STP ShaliFix FRM 50
A single-component, non-shrink, polymer-modified fibre-reinforced mortar that leaves a smooth, low-rebound finish on the very repairs people actually see.
What is it?
STP ShaliFix FRM 50 (formerly FRM 90) is a ready-mix, single-component, polymer-modified repair mortar reinforced with polypropylene fibres, formulated to trowel down to a smooth, paint-ready face.
Where is it used?
On visible vertical and overhead concrete — facades, columns, soffits, precast panels and bridge elements — where the finished repair has to blend into the surrounding surface.
Why use it?
It combines structural-grade strength and shrinkage compensation with a fine, low-rebound finish, so you get a durable patch that does not telegraph through paint or coatings.
How is it applied?
Mix with clean water to a lump-free thixotropic consistency, then apply by trowel (or spray) in lifts of roughly 12 to 50 mm, no primer or formwork needed on a properly prepared substrate.
About STP ShaliFix FRM 50
STP ShaliFix FRM 50 sits in a very specific slot in the concrete-repair toolkit. Most patch-repair mortars are chosen purely for strength and build thickness; this one is chosen when the repair also has to look right afterwards. It is a single-component, polymer-modified, fibre-reinforced dry powder that you gauge on site with clean water alone. The polymer content improves adhesion and lowers water demand, the polypropylene fibres control plastic and drying micro-cracking, and the mix is engineered to be shrinkage-compensated so the finished patch stays dimensionally stable rather than pulling away at the edges. What sets FRM 50 apart from its siblings is the surface it leaves: a smooth, closed, low-rebound finish that takes exterior masonry paint or an anti-carbonation coating cleanly once cured.
For a distributor-applicator working across Delhi NCR and the wider country, that finish quality is the practical selling point. On a facade, a column in a lobby, or a bridge pier that the public sees, a coarse structural mortar means a second skim coat and a second visit; FRM 50 lets the crew reinstate section and dress the surface in largely the same operation. Because it is thixotropic and holds its shape on vertical and overhead work without slump, and because it needs no separate bonding primer on a sound, saturated-surface-dry substrate, it keeps the repair sequence short. It is best understood as the appearance-critical member of the STP ShaliFix FRM family — reached for where a repair blend-in appearance genuinely matters rather than where raw build thickness is the only concern.
The technical insight
The mortar works on three linked mechanisms. First, the polymer disperses through the cement matrix and forms a continuous film as the mix cures; this film raises tensile bond to the parent concrete (pull-off adhesion above 1.5 MPa) and cuts permeability, which is what lets the patch resist chloride and sulphate ingress instead of becoming the weak point in the element. Second, the polypropylene fibres bridge the mortar internally, arresting the shrinkage micro-cracks that would otherwise open as free water leaves the mix, so the shrinkage compensation is both chemical and mechanical. Third, the particle grading and low water demand are tuned so the mortar stays cohesive and low-rebound during placement yet closes to a smooth face under the trowel. That last point is the real difference from a general high-build mortar: the same rheology that keeps material on an overhead soffit also lets it be dressed flat, which is why the finished repair can usually be overcoated without a separate fairing skim.
