Dr. Fixit Pidicrete URP — SBR Latex Polymer Admixture and Bonding Agent for Repair Mortars, Screeds and Waterproof Slurries
Pidilite’s multipurpose SBR latex — a liquid admixture, not a mortar. One drum turns site-mixed cement into bonding coats, polymer-modified repair mortars, waterproof slurries and hardened screeds.
What is it?
A single-component styrene-butadiene rubber (SBR) latex from Pidilite, supplied as a milky-white free-flowing liquid that is mixed with cement to make bond coats, waterproof slurries and polymer-modified mortars. It is an admixture and bonding agent, not a ready-mixed repair mortar.
Where is it used?
Spalled concrete patches on floors, columns, beams, chhajjas, slabs and parapets; sunken portions of toilets and bathrooms; small terraces, balconies and lift pits; waterproof renders on plinths and retaining walls; plaster, render and cladding bonding.
Why use it?
Plain cement slurry keys poorly to old, carbonated concrete and shrinks as it cures. SBR modification typically lifts bond strength from 0.3–0.5 MPa to 0.8–1.5 MPa, cuts water absorption by 60–70% and adds roughly 50% flexural strength, and the product complies with BS 6319 Part 2:1983 and ASTM C190-85.
How is it applied?
Blended with cement by volume (1:1 for bond coats, 1:1.5 for waterproof slurries) or dosed at 12–15% by weight of cement into mortars and screeds, then brush-applied or trowelled onto a prepared, pre-wetted substrate — always overlaid while the bond coat is still tacky.
About Dr. Fixit Pidicrete URP (SBR Latex)
Dr. Fixit Pidicrete URP (product code 301, and listed on Pidilite’s own product sheets as Dr. Fixit 301 Pidicrete URP) is a modified styrene-butadiene latex from Pidilite Industries, supplied ready to use in liquid consistency. Indian specifiers and site teams almost always ask for it simply as Dr. Fixit SBR, and that is exactly what it is: an SBR latex admixture and bonding agent, gauged into ordinary cement rather than used neat or applied as a standalone mortar. It is the material an experienced mason reaches for when new work must grip old — fresh plaster over aged concrete, a patch on a spalled chhajja, or a slurry coat sealing pinholes before waterproofing. Mixed into cement, the latex cuts drying and ageing shrinkage, improves flexural strength and surface hardness, and bonds tenaciously to concrete, masonry, stone and plaster. It meets the requirements of BS 6319 Part 2:1983 and ASTM C190-85.
Its real value on an Indian site is versatility — one drum, three jobs. The same pack works as a 1:1 bonding primer, a 1:1.5 waterproofing slurry for sunken slabs and small terraces, a mortar modifier at 6–7.5 kg per 50 kg cement bag for repairs and screeds, and a fluidity improver for cement injection grouts. That flexibility is why it turns up as often on a mason’s material list for a chhajja repair as it does on a contractor’s BOQ for a full column rehabilitation.
For our Delhi NCR client base, URP earns its place on the truck because it addresses the single most common repair failure we see on site inspections: a patch that looks fine on handover day and delaminates by the next monsoon because the applicator skipped the bonding coat or used a weak, unmodified slurry. Correctly gauged and applied wet-on-wet, URP gives new concrete or plaster a genuine mechanical and chemical key into the old substrate, and the same latex film that improves adhesion also cuts water absorption — useful on bathroom floors, terrace patches and any RCC element exposed to Delhi’s wide temperature swings and monsoon saturation cycles. Space Arc Engineering supplies genuine Pidilite stock in every pack size from 200 g trial packs up to 20 kg site drums, with 50 kg drums against order, and backs supply with method statements and application guidance for contractors, societies and consultants across Delhi NCR and Pan-India.
The technical insight
SBR latex is a dispersion of sub-micron rubber particles carried in water at 38 ± 1% solids. While the mix is fresh, those particles ride along in the pore water; as hydration consumes water and the rest evaporates, they are forced together and coalesce into a continuous polymer film threaded through the hardening cement paste, creating a cement-polymer co-matrix. The flexible polymer strands bridge microcracks as shrinkage stresses build, which is why modified mortars show higher flexural strength and far fewer plastic and drying-shrinkage cracks than neat cement mixes. The same film blocks capillary pores, reducing water permeability and slowing the erosion and rebar-corrosion mechanisms that destroy repairs. At the bond line, the tacky polymer wets old concrete much more completely than plain cement slurry and physically keys into the pore structure of the hardened substrate, so mortar placed over a still-tacky URP bond coat keys into the substrate rather than sitting on it.
