Fosroc Renderoc RG 65
Free-flow, high-strength, non-shrink cementitious micro-concrete for structural reinstatement of damaged RCC — placed without vibration in congested, restricted-access repairs.
What is it?
A single-component, pre-packed cementitious micro-concrete from Fosroc’s Renderoc RG series. It is a free-flowing, shrinkage-compensated repair concrete that needs only site addition of clean water, engineered to flow into congested reinforcement and restricted sections without vibration.
Where is it used?
Structural concrete repair and rehabilitation across India — column and beam jacketing, pier and foundation reinstatement, pile-top encapsulation, encasement build-ups, honeycomb filling and repairs to bridge decks, water-retaining structures and industrial RCC.
Why use it?
It restores load-bearing capacity where access is too tight to vibrate ordinary concrete, gains strength rapidly for early reinstatement, contains no chloride, and uses a gaseous expansion system to compensate for plastic shrinkage and settlement so the repair stays in intimate contact with the parent concrete and steel.
How is it applied?
Cut back defective concrete to a sound base, grit-blast and prime exposed steel with Nitozinc Primer, fix slurry-tight formwork with a feed hopper, pre-soak the substrate (or prime with Nitobond EP), machine-mix the powder with clean water and pour or pump from one side to avoid air entrapment, then cure with a Concure compound or wet hessian.
About Fosroc Renderoc RG 65
Fosroc Renderoc RG 65 belongs to the Renderoc RG family of flowable micro-concretes that Fosroc developed for situations where conventional concrete simply cannot be placed — narrow gaps between dense reinforcement, the underside of soffits, deep pockets and pile heads where a poker vibrator will not reach. It arrives on site as a factory-blended dry powder in moisture-resistant bags; the contractor adds only clean water in a controlled water-to-powder ratio to produce a self-levelling, pourable micro-concrete. Because the blend is pre-batched at the factory, the strength and expansion behaviour are consistent from bag to bag, removing the site-batching variation that plagues hand-mixed repair concrete. The “RG 65” suffix identifies the high-strength grade within the series, intended for structural reinstatement work where the repair must carry significant load. Like the rest of the RG range, it is built on Portland cement, graded aggregates and fillers, with admixtures that drive a gaseous expansion in the plastic state and keep water demand low. In the Indian market the RG range is one of the most widely specified micro-concretes for jacketing and pile-cap work, and Space Arc Engineering supplies it as an authorised Fosroc distributor across Delhi NCR and Pan-India, with technical guidance on substrate preparation, priming and curing.
The technical insight
The defining chemistry of Renderoc RG 65 is its gaseous (gas-generating) expansion system rather than a metallic or oxidising aggregate. As the fresh micro-concrete sets, a controlled volume of gas is liberated, producing an unrestrained plastic-state expansion of roughly 1 to 4 percent (assessed to ASTM C827). This pre-set expansion offsets the natural plastic shrinkage and settlement of cementitious material, so the hardened repair fills the formwork completely and locks against the prepared substrate and reinforcement instead of pulling away — the same mechanism that makes the product reliable for sealing pile tops as part of a waterproofing system. Because the expansion is gas-based, there are no metallic aggregates and therefore no iron-staining or chloride-driven corrosion risk, a genuine advantage in coastal and high-humidity Indian environments. The second engineering lever is a very low water demand: the powder chemistry lets the mix flow at a water:powder ratio in the region of 0.16, which is far lower than a comparable site-batched flowing concrete. Low water content is what simultaneously delivers rapid early strength, high ultimate strength and the low permeability that protects the embedded steel long term. For deep pours beyond about 100 mm the heat of hydration becomes the limiting factor, so the system is designed to be extended with clean, graded 5–12 mm saturated-surface-dry aggregate at site to bulk out the section and control temperature rise.
Where it is used
- Reinstatement of structurally damaged RCC columns, beams and piers by full-section jacketing
- Pile-top (pile-head) trimming, encapsulation and reinstatement as part of a waterproofing system
- Encasement build-ups and structural strengthening of distressed concrete members
- Filling of honeycombed, segregated or void-affected concrete where vibration is impossible
- Repair of bridge piers, abutments, decks and other infrastructure subject to load
- Reinstatement around congested reinforcement where access prevents conventional concreting
- Foundation, pile-cap and plinth repairs in coastal and high-humidity zones requiring chloride-free repair
- Deep-section repairs (extended with 5–12 mm graded aggregate) on industrial and marine structures
Key advantages
- Free-flowing and self-levelling — places into restricted, congested sections without vibration
- Gaseous expansion system compensates for plastic shrinkage and settlement, keeping the repair bonded to the substrate
- Factory pre-packed blend eliminates site-batching variation for consistent strength and quality
- Rapid early strength gain allows early formwork striking and faster reinstatement
- High ultimate compressive strength suited to load-bearing structural repair
- Low water demand gives low permeability and good long-term durability protection to embedded steel
- Contains no chloride admixture and no metallic aggregate — safe for corrosion-sensitive and coastal works
- Can be pumped or poured, and extended with graded aggregate for larger or deeper repairs
- Supports pile-top integrity as part of a waterproofing system
Limitations & considerations
- Application depth is generally limited to about 100 mm per pour; deeper sections need extension with 5–12 mm graded aggregate to control heat of hydration
- Requires slurry-tight, well-engineered formwork with feed hoppers and air vents — formwork failure or leakage compromises the pour
- Strict control of the water:powder ratio is essential; exceeding the maximum water dosage reduces strength and durability
- Reinforcement must be grit-blasted and primed (e.g. Nitozinc Primer) and the substrate pre-soaked or epoxy-primed for the repair to perform
- As a cement-based material it demands immediate, thorough curing after striking; harsh Indian drying conditions need supplementary wet curing
- Not a thin-section or feather-edge patch repair material — trowel-applied Renderoc mortars are more appropriate for shallow work
- Limited working time once mixed; placing must be continuous, so mixing capacity and labour must be planned in advance
- Cement powder releases alkali when wet — gloves, eye protection and dust masks are required during handling
Selection & best practice
Treat the repair as a system, not just a pour. Saw-cut the perimeter of the defective area to a square edge, break out to a sound base, mechanically roughen smooth surfaces, and expose corroded steel around its full circumference; grit-blast the bars bright and apply Nitozinc Primer (a second coat over any discontinuity). Build slurry-tight formwork with a feed hopper at the highest point and air vents to release trapped air, and coat it with Reebol release agent. Pre-soak the substrate for several hours, then remove free standing water immediately before placing — or prime a dry substrate with Nitobond EP. Mix only in a forced-action mixer or high-torque drill paddle at the correct, measured water dosage (never exceed the maximum), and pour or pump from one side only to push air ahead of the flow. For sections deeper than 100 mm, extend with clean 5–12 mm SSD aggregate to limit temperature rise. Cure immediately on striking with a Fosroc Concure curing compound, backed by wet hessian and polythene in hot, dry weather. In summer above 35°C store bags in shade and mix with cold water; in cold conditions use warm water up to 30°C to maintain strength development.
