Home xin The label on the cement package indicates the strength of the cement. The larger the number, the better the quality of the cement

The label on the cement package indicates the strength of the cement. The larger the number, the better the quality of the cement

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the mark of mud is the sign of cement strength. The compressive strength of cement mark measured refers to the strength of cement mortar after hardening for 28 days. For example, if the compressive strength after 28 days is 310 kg /cm2, the grade of cement is 300. The compressive strength of 300-400 kg /cm2 is 300. Ordinary cement has six grades: 200, 250, 300, 400, 500 and 600. 200-300 can be used for some housing construction. Above 400 can be used to build larger bridges or factories, as well as some important pavements and manufacture prefabricated components. What does the label of cement stand for? At present, cement has become an indispensable main material in any construction. Take a closer look. The numbers of 400, 500 and 600 are written on the cement packaging bag. Don’t underestimate these numbers. They all represent different meanings

we need high-strength cement to build large bridges, but we don’t need high-strength cement to build ordinary houses and warehouses. According to different needs, we can make products of different grades and quality. The mark of cement is their grade mark. Its specific contents include:

1 The strength after solidification, the higher the label, the higher the strength. Including compressive and tensile capacity

2. The setting speed of 700 and 800 is fast hardening cement with short setting time. It is used for emergency engineering and underwater construction

cement strength testing is generally conducted at the age of 3 days, 7 days and 28 days, and each age has different testing standards. Cement is a kind of hydraulic cementitious material. The strength increases with time. The growth is completed in a certain time. Generally, the strength growth stops after one year

in addition to various labels, the classification of cement is distinguished by different materials and characteristics, such as slag Portland cement, pozzolanic Portland cement and ordinary portland cement. There are also characteristic cements, such as acid resistant cement, heat-resistant cement, Portland resistant cement and expansive cement, which are named according to their characteristics. Classification of cement varieties

(1) Portland cement: Portland cement clinker with calcium silicate as the main component is ground with an appropriate amount of gypsum. Portland cement is commonly used in home decoration

(2) ordinary portland cement: it is made by grinding Portland cement clinker, adding an appropriate amount of gypsum and mixed materials

(3) slag Portland cement: it is made of Portland cement clinker mixed with an appropriate amount of granulated blast furnace slag and gypsum

(4) pozzolanic Portland cement: it is made by mixing and grinding Portland cement clinker, pozzolanic material and gypsum in proportion

(5) fly ash Portland cement: it is made of Portland cement clinker and fly ash mixed with an appropriate amount of gypsum and ground

(6) white portland cement (decorative cement): it is made by grinding calcium silicate as the main component and adding a small amount of iron clinker and an appropriate amount of gypsum

(7) colored Portland cement (decorative cement): it is made of white portland cement clinker and high-quality white gypsum mixed with pigments and additives. Commonly used color pigments include iron oxide (red, yellow, brown and black), manganese dioxide (brown and black), chromium oxide (green), cobalt blue (blue), group cyan (Indigo), malachite blue (sea blue), carbon black (black), etc

commonly used cement grades

225, 275, 325, 425, 525, 625, etc. the tensile strength varies according to the variety and grade, and the MPA value is between 2.8-4.5 and 3.4-8.0> the cement is easy to be used for construction and decoration. Decoration cement is similar to Portland cement, with the same construction and maintenance, but it is easy to be polluted, and the instruments and tools must be clean

cement mortar

in home decoration, cement mortar is used for floor tile, wall tile pasting and masonry. It can not only enhance the adsorption capacity between surface material and base, but also protect the internal structure. At the same time, it can be used as the leveling layer of building rough surface. Therefore, cement mortar is an essential material in installation and repair engineering

many owners believe that the greater the proportion of cement in the whole mortar, the stronger its adhesion. Therefore, they often disagree with decoration companies on the amount of cement used. In fact, it is not. Take pasting ceramic tiles as an example. If the cement label is too large, when the cement mortar sets, the cement absorbs a large amount of water. At this time, if the water of ceramic tiles on the surface layer is excessively absorbed, it is easy to crack and shorten the service life. Generally, cement mortar shall be mixed in the proportion of cement: sand = 1:2 (volume ratio)

in order to ensure the quality of cement mortar, when purchasing cement, we must pay attention to whether it is 425# Portland cement produced by large factories. Sand shall be selected. The particle size of medium sand is very suitable for use in cement mortar. Many owners think that the finer the sand, the better the mortar, which is actually a misunderstanding. The adsorption capacity of too fine sand is not strong, so it can not produce large friction and stick the ceramic tile firmly.

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