1. The differences between 325 cement and 425 cement are as follows:

1. Different uses: 325 cement is generally used for small projects such as tiling, building walls and painting walls; 425 is generally used for paving roads, big columns, building houses and other big projects.

2. Different strength: 325 cement belongs to soft cement, and its strength is far less than that of 425 cement, while 425 cement belongs to hard cement.

3. Different prices: 425 is more expensive than 325; The later maintenance of 325 cement is relatively simple.

2. Precautions for using cement:

1. Avoid hardening due to moisture: the hardened cement will reduce or even lose its original strength.

2. Avoid exposure and quick drying: if concrete or plaster is exposed after operation, its strength will be reduced or even completely lost with the rapid evaporation of water.

3. Avoid freezing at negative temperature: after concrete or mortar is mixed, if it is frozen, its cement can't be hydrated, and the water freezes and expands, then the concrete or mortar will be damaged by the powder cake that gradually deepens from the outside to the inside.

4. Avoid high temperature and extreme heat: the solidified mortar layer or concrete member will lose strength if it is often exposed to high temperature and extreme heat.

Extended information:

cement label

The strength grade of cement is the sign of cement strength, the measuring index is the compressive strength of cement, and the testing standard is mainly the strength of cement mortar after hardening for 28d. For example, the compressive strength after 28d is 42.5MPa, and the strength grade of cement is 42.5 or 42.5 R..

There is no very detailed regulation on the usage of cement strength grade. Generally speaking, it will be clearly stipulated in the design drawings. In civil construction projects, ordinary portland cement and slag portland cement are commonly used. The commonly used strength grades are P.O 42.5 and P.S 32.5/42.5.

Reference: cement label-Baidu Encyclopedia.