Hydroxypropyl Methylcellulose: Sharing a Dry-Mix Mortar Formulation for Gypsum Wall Plastering

Construction-grade HPMC chemical powder is a key product of Shijiazhuang Cellulose Co., Ltd. Serving as a thickening and water-retention agent for construction applications, it ensures excellent workability and construction results. HPMC is highly regarded and widely favored by countries around the globe.

Hydroxypropyl methylcellulose facilitates a specific dry-mix mortar formulation designed for plastering gypsum walls—a specialized mortar capable of applying thin-layer plaster finishes onto gypsum-based building materials.

Key Features:

1. Gypsum products typically exhibit a high water absorption rate, capable of absorbing up to 50% of their own weight. When conventional cement mortar is used for plastering, the rapid water absorption by the gypsum substrate makes the material difficult to handle during construction. Furthermore, because the compressive strength of cured cement mortar is significantly higher than that of the gypsum substrate, it is difficult to achieve a cohesive bond that forms a robust, unified structure. Additionally, the substantial disparity in thermal expansion coefficients between the cement mortar plaster layer and the gypsum substrate often leads to severe cracking, hollowing (delamination), and even large-scale shedding of the plaster layer over time. Our proprietary formulation was developed specifically to resolve these issues.

2. Excellent water retention and high bond strength.

3. Suitable for thin-layer plastering applications.

4. Highly compatible with gypsum-based building materials.

5. Easy to handle during application, thereby reducing labor intensity.

6. The surface of the plaster layer can be treated with waterproofing agents or used for tiling applications in accordance with standard construction practices.

7. Enhances the overall structural integrity of the mortar layer, thereby preventing cracking. What are the formulation details and ingredient ratios?

Quartz sand (0.05–0.5 mm): 500 kg; Ordinary Portland cement: 200 kg; Hydrated lime: 80 kg; Heavy calcium carbonate: 40 kg; Hemihydrate gypsum: 40 kg; Redispersible polymer powder: 7–14 kg; Hydroxypropyl methylcellulose: 2–4 kg; Polypropylene fibers (3–5 mm): 2 kg. Storage of Gypsum Dry-Mix Building Materials: Gypsum dry-mix building materials must be packaged in moisture-proof bags featuring a plastic inner liner. If stored in bulk silos or tanks, the storage vessel must be tightly sealed. For silos constructed from steel plates, the exterior of the tank body requires moisture-proofing treatment to prevent "sweating" (condensation) on the steel surface caused by environmental fluctuations, which could otherwise compromise the quality of the gypsum dry-mix products. If dry-mix gypsum building materials are stored in a dark, damp environment with poor air circulation—or if their storage period exceeds six months from the date of manufacture under normal storage conditions—a quality inspection must be conducted prior to use to ensure suitability for construction.