Fosroc Renderoc LA90
High-performance, free-flowing low-alkali micro-concrete for deep-section structural repair and reinstatement of reinforced concrete — placed by pour or pump, self-compacting, BS EN 1504-3 Class R4.
What is it?
A single-component, cementitious, free-flowing low-alkali micro-concrete supplied as a pre-bagged dry blend that needs only the site addition of clean water. It belongs to Fosroc’s Renderoc LA family of flowable repair concretes and is engineered for high-strength, deep-section structural reinstatement.
Where is it used?
Reinstating reinforced concrete in bridges, flyovers, jetties and marine structures, water-retaining structures, industrial floors, columns, beams, pile caps and foundations — especially where reinforcement is congested, access is restricted, or the host concrete is itself a high grade.
Why use it?
It combines high compressive strength and low permeability with a dual-expansion (shrinkage-compensating) system and low alkali content, so it bonds reliably, resists chloride and carbon-dioxide ingress, protects embedded steel and resists alkali-silica reaction — all while flowing into place without vibration.
How is it applied?
Break out to a sound, square-edged substrate (minimum 25 mm depth), pre-soak, fix rigid leak-tight formwork with vents and pour/pump points, mix the bag with the specified clean water in a forced-action mixer, then pour or pump the self-compacting micro-concrete into the form and cure.
About Fosroc Renderoc LA90
Fosroc Renderoc LA90 is part of the Renderoc LA range of free-flowing, low-alkali micro-concretes used for the structural repair and rehabilitation of reinforced concrete. Like its siblings Renderoc LA and Renderoc LA60, it is supplied as a ready-to-use blend of selected hydraulic cements, graded aggregates and performance additives that require only the on-site addition of clean water to produce a pourable, shrinkage-compensated micro-concrete. The number in the name reflects its position at the high-strength end of the family: where Renderoc LA60 is matched to host concrete of roughly 30-60 N/mm2, the LA90 designation targets repairs to, and reinstatement alongside, higher-grade structural concrete. For consultants and contractors in India, this matters because modern infrastructure — metro viaducts, high-rise cores, prestressed elements and heavy industrial slabs — is frequently specified at M50 and above, and a repair material must develop comparable strength and stiffness so that load is shared properly across the patch rather than concentrating at a weak interface. The product is designed to be placed by pouring or pumping into restricted and heavily reinforced locations, where a hand-applied vertical-and-overhead mortar such as Renderoc HB cannot reach. Its self-compacting nature means it displaces air and fills around congested bars without poker vibration, eliminating the honeycombing that plagues conventional concrete in tight sections. Because it is pre-bagged, the mix avoids the batch-to-batch variation of site-gauged concrete, giving consultants a controlled, declarable performance. The low alkali content and absence of added chloride make it suitable for durability-critical and chloride-exposed environments, and it is alkaline enough to re-passivate and protect cleaned reinforcement. In short, LA90 is the flowable, high-strength member of the Renderoc family for deep, structural, durability-driven repairs.
The technical insight
The defining technology in the Renderoc LA micro-concretes is the dual-expansion system. Conventional cementitious repair materials shrink as they cure, debonding at the perimeter and cracking through the patch. LA90 counters this with additives that impart controlled expansion in both the plastic and the hardened states, so the material stays in compression against the substrate and maintains an intimate bond. Equally important is the low water demand: the family is formulated to perform at a low water:powder ratio (the verified LA60 datasheet quotes a w/p of around 0.148, roughly 3.7 litres per 25 kg bag), which is what delivers both the high strength and the low permeability that protect embedded steel. A maximum 3 mm aggregate keeps the mix flowable and able to penetrate congested cages while still behaving as a true micro-concrete rather than a mortar. Controlled heat of hydration lets the LA range be placed in genuinely thick sections — the LA60 sheet cites 25 to 300 mm — without the thermal cracking that would otherwise occur in mass pours; LA90, being the higher-strength variant, follows the same flowable, thick-section logic and the local Fosroc office should be consulted for the exact declared thickness and strength envelope of the LA90 grade. The combination of high elastic modulus, low capillary absorption and resistance to carbonation and chloride ingress is what earns the family its BS EN 1504-3 Class R4 classification — the highest structural class in that European repair standard.
