Sika SikaRep Microcrete-4
A pourable, shrinkage-compensated microconcrete that self-compacts into deep, heavily reinforced repairs where a vibrator simply cannot reach.
What is it?
A factory-blended, single-component cementitious microconcrete based on Portland cement, graded aggregate and dual-stage expansion additives, mixed on site with water alone.
Where is it used?
Deep concrete repairs and section enlargement on bridges, jetties, dams, tunnels, car parks, power stations and water-treatment structures, plus column and beam jacketing.
Why use it?
It flows and self-levels into congested formwork without vibration, compensates for shrinkage, and gains high strength (>=65 N/mm2 at 28 days) for load-bearing repairs.
How is it applied?
Poured or pumped into watertight formwork after mixing at a water:powder ratio of 0.14-0.16; lifts of 25-100 mm, with coarse aggregate added for thicker pours.
About Sika SikaRep Microcrete-4
SikaRep Microcrete-4 exists to solve a problem that ordinary repair mortar and hand-packed concrete cannot: rebuilding a deep, heavily congested section of reinforced concrete where you can neither trowel material in by hand nor get a poker vibrator between the bars. It arrives as a grey dry powder that already contains selected cement, graded fillers and aggregate, and the chemistry that makes it expand rather than shrink. On site you add only clean water, and for deeper lifts you introduce your own graded coarse aggregate. The result pours like a thick liquid, finds its own level around reinforcement, and cures into a dense, structurally sound concrete that bonds to the parent substrate.
For engineers and applicators across Delhi NCR and the wider Indian market, its appeal is practical. It removes the vibration step, which is exactly the step that fails on jacketing jobs and confined repairs. Because the mix is factory controlled, batch-to-batch consistency does not depend on a site gang guessing proportions. It is iron-free and chloride-free, so it will not seed corrosion in the very reinforcement you are trying to protect. As an authorised Sika distributor and applicator, Space Arc Engineering supplies genuine 30 kg bags with correct storage and batch traceability, and can advise on the associated bonding agents and rebar primers that make the repair last.
The technical insight
The defining feature is dual-stage expansion. A conventional cement mix loses volume as it hydrates and dries, and that plastic and drying shrinkage is what pulls a repair away from the parent concrete and opens a debonding plane. SikaRep Microcrete-4 counters this with additives that generate a controlled expansion of up to 4 percent (ASTM C1090) timed across the early hydration window, so the material stays in intimate contact with the substrate and the surrounding formwork instead of contracting away from it. Combined with a low water:powder ratio of 0.14-0.16, this yields a dense, low-permeability matrix that resists the chloride and water ingress which drives long-term deterioration. The self-compacting rheology comes from the graded particle packing and flow additives: the mix consolidates under its own weight, expelling entrapped air without a vibrator, which is why it can fill the narrow annulus behind a rebar cage in a column jacket. Strength development is rapid and high, reaching >=25 N/mm2 at one day and >=65 N/mm2 at 28 days, so a repaired member can be returned to service quickly.
Where it is used
- Deep localised repair of spalled or delaminated bridge beams, columns and slabs
- Column and beam jacketing where additional structural section is required
- Section enlargement to strengthen under-designed or overloaded members
- Encasement and build-up around congested reinforcement that cannot be vibrated
- Repair of marine and hydraulic structures such as jetties, wharves, dams and reservoirs
- Rehabilitation of tunnels, mines, car parks, basements and water-treatment structures
- Machine foundations, plinths and pile-tops needing dense flowable concrete
- Precast element repair and remaking of damaged concrete sections
Key advantages
- Self-compacting flow places without any vibration, ideal for congested reinforcement
- Dual-stage expansion (up to 4 percent) prevents shrinkage debonding from the substrate
- High strengths, >=65 N/mm2 at 28 days and >=25 N/mm2 at one day, for fast return to service
- Iron-free and chloride-free, so it does not promote reinforcement corrosion
- Single-component and water-activated, giving consistent, gang-proof site batching
- Low permeability resists chloride and water ingress in aggressive environments
- Pumpable over large areas with standard screw-feed and piston pumps