Two consequences follow for site practice. First, because URP is a styrene-butadiene co-polymer rather than a simple PVA (polyvinyl acetate) homopolymer, the cured film resists re-emulsification if it gets wet again — which is precisely why it is acceptable on a bathroom floor or an exposed chhajja that will see water for decades, where a PVA bonding agent would soften. Second, dosage and curing discipline matter more here than with plain mortar: below the recommended 12–15% by weight of cement the film is discontinuous and the benefits largely disappear, and because the film only forms as water leaves the mix, prolonged ponding or continuous water curing actively works against the material.
Where it is used
- Patch repair of spalled or honeycombed concrete on floors, columns, beams, chhajjas, slabs and parapets
- Bonding primer for joining new concrete or plaster to old concrete and masonry
- Plastering bond coat on smooth, hardened concrete such as exposed beams and lift shafts before re-plastering
- Waterproofing slurry coats for sunken portions of toilets and bathrooms, small terraces, balconies, chhajjas and lift pits
- Polymer-modified repair mortars and renders in 5–25 mm thickness
- Weatherproof, frost-resistant external rendering, and waterproof renders on plinths, retaining walls and external basement faces
- Modified floor screeds and PCC toppings in 10–40 mm thickness
- Bonding new concrete toppings, IPS floors or tile screeds to old, hardened slabs
- Bedding and re-fixing of slip bricks, tiles, stone and marble cladding
- Site-mixed tile adhesive mortars needing extra grab and water resistance
- Patch repair of bridge decks and other infrastructure concrete
- Pre-paint patch repair of spalled or cracked plaster on exterior walls
- Slurry for pinhole treatment and as a fluidity improver in cement injection grouts
Key advantages
- Bond strength to prepared concrete typically rises from 0.3–0.5 MPa to 0.8–1.5 MPa — a 50–100% gain over unmodified mortar
- Water absorption of the modified mortar drops by 60–70%, cutting damp migration and re-seepage through patched areas
- Around 50% higher flexural strength, with less shrinkage cracking under thermal cycling
- One product covers bond coat, mortar admixture, waterproof slurry and grout modification — fewer SKUs to stock and fewer batching mistakes on site
- Strong adhesion to concrete, masonry, stonework, plasters and cementitious surfaces
- Compatible with all Portland cements used in India — OPC, PPC and PSC
- Hardens the surface, resists abrasion and prevents dust pick-up on floors
- Denser modified matrix improves water resistance and helps protect embedded steel from corrosion
- Improves fluidity of cement injection grouts at low water content for better penetration and bond
- Site-mixed with ordinary cement and water — no special plant, pumps or curing regime; hand mixing permitted for batches up to 25 kg
- Decades of track record on Indian sites — masons and contractors already know how to handle SBR
- Wide pack range (200 g to 20 kg, 50 kg against order) with an 18-month shelf life in sealed packs
Limitations & considerations
- Not an elastomeric standalone membrane — URP-cement slurry coats cannot bridge moving cracks and must be protected with a screed, not left exposed as the finished terrace surface
- Not a structural strengthening system — for load-bearing or seismic-retrofit work, specify a proper micro-concrete or structural repair mortar rather than a bonding-agent-modified mortar
- Performance is dosage-sensitive; under-dosing breaks the polymer film continuity and over-dosing wastes material, and the three ratios (1:1 bond coat, 1:1.5 slurry, 6–7.5 kg per bag) are not interchangeable
- Repair thickness is limited (5–25 mm for patch mortars, 10–40 mm for screeds); deep structural repairs need a dedicated repair mortar or micro-concrete system
- Bond depends entirely on preparation — saw-cut edges to at least 10 mm, remove laitance, and pre-wet to saturated surface-dry, or expect debonding
- Bond coats must be overlaid while tacky; a dried-out SBR slurry acts as a debonding layer and has to be removed and redone, so this is a supervised wet-on-wet operation, not a leave-it-overnight one
- Curing is a balancing act — moist-cure early, then air-dry; continuous water curing or ponding hinders polymer film formation
- Modified mixes stiffen faster than plain mortar, especially in hot Indian summers; batch small, adjust water at the mixing stage, and never retemper a stiffening batch with extra water
- Cannot stop active water ingress — plug running leaks with a fast-setting plugging compound before repair
- Adds meaningful cost per batch, so dose it where the performance is actually needed rather than blanket-dosing every mortar on site
- Damp modified mortars release alkali that can harm skin and eyes, so gloves and eye protection are mandatory
Selection & best practice
Preparation decides the outcome. Chip or cut back to sound concrete and roughen the surface, wire-brush or scrub to remove laitance, dust and loose particles, degrease if needed, expose and clean any corroded rebar, and saw-cut the perimeter of patch repairs to at least 10 mm depth to avoid feather edges. Saturate the surface with potable water and bring it to saturated surface-dry — damp, with no standing film of water — before starting.
