Fosroc Renderoc LA80
Single-component, free-flowing, low-alkali high-strength micro-concrete for large-volume and reinforcement-congested structural concrete repairs — placed by pouring or pumping, no vibration required.
What is it?
A pre-bagged, single-component, free-flowing low-alkali micro-concrete (flowable structural repair mortar) from Fosroc that reaches over 80 N/mm² compressive strength at 28 days and only needs clean site water to mix.
Where is it used?
Large-volume structural concrete repairs where access is restricted or reinforcement is congested — bridge piers and pier caps, columns, beam soffits, jetties, water-retaining structures, industrial floors and basements across Delhi NCR and Pan-India.
Why use it?
Its self-compacting, flowable nature fills around dense rebar and into formed pockets without vibration, while a dual-expansion system compensates for shrinkage and low permeability protects the steel against carbonation and chloride attack.
How is it applied?
Saturate and prime the prepared substrate, fix leak-tight formwork, then mix one full 25 kg bag with the specified clean water and pour or pump it into the form in a continuous operation, finishing with proper curing.
About Fosroc Renderoc LA80
Fosroc Renderoc LA80 is a high-strength member of the Renderoc LA (Low Alkali) micro-concrete family, engineered for situations where a conventional hand- or trowel-applied repair mortar simply cannot be placed. It arrives on site as a ready-blended bag of dry powders; the only site addition permitted is clean water, which removes the batching variability that plagues site-mixed concrete. Once mixed it behaves as a free-flowing, self-compacting micro-concrete that can be poured or pumped into formwork and will flow around congested reinforcement and into deep, awkward sections without any need for poker vibration. For Indian repair contractors working on heavily reinforced bridge and marine elements, this is the practical difference between a sound, void-free reinstatement and a honeycombed one. The “80” in the name denotes its headline performance: a 28-day compressive strength in excess of 80 N/mm², placing it among the higher-strength flowable repair products in the range and making it well suited to load-bearing structural members rather than cosmetic patching. Like the wider Renderoc LA family, it is formulated with low alkali content to minimise the risk of alkali-silica reaction (ASR), incorporates a dual-expansion system to compensate for shrinkage in both the plastic and hardened states, and contains no chloride admixtures, so it does not introduce aggressive ions into the repaired element. Its dense, low-permeability matrix resists the ingress of carbon dioxide, chloride ions, oxygen and water — the four agents most responsible for reinforcement corrosion in Indian conditions — helping the repair last rather than re-spalling within a few monsoons. The product is supplied in 25 kg bags and is part of Fosroc’s BS EN 1504-3 concrete-repair system, which Space Arc Engineering supplies and applies as an authorised Fosroc distributor and applicator across Delhi NCR and Pan-India, typically alongside the matching Nitobond bonding aids, Nitoprime/Nitozinc steel primers and Dekguard/Nitocote protective coatings that complete a code-compliant repair build-up.
The technical insight
Renderoc LA80 is a cement-based micro-concrete — chemically it is graded aggregate plus a low-alkali Portland cement binder, expansive agents and flow-modifying admixtures, distinct from the polymer-modified or epoxy systems used for thin patching. Its defining property is rheology: a controlled-flow, self-compacting consistency that lets it be poured or pumped and consolidate under its own weight, eliminating honeycombing without vibration even behind dense rebar. The dual-expansion mechanism is the key durability feature — a gaseous/plastic-state expansion offsets settlement and a hardened-state crystalline expansion offsets drying shrinkage, so the cast repair stays in intimate, stress-free contact with the parent concrete and develops exceptional bond without an independent bonding bridge in most cases. Because flowable micro-concretes are placed at thicker sections than trowel mortars, a strict design rule applies: always use a full 25 kg bag with the exact, datasheet-specified clean-water addition — part-bagging or extra water collapses the flow control, depresses strength and voids the Fosroc guarantee. The low-permeability, low-alkali matrix (initial water absorption and DIN 1048 permeability are tightly controlled in the family) is what gives the long-term chloride and CO2 resistance that matters for rebar protection. The LA80 grade conforms to BS EN 1504-3 as a Class R4 structural repair product and is applicable to repair principles/methods 3.2, 4.4, 7.1 and 7.2 of the standard.
