The purchase of cement for home improvement should be considered from the following aspects.
1. Look at the variety
Commonly used cements are ordinary Portland cement, which is made of Portland cement clinker, added with appropriate amount of gypsum and mixed materials: Portland slag cement, made of Portland cement clinker, mixed with appropriate amount of granulated blast furnace slag and Gypsum is ground; pozzolanic Portland cement is made by mixing Portland cement clinker, pozzolanic material and gypsum in proportion to mix and ground.
2. Look at the appearance
The amount should be sufficient, the cement bag is very full, almost not collapsed. The identification is clear and complete. Generally, the cement produced by a regular manufacturer should be marked with the following content: registered trademark, place of origin, production license number, implementation standard, packaging date, bag net weight, factory number, cement variety, etc. Inferior cement is often not indicated. Second, carefully observe the color of the cement. The normal color of cement should be off-white. If the color is too dark or changed, it may be caused by excessive mixing of other impurities.
3. Listen to the business introduction
Listen to the merchant's introduction about the cement ingredients, to infer The quality of cement. At present, some small domestic cement factories sell at low prices, violate the regulations of cement standards, repair and use cement mixtures too much, and fail to match the raw materials according to national standards. The performance of their products can be imagined. The regular manufacturers are very strict in the selection of cement raw materials.
4. Look at the source of production
It mainly depends on the cement manufacturer and production process, whether it is the product of a regular manufacturer, and whether the production process is advanced. At present, most of the cement products in the building materials decoration market are produced by small vertical kiln technology, not only the product quality is very unstable, but also the enemy of environmental protection; and some professional manufacturers adopt new dry rotary kiln production and use advanced computer technology. Control and management can ensure the stable quality of cement products.
5. Judge the shelf life by touching it by hand
Cement also has a shelf life. Generally speaking, the strength of cement after 30 days from the factory date will decrease. Therefore, the cement must be used within 30 days of the production date, otherwise the bonding ability of the cement will decrease. In addition, you can use a disposable cup to fill a little cement, add water and mix well. After 6 hours, poke and twist with your hands. If you don’t poke, you can’t twist it. Good cement. For inferior cement, the cement powder is twisted with fingers, and it has a rough feeling, indicating that the cement has a coarse and abnormal fineness, low strength and poor viscosity when used.