Hydroxypropyl methylcellulose (HPMC) is a water-soluble polymer widely used in building materials, especially in cement-based products. It plays an important role in various stages during construction and after use, especially in improving adhesion.

1. Basic characteristics and mechanism of action of HPMC
As a non-ionic cellulose ether, HPMC has high water solubility and viscosity stability. Its molecular structure contains hydroxyl and methoxy groups, which enables it to effectively adjust the consistency, viscosity and water retention of cement paste. When HPMC is dissolved in water, the solution formed has good lubricity, film-forming and adhesion properties, which are widely used in cement-based materials.

The adhesion improvement effect of HPMC is mainly achieved through the following mechanisms:

Enhanced water retention: HPMC can increase the water retention rate in cement paste, thereby preventing water from being lost too quickly and ensuring sufficient hydration of cement. The hydration reaction of cement is the key to determining its strength and adhesion. The water retention of HPMC improves the final strength and adhesion of cement-based materials.

Improve consistency and workability: HPMC can significantly increase the viscosity of cement-based materials, improve its consistency, make the material easier to operate during construction, and reduce sagging and collapse. In addition, HPMC can improve the plasticity of the material, making it more uniform during application or laying, and improving construction efficiency.

Improve bonding strength: HPMC can produce strong adhesion on the surface of the substrate by forming a thin film with adhesive force. Especially on porous substrates or smooth surfaces, HPMC increases the adhesion strength between cement-based materials and substrates, effectively preventing cracking or peeling of materials.

2. Specific benefits of HPMC in enhancing the adhesion of cement-based products
Improve the workability and viscosity of mortar
Adding HPMC to mortar can greatly improve its consistency and viscosity, making construction easier, especially when constructing vertically or at high altitudes, it can effectively prevent the sagging problem of mortar. It can improve the adhesion between mortar and substrate surface, ensure uniform application, and reduce waste and waste during construction.

Improve water retention and reduce cracking
HPMC’s high water retention is particularly prominent in dry environments. It can effectively prevent the rapid evaporation of water in cement-based materials after construction and ensure the full hydration of cement. This water retention effect reduces the problem of material cracking caused by too fast drying, especially when large-scale construction is effective. By increasing the degree of cement hydration, the overall strength and durability of the material are also enhanced.

Enhanced bonding and improved adhesion to the substrate
HPMC’s film-forming property enables it to form a sticky film on the surface of cement-based materials, improving the bonding between cement-based products and a variety of substrates. Whether it is used for materials such as concrete, bricks or gypsum boards, HPMC can provide strong adhesion to prevent problems such as shedding, delamination or hollowing of materials after drying. This is especially important for products such as thin-layer mortars and tile adhesives that require high bonding strength.

Improved anti-sagging performance
During the application of cement-based materials, especially on vertical surfaces or in high-rise building construction, it is often encountered that the material sags due to gravity. HPMC can effectively increase the viscosity and consistency of cement-based products, avoiding changes in their shape due to flow before solidification, thereby improving construction quality and reducing the number of repairs.

Improve durability and crack resistance
The adhesion provided by HPMC is not only reflected in the construction process, but also in the durability and stability after use. It can increase the flexibility and crack resistance of cement-based materials, and avoid cracks in materials when the temperature changes or the force is uneven. This flexibility extends the service life of building materials and reduces maintenance costs.

3. Application of HPMC in different cement-based products
Tile adhesive
HPMC is one of the important components of tile adhesive. Since tile adhesives have high requirements for adhesion, the addition of HPMC greatly enhances its adhesion and bonding properties, ensuring that tiles can be stable and not loose for a long time after laying. At the same time, the water retention of HPMC can prevent the cracking of cement-based tile adhesives during the drying process and improve the durability of the adhesive.

Self-leveling mortar
Self-leveling mortar requires that the material has good fluidity during construction, while not causing unevenness or sagging due to excessive fluidity. The application of HPMC in self-leveling mortar can not only ensure its leveling performance during construction, but also improve its adhesion to the substrate and reduce the occurrence of hollowing and cracks.

Waterproof coatings
HPMC is also widely used in cement-based waterproof coatings, which can effectively improve the construction performance of the coating, enhance its adhesion and waterproof performance. The water retention and film-forming properties of HPMC ensure that the waterproof coating can form a dense waterproof layer after construction and extend its service life.

As an important additive in cement-based products, HPMC significantly improves the adhesion and construction performance of these materials. By enhancing water retention, viscosity and consistency, and enhancing adhesion to the substrate, HPMC has shown significant advantages in the application of cement-based materials. Whether in the fields of mortar, tile adhesives or waterproof coatings, HPMC can effectively improve the construction efficiency and quality of the product, extend its service life, and reduce the subsequent maintenance costs. Therefore, HPMC has become an indispensable and important component in cement-based materials.