Fosroc Renderoc TG
Single-component, shrinkage-compensated cementitious repair mortar engineered for vertical and overhead concrete reinstatement in hot climates — no formwork required.
What is it?
A ready-to-use, single-component trowel-grade repair mortar based on Portland cement, graded aggregates and anti-desiccation additives, requiring only the site addition of clean water.
Where is it used?
Patch repair and reinstatement of damaged or spalled reinforced concrete and masonry — vertical faces, soffits, columns, beams and parapets, especially across hot Indian climatic zones.
Why use it?
It bonds strongly to concrete, is shrinkage-compensated, has low permeability against carbon dioxide and chloride ingress, and builds to high thickness on vertical and overhead surfaces without shuttering.
How is it applied?
Mix one 25 kg bag with 4.5 litres of clean water using a forced-action mixer, prime the prepared substrate, then trowel-apply in lifts up to 70 mm on vertical and 60 mm on overhead surfaces, finish and cure.
About Fosroc Renderoc TG
Fosroc Renderoc TG is a single-component, cementitious, trowel-grade (TG) reinstatement mortar designed for the structural repair of damaged reinforced concrete and masonry. It is supplied as a factory-blended dry powder of Portland cement, graded aggregates, special fillers and chemical additives, and is modified with anti-desiccation additives so that it cures predictably in hot, dry conditions — a deliberate design choice for the Gulf and the Indian subcontinent where ambient temperatures and surface evaporation are high. Only clean water is added on site (4.5 litres per 25 kg bag), producing a cohesive, medium-weight mortar that can be hand-trowelled into prepared repair pockets without the slumping or sagging associated with wetter mixes. Renderoc TG sits in the broader Fosroc Renderoc concrete-repair family alongside Renderoc HB (hand-applied high-build), Renderoc GP (general purpose) and Renderoc RG (free-flowing micro-concrete for formed/poured repairs). Its defining strength is high-build capability on vertical faces and soffits without formwork — making it the practical workhorse for spall repair on columns, beams, slab soffits, chajjas and facades. It is shrinkage-compensated to minimise the cracking and debonding that undermine ordinary site-batched repair mortars, contains no added chlorides that could initiate fresh corrosion, and develops low permeability to resist the re-entry of carbon dioxide and chloride ions that caused the original deterioration. In an Indian context — where carbonation-induced and chloride-induced reinforcement corrosion is the dominant cause of concrete distress in coastal, industrial and ageing urban structures — Renderoc TG functions as the reprofiling layer in a complete repair system, typically used after Fosroc Dekguard or Nitoprime ZincRich primers and often paired with a fairing/protective coat. Space Arc Engineering supplies Renderoc TG as an authorised Fosroc distributor across Delhi NCR and Pan-India, with technical support on substrate preparation, system selection and curing for site teams.
The technical insight
The engineering value of Renderoc TG lies in how its constituents are balanced for hot-weather placement rather than headline strength alone. The low water demand — 4.5 litres to a 25 kg bag, a water/powder ratio around 0.18 — keeps the capillary pore structure tight, which is what gives the cured mortar its low permeability to CO2 and chlorides and its durable 50 N/mm2 compressive strength at 28 days. The anti-desiccation additives slow surface moisture loss so that, even on a hot soffit, enough water is retained for proper hydration; this is precisely where site-batched sand-cement renders fail, drying and crazing before they gain strength. Shrinkage compensation counters drying shrinkage so the patch stays bonded and uncracked at its perimeter, preserving the monolithic behaviour the repair is meant to restore. The reported slant-shear bond strength of around 25 N/mm2 at 28 days indicates the repair acts compositely with the parent concrete rather than as a detachable skin. Equally important is what it is not: Renderoc TG is a reprofiling mortar, not a structural strengthening system — it reinstates lost section and re-establishes cover and alkalinity around reinforcement, but it does not add load capacity beyond the original design. Correct results therefore depend on disciplined substrate preparation (saw-cut edges, exposed and de-rusted steel, primer applied within the open time) far more than on the mortar chemistry itself.