Where it is used
- Reinstatement of large, heavily reinforced structural concrete sections where access is restricted
- Repair of bridge piers, pier caps, abutments, crash barriers and beam soffits
- Marine and coastal structures — jetties, sea walls, wharves and piles exposed to chlorides
- Columns, beams and shear walls in buildings requiring high-strength structural reinstatement
- Water-retaining and water-excluding structures such as tanks, reservoirs and treatment plants
- Industrial floors, machine bases and basements where deep, formed pours are needed
- Repairs to concrete damaged by alkali-silica reaction (ASR) or chloride-induced corrosion
- Encasement and reinstatement of corroded reinforcement after exposure and treatment
Key advantages
- Free-flowing, self-compacting consistency fills around congested reinforcement and into deep sections without vibration
- High 28-day compressive strength in excess of 80 N/mm² suited to load-bearing structural members
- Dual-expansion system compensates for shrinkage in both plastic and hardened states, maintaining bond
- Low alkali content minimises the risk of alkali-silica reaction (ASR)
- Low permeability gives strong resistance to carbon dioxide and chloride ingress, protecting embedded steel
- Exceptional bond to concrete substrates, generally without an independent primer
- Pre-bagged single component — only clean site water required, removing batching variability
- Contains no chloride admixtures, so no aggressive ions are introduced into the repair
- Can be placed by pumping or pouring, ideal for restricted-access locations
- Conforms to BS EN 1504-3 Class R4 for structural concrete repair
Limitations & considerations
- Must be placed into leak-tight formwork — it is a flowable pour, not a trowel-applied or overhead-buildable mortar
- Always mix a full 25 kg bag with the exact specified water; part-bagging or extra water reduces strength and voids the guarantee
- Minimum section thickness must be respected — flowable micro-concretes are not intended for thin (a few millimetre) skim repairs; use Renderoc HB/S or a polymer mortar for those
- Should not be applied when ambient temperature is below 5 C and falling
- Must not be exposed to running water during application or before final set, and water ponding is not recommended for curing
- Requires sound surface preparation, saturated-surface-dry substrate and proper curing to achieve datasheet performance
- Shelf life is limited (about 12 months in cool dry storage, much less in high heat/humidity), so stock must be rotated
- Higher material cost than ordinary site concrete or a sand-cement render — specify it where its flow and durability are genuinely needed
Selection & best practice
Break out all defective and carbonated/chloride-contaminated concrete back to a sound, mechanically roughened substrate and saw-cut the perimeter to avoid feather edges. Expose corroded reinforcement fully around its circumference, grit-blast or wire-brush it to bright steel, and apply a Fosroc Nitozinc/Nitoprime ZR steel primer. Pre-soak the prepared concrete to a saturated-surface-dry (SSD) condition. Fix rigid, grout-tight, well-braced formwork with a head box or pour point and an air-release/overflow point so the micro-concrete can flow and fully displace air. Mix each full 25 kg bag with the exact clean water stated on the current TDS using a forced-action or slow-speed drill mixer until uniform and lump-free, and pour or pump continuously from one point to avoid cold joints and entrapped air. Do not vibrate. Cure immediately and thoroughly with Fosroc Concure curing membrane or wet hessian and polythene, and protect from running water, direct sun and wind until set. For section depths, mixing water, lift sequence and high- or low-temperature working, follow the project-specific Fosroc method statement and confirm current figures against the latest LA80 datasheet before ordering.
