Fosroc Renderoc RG(L)
A cost-effective, free-flowing, non-shrink cementitious micro-concrete for repairing reinforced concrete in restricted, congested or hard-to-vibrate locations.
What is it?
A single-component, Portland-cement-based, non-shrink micro-concrete supplied as a dry pre-blended powder that needs only site addition of clean water to produce a free-flowing repair material placed without vibration.
Where is it used?
Reinstating damaged, spalled or honeycombed reinforced concrete in columns, beams, soffits and other congested sections where formwork access is tight and poker vibration is impractical.
Why use it?
It self-compacts into restricted voids around dense reinforcement, compensates for plastic shrinkage through a gaseous expansion system, gains strength quickly and contains no added chloride – all at a more economical price point than higher-grade micro-concretes.
How is it applied?
Saturate or prime the prepared substrate, prime exposed steel with Nitozinc Primer, mix the bag with 4.5-4.75 litres of clean water, then pour or pump into slurry-tight formwork from one side; cure immediately after striking.
About Fosroc Renderoc RG(L)
Fosroc Renderoc RG(L) is a general-purpose, non-shrink, cementitious micro-concrete engineered for the economical repair of damaged reinforced concrete. It belongs to Fosroc’s well-established Renderoc family of concrete repair materials, sitting alongside flowable grades such as Renderoc RG and the high-performance Renderoc HF/HB hand-applied mortars. The “(L)” designation indicates the lighter-duty, value-engineered fluid grade – it delivers the same self-levelling, pour-and-pump convenience as premium micro-concretes but is positioned for repairs where ultimate strengths and the most demanding durability targets are not the governing requirement.
The material arrives as a ready-to-use blend of dry powder based on Portland cement, graded fillers and performance additives. On site, only clean water is added to produce a free-flowing micro-concrete. The additive package gives controlled expansion in the plastic state through a gaseous expansion system, which counteracts the shrinkage and settlement that would otherwise leave voids behind formwork and at the repair interface. Because it is pre-bagged, it removes the batch-to-batch variability that plagues site-mixed sand-cement repairs and saves the labour of proportioning aggregate, cement and admixture by hand.
For Indian site conditions – congested seismic detailing, restricted urban access, repairs to flyover piers, water-retaining structures and industrial frames – Renderoc RG(L) is a practical workhorse. It flows around dense reinforcement and self-compacts without poker vibration, which is exactly what is needed in soffits, narrow column jackets and honeycombed zones where a vibrator simply cannot reach. For sections deeper than 100 mm, it is designed to be extended on site with 5-12 mm clean graded saturated-surface-dry aggregate to bulk the volume and control the heat of hydration in large pours. Space Arc Engineering supplies Renderoc RG(L) as an authorised Fosroc distributor across Delhi NCR and Pan-India, along with the companion primers and curing compounds needed for a complete, warrantable repair system.
The technical insight
The defining feature of Renderoc RG(L) is its low water demand combined with a gaseous (plastic-state) expansion system rather than the iron-based oxidising expanders found in older grouts. Fosroc’s published properties are measured at a water:powder ratio of just 0.19 at 30 degrees C, which corresponds to roughly 4.5-4.75 litres of water per 25 kg bag. Keeping the water content this low is what underpins the early strength (about 8 N/mm2 at one day) and the long-term durability – excess water is the single biggest enemy of permeability and shrinkage in cementitious repairs, so the formulation is built to flow freely without the bleed and segregation that extra water would cause. The gaseous expansion of 1-4% (unrestrained) develops while the mix is still plastic, generating a gentle restraining pressure of roughly 0.004 N/mm2 that pushes the material into full contact with the substrate and reinforcement, eliminating settlement gaps before the concrete sets. Critically, because the expansion mechanism contains no metallic aggregate and the product carries no added chloride, it avoids the corrosion and staining risks associated with iron-filling expanders. A coefficient of thermal expansion of 10-12 x 10 to the minus 6 per degree C is deliberately matched to that of host structural concrete, so the repair and the parent member move together under temperature swings instead of debonding at the interface – a thermal compatibility that is essential for the patch to behave monolithically over the service life.
