High-Performance and Sustainable Building Product Additives

Although there are numerous formulations for creating dry and ready-mixed construction materials, all share a common set of critical properties, such as water retention, strength, and workability. When developing these products, it is often challenging to balance spreadability and workability, which improve usability and application properties, with excellent adhesion and resistance to sagging and cracking, which keep product consistency and visual quality at acceptable levels.
 
If you are developing cementitious adhesives, gypsum plasters, fillers, or synthetic plasters, METHOCEL™ hydroxypropyl methylcellulose (HPMC) can help you achieve desired outcomes by controlling rheology, water retention, workability, adhesive strength, binding power, and homogeneity to maximize benefits while minimizing challenges.

METHOCEL™ water-soluble ethers are chemicals that are naturally derived from cellulose and offer excellent performance in building coatings as retarders, water-retaining agents, thickeners, and binders. They have been commonlyused in plaster, cement, lime, and mortar applications for many years.
 
METHOCEL™ acts as a water-retaining agent in cement- and gypsum-based plasters, mortar, and concrete. The water-retention functionality of METHOCEL™ can reduce water loss on the surface of concrete and at the interface where materials are joined by mortars and plasters. Better water retention helps avoid cracking around edges, improves adhesion, and allows the necessary hydration processes to take place to build better durability and compressive and tensile strength. METHOCEL™ can also extend and adjust the setting time, increase workability, and improve the pumpability of concrete, making it suitable for mechanized construction techniques. It also helps prevent weathering and moisture migration to the surface and improves viscosity, reduces shrinkage, and strengthens bonds within these products.

Characteristics and Benefits of METHOCEL™ HPMC

Workability and Plasticity: The addition of METHOCEL™ significantly improves the workability of plaster, making it smoother and easier to use without losing water. The result is a more polished look with tighter adhesion and a smoother surface to the touch. This is especially beneficial for large-scale construction projects.

Water Retention and Strength: Cement- and gypsum-based products build strength through a gelation process from a hydration reaction. In this reaction, water converts silicates in cement silicates and calcium sulfate hemihydrate in gypsum-based products into complex hydrates and calcium sulfate dihydrate, respectively, both of which increase strength. If insufficient water is present, this reaction cannot be executed completely, and poor strength will be developed. There also will be less bonding and strength development to the surface they are applied to if water is lost from the cement mortar or plaster. These surfaces are typically adsorbent and cause incomplete hydration, reducing bond strength between the product and the wall.

METHOCEL™ plays an important role in increasing the water retention of building materials, making it such that water added into a mix is used to build bond strength and shear strength and is not lost due to evaporation or absorption. The water retention properties of METHOCEL™ typically improve with increasing viscosity.

Bonding: Adding METHOCEL™ can significantly improve the bonding of cement mortar, plaster, and adhesives, particularly increasing initial bond force. The increased viscosity and adhesive properties METHOCEL™ provides ensure that the plaster, mortar, and adhesives applied to walls, bricks, or tiles do not sag or slide down and that firmer bonds are made. The amount of METHOCEL™ to add should be experimentally determined per product; too much will make the paste overly adhere to the construction tool.

Set-Retarding Effect: METHOCEL™ can be used as a set retarder in cement- or gypsum-based building materials. In many cases, this effect provides a better window of workability and allows for higher mechanical strength to develop over time.

Air-Entraining Agent: When METHOCEL™ is added to cement, many tiny bubbles form inside the material, resembling a honeycomb structure. These small bubbles can provide better cracking resistance by designating spaces for water to freeze in, which is safer for the material and improves freeze–thaw stability. Furthermore, the honeycomb structure blocks the capillary action generated after the original cement hardening and prevents water penetration, allowing the walls, the tiles, and the rest of the structure to be more waterproof. The air-entraining action also improves heat and sound insulation effects and decreases the bulk density of the product.

Recommended METHOCEL™ Cellulose Ether Grades for Building Materials
 

Grade	Typical Viscosity (2% in water at 20°C, mPa·s)	Applications
METHOCEL™ 228S	5,000	Gypsum and cement plasters, masonry mortars, grouts, and tile and block adhesives
METHOCEL™ 254	32,000	Cement plasters, masonry mortars, grouts, and cement-based tile and block adhesives
METHOCEL™ J12MS	10,000–16,500	Ready-mix tile adhesives and renders
METHOCEL™ J75MS	60,000–90,000	Ready-mix tile adhesives and renders
METHOCEL™ 240S	30,000–50,000	Tape-joint compounds