Fosroc Renderoc RSXtra
A pour-and-go, self-compacting repair concrete that lets you patch a carriageway or bridge deck at night and reopen it to traffic by morning.
What is it?
A single-component, rapid-setting, polymer-modified repair concrete supplied as a factory blend of powders and graded aggregates that you mix with clean water on site.
Where is it used?
Horizontal concrete that has to go back into service fast: highway and city carriageways, bridge decks and expansion-joint nosings, airport aprons and taxiways, industrial floors and precast yards.
Why use it?
It reaches roughly 15 N/mm2 in about 3 hours and takes pedestrian and vehicular traffic after around 4 hours at 25 degrees C, so repairs happen inside a single traffic block instead of a multi-day lane closure.
How is it applied?
Prepare and saturate the substrate, mix the bag with the specified clean water to a flowing consistency, then pour it into the prepared pocket where it self-compacts without vibration or rodding.
About Fosroc Renderoc RSXtra
Renderoc RSXtra is Fosroc’s answer to a very specific pressure faced by every roads engineer and infrastructure contractor in India: how do you repair a spalled carriageway, a broken bridge-joint nosing or a damaged apron slab when the asset simply cannot stay closed. It arrives as a single-component dry blend of cements, rapid-hardening binders, polymers and graded aggregates in a 25 kg bag. Only the site addition of clean water is permitted, which removes the guesswork of batching separate liquids and keeps the mix consistent from one bag to the next. Once gauged, it becomes a free-flowing, self-compacting repair concrete that finds its own level in the repair pocket and consolidates around reinforcement without poker vibration.
What sets it apart from an ordinary patch is the strength-versus-time curve. The cured repair develops around 15 N/mm2 in roughly three hours, about 30 N/mm2 by one day and around 45 N/mm2 at 28 days at 25 degrees C, and it will carry pedestrian and vehicular loads after approximately four hours. For a night-shift crew working under a rolling lane closure, that window is the whole point: excavate and prime in the evening, pour before midnight, and hand the lane back before the morning peak. Because it is thermally compatible with the surrounding concrete and offers good water-repellent behaviour, the repair behaves as part of the parent slab rather than a hard, brittle plug that debonds at the arris under wheel loads.
The technical insight
The performance comes from a rapid-hardening binder system that generates usable strength within hours rather than the day or more a conventional Portland-based repair mortar needs. The polymer modification does two jobs at once: it improves adhesion to the saturated substrate so the repair grips the prepared concrete, and it reduces water demand and permeability so the hardened matrix resists the ingress of water and chlorides that drive corrosion. The graded aggregate skeleton and self-compacting rheology are what make it a repair concrete rather than a mortar. Gauged to a flowing consistency, the mix has enough mobility to encapsulate rebar and fill deep, irregular pockets while still holding its aggregate in suspension, so it consolidates under its own weight and eliminates the honeycombing that manual compaction leaves behind. Matching the thermal expansion of the surrounding concrete keeps interface stresses low through daily heating and cooling cycles, which is what stops the classic pattern of a strong-but-incompatible patch cracking around its edges and lifting.
