Fosroc Renderoc LA Fiber
Fiber-reinforced, free-flowing, low-alkali micro-concrete for large-volume structural repairs in congested or restricted-access locations.
What is it?
A single-component, fiber-reinforced, free-flowing, low-alkali micro-concrete supplied as a dry pre-blended powder. It mixes with clean water on site to produce a self-compacting, shrinkage-compensated repair concrete based on Portland cement, graded aggregates, fibres and controlled-expansion additives.
Where is it used?
Reinstating large volumes of deteriorated or spalled reinforced concrete – bridge piers and crossheads, building columns and beams, jetties and marine structures, water-retaining structures, industrial floors and any repair where reinforcement is congested or access for hand placement and vibration is limited.
Why use it?
It flows into and around heavily congested rebar without vibration, fills thick sections in a single placement, resists plastic and drying shrinkage cracking through its dual expansion system and fibre reinforcement, develops high compressive strength, and protects embedded steel with an alkaline, low-chloride matrix.
How is it applied?
The substrate is prepared to a sound, saturated-surface-dry condition, formwork is fixed where required, the powder is machine-mixed with the specified water, then the mortar is poured or pumped into the prepared section and allowed to self-compact before curing.
About Fosroc Renderoc LA Fiber
Fosroc Renderoc LA Fiber belongs to the Renderoc family of concrete repair and rehabilitation products and is engineered for the situations that defeat conventional hand-applied mortars: deep, large-volume reinstatement where the steel reinforcement is densely packed or where the geometry of the repair makes it impossible to compact a stiff mortar by trowel and poker vibration. It is a factory-blended powder containing Portland cement, carefully graded aggregates, fibres and additives that impart controlled expansion in both the plastic and hardened states. On site, only the addition of clean water is needed to produce a free-flowing, self-compacting micro-concrete. Because it is self-compacting, the material displaces entrapped air and flows around the rebar cage on its own, eliminating the honeycombing and voids that plague poorly vibrated repairs. The “LA” designation reflects its low-alkali formulation, which reduces the risk of alkali-silica reaction (ASR) and makes it suitable for repairs to concrete that has itself been affected by ASR. The “Fiber” designation refers to the inclusion of reinforcing fibres that help control plastic shrinkage and micro-cracking and improve the toughness and crack resistance of the cured section. The matrix remains alkaline and contains no added chlorides, so it actively re-passivates and protects embedded steel reinforcement after repair. For Space Arc Engineering’s clients across Delhi NCR and Pan-India, Renderoc LA Fiber is the natural choice when a structural element needs to be brought back to full cross-section and durability in a single, efficient pour rather than built up in slow hand-applied layers.
The technical insight
The defining characteristic of Renderoc LA Fiber is that it is a micro-concrete, not a repair mortar – it contains coarse graded aggregate, which is why it can be placed in thick sections (the Fiber grade is suited to sections generally up to around 200 mm thick, with greater thickness achievable depending on the configuration of the repair) without the heat-of-hydration and shrinkage problems that an aggregate-free mortar would suffer at that depth. Its performance rests on three linked mechanisms. First, a dual expansion system generates controlled positive expansion while the material is still plastic and again as it hardens, offsetting both plastic settlement and drying shrinkage so the cast section stays in intimate contact with the substrate and the surrounding concrete. Second, the self-compacting rheology lets it be pumped or poured into restricted formwork and around congested reinforcement, achieving full compaction and an exceptional bond to the prepared substrate without an independent bonding primer. Third, the dispersed fibre reinforcement arrests plastic-shrinkage and early micro-cracking and adds post-crack toughness. The Renderoc LA micro-concrete platform on which this product is based typically develops in the order of 33 N/mm2 at 3 days, 45 N/mm2 at 7 days and 60 N/mm2 at 28 days compressive strength, with flexural strength of the order of 7 N/mm2 at 28 days, placing the repair concrete comfortably in the strength band of the structural concrete it reinstates. Project-specific values must always be confirmed against the current Fosroc Technical Data Sheet for the exact grade and region supplied.
