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

Specifications

Industry use cases

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.

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