STP ShaliCure PA M 20
A pigmented paraffin-emulsion curing membrane that seals moisture into fresh concrete, cutting plastic and drying shrinkage cracks without ponding or hessian.
What is it?
A non-flammable, water-based paraffin emulsion curing compound from STP that sprays onto fresh concrete and dries into a moisture-retaining membrane film, conforming to ASTM C 309 Types 2 and 1D, Class B.
Where is it used?
Interior and exterior concrete, from slabs, pavements and road works to bridge decks, canal linings and precast, plus sealing of older concrete surfaces.
Why use it?
It locks in mix water so cement hydration completes properly, reducing surface cracking, spalling, flaking and dusting while eliminating the labour and water demand of traditional wet curing.
How is it applied?
Stir the drum, then spray or apply a uniform film over clean, standing-water-free concrete immediately after finishing; the pigment shows coverage as you go, and the film dries in 3 to 5 hours.
About STP ShaliCure PA M 20
STP ShaliCure PA M 20 is the pigmented grade of the ShaliCure PA M range, a liquid membrane-forming curing compound built around a paraffin-wax emulsion. When it is applied to freshly finished concrete, the emulsion breaks and the wax coalesces into a continuous film that sits on the surface and holds the mixing water inside the slab. That retained moisture is exactly what the cement needs to hydrate fully during the critical first few days, which is when concrete is most vulnerable to plastic shrinkage cracking, early flaking and dusting. Because it conforms to ASTM C 309 Types 2 and 1D, Class B, specifiers can call it up on jobs that demand a recognised curing-membrane standard rather than relying on unverifiable site wet-curing.
The practical appeal of this grade is its light pigmentation. On a large pour, the biggest risk with any spray-applied curing compound is a patchy, missed film that leaves parts of the slab under-cured. The visible tint makes coverage self-checking, so the applicator can see where the membrane has landed and where it has not before the pigment weathers away. The product is supplied ready to use as a milky-white liquid in 20 kg and 200 kg drums, is non-flammable, and carries a 12-month shelf life in sealed condition. For engineers and contractors across Delhi NCR and Pan-India, Space Arc supplies it as an authorised distributor and applicator, so material and site guidance come from the same source.
The technical insight
Curing is not about wetting concrete, it is about not letting it dry out. Ordinary Portland cement needs roughly 0.4 parts water to every part cement to hydrate, and if surface water evaporates faster than bleed water rises, the top few millimetres hydrate incompletely and crack. ShaliCure PA M 20 works by placing a physical barrier between the concrete and the atmosphere. The paraffin emulsion is sprayed as a thin liquid, the water carrier flashes off, and the wax fraction knits into an unbroken hydrophobic membrane. This film is what does the work: tested to ASTM C 156, it limits moisture loss to under 0.55 kg/m2 over 72 hours (water retention measured at 0.29 kg/m2 loss), comfortably inside the ASTM C 309 pass criterion. The pigment adds a second mechanism at placement, giving a reflectance above 60% to ASTM E 1347, which bounces solar heat off a fresh slab in Indian summer conditions and lowers the surface temperature gradient that drives thermal cracking. Because the solids content is a modest 15 percent, the film is thin enough to weather off most trafficked surfaces over time rather than needing removal.
