Fosroc Renderoc Ultra120
Free-flowing, dual-expansion microconcrete that reinstates large or reinforcement-congested concrete sections by pouring or pumping, with no vibration required.
What is it?
A pre-bagged, cementitious, free-flowing microconcrete from Fosroc’s Renderoc repair range, formulated with a dual expansion system to compensate for shrinkage and placed by pour or pump into structural concrete sections.
Where is it used?
Reinstatement of large structural concrete sections (columns, beams, soffits, bridge elements) and confined or heavily reinforced repair zones where hand- or trowel-applied mortars cannot be properly compacted.
Why use it?
Its self-compacting, fluid nature fills congested formwork and restricted cavities without vibration, eliminating honeycombing, while low permeability and shrinkage compensation deliver a durable, well-bonded repair that protects embedded steel.
How is it applied?
Mixed to a flowable consistency, then poured or pumped into prepared, saturated-surface-dry formwork around the repair area; the material flows to fill the section and self-levels without mechanical vibration.
About Fosroc Renderoc Ultra120
Fosroc Renderoc Ultra120 is a factory-blended, cement-based microconcrete engineered for the structural repair of concrete where the section to be reinstated is too large, too deep or too congested for conventional hand-applied mortars. It belongs to the well-established Renderoc concrete-repair family, but unlike the thixotropic hand-placed grades (such as Renderoc HB or Renderoc S), Ultra120 is a free-flowing material designed to be poured or pumped into formwork. Once mixed with the specified quantity of clean water, it develops a fluid, self-compacting consistency that travels around reinforcement and into restricted cavities under its own weight, displacing entrapped air without poker or external vibration. This makes it particularly valuable on Indian infrastructure and building-repair sites where access to the damaged zone is awkward, the steel cage is dense, or vibration could disturb adjacent green concrete. The “120” in the name reflects the range’s positioning as a deep-section reinstatement microconcrete, intended for substantial repair depths rather than thin skim coats. Because it arrives pre-bagged, the cement-to-aggregate ratio and admixture dosage are controlled in the factory, removing the batch-to-batch variability that plagues site-mixed sand-cement repairs. A built-in dual expansion mechanism compensates for shrinkage in both the plastic and hardened states, helping the repair stay in intimate contact with the parent concrete and resist the debonding and edge-cracking that commonly cause repairs to fail prematurely. For Space Arc Engineering’s clients across Delhi NCR and Pan-India, Renderoc Ultra120 is the natural specification choice when a structurally significant concrete element has lost section to carbonation, chloride attack, fire damage or mechanical impact and must be brought back to full profile in a single, monolithic, durable pour.
The technical insight
The defining characteristic of Renderoc Ultra120 is the combination of a flowable (non-thixotropic) rheology with a dual expansion system. Flowability is what separates a microconcrete from a hand-placed repair mortar: the material must remain cohesive enough to avoid segregation yet fluid enough to consolidate under gravity alone. To make that work in a deep section, the binder is a low-alkali cementitious system that limits the risk of alkali-silica reaction over the long service life of a structural repair, and the formulation contains no chloride-based admixtures, so it does not introduce aggressive ions to the very steel it is meant to protect. The dual expansion system is the second key idea. Ordinary cementitious repairs shrink as they cure, and that shrinkage pulls the new material away from the substrate, opening a debond plane at exactly the interface where stress and moisture concentrate. Ultra120 counteracts this in two stages: a plastic-state expansion while the mix is still workable, and a hardened-state expansion as it gains strength, so the net volume change keeps the repair pressed against the parent concrete. The result is an intimate, primer-free bond and a dense, low-permeability matrix that slows the ingress of carbon dioxide and chlorides, the two principal drivers of reinforcement corrosion. Practically, this means the engineer specifies it for full-depth reinstatement of load-bearing elements where both mechanical performance and long-term durability of the embedded steel matter, not merely cosmetic patching.
