UltraTech Microkrete HS2
A pour-in, self-compacting micro concrete that reaches around 60 MPa in the tightest, most heavily reinforced repair sections.
What is it?
A polymer-modified, single-bag cementitious micro concrete that mixes to a flowable, self-compacting consistency and cures to a design strength of around 60 N/mm² — built for RCC sections where conventional concrete can’t get past the reinforcement cage.
Where is it used?
Column and beam jacketing, bridge pier and girder repair, dam and port structure rehabilitation, and any congested RCC member that needs structural-grade concrete poured into a tight, shuttered space.
Why use it?
It flows to every corner of the shutter without vibration, bonds firmly to old concrete and exposed rebar, and sets without the shrinkage cracks or weak bleed-water layers that undermine hand-packed repair mortars.
How is it applied?
Powder is mixed with 11-13% water by weight (6-8% if extended with 8 mm aggregate) in a mechanical mixer, then poured or pumped into a leak-tight shutter through funnels or chutes — no vibration, ever.
About UltraTech Microkrete HS2
UltraTech Microkrete HS2 sits in the middle of UltraTech’s three-grade Microkrete range — polymer-enriched, cement-based micro concretes built for micro-concreting and jacketing work rather than general construction. Where ready-mix concrete needs room for 20 mm aggregate to move around reinforcement, Microkrete HS2 is fine enough, and rheologically engineered enough, to flow through steel cages, form corners and thin repair sections under its own weight. It arrives as a single bag — cement, polymers, additives and graded fillers already proportioned — so there’s no separate sand, aggregate or admixture dosing to get wrong on site, only accurate water measurement.
That combination makes it a natural fit for structural jacketing and rehabilitation across Delhi NCR and pan-India sites: RCC columns and beams that have lost section to corrosion, bridge piers and girders due for load restoration, dam and port structures worn down by years of moisture and chloride exposure. Contractors extend it with well-graded aggregate up to 8 mm, at up to 1:1 by weight, for larger pours without giving up flow or strength — useful once a jacketing job runs into several cubic metres and every kilogram of micro concrete costs more than site-batched ready-mix.
The technical insight
The strength and the flow both trace back to the same design choice: a tightly controlled water demand (11-13% of powder weight, dropping to 6-8% once aggregate is blended in) combined with polymer modification and graded mineral fillers. The polymers improve paste cohesion and bond to old concrete and steel, which is why the mix shows nil bleeding and nil restrained expansion on test — no free water rising to leave a weak plane, and no shrinkage gap opening at the repair interface as it cures. Because the mix is engineered to self-level and self-compact, vibration is actively discouraged: shaking a paste this fine tends to separate fillers from binder rather than consolidate them. The trade-off is a firm 60-minute pot life — once water goes in, the batch has to be placed within the hour.
Where it is used
- Column and beam jacketing to restore or boost load capacity
- Micro-concreting of congested RCC members past dense reinforcement
- Bridge pier, girder and deck section repair
- Rehabilitation of distressed concrete in dams, ports and marine structures
- Reinforcement encasement after corrosion removal and anti-corrosion treatment
- Filling voids, honeycombing and spalled sections in structural members
- Structural strengthening of industrial frames and load-bearing slabs
- Large-volume repairs extended with 8 mm aggregate for economy
Key advantages
- Single-bag system — no separate site batching of ingredients
- Self-compacting flow reaches congested steel without vibration
- Design compressive strength of around 60 N/mm² at 28 days
- Non-shrink, non-expansive — nil restrained expansion on test
- Nil bleeding, so no weak water plane forms in the pour
- Strong bond to existing concrete and reinforcement steel
- Extendable 1:1 by weight with 8 mm aggregate for economy
- Ready for loading or finishing in as little as 24 hours
Limitations & considerations
- Not a substitute for structural design — get repair scope certified by a structural engineer
- Strength and bond fall sharply if water exceeds 11-13% (6-8% with aggregate)
- Cannot be placed below 5°C or above 50°C; needs extended cure below 20°C
- Requires genuinely leak-tight shuttering — any gap drains the flowable mix
- 60-minute pot life leaves a narrow working window once mixed
- Costs more per kg than site-batched concrete, though aggregate extension narrows this on large pours
Selection & best practice
Start by cutting back to sound concrete and removing oil, laitance, dust and loose material — wire brushing, water jetting or mopping, whichever the surface needs. Treat exposed or added reinforcement with an anti-corrosion coating before closing the shutter, and check the formwork itself: it has to be tight enough that not a drop of the flowable mix escapes, since any gap wastes material and lets the mix lose compaction at that point. Mix with 11-13% water by weight (6-8% with aggregate) in a mechanical mixer to a lump-free consistency, let it stand two minutes to mature, then remix briefly before pouring — never add water later to loosen the mix, since that erodes strength and bond. Pour through funnels or chutes into the lowest point of the shutter and let the material find its own level; do not vibrate. Hold the pour for a minimum of 24 hours before loading, longer if site temperatures sit below 20°C.
