Fosroc Renderoc RG(S)
General-purpose, non-shrink cementitious micro-concrete for pour-and-pump repairs to reinforced concrete where vibration is impossible.
What is it?
A single-component, pre-bagged, flowable micro-concrete that needs only site addition of clean water to produce a non-shrink, free-flowing repair concrete for reinforced sections.
Where is it used?
Restricted-access concrete repairs across India – beam soffits, column jackets/encasements, pile heads, bridge bearings and congested reinforcement zones where a poker vibrator cannot reach.
Why use it?
It self-levels and self-compacts into formwork without vibration, while a gaseous expansion system compensates for plastic shrinkage and settlement, giving full bond and dense, low-permeability repairs.
How is it applied?
Mix 4.5-4.75 L water per 25 kg bag in a forced-action mixer or paddle drill, prime steel with Nitozinc Primer and the substrate with Nitobond EP, then pour or pump into slurry-tight formwork from one side and cure with Concure.
About Fosroc Renderoc RG(S)
Fosroc Renderoc RG(S) belongs to the Renderoc family of concrete repair materials and is the flowable, formwork-placed member used when a repair cannot be hand-applied. It is supplied as a ready-to-use blend of Portland cements, graded aggregates, fillers and expansion-controlling additives. On site, the only addition permitted is clean water (and, for deep pours, approved coarse aggregate), which keeps the mix consistent and removes the batching variation that plagues site-mixed concrete. The “RG” denotes the free-flowing micro-concrete grade, and the “(S)” designation distinguishes it within the RG range supplied in the Indian market alongside RG(M) and RG(L). For Indian repair contractors, RG(S) is the go-to choice for medium-section structural reinstatement where the geometry is congested and vibration is either dangerous or simply not feasible. Because it is pre-packed and chloride-free, it suits durability-critical structures such as bridges, jetties, water-retaining tanks and industrial frames. The product is positioned as a structural micro-concrete rather than a cosmetic render: it develops genuine load-bearing strength (45 N/mm² at 28 days) and a coefficient of thermal expansion close to that of the parent concrete, so the repair and host move together through Indian temperature swings rather than debonding. Space Arc Engineering supplies Renderoc RG(S) as an authorised Fosroc distributor with technical support across Delhi NCR and Pan-India, including guidance on Nitozinc Primer, Nitobond EP and Concure curing compounds that complete the specified repair system.”
The technical insight
The defining feature of Renderoc RG(S) is its gaseous (controlled-expansion) system, which generates a slight in-situ expansion of roughly 1 to 4% in the plastic state. This is critical for poured repairs: ordinary concrete shrinks and settles as it stiffens, leaving voids and a debonded interface at the top of a beam soffit or behind a column face. The expansion offsets that plastic settlement, so the micro-concrete stays in intimate contact with the prepared substrate and the reinforcement, eliminating the honeycombing that vibration would normally cure. The formulation deliberately minimises water demand – the published properties are quoted at a water:powder ratio of just 0.19, and Fosroc is explicit that W/P must never be increased – because a low water content is what simultaneously delivers high early strength (10 N/mm² in 24 hours), low permeability and long-term durability. For sections deeper than 100 mm, the heat of hydration becomes the limiting factor; RG(S) is therefore designed to be extended with 5-12 mm clean, silt-free, saturated-surface-dry aggregate to reduce binder content per litre and control temperature rise, which paradoxically can raise strengths (up to ~50 N/mm² at 28 days in the aggregate-extended mix).
Where it is used
- Repairing damaged reinforced concrete beams, columns and slabs where access is restricted
- Column and beam encasement build-ups for structural strengthening and load upgrades
- Pile head and pile cap reinstatement, including ensuring pile-top integrity
- Repair of congested, heavily reinforced sections where poker vibration is impossible
- Soffit and overhead repairs poured into formwork with air-venting provision
- Bridge substructure, pier and bearing-shelf repairs requiring durable, low-permeability concrete
- Reinstatement of water-retaining and marine structures (chloride-free formulation)
- Filling and re-profiling of formed sections up to 100 mm deep in a single pour
Key advantages
- Highly fluid – self-levels and self-compacts into formwork with no vibration
- Gaseous expansion system compensates for plastic-state shrinkage and settlement
- Pre-bagged blend eliminates site-batching variation and guarantees consistency
- Rapid strength gain (10 N/mm² at 1 day) for early reinstatement and faster turnaround
- High ultimate strength (45 N/mm² at 28 days) and low permeability for durable repairs
- Contains no chloride admixture – safe for reinforced and prestressed concrete
- Can be poured or pumped into deep, restricted or overhead locations
- Coefficient of thermal expansion close to host concrete, minimising differential movement
- Extendable with 5-12 mm aggregate for deep pours and heat control
Limitations & considerations
- Maximum 100 mm depth per pour unless extended with approved coarse aggregate
- Requires slurry-tight, rigid formwork able to resist hydraulic pressure – adds time and cost
- Water:powder ratio fixed at max 4.75 L/25 kg bag; over-watering severely weakens the repair and is prohibited
- Needs full system priming – Nitozinc Primer on steel and Nitobond EP on substrate – to perform as specified
- Deep, large-volume pours generate heat of hydration and may need aggregate extension to avoid thermal cracking
- Cement-based and alkaline when wet; demands prompt and thorough curing or it will surface-craze in Indian heat
- Six-month shelf life, reduced further by high temperature or humidity – not for long stockpiling
- Forced-action mixing and continuous placing logistics are essential; not suited to small intermittent hand patches (use a trowel-grade Renderoc instead)
Selection & best practice
Cut back defective concrete to a sound base and mechanically roughen smooth surfaces. Expose corroded steel around its full circumference, grit-blast to a bright finish, and apply one coat of Nitozinc Primer (add a second coat over any pinholes). Pre-soak the substrate for several hours, remove free water, or alternatively prime the dry substrate with Nitobond EP. Erect slurry-tight formwork coated with Reebol release agent, with a feed hopper at the highest point and air vents at high points/soffits. Mix only 4.5-4.75 L of clean water per 25 kg bag in a forced-action mixer for 5 minutes – never exceed 4.75 L. Pour or pump immediately, feeding from one side only to avoid trapping air, and prime pump lines with cement slurry first. For sections over 100 mm, blend in 5-12 mm saturated-surface-dry silt-free aggregate to control heat. Strip formwork and cure at once with Nitobond AR or a Concure compound, backed by wet hessian/polythene in harsh drying conditions. In ambient above 35°C, store bags in shade and mix with cold water; below 15°C use warm water up to 30°C.
