STP ShaliSeal PS PG
A self-levelling, two-component polysulphide sealant that pours into horizontal expansion and construction joints and cures to a tough, UV-stable rubber that moves with the structure.
What is it?
A two-part, pouring-grade polysulphide joint sealant from STP that self-levels into horizontal joints and cures at ambient temperature to a flexible, weatherproof rubber.
Where is it used?
Horizontal expansion and construction joints in concrete roads, floors, roof terraces, parking decks, water-retaining structures and airport pavements.
Why use it?
It combines gravity-assisted filling with genuine polysulphide movement capacity and UV resistance, so exposed horizontal joints stay watertight through years of thermal cycling.
How is it applied?
Mix Base with the manganese-dioxide curing agent, then pour the blend into a primed, backer-rod-supported joint and let it flow level; no gunning or tooling of the surface is needed.
About STP ShaliSeal PS PG
ShaliSeal PS PG is STP Limited’s pouring-grade member of the ShaliSeal polysulphide family, formulated specifically for joints that lie flat. Where a gun-grade sealant has to be extruded and tooled, the PG grade is deliberately low in viscosity so that, once the two components are blended, it flows into the joint and finds its own level under gravity. The cured material is a rubbery, tear-resistant polysulphide that adheres to cementitious substrates, aluminium, glass, timber and mild steel, and it holds up to sunlight, weathering, ageing and a wide range of chemicals without staining the concrete alongside the joint.
For engineers and applicators the appeal is practical. A pourable sealant removes the labour and inconsistency of gunning long horizontal runs, gives a uniform fill in wide or irregular grooves, and produces a smooth flush finish that traffic and cleaning can pass over. Because it is a true polysulphide rather than a cheaper acrylic or bitumen filler, it recovers its shape after repeated compression and extension, which is exactly what a road, deck or terrace joint demands as temperatures swing through the Indian year. Space Arc Engineering supplies and applies ShaliSeal PS PG across Delhi NCR and pan-India, with site guidance on joint design, priming and pour sequencing.
The technical insight
Polysulphide sealants cure by a chemical reaction, not by drying, and that is the key to their durability. In ShaliSeal PS PG the liquid polysulphide polymer (a mercaptan-terminated base) is chain-extended and cross-linked when it meets the manganese-dioxide curing agent supplied as the second component. The result is a three-dimensional elastomer network that behaves like vulcanised rubber: it stretches when the joint opens in winter, compresses when it closes in summer, and springs back rather than taking a permanent set. This is why the family carries a butt-joint movement accommodation factor around plus or minus 25 percent and cures to a low Shore A hardness near 20, staying soft enough to move yet tough enough to resist tearing. The pouring grade simply adjusts the rheology of that same chemistry so it self-levels; the cured polymer, its UV stability and its chemical resistance are unchanged. Because the cure is reaction-driven, it proceeds at ambient temperature and continues even in the confined depth of a poured joint, which a solvent-release sealant cannot reliably do.