Bond coats. Brush one continuous, thin, even coat of 1:1 URP:cement (by volume) well into the surface at 4.2–4.5 m²/kg and place the repair mortar or plaster while the coat is still tacky. Never let it skin over or dry out; a dried coat must be removed and reapplied.
Waterproof slurry coats. Apply two coats of 1:1.5 URP:cement slurry 4–6 hours apart at a combined coverage of 2–2.2 m²/kg, brushing the second at right angles to the first once the first has set, then overlay with a protective screed laid to slope.
Mortars and screeds. Dry-blend cement and sand first, then gauge with the latex-water blend, batching 6–7.5 kg URP per 50 kg cement with the TDS sand and water quantities. Reduce the gauging water by roughly the volume of latex added so the mix stays workable rather than soupy. Mix in a pan mixer or with a spiral-paddle drill at 400–500 rpm for 2–3 minutes to avoid air entrapment; hand-mix only batches of 25 kg or less. Build thick repairs in layers rather than one heavy pass, and add the latex at the mixing stage — never stir it into already-finished mortar as an afterthought.
Curing. Moist-cure the finished repair with damp hessian or a curing compound for the first 24–72 hours, then let it air-dry so the polymer film can knit together. Keep the area free of foot traffic and water ponding for at least 3–5 days until the mortar has developed adequate strength, and shield fresh work from rain and direct sun. In hot weather, compensate for evaporation at the batching stage and keep batches small.
Mix ratios and site dosage
| Bonding coat / primer | 1:1 URP:cement by volume, brushed as one continuous coat; coverage 4.2–4.5 m²/kg per coat; overlay wet-on-wet while tacky |
| Waterproof slurry coating | 1:1.5 URP:cement by volume, two coats 4–6 hours apart, second brushed at right angles; coverage 2–2.2 m²/kg for both coats; protect with a screed |
| Polymer-modified repair mortar | 6–7.5 kg URP per 50 kg cement (12–15% by weight of cement) with 150 kg washed sand and about 10 litres of water; 5–25 mm thickness |
| Modified screeds and PCC toppings | Same 6–7.5 kg per 50 kg cement dosage, laid 10–40 mm thick |
| Cement injection grouts | Added as a fluidity improver at low water content to aid penetration and bond |
| Mixing method | Pan mixer or spiral-paddle drill at 400–500 rpm for 2–3 minutes; hand mixing only for batches of 25 kg or less |
| Curing regime | Moist cure 24–72 hours, then air-dry; avoid continuous water curing or ponding; protect 3–5 days |
Specifications
| Chemistry / type | Modified styrene-butadiene rubber (SBR) latex, single-component liquid admixture and bonding agent |
| Appearance | Milky white, translucent, free-flowing liquid |
| Total solids (at 105 °C) | 38 ± 1% by mass |
| pH value | 7.7 |
| Specific gravity (at 27.5 °C) | 1.01 |
| Bonding agent — mix and coverage | 1:1 URP:cement by volume; 4.2–4.5 m²/kg per coat |
| Waterproof coating — mix and coverage | 1:1.5 URP:cement by volume; 2–2.2 m²/kg in 2 coats |
| Mortar modifier dosage | 12–15% by weight of cement (6–7.5 kg per 50 kg bag) |
| Typical bond strength to prepared concrete | 0.8–1.5 MPa modified, against 0.3–0.5 MPa for unmodified mortar |
| Effect on modified mortar | Water absorption reduced by 60–70%; flexural strength up by roughly 50% |
| Cement compatibility | OPC, PPC and PSC (slightly slower early strength with blended cements, as with unmodified mortar) |
| Curing | Moist cure 24–72 hours, then air-dry; avoid prolonged ponding or continuous water curing |
| Standards | BS 6319 Part 2:1983, ASTM C190-85 |
| Packs / shelf life | 200 g, 500 g, 1, 5, 10 and 20 kg packs, 50 kg against order; 18 months in sealed packs stored cool, dry and out of direct sunlight |
Industry use cases
Housing societies and residential repair
Waterproofing slurry coats in sunken bathroom portions, balcony and chhajja patch repairs, plaster re-bonding and repair of spalled, rust-stained columns and beams during society-wide structural repair programmes.
