Dr. Fixit Repair Polymer Mortar
EN 1504-3 Class R4 structural repair mortar for high-strength, shrinkage-free reinstatement of RCC beams, columns and slabs — supplied and applied by Space Arc Engineering across Delhi NCR.
What is it?
A single-component, cementitious, fibre-reinforced and polymer-modified structural repair mortar (technical name Dr. Fixit Polymer Mortar HB) mixed with water on site and trowelled or sprayed onto damaged RCC.
Where is it used?
Spalled or corroded RCC columns, beams, slabs and soffits in residential towers, flyovers, industrial sheds, water tanks and marine/coastal structures.
Why use it?
Meets EN 1504-3 Class R4, the highest structural repair classification, with dual shrinkage compensation that resists the cracking and debonding common with ordinary patch mortars.
How is it applied?
Mechanically mixed with 4.25–4.50 L water per 25 kg bag, then hand-trowelled or wet-spray applied in layers up to 30 mm vertical or 20 mm per overhead lift, over a pre-soaked, mechanically profiled substrate.
About Dr. Fixit Repair Polymer Mortar
Dr. Fixit Repair Polymer Mortar — carried on Pidilite’s technical data sheet as Dr. Fixit Polymer Mortar HB, under the brand’s professional “Repair Pro” range — is a factory-proportioned, single-component cementitious mortar built from graded fillers, polymer additives and engineered acrylic fibres. It ships as a grey free-flowing powder in 25 kg bags; site crews add 4.25–4.50 litres of water per bag, mix mechanically for 3–5 minutes, and trowel or wet-spray it onto prepared concrete. The acrylic fibre loading gives it what the datasheet calls “dual shrinkage compensation” — engineering language for a mortar built to resist both plastic and drying shrinkage cracking, the single biggest cause of debonded patch repairs on Indian sites.
For Space Arc’s project sites across Delhi NCR, this is the mortar we specify when a column, beam or soffit has genuinely lost structural section, not for cosmetic plaster patching. It carries EN 1504-3 Class R4 classification, the highest structural repair grade in the European performance standard that Indian consultants now routinely reference in RCC rehabilitation, flyover and industrial retrofit tenders. Being chloride-free with no metallic aggregate, it is also a sound choice around exposed reinforcement in coastal and high-humidity environments, provided the rebar itself is first treated with a compatible anti-corrosive primer.
The technical insight
Two details in the datasheet matter more than the headline strength figure. First, the water:powder ratio is tightly banded at 0.17–0.18 by weight — leaner than a typical site-mixed repair mortar — because Class R4 performance depends on a dense, low-porosity matrix; the common site habit of adding “a little extra water for workability” measurably cuts both strength and the ≤0.31 kg/m²·h⁰·⁵ capillary-absorption result the product is certified against. Second, two figures appear for 28-day compressive strength — ≥45 N/mm² to BS 6319 and 46.29 MPa to EN 12190 — because the product is validated against both British and European test methods; specifiers writing to either standard can quote the matching figure rather than treating the two as inconsistent.
Where it is used
- Repair of reinforced or pre-stressed RCC beams, columns and slabs that have lost section to spalling or rebar corrosion
- Overhead and vertical patch repair of soffits, ceilings, balconies and building facades without formwork
- Reinstatement of structural members under repetitive or dynamic loading, e.g. flyover piers, bridge decks, industrial gantries
- Resurfacing of tunnels, retaining walls and water tanks ahead of a protective or waterproofing topcoat
- Restoring concrete cover over corroded reinforcement in coastal, marine and jetty structures
- Fast-turnaround structural repair in factory and warehouse sheds where quick strength gain limits downtime
- Column and beam section reinstatement as part of a wider structural strengthening or jacketing scope
- Substrate build-up before applying a Dr. Fixit waterproofing or protective coating system on rehabilitated RCC
Key advantages
- Genuine EN 1504-3 Class R4 structural classification, not a cosmetic filler mortar marketed as a repair product
- Dual shrinkage-compensated acrylic fibre system cuts the cracking and edge debonding common with plain cement:sand patch repairs
- High early strength (≥15 N/mm² at just 1 day) lets crews reload or move to the next trade faster
- Chloride-free with no metallic aggregate, so it will not accelerate corrosion of adjacent or newly exposed rebar
- Trowel- or spray-applied in layers up to 30 mm vertical / 20 mm per overhead lift, fewer passes on deep sections