- Backed by third-party test data from Shriram Institute, IIT Bombay and IIT Delhi
Limitations & considerations
- Requires watertight, secure formwork on every pour; it cannot be trowel-applied like a patch mortar
- Layer thickness is limited to 25-100 mm per pour unless graded coarse aggregate is added
- Short pot life of about 20 minutes at 30 C means only full bags should be mixed and placed promptly
- Substrate and ambient temperatures must stay within +5 C to +40 C during placement
- Needs saturated-surface-dry substrate preparation plus a bonding agent and rebar anti-corrosion primer for durable adhesion
- Formwork must stay in place at least 3 days and exposed faces need proper curing
Selection & best practice
Success is decided before the first pour. Mechanically prepare the substrate to sound concrete using breakers, grit blasting or high-pressure water, then saturate it so it is damp but free of standing water. Clean the reinforcement of rust and scale and treat it with an anti-corrosion primer such as SikaTop Armatec-110 EpoCem, which also serves as the bonding agent on dense or large areas. Erect firm, watertight formwork with adequate pressure head. Mix with 80-90 percent of the measured water first, add the full bag while mixing, then bring in remaining water and any 5-10 mm aggregate; for lifts beyond 100 mm add graded 10 mm-down aggregate at 2:1 (powder:aggregate) by weight, and never add extra water beyond the 0.14-0.16 ratio. Pour continuously to maintain flow and displace air. Leave formwork in place for at least three days, then cure exposed faces immediately with Sika Antisol curing compound. In hot weather use cool water and cool storage to control the exotherm; in cold weather use warm water to sustain strength gain.
Specifications
| Chemical base | Portland cement, selected fillers and aggregates, special additives |
| Appearance / colour | Powder / grey |
| Compressive strength (ASTM C109) | >=25 N/mm2 (1d), >=45 N/mm2 (7d), >=65 N/mm2 (28d) |
| Flexural strength (ASTM C293) | >=8 N/mm2 (7d), >=9 N/mm2 (28d) |
| Splitting tensile strength (ASTM C496) | >=3.5 N/mm2 (28d) |
| Expansion (ASTM C1090) | Up to 4 %, no shrinkage after initial set |
| Water : powder ratio | 0.14-0.16 by weight (4.2-4.8 L per 30 kg bag) |
| Layer thickness / pot life | 25-100 mm per pour; pot life ~20 min at 30 C |
| Packaging / shelf life | 30 kg bag; 6 months in sealed packaging (+5 C to +35 C) |
Industry use cases
Bridges & Highways
Rebuilding spalled pier caps, beams and deck sections where chloride-driven corrosion has stripped cover concrete and vibration access is impossible.
Structural Strengthening
Column and beam jacketing to add section and capacity to under-designed or overloaded frames in retrofit and change-of-use projects.
Marine & Hydraulic
Deep repairs to jetties, wharves, dam faces and reservoir walls needing a dense, low-permeability concrete that resists water and chloride ingress.
Industrial & Power
Restoring machine foundations, plinths and power-station structures where rapid strength gain shortens plant downtime.
Underground & Parking
Rehabilitating tunnels, basements and multi-storey car parks with congested reinforcement that only a pourable microconcrete can encase.
Frequently asked questions
What is the compressive strength of SikaRep Microcrete-4?
How much water do I add per bag?
What thickness can I pour in one lift?
Does it need vibration or a bonding coat?
How is it different from a repair mortar like Sika MonoTop?
What is the pack size and shelf life?
How we position Sika SikaRep Microcrete-4
Within the Sika family, pair SikaRep Microcrete-4 with SikaTop Armatec-110 EpoCem as the rebar primer and bonding bridge, Sikadur-32 LP IN where an epoxy bonding coat suits dense substrates, and Sika Antisol curing compound after striking formwork; for shallow, trowel-applied patch repairs on the same structure, step down to a Sika MonoTop repair mortar rather than forcing a pourable grade into a thin section. For precision machine-base and baseplate grouting, move to SikaGrout-214 IN. Across our other brands, comparable flowable repair concretes include MC-Bauchemie and Master Builders Solutions microconcretes, and for waterproofing the completed repair we can supply Dr. Fixit and Fosroc protective systems.
Fosroc Renderoc RG — Specify the Fosroc option when the project is standardised on the Fosroc concrete-repair system or a specifier prefers a shrinkage-compensated microconcrete with a matched Fosroc primer and curing regime.
Related Concrete Repair products
Source Sika SikaRep Microcrete-4 for your project
Authorised distribution, technical advice & professional application across Delhi NCR and Pan-India.