STP ShaliMastic RS TC
Three-component refined coal tar concentrate that repairs hairline pavement cracks and seals the surface against fuel, water and UV — one system for asphalt and concrete roads.
What is it?
A black, three-component refined coal tar emulsion from STP Limited that works as a crack repair-cum-sealer coat for road surfaces, meeting ASTM D5727, ASTM D490 and Federal Specification R-P-355e.
Where is it used?
Expressways, highways, parking lots, fuel and service stations, truck terminals, airfield taxiways and shoulders, school yards and driveways — any pavement exposed to fuel spillage, abrasion or harsh weathering.
Why use it?
Coal tar does not dissolve in petrol or diesel the way bitumen does, so the cured film keeps its adhesion where fuel drips daily, while sealing hairline cracks and pores that let water into the pavement structure.
How is it applied?
Site-blended slurry — concentrate mixed with clean water, ShaliFill 40 graded filler and STP Polymer Latex3 — laid as a prime coat plus one or two top coats by mechanical squeegee or airless spray.
About STP ShaliMastic RS TC
Every pavement starts failing the same way: hairline cracks open at the surface, water gets in, and the base weakens long before the wearing course looks visibly distressed. ShaliMastic RS TC from STP Limited is a preventive answer to that cycle. It is a three-component, UV-resistant refined coal tar concentrate that is slurry-mixed on site and squeegeed over asphalt or concrete pavements, where it fills hairline cracks and micro-pores and cures into a continuous black film that blocks water ingress. The product carries compliance with ASTM D5727, ASTM D490 and US Federal Specification R-P-355e — the recognised benchmarks for coal tar pavement sealers worldwide.
What sets it apart from ordinary bituminous seal coats is chemistry. Because the binder is refined coal tar rather than petroleum bitumen, the cured film shrugs off kerosene, petrol and diesel spillage that would soften and strip a bitumen-based coat. The system is also tunable: blended with graded filler and polymer latex per STP’s mix design, it builds a wear-resistant, smooth-finished surfacing suited to trafficked areas. Space Arc Engineering supplies ShaliMastic RS TC in 20 kg and 200 kg combo packs across Delhi NCR and pan-India, and can deploy trained applicator crews for highway concessionaires, fuel retail networks and facility owners.
The technical insight
The fuel resistance that defines this product comes down to solubility. Bitumen is petroleum-derived, so petroleum fuels are effectively its solvent — every diesel drip at a fuel bay slowly re-dissolves a bituminous surface. Refined coal tar comes from a different feedstock with a distinct aromatic structure, so hydrocarbon fuels cannot penetrate or lift the cured film; the TDS requirement is no loss of adhesion or penetration under kerosene exposure. The three-component format matters equally. The coal tar emulsion (47–53% non-volatiles, minimum density 1.20 at 25°C) supplies the waterproof binder; ShaliFill 40 graded filler gives the top coat body and abrasion resistance; STP Polymer Latex3 adds flexibility so the film resists cracking and flaking as the pavement flexes under traffic. Because the mix is proportioned on site, the same concentrate produces a penetrating prime coat and a filled, wear-resistant top coat.
Where it is used
- Preventive seal coating of expressway and highway stretches showing early hairline cracking
- Fuel-resistant surfacing at petrol pumps, service stations, truck terminals and vehicle depots
- Airfield taxiways, shoulders and aprons exposed to fuel spillage and weathering extremes
- Parking lots, basement ramps and industrial yard pavements under repeated tyre abrasion
- School yards, play areas, driveways and township internal roads needing a smooth renewed finish
- Dust palliative coating over old concrete pavements and hardstands
- Rejuvenation of aged, oxidised asphalt surfaces before distress progresses to potholing
- Crack sealing follow-up coat over patch-repaired flexible and rigid pavements
Key advantages
- Outstanding resistance to petrol, diesel and kerosene — no adhesion loss or penetration where bituminous sealers strip
- Seals hairline cracks and surface pores in a single operation, cutting water ingress into the pavement base
- UV-resistant coal tar film that does not chalk out or embrittle under Indian sun exposure
- Works on both flexible (asphalt) and rigid (concrete) pavements with the same material
- Site-adjustable mix design: lean prime coat or filled, wear-resistant top coat from one concentrate
- Fast turnaround — touch dry in 1 hour, full cure in 8 hours, so lanes reopen the same day
- Polymer-latex-modified film stays flexible with no cracking or flaking under traffic movement
