STP ShaliFix FRM 70
Single-component, fibre-reinforced, polymer-modified repair mortar for structural concrete restoration, built for high-build single-lift hand or spray application including overhead work.
What is it?
A single-component, polymer-modified, fibre-reinforced ready-mix dry-powder mortar from STP that needs only clean water on site to produce a thixotropic, high-strength structural repair mortar.
Where is it used?
Load-bearing RC repairs on columns, beams, girders, slab soffits, marine and underground structures, and sulphate- or chloride-attacked concrete across Delhi NCR and pan-India projects.
Why use it?
It rebuilds lost concrete section in a single thick lift, bonds without a primer, resists shrinkage cracking, and stays put overhead thanks to its thixotropic fibre-reinforced body.
How is it applied?
Prepare and pre-soak the substrate to SSD, mix at 4.8-5.4 L water per 30 kg bag, then trowel or spray-apply 12-50 mm per lift, screed level and float-finish as it stiffens.
About STP ShaliFix FRM 70
ShaliFix FRM 70 is STP’s heavier-duty structural repair mortar, aimed at the situations where concrete has genuinely lost section: spalled columns, eroded beam faces, corroded-rebar zones, fire-damaged members and marine or underground elements sitting in an aggressive environment. It arrives as a grey ready-mix powder in a 30 kg bag; the contractor adds only measured clean water on site, which removes the guesswork of batching cement, sand, polymer and fibre separately and keeps every patch consistent from the first mix to the last.
What sets the FRM 70 grade apart is the combination of high strength and a thixotropic, fibre-toughened body. It reaches over 65 MPa in compression at 28 days, yet the fresh mortar holds its shape well enough to be built up 12-50 mm in a single lift and applied overhead without sagging or slumping. That means an applicator can rebuild a bridge soffit or an underside beam in one pass rather than in thin repeated coats, and can move between hand-trowelling small patches and machine-spraying large areas using the same material. For engineers specifying a durable, low-permeability repair on load-bearing concrete, it behaves like a purpose-made structural mortar rather than a cosmetic skim.
The technical insight
The performance comes from three things working together. First, the polymer modification: a redispersible polymer improves the mortar’s grip on both the host concrete and exposed steel, so no separate bonding primer is needed and the repair moves as one with the parent section. Second, the fibre reinforcement: dispersed fibres bridge the micro-cracks that form as any cementitious mortar cures and shrinks, which is exactly what keeps a thick 50 mm lift from crazing and debonding at the edges. Third, the thixotropy: the mix is stiff at rest but flows under the shear of a trowel or spray nozzle, so it clings to vertical and overhead surfaces yet still consolidates and levels when worked. The shrinkage-controlled formulation lets the applicator complete the repair correctly in the very first application, and the resulting low-permeability matrix is what resists sulphate, chloride and oil ingress and prolongs the effective service life of the repaired member. The one chemistry limit worth respecting is pH: the matrix is not designed for liquids below pH 5.5.
Where it is used
- Structural surface repair of RC columns, beams, girders and pillars that have lost cover or section
- Underside and overhead repairs to slab and bridge soffits where a non-sag mortar is essential
- Reinstating spalled facades, eroded surfaces and irregular profiles on load-bearing concrete
- Repair of fire-damaged concrete members back to their original profile
- Marine and underground concrete structures exposed to sulphate and chloride attack
- Preparation of RC elements ahead of protective polymer coating systems
- Mass infill of large repair areas by spray application using a rotor-stator or continuous mixer pump
- Both structural and non-structural repairs on high-strength concrete elements
Key advantages
- High compressive strength exceeding 65 MPa at 28 days, suited to load-bearing repairs
- Single-layer high-build up to 50 mm in one lift, cutting the number of passes on site
- Thixotropic body that holds on vertical and overhead surfaces without slumping
- No separate primer needed – good adhesion straight onto prepared, damp host concrete
- Fibre reinforcement and shrinkage control that resist cracking in thick sections
- Resistance to sulphate, chloride and oil for durability in aggressive exposures
- Site-friendly single-component powder – just add measured water for consistent batches
