About Fosroc Renderoc RG(M)

Fosroc Renderoc RG(M) is the medium/high-strength member of Fosroc’s Renderoc RG family of fluid micro-concretes, engineered specifically for situations where conventional hand-applied repair mortars or vibrated concrete simply cannot reach. It is supplied as a ready-to-use blend of Portland cement, graded fillers and performance additives; only clean water is added on site to produce a highly flowable, shrinkage-compensated micro-concrete. The “M” denotes its position between the general-purpose RG(L)/RG(S) grades and heavier engineered grades, offering a strong balance of flow, high strength and economy for mainstream Indian structural repair work. In Delhi NCR, Mumbai, Bengaluru, Chennai and across Pan-India, ageing RCC infrastructure – flyovers, water-retaining structures, jetties, industrial floors and high-rise frames – frequently suffers carbonation- and chloride-induced corrosion, spalling and section loss. Renderoc RG(M) addresses these by restoring full cross-section in deep, congested zones where placing and compacting normal concrete is impractical. The material’s controlled gaseous expansion in the plastic state offsets the settlement and drying shrinkage that would otherwise leave voids behind reinforcement or at the top of a repair, ensuring intimate, full contact with the parent concrete and the steel. Because it is pre-bagged, the cement-to-aggregate ratio and additive dosage are factory-controlled, removing the inconsistency of site-batched grout and giving specifiers and PMC engineers a repeatable, certifiable repair. It contains no added chlorides, so it does not introduce a corrosion risk into the very reinforcement it is meant to protect. For larger or deeper pours, the powder can be extended on site with 5 mm to 12 mm clean, saturated-surface-dry graded aggregate, turning the micro-concrete into a true repair concrete for high-volume reinstatement. As an authorised Fosroc distributor, Space Arc Engineering supplies genuine, batch-traceable Renderoc RG(M) together with the full Fosroc repair system – Nitozinc / Galvashield primers, Nitobond bonding aids and Dekguard / Nitocote protective coatings – so the repair is delivered as a complete, warrantable solution rather than a single product in isolation.

The technical insight

The defining technical feature of Renderoc RG(M) is its dual-phase volume stability. In the plastic state a gaseous expansion system generates a controlled, unrestrained expansion of roughly 1 to 4 percent, counteracting plastic settlement and bleed so the micro-concrete maintains positive contact with the substrate and the underside of congested rebar – the zones where ordinary repair concrete typically traps voids. Equally important is the low water demand: the additive package allows full flow at a tight water:powder ratio, and the datasheet is explicit that the water:powder ratio must NOT be increased under any circumstances. Holding to this low w/p is what delivers both the high early strength (of the order of 24 N/mm2 at 24 hours) and the low long-term permeability that protects embedded steel. The fluidity is self-levelling: the material is designed to be poured or pumped and to consolidate under its own weight with no mechanical vibration, which is precisely why it suits restricted-access and heavily-reinforced repairs. For deep sections the design philosophy shifts from “mortar” to “concrete” – extending with 5-12 mm graded SSD aggregate not only increases yield but reduces heat of hydration and shrinkage in thick lifts. The application limit (sections up to about 100 mm in a single placement, more with aggregate extension and proper detailing) reflects this thermal/shrinkage control rather than a strength ceiling.

Where it is used

• Reinstatement of spalled and delaminated reinforced concrete columns, beams and slabs where steel is congested
• Pour-and-pump repairs to restricted-access locations such as soffits, narrow voids and behind dense reinforcement
• Encasement, jacketing and section enlargement of RCC members for structural strengthening
• Pile-head (pile-top) cropping, repair and encapsulation as part of a waterproofing system
• Repair of bridge and flyover substructures, abutments, piers and crash-barrier bases
• Reinstatement of marine and water-retaining structures – jetties, intake structures, water tanks and treatment plants
• Tunnel lining and shaft repairs where vibration of placed material is impractical
• Filling of large honeycombs, form-tie pockets and construction defects in fresh RCC

Key advantages

• Free-flowing and self-compacting – places into congested, restricted sections with no vibration
• Gaseous expansion system compensates for plastic shrinkage and settlement, ensuring full contact with substrate and steel
• High early and ultimate compressive strength (about 24 N/mm2 at 24 h, around 65 N/mm2 at 28 days) for rapid reinstatement
• Pre-bagged single component – eliminates site-batching variation and gives consistent, certifiable quality
• Contains no added chlorides – safe for use against embedded reinforcement
• Low permeability for long-term durability and protection of repaired steel
• Can be pumped or poured, and extended with 5-12 mm aggregate for deep or high-volume repairs
• Part of a complete Fosroc repair and protection system (primers, bond aids, curing and anti-carbonation coatings)

Limitations & considerations

• Requires robust, watertight formwork with a pour head and air vents – it is a flowable system, not a trowel-applied mortar
• Single-lift placement is generally limited to about 100 mm deep; deeper sections need aggregate extension and staged pours
• Water:powder ratio is fixed and must not be increased – over-watering destroys strength and the expansion system
• Substrate must be saturated surface dry and steel must be cleaned and primed before placement
• Not a cosmetic skim or fairing coat – feather edges and very thin sections should use a polymer-modified Renderoc mortar instead
• High-strength cementitious system; early strength gain and working time are temperature-sensitive in hot Indian site conditions
• Performance depends on correct surface preparation, priming, curing and an anti-carbonation top coat for full design life

Selection & best practice

Specifications

Industry use cases

How we position Fosroc Renderoc RG(M)

Renderoc RG(M) sits in the mid-to-high-strength band of Fosroc’s flowable micro-concrete range. Below it, Renderoc RG(L)/RG(S) are the economical general-purpose grades for lighter, lower-strength repairs; above and alongside it, engineered Fosroc grades (and Conbextra micro-concrete / grout products) serve very high-strength or precision-grout applications. For thin, hand-applied or feather-edge repairs, polymer-modified Renderoc mortars (e.g. Renderoc HB/FC) are the better fit, with RG(M) reserved for full-section, flowable reinstatement. Against competitors, RG(M) competes directly with Sika MonoTop / SikaGrout micro-concretes, MBS (MYK / Saint-Gobain Weber) repair micro-concretes, Dr. Fixit’s structural repair micro-concrete range, and STP (Pidilite) flowable repair systems. Its strongest argument in India is the maturity of the surrounding Fosroc system – matching primers (Nitozinc, Galvashield), bond aids (Nitobond), curing (Concure) and anti-carbonation coatings (Dekguard, Nitocote) – which lets a specifier deliver a single-source, warrantable repair rather than mixing brands. Specifiers choosing on price alone may prefer RG(L) or a competing economy micro-concrete; those prioritising high strength, full-system compatibility and consistent factory-batched quality typically standardise on the Renderoc RG(M) grade. Space Arc helps select the correct grade against the actual structural requirement rather than defaulting to the most-marketed product.

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