- Low capillary absorption (≤0.31 kg/m²·h⁰·⁵) gives useful durability once cured in wet, humid or marine exposure
- Single-component, factory-proportioned powder leaves less room for on-site batching error than multi-pack epoxy systems
- Documented third-party test data (BS 6319, EN 1504/1542/12190/12617/13687/13057) that consultants can sign off on institutional projects
Limitations & considerations
- Needs mechanical mixing (slow-speed drill with paddle, or forced-action mixer) — not a bucket-and-trowel product for small DIY patches
- Water:powder ratio is unforgiving; over-watering for easier workability directly cuts strength and durability
- Working life is only about 45 minutes after mixing, so batch size must match the crew’s actual placement speed
- Substrate must be pre-soaked for at least 2 hours, ideally 24, so it is not a same-hour, walk-up repair
- Application is temperature-bound (10–35°C substrate/ambient); very cold or peak-summer conditions need scheduling around
- It is a structural repair mortar, not a waterproofing membrane — water-exposed repairs still need a compatible topcoat
Selection & best practice
Mechanically profile and thoroughly clean the substrate (abrasive blasting or waterjetting, not just a wire brush), pre-soak for at least 2 hours — ideally 24 — and prime any exposed rebar with Dr. Fixit Zinc Rich Primer before placing mortar. Mix strictly at 4.25–4.50 litres of water per 25 kg bag; never add extra water for workability. Place in layers no thicker than 30 mm vertical or 20 mm per overhead lift, wet-on-dry between lifts, and mist-cure with water or damp burlap for the first 24 hours. Keep any curing compound on for the full 28 days and remove it completely before the next finish or waterproofing coat.
Specifications
| System / chemistry | Single-component, cementitious, fibre-reinforced, polymer-modified structural repair mortar |
| Standard compliance | EN 1504-3 Class R4 structural repair mortar |
| Water : Powder ratio | 0.17–0.18 by weight (4.25–4.50 L water per 25 kg bag) |
| Compressive strength, 28 days | ≥45 N/mm² (BS 6319 Pt.2); 46.29 MPa (EN 12190) |
| Bond strength, 28 days | ≥2 N/mm² (EN 1542); 2.44 MPa achieved without primer |
| Flexural / Tensile strength, 28 days | ≥8 N/mm² flexural / ≥4.5 N/mm² tensile (BS 6319 Pt.3 & 7) |
| Application thickness | 10 mm min; 30 mm/layer vertical; 40 mm in 2 x 20 mm layers overhead |
| Coverage / yield | ≈1.4 m² per 25 kg bag at 10 mm thickness; ~14 litres yield per bag |
| Pack size & shelf life | 25 kg bag; 6 months from manufacture, unopened, stored cool and dry |
Industry use cases
Residential RWA / society repair
Column and beam spalling repair in older Delhi NCR apartment blocks where rebar corrosion has reduced concrete cover, ahead of terrace or basement waterproofing.
Infrastructure / bridges
Structural reinstatement of flyover piers, deck soffits and retaining walls subject to vibration and repetitive traffic loading.
Industrial / warehousing
Fast-turnaround column and slab-edge repair in factory sheds, where 1-day strength gain lets operations resume with minimal downtime.
Water & wastewater structures
RCC repair of overhead tanks, STPs and retaining structures before internal waterproofing, chosen for its chloride-free, low-permeability profile.
Marine / coastal RCC
Jetty and coastal structure repair where corrosion resistance and low capillary absorption matter more than material cost.
Frequently asked questions
Is this a waterproofing product?
Can our mason apply it by hand, or do we need spray equipment?
How thick can one layer be?
Do we need to prime exposed rebar first?
How long before the repair can be painted or waterproofed over?
What does one 25 kg bag cover?
How we position Dr. Fixit Repair Polymer Mortar
Within the Dr. Fixit range, Repair Polymer Mortar (Polymer Mortar HB) is the structural-rebuild step of a wider repair system. Space Arc typically pairs it with Dr. Fixit Zinc Rich Primer on corroded rebar, Dr. Fixit Pidicrete MPB/URP as a bonding or scratch coat on porous or poured concrete, and a Dr. Fixit Crack X or Raincoat-range waterproofing coat once the structural repair has cured — so one crew and one warranty cover the full spalling-to-waterproofing scope. On institutional tenders that name two approved manufacturers, Fosroc’s Renderoc HB45 is the genuine equivalent for this same Class R4 repair scope.
Fosroc Renderoc HB45 — A genuine like-for-like: also a single-component, fibre-reinforced, polymer-modified EN 1504-3 Class R4 repair mortar for the same beam/column/soffit scope, and a specifier might choose it where the project’s approved-vendor list already names Fosroc or where its build depth (up to 80 mm vertical / 70 mm overhead per pass) better suits the repair profile.
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