STP ShaliFix FRM 40
Single-component, polymer-modified, fibre-reinforced dry mortar for high-build hand and wet-spray repair of structural and load-bearing concrete.
What is it?
A single-component, polymer-modified, fibre-reinforced dry-powder mortar from STP. You add only clean water on site to get a thixotropic mix that can be sprayed or trowelled onto structural concrete.
Where is it used?
Structural and load-bearing repairs on RC columns, beams, girders, soffits and slabs, plus marine and underground structures, fire-damaged concrete and eroded surfaces across Delhi NCR and pan-India sites.
Why use it?
It builds up to 50 mm in a single layer without formwork, bonds without a primer, controls shrinkage and reaches 40 MPa at 28 days, making full-depth patch repairs faster and more durable.
How is it applied?
Prep the substrate to a keyed, saturated surface-dry state, mix 30 kg with 4.8-5.4 L water, then apply by wet-spray or trowel in one hi-build layer of 12-50 mm and finish as it stiffens.
About STP ShaliFix FRM 40
STP ShaliFix FRM 40 is a factory-blended structural repair mortar that arrives as a grey dry powder in a sealed 30 kg bag and needs nothing on site except clean water. Once gauged at a water/powder ratio of about 0.18, it turns into a stiff, thixotropic mix that holds its shape on vertical faces and overhead soffits without slumping. That single characteristic is what makes it a working favourite for RC repair crews: a patch that would normally need shuttering and multiple thin passes can instead be sprayed or trowelled in one high-build lift, cutting both labour and the risk of cold joints between layers. Formerly sold simply as ShaliFix FRM, the “40” now signals its 28-day compressive strength grade in a family that also runs to 50 and 70 MPa versions.
The mortar is aimed squarely at engineers, applicators and consultants handling genuinely structural distress rather than cosmetic surface making-good. Its polymer modification lifts bond and durability, while polypropylene-type fibres bridge micro-cracks and hold the repair together during the vulnerable early curing hours. It is rated for sprayed application through long hose runs, which suits large infill areas, congested reinforcement zones and repairs where access is awkward. As Space Arc Engineering is an authorised STP distributor and applicator, we supply FRM 40 with the correct primers and curing products and, where a project spec calls for it, can advise on the closest Fosroc equivalent so the submitted system matches what the consultant has approved.
The technical insight
The performance of FRM 40 comes from three things working together. First, the polymer dispersed through the cement matrix reduces the water demand and refines the pore structure, which is why the product reaches a very low shrinkage of under 0.001% (ASTM C157) and prints a tensile bond above 3 MPa to the parent concrete (ASTM C1583) without needing a bonding primer. Second, the fibre reinforcement acts as internal crack-arrest: as the fresh mortar develops early strength, the fibres carry the tensile stresses that plastic and drying shrinkage would otherwise turn into surface cracking, so the repair is sound in the very first application. Third, the thixotropic rheology is deliberately engineered so the material flows under the shear of a trowel or spray nozzle but stiffens the moment that shear stops, letting it be placed at 12-50 mm on walls and overhead in one pass with very low rebound. Strength gain is quick and predictable, reaching 20 MPa at just one day and 40 MPa at 28 days (ASTM C109), so structures can be returned to load relatively early. In dry-spray mode the water is introduced at the nozzle, meaning only dry powder sits in the pump and hose and spraying can be paused and restarted without flushing the line.