Specifications
| Material type | Single-component cementitious micro-concrete (Portland cement, graded aggregates, fillers, expansion admixtures) |
| Consistency | Free-flowing / self-levelling; pourable or pumpable without vibration |
| Expansion system | Gaseous expansion (no metallic aggregate) |
| Unrestrained expansion | 1 to 4% (ASTM C827:1987) |
| Compressive strength (Renderoc RG family, BS 4551:1980, 70.7 mm cubes) | ~10 N/mm² at 1 day, ~40 N/mm² at 7 days, ~50 N/mm² at 28 days |
| Flexural strength | Not less than 5 N/mm² at 28 days (BS 4551:1980) |
| Tensile strength | ~2.0 N/mm² at 28 days |
| Young’s modulus | ~25 kN/mm² |
| Coefficient of thermal expansion | 10–12 × 10⁻⁶ /°C |
| Fresh wet density | 2100–2200 kg/m³ |
| Chloride content | Nil — contains no chloride admixture |
| Maximum application depth | Up to ~100 mm per pour (extend with 5–12 mm graded aggregate for deeper sections) |
| Packaging | 25 kg moisture-resistant bags |
| Shelf life | 6 months in original unopened bags, dry storage |
| Recommended primers | Nitozinc Primer (steel); Nitobond EP (substrate, dry); Concure range (curing) |
Industry use cases
Building structural rehabilitation
Jacketing of corrosion- or load-distressed RCC columns and beams in ageing residential and commercial buildings across Delhi NCR, restoring section and load capacity where dense links prevent vibrated concrete.
Marine & port infrastructure
Chloride-free reinstatement of pile heads, pile caps and splash-zone members on jetties and coastal structures, where the no-metallic-aggregate formulation avoids accelerating reinforcement corrosion.
Bridges & highways
Repair of bridge piers, abutments and bearing seats where flowable micro-concrete can be pumped into formwork around congested reinforcement without site batching.
Industrial & power plants
Encasement build-ups, machine-foundation and plinth reinstatement in factories and power stations needing high early strength to minimise plant downtime.
Water-retaining & sewerage structures
Reinstatement of distressed concrete in tanks, sumps and treatment works where low permeability and shrinkage compensation help maintain water-tightness.
Piling & foundation contractors
Pile-top trimming and encapsulation as part of a basement or raft waterproofing system, using the plastic expansion to seal the pile-to-cap interface.
Frequently asked questions
What exactly is Fosroc Renderoc RG 65?
How is Renderoc RG 65 different from a normal repair mortar?
What thickness or depth can be repaired in one pour?
Does it contain chlorides or metallic aggregate?
What strength does it achieve?
How much water do I add and how is it mixed?
Can Space Arc supply Renderoc RG 65 across India?
How we position Fosroc Renderoc RG 65
Within Fosroc’s own range, Renderoc RG 65 sits at the high-strength end of the micro-concrete family: choose Renderoc RG(L) for economical, general-purpose flowable repairs, RG(S)/RG(M) for intermediate grades, and RG 65 where the structural repair must carry higher loads or where pile-top integrity within a waterproofing system matters. It pairs with companion Fosroc products — Nitozinc Primer for steel, Nitobond EP as a bonding aid, Renderoc trowel mortars for shallow patching, and the Concure curing range. Against competitors, it competes directly with Sika’s MonoTop and SikaGrout micro-concrete repair systems, MBS (MasterEmaco / formerly BASF) flowable repair concretes, Dr. Fixit’s Pidicrete / micro-concrete repair range, and STP (Shalimar) structural repair products. Renderoc RG 65’s differentiators in the Indian market are the gaseous (non-metallic, chloride-free) expansion system, consistent factory pre-batching, and Fosroc’s well-established site-support network. For very shallow patches a trowel mortar is more economical, and for free-flowing cementitious grouting under base plates Fosroc Conbextra grouts are the correct choice rather than a micro-concrete. Space Arc Engineering advises on the right grade and companion system for each application and supplies the full Fosroc repair range Pan-India.
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