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Filling bean stone concrete can obtain higher strength and better waterproof performance, but the construction is relatively difficult, and it is easy to use dry hard cement mortar for filling. It's up to you.
Hello! According to the provisions of DBJ T01-26-2003 "Construction Technology Regulations for Construction and Installation Sub-projects" in the fourth volume of the fire prevention and anti-theft door installation strips: grouting in the door frame, for steel fireproof and anti-theft doors, the door frame needs to be filled with cement mortar or C20 fine stone concrete. >>>More
The better ones are filled with polyurethane foam, some are made of rock wool, and some are made of straw and cardboard.
Yes, just paint it with white cement after spraying.
Forget about gradient sound-absorbing cotton, it's just a gimmick. >>>More
Is your security door still under warranty? If you can find a store to change the door or return the door, if it is outside the warranty period, you can ask for a repair until you are satisfied.