Where it is used
- Deep-section reinstatement of reinforced columns, beams, pile caps and corbels where pour or pump placement is required
- Repair of bridge and flyover substructures, pier caps, abutments and crossheads in highway and metro projects
- Marine and coastal structures — jetties, wharves, sea walls and splash-zone elements exposed to chlorides
- Water-retaining and water-conveying structures such as tanks, reservoirs, treatment works and channels
- Reinstating concrete damaged by reinforcement corrosion, carbonation or alkali-silica reaction (ASR)
- Filling behind formwork around congested or doubly-reinforced cages that cannot be hand-packed
- High-strength industrial floor slab, foundation and machine-base repairs subject to heavy or dynamic loads
- Strengthening overlays and section enlargement on structural members requiring R4-grade properties
Key advantages
- Free-flowing and self-compacting — fills congested, restricted sections by pour or pump with no vibration and no honeycombing
- Dual-expansion system compensates for shrinkage in both plastic and hardened states, maintaining bond and minimising cracking
- High compressive strength and low permeability give an R4-class structural repair compatible with high-grade host concrete
- Low alkali content reduces the risk of alkali-silica reaction, suiting durability-critical and reactive-aggregate situations
- Chloride-free and alkaline — re-passivates and protects embedded steel, ideal for chloride-exposed and marine works
- Excellent bond to a sound, prepared substrate, generally without a separate bonding primer
- Pre-bagged single-component blend needing only clean water — eliminates site batching variation and simplifies QA/QC
- Controlled heat of hydration permits thick-section pours with reduced thermal-cracking risk
- Compatible with cathodic protection systems used in major rehabilitation schemes
Limitations & considerations
- Form-and-pour / pump material only — not a hand-applied trowel mortar for vertical or overhead patching (use Renderoc HB / HB40 for those)
- Requires rigid, leak-tight formwork with venting and pour/pump access; formwork design and pre-soaking are critical to success
- Should not be used to reinstate horizontal surfaces that would remain unrestrained (un-formed) during cure
- Substrate must be broken out to a minimum depth (typically 25 mm) with square edges — feather-edging must be avoided
- Strict control of water addition and mixing is essential; over-watering destroys the strength and low-permeability benefits
- Must be protected from freezing during cure and not exposed to moving water during application; hot-weather placing needs cool water and shade
- Mixing requires adequate forced-action plant and labour so a continuous pour can be maintained; part-bag mixing is not recommended
- LA90-specific numeric values (exact thickness limit, declared 28-day strength) are best confirmed against the current Fosroc India TDS for the project specification
Selection & best practice
Treat LA90 as a structural concrete, not a cosmetic patch. Break out to fully sound concrete with a saw-cut square perimeter (no feather edges) to a minimum 25 mm depth, expose and clean corroded steel to a bright condition, and apply Fosroc’s Nitoprime Zincrich or Nitoprime Zincrich Plus to cleaned bars where specified. Build rigid, well-braced, leak-tight formwork with air vents at high points and convenient pour or pump points, and pre-soak the substrate to a saturated-surface-dry condition so no mix water is drawn out of the repair. Mix only full bags with the exact clean-water quantity from the current TDS in a forced-action (not free-fall) mixer until uniform, pass through a coarse screen, and place continuously — never re-temper with extra water. Cure thoroughly with Concure curing membrane or taped polythene, protect from sun, wind, rain and frost, and finish exposed faces with a Dekguard / Nitocote protective-anti-carbonation coating to match the durability of the surrounding structure. Always validate the final thickness, strength and water dosage against the project-specific Fosroc India datasheet before issuing the method statement.