Commercial buildings and facility management
Spall repairs on parking floors, columns and slab soffits, re-plastering of ageing RCC frames where bond coats stop new plaster delaminating, plus hardened, dust-free screed toppings in service and utility areas.
Industrial plants and flooring
Polymer-modified PCC floor screeds and abrasion-resistant toppings in 10–40 mm thickness where forklift traffic erodes plain cement surfaces.
Infrastructure
Patch repair of bridge decks, crash barriers and drainage structures, where a site-mixed SBR mortar restores cover concrete without mobilising a full pre-bagged repair-mortar system.
Basements and substructure
Waterproof renders on retaining walls, plinth protection works and external basement faces, backed up by drainage and, where needed, membrane systems.
Renovation and plastering contractors
Bond coats when plastering over old RCC, exposed beams and lift shafts, weatherproof external renders, bedding mortar for re-fixing stone, tile and slip-brick cladding, and pre-paint patch repair of cracked exterior plaster.
Repair and rehabilitation consultants
Specification-friendly SBR (BS 6319 Part 2 / ASTM C190-85 compliant) for pinhole-sealing slurries and modified injection grouts in restoration jobs.
Frequently asked questions
Is Dr. Fixit Pidicrete URP the same thing as Dr. Fixit SBR?
What does the ‘URP’ in Pidicrete URP stand for?
Can I use Pidicrete URP straight from the container?
What is the mixing ratio for waterproofing a bathroom sunken slab?
How much URP goes into one 50 kg bag of cement for repair mortar?
What coverage should I estimate per kg?
Can I place repair mortar without a bond coat?
Can the URP-cement coating be left exposed on a terrace?
Does it work with PPC and slag cements?
How should polymer-modified mortar be cured?
Why use URP instead of plain cement slurry as a bond coat?
What pack sizes are available and how long does it keep?
How we position Dr. Fixit Pidicrete URP
Pidicrete URP is the workhorse SBR of the Dr. Fixit building-repairs range — the right choice when one liquid must handle bonding, patching and slurry waterproofing on a live site. Within the same family, use Dr. Fixit Pidiproof LW+ for integral waterproofing of fresh concrete, Dr. Fixit Crack X Shrinkfree for wider cracks needing a fibre-reinforced patching paste, Dr. Fixit Pidifin 2K for wet-area coatings that need flexibility, and finish exposed roofs with a Dr. Fixit Newcoat or Raincoat topcoat over a URP-modified base rather than instead of one. Where repairs run deeper than 25 mm or are structural, Space Arc recommends dedicated repair mortars such as the Fosroc Renderoc or Sika MonoTop ranges from our other principal brands. Contractors standardised on Fosroc or Sika can also source Nitobond SBR or Sika Latex Power from us as direct equivalents.
Fosroc Nitobond SBR — Specifiers already standardised on Fosroc’s repair range, or wanting a single-source bonding-agent-plus-mortar system alongside Fosroc’s Nitomortar and Renderoc ranges, might choose Nitobond SBR over Pidicrete URP for that reason — the core SBR-latex chemistry and use cases are essentially equivalent.
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