About Fosroc Renderoc HB30

Fosroc Renderoc HB30 is a high-performance, fibre-reinforced, lightweight concrete reinstatement mortar that forms part of Fosroc’s well-established Renderoc concrete repair range. It is certified to BS EN 1504-3 as a Class R3 structural and non-structural repair material, covering the principal repair methods 3.1, 3.3, 7.1 and 7.2 used across the rehabilitation industry. The product reaches Indian sites as a single pre-bagged blend of Portland cements, graded aggregates, lightweight fillers, fibres and chemical additives, so the contractor only adds clean water on site, removing the batching variability that plagues site-mixed sand-cement repairs. Renderoc HB30 was developed specifically for vertical and overhead patch repairs. Its low density (nominally 1700 kg/m3 fresh wet density) is the defining feature: a lightweight mortar sags far less under its own weight, which is exactly what lets it be built up in unusually thick lifts without sliding off a column face or dropping off a soffit. In practice this means sections up to 85 mm thick on vertical surfaces and up to 75 mm thick on overhead surfaces can be placed in a single application, frequently without any formwork. The minimum applied thickness is 10 mm. Where greater depth is needed, layers are built up with intermediate scratch-keying and re-priming, or formwork is introduced. The polymer modification gives the cured mortar extremely low permeability to water, carbon dioxide and chlorides, so it does not merely fill a defect but actively retards the corrosion mechanisms that caused the damage in the first place. An engineered shrinkage-compensation system supports long-term dimensional stability and reduces the cracking and debonding that undermine cheaper repairs. For Indian RCC structures, marine and coastal exposure, parking decks, water-retaining structures and industrial buildings, HB30 sits in the practical sweet spot of the Renderoc family, prioritising durability and high-build placement over the very high compressive strength offered by stronger siblings.

The technical insight

The number to understand is density, not strength. At a nominal fresh wet density of about 1700 kg/m3, Renderoc HB30 is materially lighter than a conventional repair mortar (typically 2000-2200 kg/m3). Less self-weight means less shear stress at the bond line while the mortar is still green, which is precisely why it can hold 85 mm vertically and 75 mm overhead in one lift without slumping. The trade-off is deliberate: at 30 MPa compressive strength at 28 days (10 MPa at 1 day, per EN 12190) it is tuned for compatibility with parent concrete in the 20-35 N/mm2 class, not for abrasion or traffic loading. Where higher strength is the governing requirement, Fosroc’s own Renderoc HB45 (45 MPa) is the correct step up, and for trafficked horizontal repairs Renderoc S is specified instead. The mortar is governed by a tightly controlled water:powder ratio of 0.18 (3.8-4.2 L per 22 kg bag); over-watering to improve trowelability is the single most common site error and directly lowers strength and durability. Two priming systems are non-negotiable for performance: Nitoprime Zincrich Plus over exposed, cleaned reinforcement for active anti-corrosion protection, and Renderoc Primer (a two-part bonding slurry, 3:1 by volume Part A:Part B) scrubbed into a saturated-surface-dry substrate to secure the 1.8 MPa pull-off bond. Curing with Nitobond AR sprayed as a continuous film is part of the system, not optional.

Where it is used

• Reinstatement of spalled and delaminated cover concrete on columns, beams and walls in RCC buildings
• Overhead soffit repairs to floor slabs, bridge decks, flyovers and parking-structure ceilings
• Repair of carbonation-induced and chloride-induced corrosion damage to reinforced concrete
• Rehabilitation of marine, coastal and water-retaining structures where low chloride/water permeability is required
• Patch repair of facades, chajjas, balconies and parapets on residential and commercial high-rise
• Sewage and effluent treatment structures and industrial buildings exposed to aggressive acid gases
• Vertical and overhead repairs in metro, infrastructure and heritage RCC rehabilitation projects

Key advantages

• Lightweight formulation allows extra-high build (up to 85 mm vertical, 75 mm overhead) in a single pass
• Frequently eliminates the need for formwork, speeding up vertical and overhead repairs
• Fewer cold joints than conventional mortars on deep sections
• Polymer modification delivers very low permeability to water, carbon dioxide and chlorides
• Engineered shrinkage compensation for long-term dimensional stability (<300 microstrain at 7 days)
• One-component, pre-bagged supply removes site-batching variation and quality risk
• Can be placed efficiently by wet-spray for large areas, improving density and bond
• Contains no chloride admixtures and is non-combustible (Reaction to fire Class A2)
• BS EN 1504-3 Class R3 certified, supporting consultant and tender specification

Limitations & considerations

• Not intended for high-strength applications; specify Renderoc HB45 where 45 MPa is required
• Unsuitable for trafficked horizontal surfaces due to its lightweight nature; use Renderoc S instead
• Minimum applied thickness of 10 mm must be respected for performance
• Must not be applied when temperature is below 5C and falling, or to part-mixed bags
• Should not be exposed to moving water during application; heavy rain before final set can cause surface scour
• Strictly limited to a water:powder ratio of 0.18 (3.8-4.2 L per bag); over-watering degrades strength and durability
• Requires a forced-action mixer and correct priming/curing system to achieve stated properties
• Shelf life of 12 months reduces to under 6 months in high heat/humidity, a real concern for Indian storage

Selection & best practice

Specifications

Industry use cases

How we position Fosroc Renderoc HB30

Within the Fosroc Renderoc concrete-repair range, HB30 is the lightweight, high-build vertical and overhead specialist. Step up to Renderoc HB45 when 45 MPa compressive strength governs, choose Renderoc S for trowel-applied general and trafficked horizontal repairs, and reach for the flowable Renderoc RG micro-concretes for formed, congested or deeper reinstatement. The system partners are equally important to specify: Nitoprime Zincrich Plus for steel protection, Renderoc Primer (or Nitobond EP) for bonding, Nitobond AR for curing, and the Dekguard anti-carbonation range for protecting the surrounding structure. Against competitors, HB30 maps closely to Sika MonoTop and SikaRep lightweight R3 repair mortars, MBS (MYK/BASF lineage) MasterEmaco S-series structural mortars, Dr. Fixit Pidicrete/Krystaline repair systems, and STP (Krishna Conchem) Cico-branded polymer repair mortars. For an Indian consultant or contractor, the practical case for HB30 rests on its proven EN 1504-3 R3 certification, its genuinely lightweight high-build behaviour that cuts formwork and labour on overhead and vertical work, and the reliability of a complete, single-source Fosroc repair system. Space Arc Engineering, as an authorised Fosroc distributor and applicator across Delhi NCR and Pan-India, supplies HB30 with the full system and on-site technical support.

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