Specifications
| Material type | Single-component, free-flowing, low-alkali, shrinkage-compensated cementitious micro-concrete |
| Base composition | Selected hydraulic cements, graded aggregates and additives (dual plastic + hardened expansion) |
| Standard / class | BS EN 1504-3 Class R4 (structural repair) — Renderoc LA family classification |
| Maximum aggregate size | 3 mm (family value, to aid flow and finish) |
| Application method | Pour or pump into formwork; self-compacting, no vibration required |
| Section thickness (family) | 25 mm to 300 mm per Renderoc LA60 TDS; confirm LA90 limit with local Fosroc office |
| Water addition (family ref.) | approx. 3.7 litres clean water per 25 kg bag (w/p approx. 0.148), Renderoc LA60 TDS |
| Chloride ion content | Chloride-free / very low (<0.05%); no added chloride admixtures |
| 28-day compressive strength (family R4) | R4 requires >45 MPa; LA60 result 60 MPa @ 28 days (EN 12190) — LA90 targets the high-strength end |
| Elastic modulus | >20 GPa (EN 13412, family R4 requirement) |
| Bond / pull-off strength | >2.0 MPa required; LA60 result 3.5 MPa (EN 1542) |
| Reaction to fire | Class A1 |
| Reinforcement protection | Alkaline; protects and re-passivates embedded steel; compatible with cathodic protection |
| Pack size | Pre-bagged powder, typically 25 kg bags (confirm regional pack with Space Arc) |
Industry use cases
Bridges & Highways
Reinstating pier caps, abutments and crossheads on highway and metro viaducts where R4-grade flowable concrete and pumped placement into reinforced sections are required.
Marine & Coastal
Repairing jetties, wharves and splash-zone elements in chloride-laden environments, using the low-alkali, chloride-free formulation to protect reinforcement.
Water & Wastewater
Rehabilitating tanks, reservoirs, channels and treatment-plant structures that need low-permeability, durable, formed-and-poured repairs.
Industrial & Power
Restoring heavily-loaded machine bases, foundations, pile caps and floor slabs in plants, refineries and power stations where high strength and stiffness are essential.
Buildings & High-Rise
Deep-section repair of columns, beams and shear-wall elements in RC frames built with high-grade concrete, where flowable placement around congested rebar is needed.
Frequently asked questions
Is Fosroc Renderoc LA90 a real product?
What does the ’90’ in Renderoc LA90 mean?
How is LA90 different from Renderoc HB or Renderoc GP?
Does LA90 need a bonding primer?
What surface preparation and curing does it require?
Can Space Arc Engineering supply Renderoc LA90 in Delhi NCR and across India?
How we position Fosroc Renderoc LA90
Within Fosroc’s own concrete-repair portfolio, Renderoc LA90 is the high-strength, flowable member of the Renderoc LA micro-concrete family. Specifiers typically pair it with Renderoc LA60 for medium-grade deep repairs, Renderoc HB / HB40 for hand-applied vertical and overhead patching, and Renderoc GP for general-purpose mortar work, while completing the system with Nitoprime Zincrich (rebar primer), Conbextra grouts for under-base flow, Concure curing membranes, and Dekguard / Nitocote anti-carbonation coatings for long-term protection. Against competitors in the Indian market, the closest direct equivalents to LA90 are Sika’s MonoTop and SikaGrout / SikaRep micro-concrete repair systems, MBS (MYK) Saveto’s flowable repair micro-concretes, and Dr. Fixit’s Pidicrete / structural repair micro-concrete range from Pidilite, with STP (Shalimar) offering competing repair mortars in the same space. Sika is generally the strongest like-for-like alternative for R-class structural micro-concretes, while Dr. Fixit and STP are often more readily available and price-competitive for general repair work. The honest positioning for an Indian consultant or contractor is this: Renderoc LA90 is a strong choice where you need a verified, high-strength, low-alkali, flowable structural repair from an established global brand with full system back-up and applicator support — exactly what Space Arc provides as an authorised Fosroc distributor. Where budget dominates and the strength demand is moderate, a competing micro-concrete may suffice; where the host concrete is high grade and the repair is structurally load-bearing, durability-critical or chloride-exposed, LA90 within the full Fosroc system is the safer specification. Because published numeric data specific to the LA90 grade is limited online, always confirm the exact thickness, water dosage and declared strength against the current Fosroc India technical data sheet before finalising the specification.
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