- Interchangeable hand-trowel or machine-spray application from the same bag
Limitations & considerations
- Not suitable where contacting liquids fall below pH 5.5 – a dedicated acid-resistant system is needed there
- Fresh repairs must be protected from rain, wind and standing water for the first 24 hours
- Substrate must be pre-soaked to saturated-surface-dry with no standing water, which adds a prep step
- Application is temperature-bound: substrate 5-40 C and material 5-30 C, so hot-afternoon or cold-morning windows may need managing
- Only a 30 kg pack and a 6-month shelf life, so material must be planned and rotated rather than stockpiled
- Corroded rebar must first be cleaned and primed (for example with ShaliPrime Zn R) before the mortar goes on – the product does not treat corrosion by itself
Selection & best practice
Start with honest surface preparation: cut back all loose, damaged or contaminated concrete to a keyed, aggregate-exposed surface, square-cut the repair edges vertically and grit-blast or high-pressure-water-blast rather than hammering. Expose and clean the full circumference of any reinforcement, cutting back at least 20 mm behind corroded bars; replace any bar that has lost more than 20 percent of diameter, and prime cleaned steel with a zinc-rich rebar primer such as ShaliPrime Zn R. Pre-soak the prepared substrate to saturated-surface-dry with no standing water. Mix 4.8-5.4 litres of clean water per 30 kg bag with 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. Work a thin scrape/contact coat in first, then build up wet-on-wet to the target 12-50 mm, using thicker lifts only in smaller patches or where extra reinforcement is present. Screed level, and float or sponge-finish once the mortar begins to stiffen. Keep it out of standing water, protect open repairs from rain and wind for the first 24 hours, and clean tools with water before the mortar hardens.
Specifications
| Appearance | Grey powder |
| Density | 2.25 +/- 0.10 g/cc |
| Water / powder ratio | 0.16 – 0.18 |
| Mixing water | 4.8 – 5.4 L per 30 kg bag |
| Recommended thickness range | 12 – 50 mm per lift |
| Compressive strength (28 days) | > 65 MPa (ASTM C 109) |
| Tensile strength (28 days) | > 2 MPa (ASTM C 1583) |
| Flexural strength (28 days) | > 5 MPa (ASTM C 580) |
| Yield per 30 kg bag | 0.0133 m3 |
| Application temperature | Substrate 5-40 C; material 5-30 C |
| Pack size | 30 kg bag |
| Shelf life | 6 months, unopened and sealed |
Industry use cases
Bridges & Infrastructure
Rebuilding spalled bridge soffits, piers and parapets overhead in a single thixotropic lift without falsework-mounted formwork.
Marine & Coastal
Restoring chloride- and sulphate-attacked RC in jetties, sea walls and splash-zone structures with a low-permeability repair.
Industrial Plants
Structural repair of columns, beams and load-bearing frames in plants, including fire-damaged members and heavy-abrasion faces.
Water & Underground
Reinstating section on underground tanks, basements and sumps exposed to soil sulphates and moisture ingress.
Commercial & High-Rise Retrofit
Section repair of RC columns and slab undersides during structural rehabilitation, ahead of protective anti-carbonation coatings.
Frequently asked questions
What compressive strength does ShaliFix FRM 70 reach?
How thick can I apply it in one pass?
Do I need a bonding primer before applying it?
How much water do I add and what is the coverage?
Can it be spray-applied for large areas?
Is it suitable for acidic or chemical exposure?
How we position STP ShaliFix FRM 70
Within the STP family, ShaliFix FRM 70 is the high-strength, high-build structural grade; where the loss of section is shallower or the finish needs to be finer, ShaliFix FRM 40 is the lighter-duty sister mortar, and any exposed or corroded reinforcement encountered during prep should be cleaned and primed with STP ShaliPrime Zn R zinc-rich rebar primer before the mortar goes on. For teams standardised on Fosroc, the closest equivalent is Renderoc HB, a polymer-modified high-build mortar for vertical and overhead repairs; specifiers already running a Fosroc Renderoc repair-and-coating system on a project will often prefer to keep the whole repair within that single-source warranty chain. We supply and apply across both brand families pan-India, so the choice can follow the project specification rather than what is on the shelf.
Fosroc Renderoc HB — Choose Renderoc HB when the project is already specified on a Fosroc Renderoc repair-and-protection system and you want the full repair kept within one manufacturer’s warranty chain.
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