When incorporated into dry-mix mortars, the fibres form a three-dimensional network within the cured matrix that bridges micro-cracks, reduces plastic shrinkage cracking, and improves workability by preventing mortar segregation and sagging on vertical surfaces. In GCC construction markets — where the extreme thermal cycling of concrete and plaster substrates promotes cracking — cellulose fibre is an increasingly specified additive in renders, plasters, EIFS base coats, and repair mortars.
Technical specifications
| PARAMETER | SPECIFICATION | TEST METHOD |
|---|---|---|
| CAS Number | 9004-34-6 (cellulose) | — |
| Raw Material | Wood pulp cellulose (softwood kraft) | — |
| Appearance | White to off-white fibrous powder | Visual |
| Fibre Length | 100 – 1,500 μm (grade dependent) | Optical microscopy |
| Fibre Diameter | 20 – 30 μm (typical) | — |
| Moisture Content | ≤ 8.0 % | ISO 638 |
| Bulk Density | 50 – 200 g/L (fluffy) | — |
| pH (suspension) | 6.5 – 8.0 | — |
| Typical Addition Level | 0.1 – 0.5% on dry mix weight | — |
| Shelf Life | 24 months in sealed bags, < 35°C | — |
| HS Code | 4706.30 |
Applications
- Plastic Shrinkage Crack Control in Render — Cellulose fibres distributed throughout fresh render and plaster bridge plastic shrinkage cracks as they form during drying — reducing crack width and frequency in GCC exterior renders exposed to rapid drying under hot sun and low humidity.
- EIFS Base Coat Reinforcement — Used in EIFS base coat mortars applied over polystyrene insulation boards on GCC building facades — fibres supplement the glass fibre mesh reinforcement and resist micro-cracking from thermal movement.
- Sag Resistance in Vertical Applications — Cellulose fibres improve the anti-sag and anti-slump properties of machine-applied renders and hand-applied plasters on vertical walls — reducing the risk of mortar runs on GCC hot weather application days.
- Repair Mortar Crack Bridging — Added to concrete repair mortars for GCC infrastructure repair projects to improve crack bridging capacity of repaired surfaces and reduce differential shrinkage cracking between repair material and parent concrete.
- Tile Adhesive Workability Improvement — Improves the trowelability and reduces stringiness in tile adhesives — makes the adhesive easier to comb and provides better coverage of the tile back with notched trowel application.
Key properties
- Three-dimensional fibre network bridges micro-cracks as they form
- Reduces plastic shrinkage cracking significantly vs un-fibred systems
- Improves anti-sag and anti-slump on vertical surfaces
- Good water retention synergy with HPMC
- Non-toxic, natural material — no regulatory concerns in GCC
- Compatible with all standard dry-mix mortar additives
- Does not affect setting time or final compressive strength at recommended levels
- Improves trowelability and workability of fresh mortar
Usage and recommendations
Add at 0.1–0.3% on total dry mix weight for standard renders and plasters. For crack-critical EIFS base coats: use at 0.2–0.5%. Combine with HPMC (0.2–0.3%) and RDP (2–4%) for a fully optimised GCC exterior render system. Disperse fibres in dry blend before liquid addition — fibres clump if added to wet mortar. In machine-applied systems: verify that fibre length is compatible with pump and spray nozzle dimensions. Contact Raykem for fibre length grade selection.
Packaging
- 25 kg Multi-Wall Paper Bags
- 500 kg Supersacks
Storage and shelf life
Store in sealed bags below 35°C in a dry covered warehouse. Cellulose is hygroscopic — moisture uptake increases bulk density and reduces dispersibility. Shelf life: 24 months.