STP ShaliFix EM 51
A solvent-free, three-component thixotropic epoxy mortar that patches and rebuilds concrete on vertical and overhead surfaces without sagging or shrinkage.
What is it?
A 100% solid, solvent-free, three-component (resin, hardener, graded filler) thixotropic epoxy repair mortar from STP that cures to a surface tougher than the parent concrete.
Where is it used?
Vertical and overhead repairs, spalled columns, soffits and beams, and heavy-duty patching in car parks, warehouses, dairies, food and beverage units and chemical plants.
Why use it?
It carries load fast (over 60 MPa in one day), hardens without shrinkage and stays put on walls and soffits, so structural sections are restored without formwork.
How is it applied?
Prime the sound substrate with ShaliBond 41, mix Components A, B and C in a 2:1:2 ratio, then trowel or hand-pack up to 30 mm per layer while the primer is tack-free.
About STP ShaliFix EM 51
ShaliFix EM 51 is STP’s high-strength epoxy reinstatement mortar, built for the repairs that ordinary cementitious mixes struggle with: overhead soffits, vertical column faces and any section where a patch has to bond hard, gain strength quickly and stay exactly where the trowel left it. It is a three-component system, supplied as pre-weighed resin (Comp A), hardener (Comp B) and a graded aggregate filler (Comp C). Because it is 100% solid and solvent-free, there is no odour during application and no shrinkage as it cures, which matters when you are reinstating structural concrete and cannot tolerate a patch pulling away at the edges. The material conforms to ASTM C 395-01 (2012).
For engineers and applicators in Delhi NCR and across India, the appeal is speed and confidence. The mortar develops more than 60 MPa of compressive strength in a single day and over 80 MPa by seven days, so a repaired member can often be brought back into service quickly. Its thixotropic, non-slumping consistency means it holds on vertical and overhead work up to 30 mm thick per layer without formwork. Space Arc Engineering supplies ShaliFix EM 51 as an authorised STP distributor and applicator, so you get the correct primer, the right pack size and site guidance rather than just a product on a shelf.
The technical insight
The performance comes from the epoxy chemistry doing two jobs at once. The resin-hardener system cross-links into a dense, non-absorbent polymer matrix that bonds chemically to a properly primed substrate, which is why the tensile adhesion after seven days exceeds 9 MPa and typically fails in the concrete rather than at the bond line, the substrate gives way before the repair does. The graded filler (Comp C) is what turns a neat epoxy into a structural mortar: it packs the matrix, controls the mix density to around 2.02 g/cc and delivers the compressive and flexural figures. The thixotropy is deliberate. The blend is engineered to stay stiff and non-sag at rest so it clings to a wall or soffit, yet mobilise under the trowel so it can be worked and compacted. Priming with ShaliBond 41, applied when tack-free, gives the fresh mortar a reactive surface to key into, which is what makes overhead application without formwork realistic rather than a gamble.
Where it is used
- Reinstating spalled or delaminated concrete on columns and walls where the repair must not sag
- Overhead soffit, beam and slab-underside patching without the cost and time of formwork
- Structural section repair on car park decks, ramps and industrial floors
- Bedding mortar and non-sag adhesive mortar for fixing and levelling heavy elements
- Repairs in dairies, food and beverage plants where a non-absorbent, hygienic surface is needed
- Chemical, fertiliser and metal-treatment plant floors requiring a chemical-resistant patch
- Apron, taxiway and hardstanding repairs in airport and heavy-traffic areas
- High-abrasion warehouse and workshop areas needing a durable, dust-free finish
Key advantages
- Solvent-free and 100% solid, no odour during application and no VOC-driven cure
- Hardens without shrinkage, so patch edges stay tight to the parent concrete
- Non-sag on vertical and overhead surfaces up to 30 mm per layer, no formwork needed
- Fast strength gain, over 60 MPa in one day and over 80 MPa by seven days
- Very high adhesion, over 9 MPa at seven days with failure in the concrete, not the bond
- Non-absorbent, non-dusting and chemically resistant finished surface
- Conforms to ASTM C 395-01 (2012) for specifier confidence
- Available in pre-weighed 5 kg and 15 kg combo packs, no on-site batching guesswork