Where it is used
- Reinstating spalled, delaminated or carbonation-damaged reinforced concrete columns, beams and slab soffits
- Filling honeycombs, voids and segregation defects left by poor original compaction
- Repairing congested, heavily reinforced sections where poker/internal vibration is impossible
- Concrete jacketing and encasement build-ups for structural strengthening
- Pouring or pumping repairs into restricted-access locations such as narrow column jackets and confined soffits
- Crack and defect filling in structural members where a flowable, self-compacting material is required
- Large-volume repairs when extended on site with 5-12 mm graded aggregate
Key advantages
- Free-flowing and self-compacting – places into restricted, congested sections without vibration
- Gaseous expansion system compensates for plastic shrinkage and settlement, ensuring full contact with substrate and steel
- Pre-bagged single-component powder eliminates site-batching variations and reduces labour
- Rapid early strength (about 8 N/mm2 at 1 day) allows early formwork striking and reinstatement
- Low water demand delivers low permeability and good long-term durability
- Contains no added chloride and no metallic aggregate, protecting embedded reinforcement
- Can be pumped or poured, suiting both small patches and larger formed repairs
- Economical grade – lower cost than premium micro-concretes for less demanding repairs
- Coefficient of thermal expansion matched to host concrete for monolithic behaviour
Limitations & considerations
- Single-lift application depth limited to 100 mm; deeper sections need site-added 5-12 mm aggregate to control heat of hydration
- Lower ultimate strengths (about 35 N/mm2 at 28 days) than premium micro-concretes – not ideal where high-grade structural concrete must be matched
- Requires slurry-tight formwork with feed hoppers and air vents; not a trowel-applied patch repair
- Strict water control needed – exceeding 4.75 litres per 25 kg bag compromises strength, expansion and durability
- Cement-based material requires immediate and thorough curing to avoid drying-shrinkage cracking
- Requires reinforcement priming (Nitozinc Primer) and substrate saturation or epoxy bond-coat priming for full performance
- Short 6-month shelf life and sensitivity to high temperature/humidity during storage
- Performance values are quoted at 30 degrees C; cold or very hot weather working needs adjusted procedures
Selection & best practice
Cut back defective concrete to a sound base and mechanically roughen smooth surfaces. Expose corroded reinforcement around its full circumference, grit-blast to bright metal, and apply Nitozinc Primer (a second coat if the film is discontinuous). Saturate the substrate with clean water for several hours and remove free surface water before placing, or alternatively prime the dry substrate with Nitobond EP epoxy bond aid. Erect slurry-tight formwork coated with Reebol release agent, with a feed hopper at the highest point and air vents to prevent entrapment. Machine-mix each 25 kg bag with 4.5-4.75 litres of clean water (never exceed 4.75 litres) in a forced-action mixer or with a 400-500 rpm paddle for 5 minutes to a smooth consistency; where coarse aggregate is specified, add it after the powder and water are mixed and continue for one more minute. Place immediately, pouring or pumping from one side only to avoid air entrapment. In cold conditions down to 15 degrees C use warm water up to 30 degrees C; above 35 degrees C store in shade and mix with cold water. Cure immediately after striking formwork using Nitobond AR or a Concure curing compound, supplemented by wet hessian and polythene in harsh drying conditions.
Specifications
| Material type | Single-component, non-shrink, free-flowing cementitious micro-concrete |
| Base composition | Portland cement, graded fillers and additives with gaseous (plastic-state) expansion system |
| Water:Powder ratio (test basis) | 0.19 at 30 deg C |
| Water demand | 4.5 – 4.75 litres per 25 kg bag (max 4.75 litres) |
| Compressive strength – 1 day | 8 N/mm2 (at 30 deg C) |
| Compressive strength – 7 days | 25 N/mm2 (at 30 deg C) |
| Compressive strength – 28 days | 35 N/mm2 (at 30 deg C) |
| Flexural strength | 3 N/mm2 at 28 days |
| Young’s Modulus | 22 kN/mm2 |
| Unrestrained expansion | 1 to 4% |
| Plastic expansion restraining pressure | Approx. 0.004 N/mm2 |
| Coefficient of thermal expansion | 10 – 12 x 10^-6 per deg C |
| Fresh wet density | 2100 – 2200 kg/m3 |
| Maximum single-lift depth | Up to 100 mm (deeper with 5-12 mm aggregate added) |
| Site-added aggregate (large repairs) | 5-12 mm graded SSD aggregate, 50-100% by weight of powder |
| Yield | Approx. 13.5 litres per 25 kg bag |
| Chloride content | No added chloride; no metallic aggregate |
| Packaging | 25 kg bags |
| Shelf life | 6 months in dry store, original unopened bags |
| Flammability | Non-flammable |
Industry use cases
Infrastructure & Bridges
Reinstating spalled cover concrete and honeycombing on flyover piers, abutments and pier caps where reinforcement is congested and access for vibration is restricted.
Commercial & Residential Buildings
Repairing carbonation-damaged columns, beams and slab soffits in ageing RCC frames, and reinstating sections after reinforcement corrosion treatment.
Water & Wastewater Structures
Patching honeycombs and defects in tanks, sumps and treatment structures using a chloride-free, low-permeability material compatible with the host concrete.
Industrial Plants
Restoring damaged structural concrete in factories, warehouses and process buildings where downtime must be minimised by rapid early strength gain.
Structural Strengthening
Forming concrete jackets and encasement build-ups around existing columns and beams to upgrade load capacity, poured into slim formwork without vibration.
Precast & Construction Defect Rectification
Filling segregation voids and form defects in cast-in-situ and precast elements where a flowable, self-compacting repair is needed.
Frequently asked questions
What is Fosroc Renderoc RG(L) used for?
How much water do I add per 25 kg bag?
What thickness can Renderoc RG(L) be applied in?
How is Renderoc RG(L) different from standard Renderoc RG?
Does Renderoc RG(L) need formwork and curing?
Is it safe for reinforced concrete and does it contain chloride?
What is the shelf life and packaging?
How we position Fosroc Renderoc RG(L)
Within the Fosroc range, Renderoc RG(L) is the economical, general-purpose flowable micro-concrete – choose it for routine repairs and jacketing where self-compaction matters but ultimate strength is not critical. Step up to Fosroc Renderoc RG, Renderoc RG65 or other high-grade micro-concretes when the repair must match high-strength structural concrete or meet stricter durability criteria; use trowel-applied Renderoc HB/HF/GP mortars for vertical and overhead patch repairs that cannot be formed. Companion Fosroc products complete the system: Nitozinc Primer for reinforcement, Nitobond EP/AR as bond aids, and the Concure range for curing. Against the wider Indian market, it competes with Sika MonoTop and SikaGrout micro-concretes, MBCC/Master Builders Solutions (MasterEmaco) flowable repair concretes, Dr. Fixit Pidicrete/Krishna micro-concrete repair systems, and STP (Sika-owned) repair ranges. The honest case for Renderoc RG(L) is value: where a project needs a proven, branded, non-shrink flowable repair material for less demanding structural concrete – and the contractor wants pre-bagged consistency without paying premium-grade prices – it is a sound specification, provided the limited 35 N/mm2 28-day strength and 100 mm single-lift depth suit the application.
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