Specifications
| Product type | Single-component, free-flowing, low-alkali, high-strength micro-concrete (flowable structural repair) |
| Base chemistry | Cement-based, pre-blended graded aggregate with dual-expansion system; no chloride admixtures |
| 28-day compressive strength | Greater than 80 N/mm² (the ’80’ designation) |
| Application thickness | Approx. 10 mm to 100 mm per lift (Renderoc LA family up to ~150 mm depending on repair geometry) |
| Standard / classification | BS EN 1504-3, Class R4 (structural); repair methods 3.2, 4.4, 7.1, 7.2 |
| Flexural strength (Renderoc LA family reference) | Greater than 7 N/mm² at 28 days |
| Tensile strength (Renderoc LA family reference) | Greater than 5 N/mm² at 28 days |
| Permeability (DIN 1048, family reference) | Less than 10 mm |
| Placement method | Poured or pumped into formwork; self-compacting, no vibration required |
| Mixing | Clean site water only; use a full bag — no part-bagging or extra water |
| Yield | Approx. 12 litres per 25 kg bag |
| Pack size | 25 kg bag |
| Minimum application temperature | Do not apply below 5 C and falling |
| Shelf life | 12 months in cool, dry, unopened storage (reduced in high heat/humidity) |
Industry use cases
Bridges & Highways
Reinstating spalled, chloride-attacked pier caps, abutments and crash barriers on NHAI and state-highway structures where reinforcement is dense and a high-strength, durable pour is required.
Marine & Ports
Repairing jetty beams, wharf decks and piles in coastal Gujarat, Maharashtra and the eastern seaboard, where low permeability and chloride resistance directly extend service life.
Water & Wastewater
Restoring structural sections of overhead tanks, clarifiers, reservoirs and treatment-plant walls, using a low-alkali, no-chloride micro-concrete compatible with water-retaining duty.
Commercial & Industrial Buildings
High-strength structural reinstatement of columns, beams and shear walls in ageing RCC buildings, basements and parking structures across Delhi NCR during rehabilitation works.
Industrial Plants
Repair and encasement of machine foundations, equipment plinths and floor slabs in cement, power and process plants where deep formed pours and early strength gain matter.
Frequently asked questions
What exactly is Fosroc Renderoc LA80 and how is it different from a normal repair mortar?
What thickness can Renderoc LA80 be applied at?
Does it need a bonding primer or a bonding coat?
How much water do I add and why is the dosage so strict?
Is Renderoc LA80 suitable for marine and chloride-exposed structures?
How many bags will I need and what is the yield?
How is it different from Renderoc LA or LA55, and what are the alternatives?
How we position Fosroc Renderoc LA80
Within Fosroc’s BS EN 1504-3 concrete-repair system, Renderoc LA80 sits at the high-strength, flowable end of the Renderoc LA (Low Alkali) micro-concrete family — above standard Renderoc LA (~60 N/mm²) and LA55, and used where the designer calls for a Class R4 structural pour around congested steel. On a typical Space Arc repair build-up it is paired with Fosroc Nitozinc or Nitoprime ZR for reinforcement priming, Nitobond EP/AR where a bonding bridge is specified, Renderoc HB or S for the hand-applied trowel work it cannot do, and Dekguard or Nitocote anti-carbonation coatings to protect the finished repair; where a non-flowable cavity grout is needed instead, Conbextra micro-concrete grouts are the companion choice. For procurement teams comparing brands, credible alternatives in India include Sika (SikaGrout and MonoTop micro-concretes), MBS/MYK Laticrete, Dr. Fixit (Pidilite) and STP repair-concrete ranges — broadly equivalent on paper but differing in admixture package, EN 1504-3 classification and local technical support. Space Arc Engineering’s value as an authorised Fosroc distributor and applicator is matching the right grade to the structural specification, supplying genuine stock with current datasheets across Delhi NCR and Pan-India, and backing it with method statements and applicator support so the repair is both code-compliant and durable. Always confirm the latest LA80 datasheet figures and Fosroc method statement before finalising a specification or order.
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