Where it is used
- Full-depth reinstatement of large structural concrete sections such as columns, beams and pier caps
- Repair of heavily reinforced or congested elements where hand-placed mortar cannot be compacted around the steel
- Pumped or poured repairs in confined, hard-to-access locations where trowel application is impractical
- Restoration of concrete lost to carbonation-induced or chloride-induced reinforcement corrosion
- Reinstatement of fire-damaged or impact-damaged structural concrete
- Repairs to bridge substructures, soffits and other infrastructure elements requiring formwork-and-pour techniques
- Re-profiling of sections where low permeability protection against CO2 and chloride ingress is required
Key advantages
- Free-flowing, self-compacting consistency consolidates under gravity with no vibration, eliminating honeycombing
- Flows around congested reinforcement and into restricted cavities that hand-applied mortars cannot reach
- Dual expansion system compensates for shrinkage in both plastic and hardened states for an intimate, lasting bond
- Develops exceptional bond to the concrete substrate without the need for a separate bonding primer
- Low alkali content minimises the risk of alkali-silica reaction over the life of the repair
- Contains no chloride admixtures, so it does not introduce corrosive ions to embedded steel
- High strength with low permeability provides strong protection against carbon dioxide and chloride ingress
- Pre-bagged factory blend removes site-batching variation and ensures consistent, repeatable performance
- Can be placed by pour or by pump, giving flexibility for difficult or elevated repair locations
Limitations & considerations
- Suited to deeper, formed/flowable repairs, not thin feather-edges or shallow patches better served by thixotropic grades like Renderoc HB or Renderoc S
- Requires formwork (or at minimum edge containment) for pour and pump placement, adding time and cost versus trowel application
- Being a flowable microconcrete, it needs a sealed, leak-tight shutter; gaps will cause loss of material and air entrapment
- Substrate must be properly prepared, sound and brought to a saturated-surface-dry condition for the bond and expansion system to perform
- As a cementitious material it is sensitive to ambient temperature and wind; hot-weather and curing precautions are essential in Indian summer conditions
- Performance depends on adding only the specified water quantity, since over-watering causes segregation, bleed and strength loss
- Verify the current regional Technical Data Sheet for exact strength, thickness and yield figures before specification, as published values vary by market and revision
Selection & best practice
Treat Renderoc Ultra120 as a formed-and-poured structural repair, not a patch. Begin by breaking out all loose, carbonated or chloride-contaminated concrete back to sound material, exposing and cleaning corroded reinforcement to bright metal and applying a Fosroc Nitozinc or Nitoprime reinforcing-steel primer where the corrosion-protection system calls for it. Saturate the prepared substrate and bring it to a saturated-surface-dry (no standing water) condition so the parent concrete does not draw mix water and the expansion system can act against a damp face. Build a clean, rigid, leak-tight shutter with a pour point and a head of material to drive flow and self-consolidation, and provide a vent at the high point so displaced air can escape. Mix mechanically with a forced-action mixer using only the water dosage stated on the current TDS, mixing until uniform and lump-free; do not retemper. Pour or pump continuously and from one side to push air ahead of the material and avoid cold joints. After placement, cure thoroughly with Fosroc Concure curing membrane or wet hessian, especially in Delhi NCR summer heat and wind, to control plastic shrinkage and develop full strength. Always confirm depth limits, water demand and curing requirements against the latest regional datasheet for the batch supplied.
Specifications
| Product type | Free-flowing, cementitious microconcrete for structural concrete repair |
| Form / placement | Self-compacting; placed by pouring or pumping (no vibration required) |
| Binder system | Low-alkali cementitious; contains no chloride admixtures |
| Shrinkage control | Dual expansion system (plastic-state and hardened-state expansion) |
| Bonding | Exceptional bond to concrete substrate without an independent primer |
| Durability | High strength with low permeability to carbon dioxide and chlorides |
| Supply form | Pre-bagged factory blend (eliminates site-batching variation) |
| Typical use depth | Deep-section reinstatement (confirm exact min/max thickness on current regional TDS) |
| Compressive / flexural strength | High structural strength (refer to current regional TDS for exact MPa values) |
Industry use cases
Infrastructure / bridges
Reinstating spalled, corrosion-damaged pier caps, abutments and soffits where pumped placement around dense reinforcement avoids the honeycombing that hand patching leaves behind.
Commercial & high-rise buildings
Full-depth repair of columns and beams in occupied structures in Delhi NCR, where a poured microconcrete restores load-bearing section without vibration disturbing adjacent elements.
Industrial plants & warehouses
Restoring chemically or mechanically degraded structural members where low permeability protects re-exposed steel from continued chloride or CO2 attack.
Water-retaining & marine structures
Section reinstatement on chloride-exposed concrete where the low-alkali, chloride-free formulation and dense matrix support long-term corrosion durability.
Repair & rehabilitation contractors
A specification-grade, pre-bagged alternative to site-batched concrete for confined or congested repairs, giving consistent results and a single-pour monolithic finish.
Frequently asked questions
What is Fosroc Renderoc Ultra120 used for?
How is Renderoc Ultra120 different from Renderoc HB or Renderoc S?
Does Renderoc Ultra120 need a bonding primer?
Does it require vibration during placement?
What thickness and strength can Renderoc Ultra120 achieve?
Is Renderoc Ultra120 suitable for repairs exposed to chlorides?
How we position Fosroc Renderoc Ultra120
Renderoc Ultra120 sits at the deep-section, flowable end of the Fosroc Renderoc concrete-repair range. Where Renderoc HB and Renderoc S handle hand-applied vertical and overhead patching, and Renderoc RG or Conbextra grouts handle precise gap and baseplate filling, Ultra120 is the choice for reinstating large, congested or hard-to-access structural sections by pour or pump. It is best used as part of a full Fosroc repair system alongside a reinforcing-steel primer (Nitozinc/Nitoprime) and a Concure curing membrane. Comparable microconcrete repair products from other manufacturers include Sika MonoTop and SikaGrout flowable repair concretes, MBS (MBCC/Master Builders) MasterEmaco S-series flowable mortars and microconcretes, Dr. Fixit’s structural repair microconcrete range, and STP (Pidilite) Zycosil/Polyalk repair systems. Space Arc Engineering recommends matching the grade to the actual repair geometry: thixotropic mortars for shallow facial patches, and a flowable microconcrete such as Renderoc Ultra120 for deep, formed, structurally significant reinstatement. As an authorised Fosroc distributor for Delhi NCR and Pan-India, Space Arc can advise on the correct grade, confirm current TDS values for your specification, and supply the complete repair system.
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