Concrete Repair / Spalling

How to Choose?

Select based on repair location and concrete strength:

• General repair (older buildings, lower-strength concrete) → Class 25 repair mortar, e.g. Optimix RM725, Unicell 25, Renderoc HB25
• Structural repair (high-strength concrete, beams/columns) → Class 40 repair mortar, e.g. Unicell 40, Optimix RM740, Renderoc HB40
• Pre-application primer → Unicell Primer for bonding new mortar to old concrete

Class 25 vs Class 40

Class 25 is for older buildings with original concrete strength of 20-30 MPa, with a lower elastic modulus to match aged concrete. Class 40 is for modern structures with concrete strength 40 MPa and above. Both must comply with HK Housing Authority specifications and hold PCCS-RM certification. Government projects require certified products.

Brands Available

Wah Hing supplies repair mortars and primers from Sika Ronacrete, Fosroc, Optimix, Mapei and Weber. Most products typically in stock. WhatsApp us for product details and technical advice.