Limitations & considerations
- It is an epoxy repair mortar, not a decorative render or thin skim, minimum practical build is needed for structural function
- Maximum 30 mm per layer, deeper repairs must be built up in lifts
- Substrate must be genuinely sound, dry and primed with ShaliBond 41; new concrete should be at least 28 days old with moisture below 5%
- Pot life is only 30 to 40 minutes per 100 g at 28 degrees C, so mix in working quantities and clean tools before it sets
- Epoxy cure and pot life shift with temperature, plan around Indian summer heat and cure below the resin’s limits
- Higher material cost than cementitious repair mortars, best reserved for repairs that genuinely need epoxy performance
Selection & best practice
Prepare the surface honestly, this decides the repair. On old concrete, scabble, grind or grit-blast back to a sound substrate and strip all laitance; burn or acid-etch off oil and grease, then let it dry. On new concrete, confirm it is at least 28 days old with moisture content under 5%. Prime with ShaliBond 41 and wait until it is tack-free. Mix the full pre-weighed Comp B into Comp A for about three minutes with a slow-speed drill and paddle, then add all of Comp C and mix a further two minutes until every aggregate particle is coated. Apply immediately by spatula, trowel, notched trowel or gloved hand, compact well, and finish with a steel trowel. Keep each lift to 30 mm and build up thicker sections in layers. Because pot life is 30 to 40 minutes, mix only what you can place in that window and clean all tools with STP Epoxy Thinner before the material hardens.
Specifications
| Product type | 3K solvent-free thixotropic high-strength epoxy repair mortar |
| Compressive strength | > 60 MPa (1 day), > 80 MPa (7 days) |
| Flexural strength (14 days) | > 24 MPa |
| Tensile strength (14 days) | > 8 MPa |
| Tensile adhesion (7 days) | ≥ 9 MPa (concrete failure) |
| Mix density @ 30°C | 2.02 ± 0.05 g/cc |
| Consumption | 2 – 2.2 kg / m² / mm |
| Mixing ratio (A:B:C by weight) | 2 : 1 : 2 |
| Pot life (100 g) | 30 – 40 minutes |
| Max thickness per layer | 30 mm |
| Standard | ASTM C 395-01 (2012) |
| Pack size | 5 kg and 15 kg combo packs |
| Shelf life | 12 months, unopened, cool and dry |
Industry use cases
Bridges & Elevated Structures
Restoring spalled soffits, beam undersides and pier faces overhead, where a non-sag epoxy mortar reinstates section without slung formwork.
Car Parks & Infrastructure
Patching delaminated deck and ramp concrete with a fast-strength, abrasion-resistant mortar that can be reopened to traffic quickly.
Food, Beverage & Dairy
Repairing floors and plinths with a non-absorbent, non-dusting, chemical-resistant surface suited to wash-down and hygiene requirements.
Chemical & Fertiliser Plants
Reinstating attacked or spalled concrete in aggressive environments where chemical resistance and hard, dense surfacing are essential.
Airports & Heavy Hardstanding
Emergency and permanent repair of apron, taxiway and workshop areas needing high compressive strength and quick return to service.
Frequently asked questions
Can ShaliFix EM 51 really be used overhead without formwork?
How much ShaliFix EM 51 do I need?
What primer must I use, and can I skip it?
How quickly can the repair take load?
What is the pot life and how should I plan mixing?
What pack sizes does it come in and how long does it store?
How we position STP ShaliFix EM 51
ShaliFix EM 51 is the epoxy-mortar tier of STP’s repair range, use it where cementitious repair is not enough. For deeper large-area reinstatement or flowable sections, pair it with STP’s ShaliFix MC micro-concrete or the ShaliFix FRM fibre-reinforced sprayable mortars; for cosmetic thin-section and fairing work, a polymer-modified cementitious mortar is the more economical choice. Always specify the ShaliBond 41 epoxy primer alongside it, and STP Epoxy Thinner for tool cleaning. Where a project is standardised on Fosroc, the equivalent is Nitomortar S. Across our other brands, engineers who prefer Sika would look at the Sikadur epoxy mortar family, and Dr. Fixit or MC-Bauchemie offer comparable epoxy repair systems, our team can match the right one to your specification and site conditions.
Fosroc Nitomortar S — Choose Nitomortar S when the project is already standardised on Fosroc’s constructive-solutions system, or when you need a proven three-component solvent-free epoxy reinstatement mortar with matching Fosroc primers and documentation.
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