Sika Ronacrete Unicell 40S

Unicell 40S — Class 40 Window Frame Waterproof Grout

Unicell 40S is a pre-packed vinyl acetate copolymer modified mortar requiring only the addition of clean water to produce a high-performance grout for filling gaps around window frames, door frames, and fire shutter frames. It conforms to the Hong Kong Housing Authority specification for Class 40 Repair Mortar System (HKHA Class 40 RMS). Suitable for thick section application in both structural and non-structural uses, with excellent waterproofing and water resistance properties.

Key Features

• Compliant with HKHA Class 40 Repair Mortar System specification
• High build application capability
• Simple to mix — just add water
• Pre-packed for quality control and convenience
• Suitable for structural applications
• Waterproof and water resistant
• Shrinkage compensated (no cracking in Coutinho Ring test)
• Low VOC

Typical Applications

• Window frame to concrete gap filling
• Door frame gap filling
• Fire shutter frame gap filling

Why Choose Unicell 40S?

• HKHA approved: Meets Class 40 RMS specification for public housing projects
• High strength: 28-day compressive strength exceeding 40 MPa
• Waterproof: Very low water absorption (28-day ISA <0.1 ml/m²/s @ 10 min)
• Non-shrink: No cracking in Coutinho Ring test from 1 to 28 days
• Easy to use: Pre-bagged formula, just add water and mix

Packaging & Consumption

Technical Specifications

Water Absorption Data

Important Notes

• Remove all dust, loose material, and laitance from the concrete surface
• Thoroughly wet concrete surfaces with clean water before application
• For application thickness over 70 mm, apply Unicell Primer first
• Empty entire bag into mixing vessel, add 3.5-4.5 litres of clean water, mix until a homogeneous workable mortar is achieved
• Compact the mortar firmly into the gap between frame and concrete to fill all voids
• Finish mortar surfaces with steel trowel 2-3 hours after application
• Clean all tools with water immediately after use

FAQ

What is the difference between Unicell 40S and standard repair mortar?

Unicell 40S is specifically designed for window frame grouting and meets the HKHA Class 40 specification. Its waterproofing properties (very low water absorption) and shrinkage compensation make it particularly suitable for window frame applications, effectively preventing water ingress around frames. Standard repair mortars may not achieve the same waterproofing and impermeability standards.

Can Unicell 40S be used for general concrete repair?

Unicell 40S is primarily designed for window, door, and fire shutter frame grouting. For general concrete repair, use Unicell 40 (general Class 40 repair mortar) or Unicell 25 (Class 25 repair mortar) from the same range.

How much water is needed per bag of Unicell 40S?

Add 3.5 to 4.5 litres of clean water per 25 kg bag, mixing until a homogeneous workable mortar is achieved. Consumption is approximately 67 bags per cubic metre.