About Fosroc Lokfix S (FS)

Fosroc Lokfix S (FS) belongs to the Lokfix family of “mix and place” polyester resin anchoring grouts. Chemically it is a two-pack system: a can of unsaturated polyester resin and a separate pre-weighed catalysed filler (hardener) that, when blended, undergoes a rapid exothermic cure to lock embedded steel into the host substrate. The “S” denotes the pourable grade engineered for vertical downward holes, while the “FS” tag identifies the fast-set chemistry intended for application across roughly 8°C to 27°C, where contractors need rapid gel and early load application without waiting for cementitious grout to mature. Unlike cement-based non-shrink grouts (such as Fosroc Conbextra) that are used to bed plates and fill large voids, Lokfix S is a chemical anchor: a controlled annular thickness of resin bonds a single bar or bolt to the wall of a drilled hole. Because it is filled polyester rather than neat resin, it carries high compressive and shear loads, resists vibration loosening, and stays dimensionally stable since it is non-expansive — so it will not crack the surrounding concrete edge the way an expansion bolt can. The Lokfix range is tested to BS 6319 and BS 5080, and the system is recognised against BS EN 1504-6 for anchoring of reinforcing steel bars. For Indian contractors, consultants and procurement teams, the practical appeal is speed and reliability: pre-measured packs remove batching guesswork on site, the grout tolerates the damp holes common in monsoon and basement work, and anchors can be loaded within hours, compressing programme time on infrastructure, industrial and retrofit jobs. Space Arc Engineering supplies Lokfix S (FS) as an authorised Fosroc distributor and applicator across Delhi NCR and Pan-India, with technical guidance on hole geometry, embedment depth and grade selection.

The technical insight

The engineering behind Lokfix S is hole geometry and bond, not bearing. The minimum embedment depth is derived from BS 8110 shear-stress limits in the concrete using the formula minimum hole depth = 0.6Y x 0.25d1squared / (S x d2), where Y is the characteristic yield stress of the steel (~425 N/mm2 in the India TDS), S is the permitted concrete shear stress (e.g. 2.1 N/mm2 at 20 N/mm2 concrete rising to ~3.4 N/mm2 above 40 N/mm2), d1 is bar diameter and d2 is hole diameter. In practice that means a 16mm bar in 20 N/mm2 concrete needs roughly 390mm embedment, while a 20mm bar in higher-grade concrete needs ~485mm — the anchor’s capacity is governed by the weaker of the concrete cone and the resin-to-bar bond, so embedment, not resin volume, is the lever. The second critical variable is gel time, which is strongly temperature-dependent: about 40 minutes at 20°C, 15 minutes at 30°C and only 7 minutes at 40°C, with the corresponding minimum time before load being 7, 7 and 3 hours. On a hot Indian afternoon the working window can collapse to single-digit minutes, so packs must be mixed at the hole and placed immediately. The cured grout reaches an ultimate compressive strength in excess of 90 N/mm2, shear strength of 30 N/mm2 (BS 6319 Pt 2), tensile strength of 14 N/mm2 at 7 days and flexural strength of 32 N/mm2. Rough-sided, dust-free holes are non-negotiable — the resin keys mechanically into the hole wall, so smooth diamond-drilled holes must be under-reamed and all drilling dust flushed out, or pull-out capacity drops sharply.

Where it is used

• High-strength anchoring of foundation and holding-down bolts for plant, machinery and structural steel base plates
• Permanent installation of reinforcement starter bars and rebar dowels into existing concrete (post-installed rebar / dowelling)
• Fixing of crash barriers, safety fences, balustrades, handrails and guardrails into concrete or masonry
• Anchoring railway track fastenings, sleeper bolts and rail-side fixtures subject to vibration
• Tie-back anchors and ground anchors for towers, cranes, retaining structures and dock sills
• Anchoring into natural rock, brickwork and masonry for civil and slope-stabilisation works
• Wet or underwater anchoring where holes cannot be kept dry, including basements, water-retaining structures and marine works

Key advantages

• Ultra-rapid strength gain — anchors can be loaded within hours, not days, shortening site programmes
• Tolerant of wet, damp and even submerged holes, unlike many epoxy and cementitious anchoring systems
• Pre-weighed two-part packs eliminate on-site batching errors and give consistent, reproducible anchor capacity
• Non-expansive cure — will not generate bursting stress at concrete edges or in close-to-edge fixings
• High shear (30 N/mm2) and ultimate compressive strength (>90 N/mm2) with strong vibration resistance
• Corrosion-resistant and chemically resistant to fresh/salt water, petrol, oils, grease and most acids, alkalis and solvents
• Tested to recognised standards (BS 6319, BS 5080) and aligned with BS EN 1504-6 for anchoring reinforcing bars

Limitations & considerations

• Styrene-based and flammable — flash point of the resin is about 29°C; keep away from ignition sources and ensure ventilation
• Strong odour and resin/solvent sensitisation risk; gloves, eye protection and adequate ventilation are essential, especially in confined spaces
• Short and temperature-sensitive working time — gel can fall to ~7 minutes at 40°C, so packs must be mixed at the hole and placed at once
• S grade is for vertical down holes only; horizontal and overhead holes require the thixotropic Lokfix P grade to stop flow-out
• Performance depends entirely on hole preparation — smooth, dusty or poorly flushed holes drastically reduce pull-out capacity
• Shelf life is limited to 12 months below 20°C and only about 6 months in tropical storage, so stock must be rotated
• Suited to discrete bar/bolt anchoring, not large-void or base-plate bedding — use a cementitious grout (e.g. Conbextra) for those

Selection & best practice

Specifications

Industry use cases

How we position Fosroc Lokfix S (FS)

Within the Fosroc range, Lokfix S (FS) sits alongside Lokfix P (the thixotropic grade for horizontal and overhead holes) and the epoxy-based Lokfix EP / E55 / E75 anchors, which trade Lokfix’s ultra-fast polyester cure for the higher chemical resistance, lower odour and creep performance of epoxy in demanding or sustained-load fixings. For large-void grouting and base-plate bedding rather than single-bar anchoring, the natural companions are Fosroc’s cementitious non-shrink grouts such as Conbextra GP2/HF/EP, and for surface preparation/dowel bonding the Nitobond range. Against the wider Indian market, the closest competitor systems are Sika AnchorFix and Sika Icosit polyester/epoxy anchors, Hilti’s HIT injection adhesives (HIT-RE/HIT-HY) where a cartridge injection workflow is preferred, and MYK/MBS, Dr. Fixit (Pidilite) and STP (Shalimar Tar Products) anchoring grouts at the value end of the market. Lokfix’s distinguishing strengths are its pre-weighed mix-and-place packs, genuine tolerance of wet and submerged holes, and rapid same-day load capacity, which make it a strong default for fast-track infrastructure, industrial and retrofit anchoring. Where very long working time, injectable application into deep or congested holes, or maximum chemical/creep resistance is the priority, an epoxy Lokfix grade or a cartridge injection system may be the better technical fit. Space Arc Engineering, as an authorised Fosroc distributor and applicator across Delhi NCR and Pan-India, can advise on grade selection, embedment design and substrate-specific detailing.

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