Where it is used
- Emergency reinstatement of spalled or delaminated highway and city-road carriageways
- Repair of bridge deck slabs and reprofiling of expansion-joint nosings and arrises
- Runway, taxiway and apron slab repairs at airports where downtime is measured in hours
- Fast-track patching of heavy-duty industrial and warehouse floor slabs
- Making good defects and damage in precast concrete units at the casting yard
- Reinstatement around drainage gullies, manhole frames and road ironwork
- Repair of loading bays, ramps and hardstandings subject to early trafficking
- General horizontal concrete repairs where self-compaction into deep pockets is needed
Key advantages
- Reopens repairs to pedestrian and vehicular traffic in about 4 hours at 25 degrees C, shrinking lane-closure windows
- Single-component: only clean water is added on site, so batching stays consistent and error-free
- Self-compacting flow fills deep and congested pockets without vibration, avoiding honeycombing
- High early strength of around 15 N/mm2 at 3 hours with about 45 N/mm2 at 28 days
- Thermally compatible with the parent concrete, keeping interface stresses low and resisting edge cracking
- Good water-repellent character helps resist water and chloride ingress into the repair
- Supplied ready-blended in 25 kg bags for predictable yield and simple site logistics
- Suited to both internal and external horizontal repairs across roads, bridges and industrial floors
Limitations & considerations
- Formulated for horizontal, pourable repairs; it is not a hand-applied mortar for vertical or overhead sections
- Fast set means very short working time, so mixing must be sized to what the crew can place immediately
- High-temperature site conditions accelerate setting further and can require pre-cooled mixing water and careful planning
- Overwatering to extend flow will reduce strength and durability and must be avoided
- Requires correct saturated-surface-dry substrate preparation and, where specified, a compatible primer for full bond
- Because it gains strength through hydration, curing discipline still matters despite the rapid early set
Selection & best practice
Success with RSXtra is decided before the bag is opened. Break out all loose and unsound concrete back to a sound, roughened substrate, expose and clean any corroded reinforcement, and prepare the edges as a clean saw-cut or square arris rather than a feather edge. Saturate the substrate to a saturated-surface-dry condition so the parent concrete does not rob the mix of gauging water. Because the working time is short, stage everything first: pre-position the prepared pocket, formwork or edge dams, water, mixing gear and the crew, then mix only the quantity that can be poured at once using the manufacturer’s specified clean water addition and a forced-action mixer. Pour continuously and let the material self-compact; do not over-trowel or add water to stiffening material. In hot Indian site conditions, pour during cooler hours, keep bags shaded, and consider pre-cooled water to preserve the working window. Protect and cure the fresh surface promptly, and hold off on any protective coating or overlay until the repair has stabilised sufficiently for the system being applied.
Specifications
| Product type | Rapid-setting, polymer-modified, self-compacting cementitious repair concrete |
| Composition | Single-component factory blend of powders and graded aggregates; add clean water only |
| Compressive strength (3 hours, 25 C) | Approx. 15 N/mm2 |
| Compressive strength (1 day, 25 C) | Approx. 30 N/mm2 |
| Compressive strength (28 days, 25 C) | Approx. 45 N/mm2 |
| Return to traffic | Pedestrian and vehicular after approx. 4 hours at 25 C |
| Placement | Poured and self-compacting; no vibration required |
| Pack size | 25 kg bag |
| Use | Internal and external horizontal concrete repairs |
Industry use cases
Highways & Roads
Night-shift reinstatement of spalled carriageway slabs and potholes under a rolling closure, with the lane handed back before the morning peak.
Bridges & Infrastructure
Repair of deck slabs and rebuilding of expansion-joint nosings where the deck must carry traffic again within the same shift.
Airports
Rapid patching of runway, taxiway and apron slabs during short maintenance windows between aircraft movements.
Industrial Flooring
Fast-track repair of heavy-duty factory and warehouse floors and loading bays so forklift and vehicle traffic resumes the same day.
Precast Yards
Making good cast-in defects and handling damage on precast units without holding up the production line.
Frequently asked questions
How soon can we open a RSXtra repair to traffic?
Is Renderoc RSXtra a mortar or a concrete?
Do we need to add anything besides water?
What thickness and volume can it be poured at?
Can it be used for vertical or overhead repairs?
How is it supplied and how much do we order?
How we position Fosroc Renderoc RSXtra
Renderoc RSXtra sits at the rapid, horizontal end of Fosroc’s Renderoc concrete-repair range, chosen specifically when the asset has to reopen to traffic within hours. Where the repair is a vertical face, soffit or reprofiling job that must be hand-placed, Fosroc Renderoc HS Xtra is the natural partner; for high-early-strength trowel-applied patch repairs, Renderoc RG covers fast-track work that does not need a pour. For deep structural voids and rebar encasement, Fosroc’s free-flow micro-concretes in the Renderoc RG family are the companion products. Substrate preparation and protection are completed with matching Fosroc systems such as Nitobond bonding aids and Nitoprime primers, with Dekguard or Nitocote protective coatings over the finished repair once it has cured. As an authorised distributor and applicator across Delhi NCR and Pan-India, Space Arc Engineering can also advise where a comparable rapid repair concrete from Sika, MC-Bauchemie or Master Builders Solutions may better fit a client’s approved-vendor list or a particular specification.
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