About STP ShaliSeal PS PG I

STP’s ShaliSeal PS PG I sits in the polysulphide family of joint sealants, but it is built specifically for joints you seal from above — floor slabs, pavements, runways and other horizontal surfaces. The base polymer is blended with a manganese-dioxide curing agent that, once mixed, chemically cross-links at ambient temperature into a flexible, tear-resistant rubber. Because the mixed material is a pouring grade, it flows under its own weight and self-levels, so an applicator does not have to tool a horizontal bead the way a gun-grade sealant demands. The cured seal accommodates continuous thermal and structural movement, recovers its shape after long spells of compression or extension, and holds up against UV, rain, chemical splash, ageing and shrinkage.

The distinguishing feature of the “I” variant is adhesion. Standard polysulphide pouring sealants bond well to clean concrete but can be temperamental on smooth, non-porous faces. ShaliSeal PS PG I is reformulated to key more firmly onto cementitious substrates, aluminium, glass, wood and mild steel, which matters on real sites where a single joint often runs between two different materials — a concrete deck meeting an aluminium frame, or a steel embed cast into a slab. For engineers and applicators across Delhi NCR and the rest of India, that translates into fewer adhesion failures at mixed-substrate interfaces and a longer service life before the joint needs attention.

The technical insight

Polysulphide sealants cure by oxidative cross-linking rather than by drying. The liquid polysulphide base carries reactive thiol (-SH) end groups; when the manganese-dioxide hardener is stirred in, it oxidises those groups and knits the chains into a three-dimensional elastomer. That chemistry is why the material stays permanently rubbery instead of going brittle, and why it recovers after being stretched or squeezed — the cross-linked network behaves like a spring. The pouring grade is simply a lower-viscosity version of that same chemistry: it is thin enough to flow and level in a horizontal groove yet still cures to the same elastic solid. The improved-adhesion package works by wetting out low-energy, non-porous surfaces more effectively so the sealant makes intimate contact before cure, which is exactly where ordinary polysulphides tend to peel. A cured specific gravity of about 1.60 and roughly 450% elongation at break give the seal both body and the reserve of stretch it needs to track joint movement without splitting.

Where it is used

• Horizontal expansion joints in industrial, commercial and residential floors
• Contraction and construction joints in concrete roads, pavements and hardstandings
• Movement joints on bridges, flyovers, subways and elevated decks
• Runway and taxiway joints in airport infrastructure
• Joints in water-retaining structures such as water tanks, swimming pools and reservoirs
• Sealing joints in canals, aqueducts and dam appurtenant works
• Mixed-substrate joints where concrete meets aluminium, steel, glass or timber
• Deck and podium joints exposed to sunlight and standing water

Key advantages

• Self-levelling pouring grade fills horizontal joints without tooling
• Improved adhesion to concrete, aluminium, glass, wood and mild steel
• Cures at ambient temperature to a flexible, tear-resistant rubber
• Excellent recovery after prolonged compression or elongation
• UV, weather and ageing resistant for exposed horizontal joints
• High movement accommodation, up to around plus-or-minus 25% in butt joints
• Broad chemical resistance and non-staining once cured
• Conforms to recognised standards including IS 12118, BS 4254 and ASTM C 920

Limitations & considerations

• Pouring grade only suits horizontal joints; use gun grade PS GG on vertical or overhead joints
• Two-part material with a limited pot life of roughly 2 hours at 25C once mixed, so mix only what can be poured in time
• Do not use in grooves wider than about 50 mm
• Non-porous substrates generally require the correct primer to guarantee the improved-adhesion bond
• Not a structural or load-bearing filler; it seals movement, it does not transfer load
• Full cure in tropical conditions takes several days, during which the joint must be protected from traffic and water

Selection & best practice

Specifications

Industry use cases

How we position STP ShaliSeal PS PG I

Within the STP ShaliSeal PS family, choose ShaliSeal PS PG I when a horizontal joint runs across mixed or non-porous substrates and adhesion is the priority; step down to the standard ShaliSeal PS PG for straightforward concrete-to-concrete horizontal joints; and switch to the gun-grade ShaliSeal PS GG for any vertical, sloped or overhead joint that has to be tooled. Where a project is specified around Fosroc, the equivalent two-component polysulphide is Thioflex 600 in its pouring/self-levelling grade. As an authorised distributor and applicator across Delhi NCR and Pan-India, Space Arc supplies this product alongside compatible joint primers, backer rods and bond-breaker tapes, and can advise on the right grade and brand for the substrate and movement in your joint.

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