The strength ages of various cements are unified as 3d and 28d. The strength test method is in accordance with Cement Mortar Strength Test Method (ISO Method) (GB/T17671KLOC-0/999) (ISO method for short, this standard was implemented in May 1999+0).
The strength of various commonly used cements is divided into eight grades: 32.5, 32.5R, 42.5, 42.5R, 52.5, 52.5R, 62.5R and 62.5r. ..
The corresponding new product standards are portland cement, ordinary portland cement (GB 175 1999), slag portland cement, pozzolanic portland cement and fly ash portland cement (GB 1344 1999) and composite portland cement (GB 1299)
These three standards came into effect on 1 99965438+February1day.
Considering the actual situation of cement production, inspection and use, the transition period of 1 year is stipulated.
During the transition period, the new and old cement standards will be parallel, thus achieving a smooth transition.