Where it is used
- Large-volume structural reinstatement of spalled or delaminated reinforced concrete columns, beams and crossheads
- Repairs to bridge substructures – piers, abutments, pier caps and bearing shelves – where rebar is congested
- Marine and coastal structures such as jetties, wharves and sea walls affected by chloride-induced corrosion
- Water-retaining and water-excluding structures including tanks, reservoirs and treatment works
- Repairs to concrete affected by alkali-silica reaction (ASR) where a low-alkali reinstatement is specified
- Industrial and warehouse columns, plinths and machine bases requiring full-section restoration
- Encasement and jacketing of corroded or under-strength members where formwork can be set up
- Pour or pump placement into restricted-access voids and thick sections that cannot be vibrated by hand
Key advantages
- Free-flowing and self-compacting – fills congested rebar cages and restricted sections without vibration, eliminating honeycombing
- Can be placed in thick sections in a single pour (generally up to around 200 mm), reducing the number of repair layers and site visits
- Dual expansion system compensates for shrinkage in both the plastic and hardened states, keeping the repair bonded and crack-resistant
- Fibre reinforcement controls plastic-shrinkage cracking and improves toughness of the cured concrete
- Low-alkali formulation minimises the risk of alkali-silica reaction and suits repairs to ASR-affected concrete
- Develops high compressive strength compatible with structural parent concrete
- Exceptional bond to a properly prepared substrate without the need for a separate bonding primer
- Contains no added chlorides and remains alkaline, re-passivating and protecting embedded steel reinforcement
- Factory pre-blended – only clean water is added on site, giving consistent, repeatable quality
- Can be placed by pump for high-output or hard-to-reach repairs
Limitations & considerations
- Requires formwork (and pump or pour access) for most applications – it is not a trowel-applied patch mortar and is not suited to thin feather-edged repairs
- Minimum and maximum section thicknesses must be respected; very thin sections should use a hand-applied Renderoc mortar instead
- Substrate must be cut back to a sound, mechanically prepared, saturated-surface-dry condition and corroded steel must be cleaned and primed before placement
- Water addition must be controlled precisely – over-watering reduces strength, increases shrinkage and can cause segregation or bleeding
- Working time is limited; mixed material must be placed promptly and is temperature-sensitive in Indian summer conditions, so hot-weather precautions and prompt curing are essential
- Proper wet or membrane curing is mandatory to develop the stated strengths and durability
- As a cement-based product it is not a substitute for crack injection, structural strengthening with plates or laminates, or waterproofing where those are the primary need
- Exact grade, pack size and published values vary by region – the current local Fosroc TDS must govern specification and dosage
Selection & best practice
Saw-cut the perimeter of the repair to a minimum depth to avoid feather edges, then break out all loose, carbonated, chloride-contaminated or delaminated concrete back to a sound substrate using non-percussive or light breakers to avoid micro-cracking. Expose corroded reinforcement fully around its circumference, grit-blast or wire-brush it to bright metal to the standard required, and apply a Fosroc reinforcement primer such as Nitoprime Zincrich where specified. Bring the substrate to a saturated-surface-dry (SSD) condition and fix rigid, grout-tight, adequately braced formwork with provision to pour or pump from the lowest point upward to displace air. Machine-mix using a forced-action or pan mixer with only the specified quantity of clean water to achieve a flowing, lump-free consistency; do not retemper. Place continuously and promptly, working the material to vent trapped air, and finish to the formwork. Cure immediately and thoroughly with Fosroc Concure curing membrane, wet hessian or polythene, paying particular attention to hot and windy Indian site conditions. Always work to the current Fosroc Technical Data Sheet and method statement for the exact grade supplied, and confirm thickness, water demand and yield for your batch.