- Complies with ASTM D5727, ASTM D490 and Federal Specification R-P-355e
Limitations & considerations
- Weather-window dependent: apply only when no rain is forecast for 24 hours and ambient temperature is between 10°C and 45°C
- A surface treatment, not a structural repair — cracks wider than 1 mm must first be corrected with ShaliTex Sealing Compound/ShaliPatch (flexible) or ShaliPatch EC (concrete)
- New concrete pavements must be at least 28 days old and fully cured before coating
- Needs its companion components (clean pH 7–8 water, ShaliFill 40, STP Polymer Latex3) batched accurately — it is not a single-pack, stir-and-apply product
- Coal tar handling demands proper PPE and ventilation; skin and eye contact must be avoided during mixing and laying
- Best results require mechanical squeegee or specialised airless spray equipment rather than hand brushing on large areas
Selection & best practice
Start with the substrate: blow down the pavement with dry compressed air to remove loose gravel, dust, oil and grease, and confirm the surface is sound, even and free of standing water. Pre-fill any crack wider than 1 mm — use ShaliTex Sealing Compound or ShaliPatch on asphalt, ShaliPatch EC on concrete — and hold new rigid pavements until 28 days old. Batch the mix with clean water of pH 7–8, free of harmful salts. For the prime coat, blend 500 g concentrate with 500 g water and 25 g STP Polymer Latex3 per square metre, apply, and allow one hour to dry. For each top coat, blend 500 g concentrate with 300–400 g water, 200–225 g ShaliFill 40 and 25 g Latex3 per square metre; one top coat suits low-to-medium traffic, two coats for old pavements or heavy traffic, laid at one-hour intervals. Spread and mechanically squeegee for a uniform film, and finish with a ShaliSeal RS TC top-up where a polymer-modified wearing sheen is specified.
Specifications
| Base / form | Refined coal tar; black emulsion-slurry, three-component system |
| Standards compliance | ASTM D5727, ASTM D490, Federal Specification R-P-355e |
| Density @ 25°C | 1.20 minimum |
| Non-volatiles | 47–53% by weight (ash content of non-volatiles 30–40%) |
| Drying time | Touch dry 1 hour; full cure 8 hours |
| Consumption (concentrate) | 500 g/m² per coat — prime plus 1–2 top coats per mix design |
| Application temperature | 10°C to 45°C ambient; no rain forecast for 24 hours |
| Packing | 20 kg and 200 kg combo packs |
| Shelf life / storage | 12 months unopened; store cool, dry, under shed, away from heat |
Industry use cases
Highways & Expressways
Concessionaires and O&M contractors use it as a planned preventive seal on stretches showing early hairline cracking, deferring costly resurfacing and keeping water out of the pavement base.
Fuel Retail & Fleet Depots
Forecourts, truck terminals and bus depots specify it because the coal tar film withstands daily petrol and diesel drips that dissolve conventional bituminous surfaces.
Airfields & Aviation
Taxiways, shoulders and apron edges exposed to jet fuel spillage and extreme weathering get a fuel-proof, UV-stable seal that meets US federal pavement-sealer specifications.
Industrial & Logistics Parks
Container yards and heavy-vehicle parking areas take the two-top-coat filled mix for a smooth, abrasion-resistant surface that also controls dust on old concrete hardstands.
Townships & Institutions
Facility managers refresh internal roads, school yards, play areas and driveways with a uniform black finish that reads as new pavement at a fraction of overlay cost.
Frequently asked questions
Why choose a coal tar sealer over a cheaper bitumen-based seal coat?
How much material do I need per square metre?
Can it be applied on concrete roads or only on asphalt?
How quickly can traffic return after coating?
What surface preparation is essential before sealing?
What pack sizes are available and what else must I order with it?
How we position STP ShaliMastic RS TC
ShaliMastic RS TC sits inside a complete STP road-maintenance system, and it performs best when specified that way. Pair it with ShaliTex Sealing Compound or ShaliPatch for pre-filling wider cracks in asphalt, ShaliPatch EC for concrete pavement repairs, and finish with ShaliSeal RS TC where a polymer-modified UV-resistant top sheen is wanted. ShaliFill 40 and STP Polymer Latex3 are integral to the mix design rather than optional extras. For movement joints in concrete pavements and hardstands — a different problem from surface sealing — Space Arc supplies Fosroc joint sealants from the Nitoseal range, and for heavy-duty fuel-station aprons needing a trowelled surfacing we can advise on mastic and screed alternatives from our wider portfolio.
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