Fosroc Renderoc LA55

Product Overview

Renderoc LA55 is a ready-to-use blend of dry powders requiring only the site addition of clean water to produce a free-flowing, shrinkage-compensated micro-concrete suitable for large-volume concrete repairs at substantial thicknesses. Based on Portland cement, graded aggregates, and additives that impart controlled expansion in both plastic and hardened states while minimising water demand. Low alkali content minimises alkali-silica reaction risk. The hardened product exhibits excellent thermal compatibility with concrete and outstanding water-repellent properties. Aggregate grading is designed for uniform mixing and to eliminate segregation under pumping pressures. Low water requirement ensures fast strength gain and long-term durability.

Features

• Dual Expansion Shrinkage Compensation — Compensates for shrinkage in both plastic and hardened states, reducing cracking risk
• Low Alkali Formula — Low alkali content minimises risk of alkali-silica reaction (ASR)
• Bonds Without Primer — Exceptional bond to concrete substrates without independent primer
• Pumpable and Pourable — Suitable for placement by pumping or pouring into restricted locations
• Self-Compacting — Eliminates honeycombing and displaces air without vibration
• High Strength, Low Permeability — High compressive strength combined with extremely low permeability for maximum carbonation and chloride protection
• Single Component — Pre-bagged to overcome site-batched variations, just add water
• No Chloride Admixtures — Will not contribute to reinforcement corrosion
• Chemical Resistant — Cured micro-concrete is highly impermeable to acid gases, chloride ions, oxygen, and water

Applications

• Large Structural Repairs — Marine structures, bridge columns and beams, major concrete reinstatement
• Restricted Access Locations — Small or confined areas where hand-and-trowel application is impractical (e.g. honeycombing in precast segments)
• Salt Water Damage — Repair of concrete contaminated by salt water
• Rail Infrastructure — Light railway wall repairs and station structures
• Cathodic Protection Systems — Repair mortar compatible with cathodic protection
• ASR Prevention — Structures requiring minimised alkali-silica reaction risk

Certifications

• Conforms to UK Department of Transport Standard BD27/86, Clause 4 for materials for repair of concrete highway structures (per manufacturer)
• Conforms to DTp Specification for Highway Works, Clause 1704.6 for control of alkali-silica reaction (per manufacturer)
• Complies with UK Water Fittings Bye-laws Scheme Tests of Effect on Water Quality (per manufacturer)

Application Guide

• Formwork Preparation — Erect rigid, sealed formwork with provision for pouring access, drainage, and air venting
• Surface Preparation — Saw-cut repair edges to avoid feathering; remove dust, oil, rust, and unsound material
• Steel Priming — Apply Nitoprime Zincrich (WB) anti-corrosion primer to exposed reinforcement
• Substrate Saturation — Saturate prepared substrate with clean water several hours before placing; drain excess before pouring
• Mixing — Use forced-action mixer; free-fall mixers must not be used; never mix part bags
• Placing — Place promptly after mixing to benefit from full fluidity and expansion; can be pumped
• Curing — After formwork removal, soak with clean water and spray with curing membrane (e.g. Concure WB)
• Protective Coating — Recommend Dekguard anti-carbonation coatings for surrounding areas

Packaging

25KG bag (single-component pre-blended powder, just add water)

Notes

• Do not use when the temperature is below 5 degrees and falling
• Do not mix part bags
• Do not use for horizontal areas where the surface remains unrestrained during curing
• Do not expose to moving water during application
• Mixing instructions must be strictly followed, particularly water quantity and mixing time
• Shelf life of 12 months in original unopened bags stored in dry conditions (per manufacturer)
• Wear protective gloves, eye protection, and respiratory equipment during application
• For detailed application methods, coverage rates, and technical parameters, refer to the official product data sheet

FAQ

What is the difference between Renderoc LA55 and GP?

LA55 is a self-levelling micro-concrete with high fluidity, placed by pouring or pumping, designed for large-volume deep repairs (typically at substantial thicknesses). GP is a medium-weight hand-applied mortar placed by gloved hand or trowel, suitable for general-purpose repairs at moderate thicknesses. Use LA55 for major structural repairs; use GP for general localised patching.

Does Renderoc LA55 need vibration?

No. LA55's self-compacting nature automatically displaces air and fills the formwork without vibration. This is one of its key advantages, making it particularly suitable for repairs around dense reinforcement and in confined spaces.

Does Renderoc LA55 need a primer?

Under normal conditions, the substrate only needs to be saturated with clean water — no independent primer is required. LA55 achieves exceptional bond directly to pre-soaked concrete substrates. Epoxy bonding aid is only needed in special circumstances such as where a substrate barrier is required.

How much does Renderoc LA55 cost?

Please contact us via WhatsApp for the latest pricing. We offer in-store pickup in Mong Kok and delivery across Hong Kong.