Cellulose ether is a type of non-ionic polymer obtained by chemical modification of natural cellulose. It has good water solubility and chemical stability. It plays a very important role in building materials, especially in mortar. It is widely used in tile adhesive, plaster mortar, self-leveling mortar, thermal insulation mortar and other fields.
1. Types of cellulose ethers
Common cellulose ethers are mainly the following:
Hydroxypropyl methylcellulose (HPMC): The most widely used type, with excellent water retention and thickening properties.
Methyl cellulose (MC): An early cellulose ether with slightly weaker water retention and limited use.
Hydroxyethyl methylcellulose (HEMC): Similar in performance to HPMC, but slightly different in solubility.
Hydroxyethyl cellulose (HEC): Mainly used in water-based coatings, less used in mortar.
Among them, HPMC is most commonly used in dry mortar.
2. Mechanism of action of cellulose ether in mortar
Water retention
One of the most important functions of cellulose ether is to significantly improve the water retention of mortar. During the construction process of mortar, if the water evaporates too quickly or is excessively absorbed by the base, it will cause early drying, affect the hydration reaction of cement or gypsum, and reduce the strength. Cellulose ether can form a colloidal solution in the mortar, encapsulate the water, delay its release, ensure the full hydration reaction, and enhance the bonding force and final strength.
Thickening property
Cellulose ether has a good thickening effect, which can improve the consistency and bonding of the mortar and improve the construction performance. Reasonable viscosity can make the mortar easier to apply, have good ductility, and not easy to sag, especially when it is constructed on vertical surfaces. At the same time, it can also prevent mortar stratification, water seepage and other phenomena, and improve the uniformity and stability of the mortar.
Improving construction performance
Cellulose ether can significantly improve the construction feel of the mortar, making the construction smoother and easier, and improving the construction efficiency. At the same time, its lubricating effect on construction tools also helps to reduce the physical exertion of construction workers.
Anti-slip property
Adding cellulose ether to tile adhesive or plaster mortar can effectively improve the anti-slip property of mortar, and keep tiles from sliding even in thick layer construction or heavy brick pasting.
Extending the open time
The open time refers to the time that the mortar has good bonding ability after the construction workers apply it to the base. Cellulose ether significantly extends the open time of mortar by retaining water and slowly releasing water, providing more adjustment time for construction and avoiding bonding failure due to too fast drying.
Improving anti-cracking performance
Good water retention and elastic properties enable cellulose ether to reduce shrinkage stress and crack risk during drying, making it particularly suitable for floor self-leveling and internal and external wall plaster mortar.
3. Factors affecting cellulose ether on mortar performance
Addition amount: Too low addition amount cannot play its due function, and too much addition amount may lead to too high viscosity and construction difficulties. Therefore, it is necessary to adjust according to the formula, and the conventional addition amount is between 0.2% and 0.7%.
Degree of substitution: The degree of substitution affects the solubility and viscosity of cellulose ether, which is directly related to its water retention and thickening effect in mortar.
Particle fineness: The finer the particles, the faster the dissolution speed and the better the dispersion uniformity, which helps to improve the overall performance of mortar.
4. Precautions for use
Dispersion method: When used in dry mortar, cellulose ether needs to be fully mixed with other powders to avoid agglomeration or uneven distribution.
Environmental factors: Temperature and humidity will affect its water retention performance. It is recommended to use high-viscosity and high-water retention products in high-temperature and dry environments.
Formula compatibility: Compatibility testing is required with other additives (such as redispersible latex powder, retarders, etc.) to avoid mutual cancellation of performance.
The application of cellulose ether in dry mortar not only improves the construction and durability of mortar, but also promotes the development of modern building materials towards industrialization and standardization. Its main functions include water retention and thickening, improving construction performance, anti-slip, extending open time, and improving crack resistance. Under the current development trend of green, energy-saving and environmentally friendly buildings, the application of cellulose ether will be more extensive, and its performance will be continuously optimized and improved.
Post time: May-07-2025