How many kinds of cement are there?

There are four kinds of cement: P.O52.5 cement, P.O42.5 cement, P.C32.5R cement and PC32.5R home improvement cement.

1, P.O52.5 cement

Cement has a high early age, and its three-day compressive strength reaches 27 MPa, which is 4 MPa higher than the national standard. It is beneficial to shorten the construction period, and has good wear resistance, high impermeability and corrosion resistance. Cement has stable performance and is suitable for preparing high-performance and high-grade concrete. The cement is stable in color, and can be widely used in exposed projects with plain ash without decoration on the surface.

2, P.O42.5 cement

High early strength and short setting time. The three-day strength can reach 23 MPa, which is higher than the national standard of 6 MPa, which can effectively shorten the construction period. The hydration and hardening speed is fast, the hydration heat is concentrated, the concrete has good frost resistance, low bleeding rate, small drying shrinkage and good wear resistance. Suitable for foundation engineering, beam, plate and column pouring and ground engineering of civil buildings. Suitable for large factories, high-rise buildings, bridges, docks, roads, airports and so on. Suitable for poles, prestressed members, etc.

3.P.C32.5R cement

Cement reached 18 MPa in three days and 38 MPa in 28 days, which was 8 MPa higher than the national standard in the early stage. The hardened cement paste has compact structure, good water retention, low bleeding rate and obviously improved physical properties. C30 and below concrete is widely used in industrial and civil buildings. It is suitable for masonry and plastering of general building projects and construction of non-important structural parts.

4, PC32.5R home improvement cement

Cement reached 18 MPa in three days and 38 MPa in 28 days, which was 8 MPa higher than the national standard in the early stage. Short setting time, good water retention, low bleeding rate, high viscosity of cement mortar and few microcracks. This product is developed for home improvement projects, and is suitable for masonry, plastering and tiling in decoration projects.

The history of cement

1756, British engineer J. Smeaton found that in order to obtain hydraulic lime, limestone containing clay must be used for firing; The ideal composition of masonry mortar for underwater structures is made of hydraulic lime and volcanic ash. This important discovery laid a theoretical foundation for the research and development of modern cement.

1796, an Englishman J. Parker burned a kind of cement with marl, which was brown in appearance, much like a mixture of lime and volcanic ash in ancient Rome, and named it Roman cement. It is also called natural cement because it is made of natural marl and contains no ingredients. It has good hydraulic and rapid setting characteristics, and is especially suitable for projects in contact with water.