Cement, powdered hydraulic inorganic cementitious material. After adding water, it becomes a slurry, which can be hardened in air or hardened in water, and can firmly bind sand, stone and other materials together. Cement is an important building material. Mortar or concrete made of cement is strong and durable and is widely used in civil engineering, water conservancy, and national defense projects.
Use and purchase
In home decoration, cement mortar is used for floor tiles, wall tiles and masonry, etc. It not only enhances the adsorption capacity of the surface material and the base layer, but also protects the internal structure. At the same time, it can be used as a leveling layer for building rough surfaces. So in the renovation project, cement mortar is an essential material.
Many customers believe that the greater the proportion of cement in the entire mortar, the stronger the adhesiveness, and therefore often disagree with the decoration company on the use of cement. In actual fact, in the case of paste tiles, if the cement number is too large, when the cement mortar condenses, the cement absorbs a large amount of water. At this time, the ceramic tile surface moisture is easily absorbed and cracked, shortening the service life. Cement mortar should generally be stirred at a ratio of cement:sand=1:2 (volume ratio).
At present, there are many types of cement on the market, including Portland cement, ordinary portland cement, composite Portland cement, slag portland cement, etc., and commonly used in home decoration is ordinary portland cement or composite portland cement. .
The use of cement eight bogey
(1) Avoid moisture and hard
Cement that is hardened by moisture will reduce or even lose its original strength. Therefore, the specification requires that cement that has been delivered for more than three months should be retested and used according to the test results. For cement that has been dampened into clusters or hardened, it must be used after sifting. The lumps that have been sieved are finely crushed or finely milled and are generally used as masonry mortar or plaster mortar for minor works. For one-touch or pinch-to-powder cement lumps, strength levels can be appropriately reduced.
(2) Avoid exposure and dry
If the concrete or plaster is exposed after the operation, its strength will be reduced or even completely lost with the rapid evaporation of moisture. Therefore, the construction must be strictly cleaned and fully wetted before the construction; the construction should be strictly covered and watered and maintained in accordance with the specifications.
(3) Avoid negative temperature and freezing
After the concrete or mortar is mixed, if it is frozen, the cement cannot be hydrated, and if the water icing expands, the concrete or mortar will be damaged by the powder and cracks that are gradually deepened from the surface to the inside. Therefore, the construction project should be strictly observed. Winter Construction Procedures (JGJ104-97) for construction.
(4) Avoid hot heat
After the solidified mortar layer or concrete component, if it is often under high temperature and hot conditions, there will be strength loss because of the decomposition of calcium hydroxide in the cement stone under high temperature conditions; in addition, some aggregates are also under high temperature conditions. Decomposition or volume expansion.
For long-term high temperature occasions, fireproof bricks can be used for isolation and protection of ordinary mortar or concrete. In case of higher temperatures, special heat-resistant concrete shall be used, and a certain amount of ground heat-resistant material may also be incorporated into the concrete.
(5) Avoid soft grass
The cement can be firmly bonded or gripped with a hard, clean base, but the bond grip strength is related to the smoothness of the base face. In the smooth construction of the grass-roots level, must be brushed nettle before brushing, in order to make the cement and the base layer firmly bonded.
The grime, greasy, acid and alkali substances on the grassroots level all play a role in isolation. They must be carefully cleaned and cleaned. Afterwards, they must first brush a prime grout and then apply mortar or concrete.
Cement in the solidification process to produce shrinkage, and in the wet and dry, hot and cold changes in the process, it and the loose, weak base of the volume change is very incoherent, will inevitably occur emptying or cracks, making it difficult to bond firmly. Therefore, wood, slag mats, and lime soil cushions cannot be firmly bonded to mortar or concrete.
(6) Avoid aggregate impure
As gravel for concrete or cement mortar aggregates, if there is dust, clay or other organic impurities, it will affect the bond strength between the cement and sand, stone, and ultimately reduce the compressive strength. Therefore, if the impurity content exceeds the standard, it must be cleaned before use.
(7) Avoid thick gray water
People often ignore the effect of water consumption on the strength of concrete. In order to facilitate the pouring of concrete during construction, sometimes the mix ratio is not carefully performed, and the concrete is mixed very thinly. Since hydration requires only about 20% of the weight of the cement, the excess moisture will leave a lot of voids in the concrete, which will reduce the strength of the concrete. Therefore, under the premise of guaranteeing the compaction of the cast, the mixing water should be minimized.
Many people think that the more cement used for plastering, the more sturdy the plaster layer. In fact, the greater the amount of cement, the thicker the mortar, the greater the amount of shrinkage of the plaster layer and the more cracks that result. Under normal circumstances, plastering should first use 1: (3 - 5) coarse mortar to wipe the leveling layer, then use 1: (1.5 - 2.5) of cement mortar to wipe a thin surface layer, avoid using too much cement.
Acidic materials and calcium hydroxide in the cement will have a neutralization reaction. The volume of the product is loose and expands. As a result, the concrete or plaster layer is gradually eroded and disintegrated, so that the cement is not subject to acid corrosion.
Acid-resistant mortars and acid-resistant concrete should be used in places or containers that are exposed to acidic substances. Slag cement, pozzolan cement, and fly ash cement all have better acid resistance, and these three types of cement should be used to prepare acid-resistant mortar and concrete. Strictly requiring acid-resistant corrosion does not allow the use of ordinary cement.
Confucius decoration study decoration cement home decoration decoration decoration company okay ceramic tiles ceramic tile
Bulk Activated Carbon,Granular Activated Carbon,Activated Carbon
Coal-Based Activated Carbon,Activated Carbon Co., Ltd. , http://www.nbactivatedcarbon.com