cement product standards all refer to GB/T 17671-1999 method as the strength test method of cement mortar, and no longer use GB 177-85 method. Therefore, the GB/T 17671-1999 method is promoted to mandatory method, while the GB 177-85 method is reduced to recommended method.

2, cement label to strength grade

The six old cement standards implement cement labels expressed by Kgf/cm2, such as 32.5, 42.5, 42.5R, 52.5, 52.5R, etc. The six new cement standards implement strength grades expressed in Mpa, such as 32.5, 32.5R, 42.5, 42.5R, 52.5, 52.5R, etc., so that the value of the strength grade is the same as the minimum value of the 28-day compressive strength index of cement. The new standard also unified the strength grade of China's cement, Portland cement is divided into three grades of 6 types, 42.5, 42.5R, 52.5, 52.5R, 62.5, 62.5R, the other five major cement is also divided into 3 grades of 6 types, namely 32.5, 32.5R, 42.5, 42.5R, 52.5, 52.5R

3. Strength age and strength index setting of each age

The cement strength age of the six new cement standards is 3 days and 28 days, and each age has the requirements of bending and compressive strength indicators.