What is the cement mortar ceiling?

The cement mortar ceiling refers to the cement mortar plaster on the bottom of the concrete floor slab of the room ceiling, which is generally 20mm thick. Located at the bottom of the ceiling.

Cement mortar plastering is a method used for waterproofing and plugging in the 1950s and 1960s. The basic method is to clean and moisten the concrete or masonry base. There are two types: plain cement slurry and cement mortar. Plastering the layers alternately five times becomes "five-layer plastering", and missing one layer of cement slurry means "four-layer plastering".

The first layer of cement slurry is 2mm, with a water-cement ratio of 0.4~0.5, and is applied in two steps. The second layer of cement mortar is 4~5mm, with a water-cement ratio of 0.4~0.5, 1 part cement + 2.5 parts sand, and is carried out when the plain cement slurry is initially set. The third layer of plain cement mortar is 2mm thick with a water-cement ratio of 0.37~0.4. It should be carried out after the second layer of cement mortar has solidified and has a certain strength. The fourth layer of cement mortar is 4~5mm thick and has the same proportion as the second layer. The fifth layer is a plain cement slurry layer with a water-cement ratio of 0.55~0.6. When constructing the leaking area, it is necessary to first plug the leak with water glass, and then apply five layers of plastering. This process requires some skills. Due to the complexity of the process, it requires careful operation and maintenance. With the development of modern materials and technology, it is no longer used. Of course, ordinary bricklayers and technicians are no longer aware of this practice. This process method is very effective in the era when technical materials are lacking, and the waterproof and crack-resistant effect is very good.