Specifications
| Chemistry | Polymer-modified, cement-based micro concrete |
| Compressive strength (28 days) | Around 60 N/mm² design strength |
| Flexural strength (28 days) | 10 N/mm² |
| Tensile strength (28 days) | 5 N/mm² |
| Split tensile strength (28 days) | 3 N/mm² |
| Wet density | 2250-2350 kg/m³ |
| Bulk density | 1500-1650 kg/m³ |
| Water demand (neat) | 11-13% by weight |
| Water demand (with aggregate) | 6-8% by weight |
| Aggregate extension | Up to 8 mm well-graded, up to 1:1 by weight |
| Pot life | Approx. 60 minutes |
| Time to subsequent loading | Minimum 24 hours |
| Bleeding (ASTM C940) | Nil |
| Restrained expansion | Nil |
| Abrasion resistance (IS 1237) | 0.35 mm |
| Rapid chloride penetration (ASTM C1202) | Moderate |
| Standards compliance | ASTM C109, C580; IS 5816:1999, IS 1237:2012 |
| Placement temperature range | 5°C to 50°C |
| Shelf life | 6 months from manufacture, stored cool and dry |
| Pack sizes | 25 kg and 40 kg bags |
Industry use cases
Bridges & Flyovers
Pier, girder and deck-section repair on rehabilitation works across Delhi NCR, where fast, vibration-free placement matters
Industrial & Factory Structures
Column and beam jacketing to restore load capacity on RCC frames damaged by corrosion or impact
Dams, Ports & Marine Structures
Rehabilitation of concrete exposed to sustained moisture, tidal action and chloride attack
Residential & Commercial RCC Retrofit
Beam and column strengthening after fire, seismic distress or long-term corrosion
Infrastructure & Metro Structures
Encasement repairs on heavily reinforced sections conventional concrete can’t reach
Frequently asked questions
What’s the difference between Microkrete HS1, HS2 and HS3?
Can I add extra water if the mix feels stiff?
Does it need to be vibrated after pouring?
Can aggregate be added for large-volume repairs?
How soon can the repair take load?
How we position UltraTech Microkrete HS2
Microkrete HS2 is the mid-strength option in UltraTech’s three-grade Microkrete range — pair it with Microkrete HS1 for less critical, lower-load repairs, or step up to HS3 where the design calls for the highest strength grade in the family. For grouting rather than pour-in jacketing, UltraTech’s Basekrete range covers precision and construction grouting on the same sites. Space Arc also stocks Fosroc’s equivalent flowable microconcrete for teams standardised on that brand, and we typically pair any Microkrete jacketing job with an anti-corrosion primer on the exposed rebar and, where the structure sees water, a protective waterproofing coat over the finished section.
Fosroc Fosroc Renderoc RG — Renderoc RG is Fosroc’s equivalent single-component, flowable microconcrete for congested jacketing work — it’s documented at around 50 N/mm² compressive strength, a touch below Microkrete HS2’s ~60 N/mm², so specify by your load calculation rather than by brand alone.
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