Where it is used
- Structural and load-bearing repair of RC columns, beams, girders and pillars
- Surface repair of RC elements as a base before protective polymer coatings
- Overhead and vertical soffit repairs where formwork is impractical
- Mass infill of large spalled or eroded areas via wet or dry spray
- Reinstatement of fire-damaged and chemically eroded concrete
- Repair of marine concrete structures exposed to chloride attack
- Repair of underground structures needing low-permeability mortar
- Protection of concrete against sulphate and chloride ingress
Key advantages
- High strength with strong bond to both concrete and steel, no primer required
- Single-layer hi-build placement up to 50 mm for vertical and overhead repairs
- Thixotropic mix stays put on soffits and walls without slumping
- Very low rebound during spray application, reducing material waste and cost
- Built-in shrinkage control lets the repair be completed correctly in one pass
- Fibre reinforcement bridges micro-cracks and improves early crack resistance
- Resistant to sulphate, chloride and oil for durable service life
- Low-permeability matrix helps prolong the effective working life of the repair
Limitations & considerations
- Not suitable where the mortar will contact liquids below pH 5.5
- Must be placed within the recommended 12-50 mm thickness band; thicker sections need smaller patches or added reinforcement
- Requires a properly prepared, keyed and saturated surface-dry substrate free of standing water
- Substrate must be 5-40 C and material 5-30 C, so hot-weather placing needs planning
- Fresh repairs need protection from rain, wind and aggressive weather for the first 24 hours
- Cement-based system with a 6-month shelf life; old or damp-stored stock should not be used
Selection & best practice
Get the substrate right first: remove all loose, damaged or contaminated concrete down to a sound, keyed and aggregate-exposed surface, cut the patch edges vertically, and expose and clean the full circumference of any reinforcement. Where bars are corroded, cut back at least 20 mm behind them, grit-blast off the rust, and prime with ShaliPrime Zn R or Zn Ph; replace any bar that has lost more than 20% of its diameter. Pre-soak the prepared area so it is saturated surface dry with no standing water. Mix one 30 kg bag with 4.8-5.4 L of clean potable water using a mechanical mixer for 2-3 minutes to a lump-free thixotropic consistency, let it stand a minute to release entrapped air, then remix for 30 seconds. Apply a thin scrape or contact coat first, then build up wet-on-wet to the required 12-50 mm and screed level. For overhead or thick zones work in smaller patches. Trowel or float as the mortar starts to stiffen, keep it out of standing water, and protect it from rain and wind for the first 24 hours. Clean tools with water immediately, before the material hardens.
Specifications
| Physical appearance | Grey powder |
| Density | 2.25 +/- 0.10 g/cc |
| Water / powder ratio | 0.18 (approx. 4.8-5.4 L per 30 kg bag) |
| Recommended thickness | 12-50 mm per application |
| Compressive strength (ASTM C109) | 20 MPa at 1 day; 40 MPa at 28 days |
| Tensile bond strength (ASTM C1583) | >3 MPa at 28 days |
| Flexural strength (ASTM C580) | >5 MPa at 28 days |
| Shrinkage (ASTM C157) | <0.001% |
| Application temperature | Substrate 5-40 C; material 5-30 C |
| Packing / shelf life | 30 kg bag; 6 months in sealed original packing |
Industry use cases
Infrastructure & bridges
Wet-spray reinstatement of spalled RC beams, girders and soffits where 40 MPa strength and no-formwork placement keep structures in service.
Marine & coastal
Repair of chloride-attacked jetty, pier and seawall concrete using the low-permeability, sulphate/chloride-resistant mortar.
Water & underground works
Patching of tanks, basements and tunnels where a dense, low-permeability repair helps resist water ingress.
Industrial plants
Fast return-to-service repair of fire-damaged or chemically eroded columns and pillars, with 20 MPa strength gained in a day.
Buildings & high-rise
Structural patch repair of columns and slab soffits ahead of protective anti-carbonation or polymer coatings.
Frequently asked questions
Is ShaliFix FRM 40 the same as the old ShaliFix FRM?
How much water do I add per bag?
Do I need a bonding primer or SBR slurry first?
What thickness can I build in one layer?
Can it be sprayed as well as hand-applied?
What pack size and shelf life does it have?
How we position STP ShaliFix FRM 40
Within the STP range, FRM 40 is the mid-grade choice: step up to ShaliFix FRM 50 or FRM 70 when the specification demands higher compressive strength, and pair it with ShaliPrime Zn R or Zn Ph for rebar protection and an STP anti-carbonation or protective coating over the finished repair. For jobs approved on a Fosroc system, Space Arc also stocks the Fosroc Renderoc line as a direct alternative, and for congested, hard-to-vibrate sections a flowable microconcrete such as Fosroc Renderoc RG may suit better than a sprayed mortar.
Fosroc Renderoc HB45 — Specify the Fosroc option when the project is tendered on a BS EN 1504-3 R4 classified system or the consultant has approved Renderoc, as HB45 is the equivalent fibre-reinforced, polymer-modified high-build hand and spray-applied structural repair mortar.
Related Concrete Repair products
Source STP ShaliFix FRM 40 for your project
Authorised distribution, technical advice & professional application across Delhi NCR and Pan-India.