UltraTech Microkrete HS1
The micro-concrete engineers reach for when a repair has to carry real structural load, not just look patched up.
What is it?
A single-component, polymer-modified micro-concrete from UltraTech’s Microkrete range, factory-proportioned so the only site addition is clean water, engineered to a designed compressive strength of around 80 MPa.
Where is it used?
Column and beam jacketing, bridge pier and flyover rehabilitation, dam and port structures, corroded-reinforcement encasement, and any RCC section where the rebar cage is too congested for conventional concrete to reach.
Why use it?
It flows into tight, heavily reinforced formwork under its own weight, bonds firmly to the old concrete and steel it’s cast against, and hardens into a dense, low-permeability repair that is built to match or exceed the parent structure’s strength.
How is it applied?
Site crews mix it with a measured quantity of water to a flowable consistency, pour or pump it into rigid, grout-tight shuttering with proper vent points, and follow up with wet or compound curing until the repair has gained its full strength.
About UltraTech Microkrete HS1
UltraTech Microkrete HS1 sits at the top of UltraTech’s three-grade Microkrete range, positioned specifically for repairs where the designer has called out a genuine structural strength target rather than just cosmetic reinstatement. It is a cement-based system built up with polymers and graded fillers, supplied as a single dry-powder bag that only needs water on site — there’s no second component to weigh out, no admixture to dose separately, and no room for a site crew to accidentally under- or over-proportion the mix. That factory control matters more than it sounds: on a jacketed column or a pier cap repair, strength consistency from one batch to the next is what an engineer is actually signing off on when they specify a micro-concrete over a hand-applied mortar.
What separates a micro-concrete like HS1 from an ordinary repair mortar is how it’s placed. Repair mortars are trowelled or sprayed onto a surface in layers; micro-concrete is poured or pumped into a mould, the way you’d cast fresh concrete, except the section is usually too congested with rebar, too thin, or too inaccessible for a normal concrete mix to fill without leaving voids. HS1’s free-flowing, self-compacting behaviour is what makes that possible — it finds its way around tie bars, stirrups and lapped reinforcement without a vibrator, and because it’s non-shrink, it stays in intimate contact with the surrounding concrete and steel as it cures rather than pulling away at the interface. For Space Arc’s customers across Delhi NCR and beyond, that’s the difference between a repair that’s still performing structurally ten years later and one that needs revisiting.
The technical insight
The 80 MPa target is reached through three things working together, not one clever additive. First, the polymer modification in the binder system improves the bond between the fresh micro-concrete and the old, often carbonated or chloride-contaminated substrate it’s cast against — this interface is usually the weakest point in any concrete repair, and polymers close that gap mechanically as well as chemically. Second, the mix is engineered with graded fillers and, where volumes justify it, up to 8 mm coarse aggregate; this controls the heat of hydration and drying shrinkage that would otherwise crack a large-volume pour, while keeping material cost sensible compared to running neat micro-concrete without aggregate extension. Third, the rheology is tuned so the mix stays fluid and self-levelling long enough to be poured through restricted access points and flow around dense reinforcement, then sets without segregation or bleeding. Together, this is what lets a repair section reach a strength grade that’s often higher than the original concrete it’s replacing — which is exactly the point when the repair is meant to restore or upgrade structural capacity, not just cover a defect.
