When it comes to cement, we are all familiar with it, whether it is decoration or construction. We all know that the quality of cement directly affects the living of our house, so everyone pays special attention when shopping. However, we found that we did not understand building materials cement when we chose. So what do you need to pay attention to when purchasing building materials cement? Today, Xiaobian will take a look at the building materials cement buying skills and cement purchase precautions!
Building materials cement buying tips
1. Understand the danger of fake cement. The cement market is rather confusing. If you are not careful, you may encounter fake cement. False cement is generally produced by small workshops and put on the building materials market after being put on a brand-name cement packaging bag. False cement is more harmful.
Not only does it often contain excessive levels of radioactive materials, it is a threat to human health. What is even more frightening is that because of poor coagulation, it is easy to cause problems such as crispness and wall peeling, and repairing is very troublesome.
2, the eye of the eye, the true cement really cement bag on the side or the back will have a batch number indicating the date of production, because the cement is prone to moisture or agglomeration after a long time, generally from the factory to the purchase time will not exceed one week, the implementation standard should be GB175-2007 . False because it is produced by a small workshop, there is generally no batch number or an expired package.
3. Check the national standard for the appearance of cement packaging: the cement type, label, factory name and factory number in the cement packaging label are not all non-conforming products. You can also look at the binding line of the package and look at the brand label. There are 4 words of “green product†on the top of the paper bag. The sealing edge of the sealing is rounded. If it is 2 pieces of paper, it means the package has been opened. The brand label behind the real cement bag is more flexible, and the fixed word is written in small carcass, which is quite different from fake cement.
4, said cement weight cement can be bagged or bulk. However, the net weight of the bagged cement is 50kg per bag and must not be less than 98% of the weight of the bag. 20 bags can be randomly selected, as long as the total weight of the cement is not less than 1000kg is the qualified weight. The bag weight requirements must comply with these principles.
5, to distinguish the color of the cement to observe whether the color is dark gray or dark green, the color is yellow, white (yellow, clinker is raw material, white indicates that the amount of slag is too much), the cement strength is relatively low. In general, the normal color of cement should be grayish white. If the color is too dark or changes, there may be too many other impurities.
Building materials cement purchase considerations
1, strength
Strength is one of the most important technical indicators reflecting the cementation performance of cement. It is the ability of cement to be damaged by external forces after curing at a certain age (3d, 28d). The strength of the cement is generally divided into compressive strength and flexural strength in the form of force. GB175-2007 divides cement into different strength grades with 28d compressive strength.
2, condensation time
The time from the mixing of water to the loss of fluidity, that is, the time required to develop from a plastic state to a solid state, is divided into initial setting time and final setting time. In order to allow concrete and mortar to have sufficient time for mixing, transportation, pouring or masonry, the initial setting time of the cement should not be too early; when the construction is completed, it is required to harden as soon as possible to produce strength, so the solidification time cannot be too late. GB175-2007 stipulates that the initial setting time of cement shall not be less than 45min, and the final setting time shall not exceed 600min (potassium cement is not more than 390min).
3, security
It is the stability of volume change after cement slurry hardening. The uniformity of volume change after cement solidification and hardening is one of the important indexes for evaluating the quality of cement. After cement solidification and hardening, local expansion occurs due to internal chemical reaction, which leads to the destruction of hardened structure, that is, the so-called cement volume stability is bad. If there is poor stability, it will easily cause engineering quality safety risks. National standard GB175-2007 stipulates that cement stability must be qualified
Cement is one of the most important materials when we build a house, so you need to know the relevant knowledge when you buy it and then choose to buy it. The above is the small building of today's building materials cement buying tips and cement purchase notes to end here, want to know more information, please continue to pay attention to the decoration home.
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