Specifications
| Material type | Single-component, non-shrink cementitious flowable micro-concrete |
| Base | Portland cements, graded aggregates, fillers and expansion additives |
| Compressive strength (1 day) | 10 N/mm² at W/P 0.19, 30°C |
| Compressive strength (3 days) | 27 N/mm² at W/P 0.19, 30°C |
| Compressive strength (7 days) | 35 N/mm² at W/P 0.19, 30°C |
| Compressive strength (28 days) | 45 N/mm² at W/P 0.19, 30°C |
| Tensile strength | 2.0 N/mm² at 28 days |
| Flexural strength | 5 N/mm² at 28 days |
| Young’s Modulus | 24 kN/mm² |
| Expansion characteristics | 1 to 4% (plastic state) |
| Coefficient of thermal expansion | 11 x 10⁻⁶ /°C |
| Thermal conductivity | 1.04 W/m°C |
| Fresh wet density | 2170 kg/m³ |
| Water:powder ratio | 0.19 (4.5-4.75 L per 25 kg bag, max 4.75 L) |
| Maximum application depth | Up to 100 mm per pour (deeper with added 5-12 mm aggregate) |
| Chloride content | Contains no chloride admixture |
| Yield | Approximately 13.7 litres per 25 kg bag |
| Packaging | 25 kg bags |
| Shelf life | 6 months in dry, unopened original bags |
Industry use cases
Bridges & Infrastructure
Reinstatement of distressed pier caps, bearing shelves and beam soffits on highway and rail bridges, poured into formwork where traffic loading and congested reinforcement rule out vibration.
Marine & Water Structures
Repair of jetty beams, sea-water intake structures and water-retaining tanks where the chloride-free, low-permeability micro-concrete resists further reinforcement corrosion.
Industrial & Power Plants
Encasement build-ups and column-base repairs in factories, cement plants and power stations where structures must be strengthened and returned to service quickly.
Piling & Foundations
Pile head and pile cap reinstatement to ensure pile-top integrity before capping beams are cast, in deep restricted pours.
Commercial & High-Rise Buildings
Structural repair of corrosion-damaged columns and beams in ageing RCC frames across Delhi NCR, where formed flowable repair restores section without disrupting occupied floors.
Frequently asked questions
What is Fosroc Renderoc RG(S) used for?
How deep can Renderoc RG(S) be applied in one pour?
How much water does Renderoc RG(S) need per bag?
What strength does Renderoc RG(S) achieve?
Does it need priming and special formwork?
Is Renderoc RG(S) chloride-free and safe for reinforced concrete?
How we position Fosroc Renderoc RG(S)
Renderoc RG(S) is the formwork-poured, flowable repair grade within the Fosroc Renderoc system – choose it over hand-applied Renderoc HB / Renderoc Plug / Renderoc S when the section is deep, congested or overhead and cannot be trowelled or vibrated. Within the flowable range it sits between sibling grades such as Renderoc RG(M) and Renderoc RG(L), which differ in aggregate grading and pour depth; for pure cavity grouting under base plates use Conbextra GP2 instead. The companion system products are Nitozinc Primer (rebar protection), Nitobond EP (bonding aid) and the Concure curing compounds. Compared with competitor micro-concretes – Sika MonoTop / SikaGrout, MBS (MYK Schomburg) repair micro-concretes, Dr. Fixit Krystaline/Pidicrete repair range and STP (Sika-owned legacy) systems – Renderoc RG(S) competes on its proven gaseous expansion system, India-wide technical support and an established track record on infrastructure projects. Specifiers cross-evaluating brands should match grade-for-grade on compressive strength, expansion class, chloride content and maximum pour depth rather than on price alone. Space Arc Engineering supplies the complete Fosroc repair system with site support across Delhi NCR and Pan-India.
Related Concrete Repair products
Source Fosroc Renderoc RG(S) for your project
Authorised distribution, technical advice & professional application across Delhi NCR and Pan-India.