Where it is used
- Patch repair of spalled and delaminated reinforced concrete on columns, beams and slab soffits
- Reinstatement of concrete cover lost to carbonation- or chloride-induced reinforcement corrosion
- Vertical and overhead repairs where formwork cannot practically be erected
- Repair of honeycombing, blowholes and form-stripping defects in cast concrete
- Facade, parapet, chajja and balcony edge reinstatement on ageing buildings
- Repair of concrete in hot, high-evaporation environments across the Gulf and India
- Filling voids and defects greater than 10 mm deep in concrete and masonry
- Reprofiling within a Fosroc repair-and-protect system ahead of a protective anti-carbonation coating
Key advantages
- Single-component — only clean water added on site, reducing batching error and improving consistency
- Anti-desiccation additives make it suitable for hot, dry climatic conditions where ordinary mortars dry out
- High-build on vertical (up to ~70 mm) and overhead (up to ~60 mm) surfaces without formwork
- Shrinkage-compensated to resist cracking and edge debonding of the repair
- Low permeability provides good resistance to carbon dioxide and chloride re-ingress
- Excellent bond to a properly prepared concrete substrate, giving composite repair behaviour
- Contains no added chlorides, so it will not initiate fresh reinforcement corrosion
- Good handling and trowelling characteristics at low water content
- Part of a complete, compatible Fosroc repair-and-protection system with established primers and coatings
Limitations & considerations
- A reprofiling/repair mortar only — it does not add structural load capacity or replace strengthening systems
- Should not be applied when ambient temperature is below 5 degrees C and falling
- Must not be exposed to running water during application or before final set
- Intended for repairs greater than 10 mm deep; thin feather edges are not appropriate
- Strict water dosage required — adding extra water or using part-bags adversely affects strength and durability
- Performance depends heavily on correct substrate preparation, steel cleaning and priming
- Requires proper curing in hot conditions despite anti-desiccation additives to achieve rated properties
- Not a free-flowing mortar — for large formed or poured pours a micro-concrete such as Renderoc RG is more suitable
Selection & best practice
Mechanically break out all loose, carbonated and chloride-contaminated concrete back to sound material and saw-cut the repair perimeter to about 10 mm to avoid feather edges. Fully expose corroded reinforcement, grit-blast or wire-brush it to bright metal, and apply an anti-corrosion primer (e.g. Fosroc Nitoprime ZincRich) where required. Pre-soak the substrate to a saturated surface-dry condition and apply the recommended bonding primer within its open time. Mix a full 25 kg bag with exactly 4.5 litres of clean water in a forced-action mixer for 3-5 minutes — never gauge by eye or add extra water. Apply firmly by trowel in lifts within the stated vertical/overhead thickness limits, building up where deeper section is needed and scoring intermediate lifts for key. Finish to profile, then cure immediately and thoroughly — in Indian summer conditions protect from direct sun and wind and use Fosroc Concure curing membrane or damp hessian. For maximum durability, overcoat the completed repair with an anti-carbonation protective coating to re-establish a continuous barrier across patch and parent concrete.
Specifications
| Product type | Single-component, shrinkage-compensated trowel-grade cementitious repair mortar |
| Composition basis | Portland cement, graded aggregates, special fillers, chemical additives, anti-desiccation additives |
| Compressive strength (7 days) | 40 N/mm2 |
| Compressive strength (28 days) | 50 N/mm2 |
| Slant shear bond strength (28 days) | ~25 N/mm2 |
| Fresh wet density | 1850 kg/m3 |
| Water requirement | 4.5 litres per 25 kg bag |
| Yield | ~15.8 litres per 25 kg bag |
| Application thickness (vertical) | Up to ~70 mm |
| Application thickness (overhead) | Up to ~60 mm |
| Minimum repair depth | Greater than 10 mm |
| Initial setting time | Approximately 2-3 hours |
| Final setting time | Approximately 4-6 hours |
| Minimum application temperature | Not below 5 degrees C and falling |
| Chloride content | No added chlorides |
| Packaging | 25 kg bag |
Industry use cases
Coastal and marine structures
Reinstating chloride-damaged concrete cover on jetties, sea-facing facades and structures along India’s coastline, where the low-permeability mortar resists further chloride ingress.
Commercial and residential buildings
Repairing spalled column faces, beam edges, slab soffits, balconies and chajjas on ageing urban buildings in Delhi NCR without erecting formwork.
Industrial plants and refineries
Patch repair of corrosion-affected RCC frames, plinths and equipment foundations in chemically aggressive, high-temperature environments.
Bridges and infrastructure
Reprofiling spalled pier caps, soffits and parapets as part of a repair-and-protect cycle on highway and urban transport structures.
Water-retaining and treatment structures
Reinstating deteriorated concrete in tanks, sumps and channels (kept off running water until final set) ahead of a protective lining.
Frequently asked questions
What is Fosroc Renderoc TG used for?
How much water do I add to a 25 kg bag of Renderoc TG?
What thickness can Renderoc TG be applied at?
What is the compressive strength of Renderoc TG?
How does Renderoc TG differ from Renderoc HB, GP and RG?
Is Renderoc TG a structural strengthening product?
How we position Fosroc Renderoc TG
Renderoc TG is Fosroc’s hot-climate trowel-grade member of the Renderoc repair-mortar range and is best positioned as the everyday hand-applied reprofiling mortar for vertical and overhead concrete repair. Within the Fosroc family, choose Renderoc TG for hot-weather hand application without formwork; step up to Renderoc HB for higher single-pass build, Renderoc GP for lighter general-purpose patching, or Renderoc RG/Conbextra micro-concrete where the repair is formed and poured rather than trowelled. It is normally specified alongside Fosroc primers (Nitoprime ZincRich for steel), Concure curing membranes and an anti-carbonation protective coating such as Dekguard to complete a durable repair-and-protect system. Against competitors, Renderoc TG competes directly with Sika MonoTop and Sika Rep-grade mortars, MBS (MYK / BASF Master Builders) MasterEmaco repair mortars, Dr. Fixit Krack-X / Pidicrete repair systems, and STP (Shalimar / Choksey) repair mortars; many of these meet EN 1504-3 repair-mortar classifications, and on India-specified jobs the deciding factors are usually documented compliance, distributor technical support and a fully compatible primer-and-coating system rather than the mortar in isolation. Space Arc Engineering positions Renderoc TG honestly as a proven repair mortar — not a strengthening solution — and supports specifiers in choosing the correct grade and full system for the exposure condition.
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