Where it is used
- Horizontal expansion and contraction joints in concrete road and highway pavements
- Construction and movement joints in industrial and warehouse floor slabs
- Joints on roof terraces, podiums and exposed horizontal decks
- Parking-deck and ramp joints subject to traffic and thermal movement
- Airport taxiway and runway pavement joints
- Base and floor joints in water-retaining structures such as tanks, reservoirs, canals and swimming-pool surrounds
- Joints between precast or in-situ concrete pipeline and channel sections
- Wide or irregular horizontal grooves where gun-grade sealant is difficult to fill evenly
Key advantages
- Self-levelling flow fills horizontal joints under gravity, giving a uniform seal with minimal labour
- Genuine polysulphide elasticity with excellent recovery after repeated compression and extension
- UV-resistant, so it suits sun-exposed horizontal surfaces without hardening or crazing
- Non-staining to adjacent concrete, keeping road and deck edges clean
- Bonds to concrete, aluminium, glass, timber and mild steel, covering mixed-substrate joints
- Cures at ambient temperature, so no heating or hot-pour equipment is required
- Resistant to weathering, ageing, shrinkage and a broad range of chemicals
- Conforms to recognised polysulphide sealant standards (IS 12118, BS 4254, BS 5212, ASTM C 920)
Limitations & considerations
- Pouring grade is for horizontal joints only; vertical, overhead or sloping joints need the gun-grade ShaliSeal PS GG
- Not suitable for grooves exceeding 50 mm in width, where an alternative jointing system is required
- Depth of the poured joint must not exceed its width, so a correctly sized backer rod is essential
- Being a two-component reactive sealant, it has a limited pot life once mixed and must be poured promptly
- Requires a primed, dry, sound substrate with surface moisture below about 5 percent for reliable adhesion
- Not intended as a wearing surface for direct point loads; it is a joint seal, not a floor topping
Selection & best practice
Design the joint first: fit a closed-cell backer rod to control depth, keep the sealed depth no greater than the joint width, and mask both edges for a clean line. Clean the groove back to sound concrete with dry compressed air and mechanical means, confirm surface moisture is within limits, and apply the recommended primer to the joint faces. Mix the pre-weighed Base and curing agent thoroughly with a slow-speed paddle (around 400 rpm) to a uniform grey with no entrapped air, then pour the blend into the joint promptly and let it self-level; work within the pot life and complete each run in one pass. Remove masking tape before the sealant sets, and allow ambient cure to develop full properties over several days before subjecting water-retaining joints to service or immersion. For potable-water or continuously submerged joints, confirm the specific grade and full-cure period with the manufacturer before commissioning.
Specifications
| Product type | Two-component, pouring-grade polysulphide joint sealant |
| Curing system | Manganese-dioxide (MnO2) based curing agent |
| Colour | Grey |
| Specific gravity | 1.60 ± 0.05 at 23°C |
| Standards conformity | IS 12118 Part 1:1987, BS 4254, BS 5212:1990 Part I (Type F & FB), ASTM C 920 |
| Service temperature | -40°C to +85°C |
| Movement accommodation factor | Approx. ±25% butt joints (polysulphide family) |
| Maximum groove width | 50 mm |
| Storage | Cool, dry, shaded conditions; avoid below 0°C and above 50°C |
Industry use cases
Roads & Highways
Sealing transverse and longitudinal joints in concrete carriageways, where a poured seal fills the full joint width and flexes with pavement thermal movement.
Water Retaining Structures
Floor and base joints in tanks, reservoirs, canals and pool decks that must stay watertight while accommodating structural movement.
Airports & Pavements
Taxiway, apron and runway joints that demand a durable, fuel- and weather-resistant elastic seal on large exposed horizontal areas.
Industrial & Terrace Floors
Expansion joints in factory floors, podiums and roof terraces where a self-levelling flush seal handles traffic and daily thermal cycling.
Frequently asked questions
What is the difference between ShaliSeal PS PG and PS GG?
Is ShaliSeal PS PG suitable for water-retaining structures?
Does it need a primer?
What joint sizes does it suit?
Is it UV resistant for exposed rooftops and roads?
Can Space Arc supply and apply it anywhere in India?
How we position STP ShaliSeal PS PG
ShaliSeal PS PG sits alongside its gun-grade sibling ShaliSeal PS GG within the same STP polysulphide family; specify PG for horizontal joints and PS GG for vertical, overhead or sloping joints. For projects standardised on Fosroc, the direct equivalent is Fosroc Thioflex 600 PG, with the gun-grade Thioflex 600 GG covering non-horizontal joints. Where a project needs different chemistry rather than polysulphide, Space Arc can also advise on polyurethane and hybrid sealants from our other brand lines for high-movement or trafficked joints.
Fosroc Thioflex 600 PG — A specifier standardised on Fosroc, or working to a Fosroc-approved schedule, may prefer Thioflex 600 PG as the directly equivalent pourable polysulphide for horizontal concrete and water-retaining joints.
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