Where it is used
- RCC column and beam jacketing for strength upgrades or seismic retrofit
- Structural repair of bridge piers, pier caps and flyover soffits
- Repair of heavily congested, high-rebar-density sections
- Dam, spillway, port and marine structure rehabilitation
- Encasement of corroded or newly replaced reinforcement
- Machine foundation and heavy-duty industrial floor repair
- Large-volume micro-concreting where an 80 MPa design strength is specified
- Structural sections exposed to sustained moisture or chloride attack
Key advantages
- Reaches a designed compressive strength of around 80 MPa, the highest grade in UltraTech’s Microkrete range
- Self-compacting and free-flowing, so it fills congested cages without a vibrator
- Accepts up to 8 mm coarse aggregate for larger, more economical pours with lower shrinkage
- Polymer-modified for genuine bond strength to both old concrete and reinforcing steel
- Non-shrink formulation that keeps the repair in full contact with the substrate as it cures
- Dense, low-permeability matrix that resists water and chloride ingress after curing
- Single-component bag mix removes on-site proportioning errors between binder and admixture
- Compressive strength verifiable to IS 5816, so QA/QC teams have a standard test method to cite
Limitations & considerations
- Needs rigid, grout-tight formwork with pour and vent points properly designed in — poor shuttering is the most common cause of a failed pour
- It’s a pour/pump product, not a trowel-applied patch — crews need casting experience, not just plastering skill
- Costs meaningfully more per bag than a general-purpose repair mortar or plain concrete, and that premium is only justified when 80 MPa is genuinely required
- The pour has to be continuous through to completion; stopping partway risks a cold joint at the strength-critical interface
- Wet or compound curing is not optional — skipping it undermines the very strength gain the product is bought for
- Adding coarse aggregate changes the mix’s flow behaviour, so proportions should follow the manufacturer’s guidance rather than site improvisation
Selection & best practice
Start with the substrate, not the mix: cut back to sound concrete, expose and clean any corroded reinforcement, and bring the surface to a saturated-surface-dry condition before shuttering goes up. Formwork has to be genuinely grout-tight — even small gaps let the flowable mix escape and leave honeycombing behind — and it needs pour points positioned to keep the head of material low enough to avoid segregation, plus vent points at high spots so trapped air has somewhere to go. Mix only with clean water, to the consistency the datasheet calls for, and pour in one continuous operation from a single point wherever the geometry allows, working the material along the form rather than dropping it from height. Where coarse aggregate is being added for a larger pour, get the proportioning right before the pour starts — this isn’t something to eyeball mid-batch. Once placement is done, curing is where a lot of otherwise good pours lose strength: keep the surface wet or apply a compatible curing compound for the full period specified, particularly in Delhi NCR’s dry, hot pre-monsoon months when surface moisture disappears fast. Space Arc’s site teams handle formwork review, trial pours and curing supervision alongside supply, which is usually where a marginal repair turns into a reliable one.
Specifications
| Product type | Single-component, polymer-modified micro-concrete |
| Designed compressive strength | ~80 MPa (HS1 grade) |
| Form | Grey, factory-blended dry powder |
| Mixing | Site addition of clean water only |
| Approximate water demand | ~15% by weight of powder (confirm with trial mix) |
| Maximum coarse aggregate | Up to 8 mm, for extended-volume placements |
| Placement method | Self-compacting; pour or pump; no vibration required |
| Shrinkage behaviour | Non-shrink |
| Pack size | 40 kg bag |
| Test standard for strength | IS 5816, with relevant ASTM methods referenced in manufacturer literature |
Industry use cases
Bridges and flyovers
Pier, pier cap and soffit jacketing on live corridors, where fast turnaround and minimal traffic disruption matter as much as final strength.
Industrial and manufacturing
Machine foundation and heavy floor repairs that have to go back into service under continuous production loads.
Marine and port infrastructure
Jetty, berth and quay wall rehabilitation in chloride-laden environments where low permeability is a durability requirement, not a nice-to-have.
High-rise residential and commercial
Column strengthening for load upgrades, additional floors, or seismic retrofit where the repair section must genuinely out-perform the original design strength.
Water infrastructure
Dam, spillway and canal structure repairs exposed to sustained water contact and abrasive flow.
Frequently asked questions
What does the “HS1” in the name actually mean?
Do I need to vibrate it during placement?
Can I add coarse aggregate to any pour?
What kind of formwork does it need?
Is it suitable for marine or underwater structures?
How soon can the repaired section be loaded?
How we position UltraTech Microkrete HS1
Within UltraTech’s own Microkrete family, HS1 is the top-strength option — step down to HS2 (~60 MPa) or HS3 (~40 MPa) where the structural repair doesn’t demand 80 MPa, since both cost less and are easier to justify on smaller jacketing jobs. For surface-level patch repair that doesn’t need a poured micro-concrete section at all, UltraTech Basekrete is the more appropriate (and more economical) Space Arc product. Where the specification calls for a BS EN 1504-compliant system instead of an IS/ASTM one, Fosroc’s Renderoc range — also on Space Arc’s line card — covers similar free-flowing, non-shrink micro-concrete territory. Our technical team can walk through the actual strength requirement on your drawings before you commit to a grade or a brand.
Fosroc Fosroc Renderoc RG — Renderoc RG is Fosroc’s equivalent single-component, free-flowing, non-shrink micro-concrete for congested-reinforcement jacketing and large-volume repairs, and it’s the closer BS EN 1504 route if your specification is written to that standard rather than IS/ASTM. It isn’t a strength-for-strength match, though — Renderoc RG’s published strength sits well below HS1’s ~80 MPa design target, so it lines up more closely with UltraTech Microkrete HS2 territory. Where 80 MPa is a hard structural requirement, HS1 remains the product to specify; talk to us if you’re comparing the two against your drawings.
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