Specifications
| Product type | Fiber-reinforced, free-flowing, low-alkali micro-concrete (single-component, cement based) |
| Base | Portland cement, graded aggregates, fibres and controlled-expansion additives |
| Application method | Self-compacting – placed by pouring or pumping; no vibration required |
| Section thickness | Generally up to approx. 200 mm; greater thickness achievable depending on repair configuration |
| Shrinkage control | Dual expansion system (plastic and hardened state) plus fibre reinforcement |
| Compressive strength (Renderoc LA micro-concrete platform, indicative) | approx. >33 N/mm2 at 3 days, >45 N/mm2 at 7 days, >60 N/mm2 at 28 days |
| Flexural strength (platform, indicative) | approx. >7 N/mm2 at 28 days |
| Water demand (Renderoc LA, indicative) | approx. 3.38 litres of clean water per 25 kg bag |
| Chloride content | No added chlorides; alkaline matrix protects embedded steel |
| Bonding | Exceptional bond to prepared substrate without independent primer |
| Standard | Concrete repair to BS EN 1504-3 principles (confirm grade/class on local TDS) |
| Pack size | Typically supplied in 25 kg bags (confirm regional pack) |
| Curing | Wet cure or apply Fosroc Concure curing membrane immediately after finishing |
Industry use cases
Bridges & Highways
Reinstating chloride- and carbonation-damaged pier caps, crossheads and abutments where the reinforcement cage is dense and a vibrated mortar cannot be compacted; the self-compacting micro-concrete is pumped into formwork to restore full cross-section.
Marine & Ports
Repairing jetty beams, deck soffits and sea-wall sections suffering chloride-induced rebar corrosion, using the low-chloride, steel-protecting matrix to extend service life in aggressive coastal exposure.
Water & Wastewater
Restoring columns, beams and walls in tanks, reservoirs and treatment works where a high-strength, shrinkage-compensated, low-alkali reinstatement is needed to keep the structure watertight and durable.
Commercial & Industrial Buildings
Full-section repair and jacketing of corroded or under-strength RCC columns, plinths and machine bases in factories, warehouses and high-rise structures, often as part of a structural rehabilitation scheme.
Heritage & ASR-affected Structures
Reinstating concrete affected by alkali-silica reaction where the low-alkali formulation avoids re-triggering the reaction while returning the element to structural strength.
Frequently asked questions
What exactly is Fosroc Renderoc LA Fiber and how is it different from an ordinary repair mortar?
How thick a section can Renderoc LA Fiber be placed in?
Does it need formwork, and can it be pumped?
Why choose Renderoc LA Fiber over Renderoc RG or a hand-applied Renderoc mortar?
How should the surface be prepared before placing it?
Is it suitable for marine and water-retaining structures in India?
What pack size does it come in and how much water is added?
How we position Fosroc Renderoc LA Fiber
Renderoc LA Fiber sits at the high-flow, large-volume end of Fosroc’s concrete repair range. Within the Fosroc family it is the fiber-reinforced, low-alkali sibling of the standard Renderoc LA micro-concrete and Renderoc RG / RG(L) non-shrink micro-concretes; where you need a thinner hand-applied patch you would step across to thixotropic mortars such as Renderoc HB, and the repair is typically completed with Nitoprime Zincrich reinforcement primer and Fosroc Concure curing membrane, often within a Renderoc protective coating system. Against the wider Indian market, credible alternatives for fiber-reinforced or flowable micro-concrete repair include Sika MonoTop and SikaGrout / SikaRep micro-concretes, MBS (MBCC / Master Builders Solutions) MasterEmaco S-series repair concretes, Dr. Fixit’s Krishna / Pidicrete repair range, and STP (Shalimar / STP Limited) repair micro-concretes. Renderoc LA Fiber’s particular strengths are its combination of self-compacting flow into congested reinforcement, dual-expansion shrinkage compensation, fibre toughening and a low-alkali, low-chloride matrix – a useful specification when ASR risk or steel protection is a concern. As an authorised Fosroc distributor and applicator serving Delhi NCR and Pan-India, Space Arc Engineering supplies Renderoc LA Fiber with current technical data sheets, method statements and on-site application support, and can recommend the correct grade for your structure. Always verify the exact grade, pack size and published values against the latest Fosroc Technical Data Sheet for the product supplied to your project.
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