Where it is used
- Curing of freshly placed concrete slabs, rafts and floors where wet curing is impractical
- Road, highway and pavement concrete requiring uniform, verifiable membrane coverage
- Bridge decks, flyover slabs and other large horizontal exposed pours
- Canal linings, reservoir walls and water-retaining structures during construction
- Precast yards and factory casting beds needing rapid, low-labour curing
- Vertical and sloping faces such as columns, beams and retaining walls that are hard to pond
- Sealing and dust-proofing of existing or older concrete surfaces
- Warehouse, industrial and airport apron slabs before subsequent finishes
Key advantages
- Conforms to ASTM C 309 Types 2 and 1D, Class B, giving a specifiable curing standard
- Pigmented film makes coverage visually self-checking, reducing missed or under-cured areas
- Single spray application replaces ponding, hessian and repeated water curing, cutting labour and water use
- Reflectance above 60% helps keep fresh slabs cooler and limits thermal cracking
- Non-flammable water-based emulsion, safer to store and handle than solvent grades
- Compatible with many paints, adhesives and resilient floor coverings after weathering
- Helps eliminate surface dusting and hardens the wearing surface by promoting full hydration
- Resistant to yellowing, so it does not discolour architectural or exposed concrete
Limitations & considerations
- A curing membrane, not a decorative or wearing coat; it weathers off and is not a permanent sealer
- Where bonded overlays, screeds or coatings will follow, the film must be mechanically removed (grinding or shot-blasting) to ensure adhesion
- Do not apply below 4 degrees C ambient; material must be warmed to at least 10 degrees C before use
- Film integrity depends on an even, unbroken application, so patchy spraying reduces curing efficiency
- Surface must be clean and free of standing water and contaminants, or the membrane will not form or bond properly
- Pigment provides only temporary application guidance and is not a long-term colour or aesthetic finish
Selection & best practice
Apply as soon as the surface sheen of bleed water has disappeared and the concrete can take the film without marring; on hot, windy days this window is short, so keep pace with the finishing crew. Invert the drum for at least two hours before opening, then stir with a slow-speed mixer at around 400 rpm to a homogeneous milky liquid before spraying. Lay down a continuous, uniform coat and use the pigment to confirm no gaps or thin patches, overlapping passes at right angles on large slabs. Keep off the surface for the 3 to 5 hour drying period before traffic. Where a bonded topping, tile bed or coating is planned, treat this as a temporary cure only and programme mechanical removal of the residual film before that work starts. Clean tools with water immediately, before the material hardens, and store unused stock cool, dry and under cover.
Specifications
| Product type | Paraffin-based pigmented membrane curing compound (water-based emulsion) |
| Standard conformance | ASTM C 309, Types 2 and 1D, Class B |
| Physical appearance | Milky white liquid |
| Theoretical coverage | 4.9-7.4 m2/L on textured concrete; 7.4-8.6 m2/L on smooth concrete |
| Drying time | 3-5 hours before exposure to traffic (surface dependent) |
| Moisture loss (ASTM C 156) | < 0.55 kg/m2 in 72 hours |
| Reflectance (ASTM E 1347) | > 60% |
| Solids content / Specific gravity | 15 +/- 1% solids; SG 1.07 +/- 0.2; pH 6.60 |
| Packing and shelf life | 20 kg and 200 kg drums; 12 months in sealed condition |
Industry use cases
Roads and Highways
Large pavement and carriageway pours are cured in a single spray pass, with the pigment confirming full coverage across the lane so no stretch is left under-cured.
Bridges and Infrastructure
Exposed bridge decks and flyover slabs get consistent moisture retention and a reflective film that limits thermal cracking under direct sun.
Water Retaining Structures
Canal linings, reservoir walls and channels are cured reliably on faces where ponding or continuous wetting is impractical to maintain.
Precast and Industrial Flooring
Casting beds and factory floor slabs cure with minimal labour and no water demand, freeing crews and speeding bed turnaround.
General Building Construction
Suspended slabs, rafts and columns across a site are cured to a recognised ASTM standard without the manpower of hessian-and-water regimes.
Frequently asked questions
Is ShaliCure PA M 20 the same as the old ShaliCure PA M?
How much area does one drum cover?
Do I need to remove the film before tiling or applying a coating?
Why is it pigmented if the film weathers away?
Can it be used in cold weather?
What pack sizes and shelf life does it have?
How we position STP ShaliCure PA M 20
Within the STP ShaliCure family, PA M 20 is the pigmented paraffin grade chosen when visible coverage verification matters on large pours; the PA M 5 and PA M 10 grades cover the same paraffin chemistry in different pack and application economics, while ShaliCure Acrylate (and Acrylate WB) and ShaliCure SS White or SS Transparent offer acrylic and resin-based options where a clearer film or a curing-plus-sealing finish is preferred. Across our other brands, the closest equivalents are Fosroc Concure WB and MC-Bauchemie curing compounds; specifiers standardised on Fosroc for a project will often pair this curing step with Fosroc concrete repair and admixture systems, and Space Arc can supply either family from stock with matched site guidance.
Fosroc Concure WB — Choose Concure WB when the project specification or QA regime is already standardised on Fosroc, or when a clear (non-pigmented) water-based wax-emulsion curing membrane to ASTM C 309 is preferred over a pigmented film.
Related Concrete Admixtures products
Source STP ShaliCure PA M 20 for your project
Authorised distribution, technical advice & professional application across Delhi NCR and Pan-India.