Sika Ronacrete Unicell Primer

Features

• Rebar passivation — forms anti-corrosion barrier on steel
• Bond enhancement — significantly improves mortar-to-substrate adhesion
• Waterproof barrier — blocks moisture and harmful ion penetration
• Water-based, low VOC
• Simple to mix with cement and apply
• Economical
• Designed for Unicell range, also compatible with other cementitious mortars

Unicell Concrete Repair System

1. Step 1: Unicell Primer — rebar primer + substrate bond coat
2. Step 2: Unicell 25 or 40 — repair mortar to fill spalled areas
3. Step 3: Surface finish — render or paint

Applications

• Rebar corrosion protection in reinforced concrete
• Substrate priming before concrete repair
• Bond enhancement for thin/thick mortar
• Mortar screed and render priming

Why Choose Unicell Primer

• Dual function: bonding primer and rebar passivation in one
• High bond strength: exceeds HKHA requirements when used with Unicell mortars
• Low VOC, eco-friendly: water-based formula
• Economical

Packaging

Comparison: Unicell Primer vs Mapefer vs Fosroc Primer

Important Notes

• Remove all defective concrete to sound substrate; clean loose rust
• Cut repair edges to adequate depth to avoid feather edges
• Mix with cement using low-speed drill
• Allow rebar coat to dry, then apply bond coat to rebar and concrete surface
• Apply repair mortar (Unicell 25/40/WF) while bond coat is still wet/tacky
• If primer dries, re-apply before proceeding
• For detailed application methods, coverage rates and technical parameters, refer to the official product data sheet

FAQ

What is the difference between Unicell Primer and Mapefer?

Unicell Primer is a liquid polymer that requires mixing with cement — provides both bonding and rebar passivation. Mapefer 1K is a ready-to-use cementitious anti-corrosion mortar. Match primer to repair mortar brand: Unicell Primer with Unicell, Mapefer with Mapei.

Is primer mandatory?

For exposed rebar, strongly recommended for corrosion protection. Even for surface repairs without exposed steel, primer significantly improves bond strength and reduces future debonding risk.