About Fosroc Lokfix S25

Fosroc Lokfix S25 is the pourable member of the Lokfix resin-anchoring family, engineered for one of the most common and most safety-critical jobs on a construction site: fixing steel into hardened concrete after the structure has already been cast. Where a structural engineer specifies starter bars for a new lift, holding-down bolts for a base plate, dowels across a construction joint, or fixings for balustrades, barriers and safety fences, Lokfix S25 provides the chemical bond that transfers load from the bar into the host material. It is a two-component polyester system, supplied as a can of resin and a pre-weighed bag of catalysed filler inside a plastic mixing pail, so the correct ratio is built into the pack and there is no on-site batching error. The mixed yield is 2.5 litres per pack. The S25 designation tells the applicator exactly what they are getting: S for the pourable (self-levelling) grade used in vertical-down holes, and 25 for the nominal 25-minute gel time at 20 C. That gel time is the practical heart of the product, long enough for a crew to mix, pour and set multiple bars in a working session, yet short enough that loading can typically begin around two hours later. For India, where post-installed rebar connections, retrofit dowelling and bolt anchorages are routine across infrastructure, industrial and retrofit projects, Lokfix S25 is a workhorse for situations that demand a fast, reliable, non-shrink anchorage without waiting days for a cementitious grout to cure. Space Arc Engineering supplies it as part of the broader Fosroc anchoring and grouting range, alongside companion products for situations where polyester is not the right tool.

The technical insight

The chemistry is the first thing to get right on a specification. Lokfix S25 is a polyester resin grout, not an epoxy, and that distinction drives both its strengths and its limits. Polyester cures by a fast free-radical reaction, which is why a vertical-down anchor can move from pour to a minimum loading time of roughly 2 hours at 20 C, far quicker than any cementitious grout. The cured matrix reaches 100 MPa compressive, 11 MPa tensile and 19 MPa flexural strength at 28 days, with a chloride ion content below 0.05 percent and a glass transition temperature of about 73.5 C. Performance is verified to the EN 1504-6 anchoring test suite: pull-out displacement stays under 0.6 mm at a 75 kN bond load, and creep under a sustained 50 kN load over three months remains within 0.6 mm. The product is temperature-sensitive in a way installers must plan for. Gel time stretches to about 130 minutes at 5 C but collapses to roughly 10 minutes at 30 C, so in Indian summer conditions the crew has a genuinely short window and should mix smaller quantities and work fast. Geometry also matters: the hole should be 8 to 40 mm greater in diameter than the bar, giving an annular gap of 4 to 20 mm, and the bond relies on a rough-sided, dust-free hole produced by rotary percussive drilling with air or water flushing. Diamond-drilled holes are too smooth and must be under-reamed or roughened. Finally, it is flammable, with a flash point of 29 C, which governs storage and handling on site.

Where it is used

• Anchoring rebar starter bars into hardened concrete for new construction lifts and extensions
• Fixing base-plate and holding-down bolts for steel columns, machinery and equipment
• Installing MOT/highway bolts and dowels in bridge, flyover and road infrastructure works
• Setting tie bars and dowels across construction and movement joints in slabs and pavements
• Anchoring balustrades, handrails, crash barriers and safety fences into concrete or masonry
• Post-installed dowelling for retrofit, strengthening and structural repair of existing structures
• Fixing into brickwork, masonry and rock where a fast, non-expansive chemical anchor is required
• Submerged or wet-condition anchorages such as marine, water-retaining and below-grade fixings

Key advantages

• Fast strength gain with a typical minimum loading time of about 2 hours at 20 C
• High cured strength: 100 MPa compressive, 11 MPa tensile and 19 MPa flexural at 28 days
• Certified to BS EN 1504-6 and conforms to Highways Agency IAN 104/07
• Non-expansive, so it will not split or stress the surrounding concrete or masonry
• Pre-measured packs eliminate on-site mixing-ratio errors and give a consistent 2.5 L yield
• Can be placed underwater and used in dry or damp holes
• Resistant to vibration, shock and a wide range of chemicals once cured
• Low chloride ion content (below 0.05 percent), safe alongside reinforcement

Limitations & considerations

• Polyester, not epoxy: lower long-term creep and chemical performance than epoxy systems for the most demanding fixings
• Flammable with a 29 C flash point; requires careful storage, no naked flames and good ventilation
• Gel time drops to around 10 minutes at 30 C, leaving a very short working window in hot Indian conditions
• Should not be used where load-bearing performance must be maintained under fire conditions (use a cementitious grout such as Conbextra GP/HF instead)
• Pourable grade is for vertical-down holes only; horizontal or overhead fixings need a gel/thixotropic grade
• Requires rough-sided, dust-free, correctly sized holes (8 to 40 mm larger than the bar); smooth diamond-drilled holes must be roughened
• Partial packs cannot be mixed, which can waste material on small fixing counts
• 12-month shelf life at 20 C, reduced at higher storage temperatures

Selection & best practice

Specifications

Industry use cases

How we position Fosroc Lokfix S25

Within the Fosroc range, Lokfix S25 is the pourable, fast-set polyester anchor for vertical-down holes, and it sits alongside clear companions: Lokfix P25 (the gel grade for horizontal and overhead holes), Lokfix S (FS) for larger or specialised fixings, and Lokfix EP, the epoxy grade for the most demanding anchorages needing higher creep and chemical performance. Where fire resistance or non-flammable structural grouting is required, the cementitious Conbextra GP and Conbextra HF are the correct choices rather than any resin anchor, and Fosroc itself directs specifiers to these for fire-exposed conditions. Bars are commonly prepared and primed within the wider Fosroc Nitobond and Nitoprime systems on repair projects. In the Indian market, credible alternatives a consultant may evaluate include Sika AnchorFix and Sika Icosit polyester/epoxy anchoring resins, MBS (MYK Schomburg) anchoring grouts, STP and Dr. Fixit fixing and grouting products, and Hilti chemical anchor systems for cartridge-based applications. Lokfix S25 distinguishes itself with its BS EN 1504-6 certification, Highways Agency IAN 104/07 conformity, pre-measured error-free packs and proven pull-out performance, making it a dependable specification where a fast, non-expansive, code-compliant vertical anchor is needed. Space Arc Engineering supplies Lokfix S25 and the full Fosroc anchoring and grouting range across Delhi NCR and Pan-India, with application guidance for correct grade selection.

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