Hydroxypropyl Methylcellulose (HPMC) is a non-ionic cellulose ether chemically modified from natural cellulose. Due to its excellent water retention, thickening and film-forming properties, HPMC has been widely used in the construction industry, especially in gypsum-based building materials. Gypsum-based material is a common building material and is widely used in interior and exterior wall decoration, adhesives and screeds. The introduction of HPMC has significantly improved the performance of gypsum-based materials, making them more excellent in terms of constructability and durability.

1. HPMC improves the working performance of gypsum-based materials

Improve water retention
One of the main functions of HPMC is to significantly improve the water retention of gypsum-based materials. During the hydration process, gypsum needs sufficient water to complete the hardening reaction. Insufficient water will lead to incomplete hardening, reduced strength and other problems. HPMC can reduce the evaporation rate of water by forming a uniform colloidal film, thereby ensuring that the hydration process of gypsum can proceed smoothly. This not only improves the strength of the material but also extends its service life. In addition, the water retention of HPMC makes the slurry smoother during construction, making it easier to apply and avoid shrinkage cracks caused by water loss.

Improve workability
HPMC can significantly improve the workability of gypsum-based materials, making them easier to apply, level and calender. Its thickening effect enables the slurry to maintain appropriate viscosity and fluidity, making it less likely to stratify and flow. At the same time, HPMC improves the lubricity of gypsum materials, making it feel better during construction and easier to operate. This is especially important for large-area painting or fine decoration, reducing the possibility of rework and improving construction efficiency.

Extend opening hours
During the construction process, gypsum-based materials require a certain open time (that is, the time they can be operated) to ensure that workers can complete the application or leveling work within the appropriate time period. HPMC can delay the evaporation of water through its good water retention and thickening properties, thereby extending the opening time of the material. This gives workers more time to make fine adjustments and ensure construction quality.

2. HPMC improves the mechanical properties of gypsum-based materials

Increase intensity
The water retention effect of HPMC can not only ensure the sufficient hydration of gypsum, but also play a positive role in promoting the early strength development of gypsum-based materials. During the hydration process, HPMC adjusts the distribution of water to make the gypsum crystal structure more compact and uniform, thereby improving the early strength of the material. At the same time, the addition of HPMC also reduces the porosity in the slurry, allowing the gypsum-based material to exhibit higher compressive strength and flexural strength after hardening.

Improve crack resistance
Gypsum-based materials are prone to drying shrinkage cracks during the drying process, which is caused by volume shrinkage caused by evaporation of water. HPMC effectively reduces the occurrence of dry shrinkage cracks by adjusting the water evaporation rate and increasing the toughness of the material. In addition, the plasticity of HPMC gives the material a certain degree of elasticity and deformability during the drying and hardening process, further enhancing the material’s crack resistance. This can effectively reduce the problem of surface cracks caused by dry shrinkage when gypsum-based materials are used in large areas such as interior walls and exterior walls.

3. Effect of HPMC on the durability of gypsum-based materials

Improve freeze-thaw resistance
Due to its porous structure, gypsum-based materials are easily affected by freeze-thaw cycles in the environment, leading to problems such as reduced structural strength and surface weathering. After HPMC is introduced into gypsum-based materials, it can reduce the migration of water in the material through its water retention effect and reduction of porosity, thereby reducing the damage to the material caused by freeze-thaw cycles. In addition, the film-forming property of HPMC can form a protective film on the surface of the material, further enhancing the material’s freeze-thaw resistance.

Improve carbonation resistance
Gypsum-based materials are prone to carbonization reactions when exposed to air, resulting in loss of strength and surface chalking. The film-forming effect of HPMC can form a dense protective layer on the surface of the material to prevent the penetration of carbon dioxide, thereby reducing the occurrence of carbonization reactions. At the same time, the water retention effect of HPMC makes the gypsum more fully hydrated, further enhancing the material’s anti-carbonation performance. This allows the gypsum-based material to show better durability in long-term use, especially when used outdoors.

4. Improved environmental adaptability of HPMC to gypsum-based materials

Improve the water resistance of materials
Gypsum-based materials usually soften and dissolve easily when exposed to water, which limits their use in humid environments. The water retention and film-forming properties of HPMC can enhance the water resistance of gypsum materials, making them less susceptible to water erosion in humid environments. By forming a waterproof layer on the surface, HPMC enables the gypsum material to maintain good physical properties and strength after contact with moisture, making it less prone to corrosion.

Improve resistance to chemical corrosion
HPMC can also improve the chemical resistance of gypsum-based materials. The dense film layer it forms on the material surface not only blocks the intrusion of moisture, but also prevents the penetration of acid and alkali substances and reduces material damage caused by chemical corrosion. This property allows gypsum-based materials to be used in more demanding environments, such as those in industrial buildings that are subject to chemical attack.

Through its unique multiple functions such as water retention, thickening, and film-forming properties, HPMC has significantly improved the working performance, mechanical properties, durability, and environmental adaptability of gypsum-based building materials. The addition of HPMC not only improves the construction convenience of gypsum-based materials, but also enhances its durability and environmental adaptability, giving it wider application prospects in the construction field.