Fosroc Renderoc LA55 Lightweight Repair Mortar
Renderoc LA55 is a single-component, low-alkali, high-flow cementitious micro-concrete for repair of large concrete structures such as marine structures, bridge columns and beams, and chloride-contaminated concrete. Its self-levelling, no-vibration characteristics suit narrow spaces difficult to work by hand (e.g. precast honeycomb, light rail wall repair) and can be used with cathodic protection systems.
| Packaging | 25 kg / bag |
|---|---|
| Colour | Grey |
| Coverage | 1 inch thickness: approx. 5 sq.ft / 25 kg (Actual coverage varies with substrate conditions and application thickness) |
Applications
- Large structural concrete repair (e.g. marine structures, bridge piers, bridge beams)
- Honeycomb repair of precast concrete elements (e.g. light rail walls)
- Repair of seawater or chloride-contaminated concrete
- Repair mortar compatible with cathodic protection systems
- Hard-to-reach or rebar-dense locations (pumped or poured application)
Advantages
- Self-levelling, no vibration — high flow fills all space in the formwork, expels air and avoids honeycomb, ideal for compact Hong Kong sites with dense reinforcement
- Dual expansion system — compensates shrinkage in both plastic and hardened stages, reducing crack risk
- Low alkali content — sodium oxide approx. 2.9 kg/m³ (well below the 3.0 kg/m³ limit), reducing alkali-silica reaction (ASR) risk, suitable for concrete with local river sand or reactive aggregates
- Excellent bond — bond strength to concrete substrates up to 5.4 N/mm² (slant shear test, no separate primer required)
- High strength, low permeability — 28-day compressive strength of 57 N/mm²; very low water absorption (10-minute ISAT of only 0.08 ml/m²/sec), effectively resisting chloride and CO2 ingress and preventing reinforcement corrosion
- Carbonation and salt resistance — a 50 mm layer provides a carbonation barrier equivalent to 2000 mm of concrete or 950 m of air, suited to Hong Kong's high humidity and coastal environment
- Fast hardening and high early strength — 1-day compressive strength of 19 N/mm², accelerating formwork striking and subsequent works
- Consistent premixed quality — factory batched, only water added on site, avoiding site batching errors
- Chloride-free admixtures — no chloride introduction, protecting reinforcement