About Sika Sikadur-43 IN

Sikadur-43 IN is Sika’s thixotropic, three-part epoxy patch-repair and bonding mortar, built from a combination of epoxy resins and specially graded fillers. It arrives on site as a pre-proportioned kit — the resin (Part A), the hardener (Part B) and the filler (Part C) are supplied in the correct ratio, so the crew mixes the whole unit rather than guessing dosages. Once the three parts are blended to a single uniform colour, the material behaves like a stiff, buttery mortar that stays where it is placed: it will not slump off a vertical face or drip from an overhead soffit, which is exactly what a repair mortar needs when you are rebuilding a spalled column or a corroded beam corner.

What makes it a structural product rather than a cosmetic filler is the cured performance. Sikadur-43 develops very high compressive strength — of the order of 100 N/mm² within a week under warm conditions — along with strong adhesion to concrete, stone, brick and steel, good abrasion resistance and resistance to a range of oils, fuels and dilute chemicals. It cures without shrinkage, tolerates damp (though not wet) substrates, and needs no separate priming coat. For Indian repair and rehabilitation work — parking decks, industrial floors, effluent structures, bridge elements — that combination lets a contractor reinstate lost concrete section and load capacity in a single trowel-applied operation.

The technical insight

The material works because it is a filled epoxy system rather than a cement one. There is no cement, no water of hydration and therefore no drying shrinkage or carbonation to worry about — the resin and hardener cross-link into a dense, closed polymer matrix, and the graded quartz-type filler carries the compressive load and controls the thermal movement. That chemistry is what produces the high early strength and the chemical resistance: a cured epoxy simply does not have the porous, alkaline capillary structure that lets oils, chlorides and dilute acids attack ordinary repair concrete. The thixotropy is deliberate too — the mix is engineered to flow under the trowel yet stand up under its own weight the instant you stop working it, so a 20-30 mm build on a vertical or overhead face stays put through cure. Because the epoxy wets and grips the substrate on its own, it bonds directly to sound, prepared concrete and steel without a primer, and it will develop that bond on a surface that is damp rather than bone-dry — useful in real site conditions where you cannot always guarantee a fully dry substrate.

Where it is used

• Structural patch repair of spalled or honeycombed concrete beams, columns and soffits
• Rebuilding damaged edges, corners and arrises on concrete members
• Filling cavities, blowholes and voids in concrete and masonry
• Re-profiling and repair of industrial and warehouse floor slabs subject to traffic and abrasion
• Bonding and repair across mixed substrates — concrete, natural stone, brick, fibre cement and steel
• Reinstating cover and section in chemically aggressive zones such as effluent tanks and process areas
• Repairs to bridge, flyover and parking-deck elements where high early strength is needed
• Localised abrasion-resistant wearing patches on heavily worn floor areas

Key advantages

• Three components pre-batched in the correct ratio — mix the whole unit, no on-site dosing errors
• Very high compressive strength (of the order of 100 N/mm² at 7 days in warm conditions) for genuine structural repair
• Thixotropic and non-sag — holds full thickness on vertical and overhead surfaces without slumping
• Bonds directly to concrete, stone, masonry and steel with no separate primer coat
• Cures under damp conditions, so a fully dry substrate is not mandatory
• Cures without shrinkage, avoiding the cracking and debonding seen with poorly cured cementitious patches
• Good resistance to abrasion and to oils, fuels and dilute chemicals
• Solvent-free formulation, better for confined and enclosed working areas

Limitations & considerations

• Application temperature is limited to roughly +5°C to +40°C; pot life shortens sharply as ambient temperature and batch size rise, so mix small quantities in Indian summer heat
• Not designed for large-volume or full-depth reconstruction — for deep or high-volume section loss a cementitious micro-concrete is more economical
• Epoxy repairs are far stiffer and less vapour-permeable than the surrounding concrete, so they are not suited to thin feather-edged cosmetic skims over wide areas
• Requires a sound, clean, laitance-free substrate; it will not compensate for weak, contaminated or unprepared concrete
• Substrate may be damp but must not be wet, running or under standing water
• Higher material cost per kg than cement-based mortars — best reserved for structural, chemical-exposure or high-abrasion repairs where that performance is actually needed

Selection & best practice

Specifications

Industry use cases

How we position Sika Sikadur-43 IN

Within the Sika range, Sikadur-43 IN sits alongside Sikadur-41 IN — a companion epoxy patching mortar — where you can select the grade that best matches the working temperature and pot-life you need on the day. Where the underlying concrete needs a bonding bridge before a fresh overlay, pair it with a Sika epoxy bonding agent; where the repair is deep or high-volume, a cementitious micro-concrete from the Sika Monotop range is the more economical route and Sikadur-43 is better kept for the structural and chemically exposed patches. Across our other brands we also stock equivalent epoxy repair systems from Fosroc (Nitomortar) and Dr. Fixit, so if you are matching an existing specification, an approved-vendor list or a particular price point, we can cross-quote a like-for-like alternative rather than force a single brand.

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