Where it is used
- Smooth-finish patch repair of RC columns, beams and walls in occupied or public-facing buildings
- Facade and architectural concrete reinstatement where the repair must blend into the surrounding surface before painting
- Overhead soffit and beam-underside repairs that need to hold shape without slump or formwork
- Surface repair of precast concrete panels and elements ahead of coating
- Bridge, flyover and pier concrete repair where finished appearance and durability both matter
- Reinstatement of spalled cover concrete over treated reinforcement
- Preparing repaired RC surfaces to receive anti-carbonation or exterior masonry coatings
- Making good honeycombed or form-marked concrete on visible structural faces
Key advantages
- Smooth, low-rebound finish that is paint-ready and reduces the need for a separate skim coat
- Single-component — only clean water is added on site, so batching errors are minimal
- Non-shrink and dual shrinkage-compensated, keeping the patch dimensionally stable and crack-resistant
- Polypropylene fibre reinforcement controls micro-cracking and improves cohesion
- Thixotropic consistency allows vertical and overhead application without formwork
- No separate bonding primer required on a sound, saturated-surface-dry substrate
- Low rebound cuts material wastage during trowel or spray application
- Overcoatable with exterior masonry paint or anti-carbonation coatings after full cure
Limitations & considerations
- It is a repair mortar, not a structural grout — it is not intended for deep load-transfer voids or gap filling under baseplates
- Build thickness per lift is bounded; sections beyond the recommended range must be built up in layers with correct inter-layer timing
- Bond and finish depend heavily on surface preparation — loose, laitance-covered or contaminated concrete will compromise adhesion
- Ambient and substrate temperature must sit within the working window; hot, dry or windy conditions demand active curing to avoid surface crazing
- Corroded reinforcement must be cleaned and primed separately before patching — the mortar alone does not arrest active rebar corrosion
- Working time is limited once gauged, so only mix what the crew can place and finish within the pot life
Selection & best practice
Get the substrate right first — remove all loose and delaminated concrete, cut the repair edges square to about 10 mm depth to avoid feather-edging, and expose a keyed, clean aggregate surface by grit or high-pressure water blasting. Where rebar is corroded, cut back to at least 20 mm behind the bar, grit-blast off corrosion products and prime with a rebar primer from the same STP family before mortaring. Pre-wet the prepared area to a saturated-surface-dry condition. Gauge FRM 50 with clean water at the manufacturer’s ratio and mix mechanically to a lump-free, thixotropic consistency; let it stand briefly to release entrapped air, then remix. Apply firmly to squeeze out air voids at the bond line, build up in lifts within the recommended thickness range, and dress to a smooth face as it stiffens. Cure properly — moist curing or a curing membrane — and allow the full 28-day cure before applying decorative or protective coatings.
Specifications
| Product type | Single-component, polymer-modified, fibre-reinforced smooth repair mortar |
| Physical form | Grey ready-mix dry powder |
| Reinforcement | Polypropylene fibres |
| Compressive strength (28 days) | >35 MPa |
| Flexural strength (28 days) | Above 6 MPa |
| Bond / pull-off adhesion | >1.5 MPa |
| Recommended thickness range | 12–50 mm per application |
| Finish | Smooth, low rebound |
| Shrinkage | Non-shrink / shrinkage compensated |
Industry use cases
Commercial & Institutional Buildings
Reinstating spalled columns, beams and soffits in lobbies, atria and occupied floors where the repair has to disappear under paint rather than stand out as a rough patch.
Bridges & Infrastructure
Repairing piers, girders and deck soffits on visible highway and rail structures, giving a smooth, durable surface ready for anti-carbonation protection.
Facade & Architectural Concrete
Making good exposed and fair-faced concrete facades so the finished elevation reads as continuous once decorative coatings go on.
Precast Concrete
Surface repair of cast panels and elements, closing blemishes and minor spalls before the units are coated or installed.
Marine & Aggressive Exposure
Patching cover concrete on structures facing chloride and sulphate exposure, where the low permeability of the polymer-modified mortar helps protect the reinforcement.
Frequently asked questions
How is ShaliFix FRM 50 different from the other FRM grades?
Was this product called something else before?
Do I need a bonding primer before applying it?
How thick can I apply it in one pass?
Can I paint over the repair, and when?
Is it suitable for overhead soffit repairs?
How we position STP ShaliFix FRM 50
Within the STP range, pair ShaliFix FRM 50 with a ShaliPrime Zn rebar primer for any repair where reinforcement is exposed or corroded, and step up to a higher-build ShaliFix FRM grade when the job is about raw section reinstatement rather than finished appearance. Where the repaired surface will face carbonation or chloride exposure, follow the patch with an STP anti-carbonation or protective coating once cured. If a project is specified around the Fosroc system, the equivalent structural repair mortar is Fosroc Renderoc HB40, and a Fosroc Renderoc FC fairing coat covers the fine cosmetic-blinding role. As an authorised distributor and applicator across Delhi NCR and Pan-India, Space Arc can supply and apply either brand family to suit the specification.
Fosroc Renderoc HB40 — Choose the Fosroc option when the project is specified around the Fosroc repair system or requires an EN 1504-3 classified high-build vertical and overhead mortar; FRM 50 remains the pick when a smoother, paint-ready finish on visible concrete is the priority.
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Authorised distribution, technical advice & professional application across Delhi NCR and Pan-India.