Cement is generally divided into ordinary Portland cement, Portland cement mixed with mixed materials and special cement. Its main components are as follows:

1. The main components of ordinary Portland cement are limestone, clay, and iron ore powder. It is made of limestone, clay, and iron ore powder ground and mixed in proportion. The mixture at this time is called raw meal. Then it is calcined, usually at a temperature of about 1450 degrees, and the calcined product is called clinker. Then the clinker and gypsum are ground together and mixed in proportion to become cement.

2. The main components of Portland cement mixed with mixed materials are limestone, clay, iron ore powder and mixed materials.

It is to add other substances to ordinary Portland cement in proportion and through certain processing procedures to achieve special effects, such as slag cement, pozzolanic Portland cement, fly ash Portland cement, Composite Portland cement, etc. The raw materials of these cements have more active mixed materials or inactive mixed materials than the original ordinary Portland cement.

3. The main components of special cement are limestone and other components. There are only some differences in the material stage and production process. For example, the material of high alumina cement (aluminate cement) is bauxite and limestone, which are calcined to obtain clinker and then ground into aluminate cement.

Tips for purchasing cement

1. Look at the time and the production date of the cement. The performance of cement that exceeds the validity period of 30 days has declined. The strength of cement decreases by 10%-20% after three months of storage, by 15%-30% after six months, and by 25%-40% after one year. High-quality cement can solidify in more than 6 hours. Cement that cannot set for more than 12 hours is of poor quality.

2. Check the appearance to see whether the cement paper bag packaging is intact and whether the markings are complete. The markings on the paper bag include: factory name, production license number, cement name, registered trademark, variety (including variety code), label, packaging year, month, day and serial number.

3. Look at the color. Observe whether the color is dark gray or dark green. The color is yellow or white (yellow indicates that the clinker is raw material, white indicates that the slag content is too much). relatively low.

4. Twist the cement powder with your fingers. If you feel it has a slightly fine, sandy, and powdery feel, it indicates that the cement fineness is normal.

Reference for the above content? Baidu Encyclopedia-Cement