STP ShaliCrete
One acrylic-polymer liquid, three jobs on site — bonding coat, waterproof coating and repair-mortar modifier — used across Delhi NCR repair and renovation work.
What is it?
A single-component, water-based acrylic polymer liquid. Mixed with cement (and sand, depending on the job), it becomes a bonding slurry, a brushable waterproof coating, or a polymer-modified repair mortar.
Where is it used?
Sunken toilets and kitchens, terraces, sumps and water tanks, precast members, construction joints, spalled RCC repairs, and exterior wall plaster on residential, builder-floor and light commercial sites.
Why use it?
It replaces three separate purchases — a bonding agent, a waterproofing coat and a mortar modifier — with one drum, while adding flexibility, tensile and bond strength, and lower permeability to whatever cement mix it goes into.
How is it applied?
Mixed neat with cement into a lump-free slurry (the ratio varies by job — waterproofing, bonding or mortar), brush-applied in two coats 5-6 hours apart, then moist-cured for 24 hours before a protective 15-25 mm screed or plaster goes over it.
About STP ShaliCrete
STP Limited — the Kolkata-headquartered construction chemicals major behind the Shali brand, with 85 years in the Indian market — describes ShaliCrete as a “multifunctional acrylic polymer,” and that’s an accurate description rather than marketing gloss. Chemically it is a water-based acrylic polymer emulsion at roughly 30% solids, supplied as a free-flowing white liquid that dries to a clear, colourless film. On its own it does nothing structural; its job is to be gauged into cement, sand-cement mortar or concrete, where the polymer film binds the matrix more tightly, seals capillary pores against water ingress, and gives the hardened mix flexibility and tensile strength that plain cement mortar lacks. That is why the same drum works as a bonding coat between old and new concrete, a waterproofing slurry brushed under tiles, and the gauging liquid for a polymer-modified repair mortar — three different mixing ratios, one base material.
For Delhi NCR renovation and repair work — where a large share of our call-out volume is bathroom and toilet re-waterproofing, terrace leak fixes and RCC spalling repair in older DDA flats, builder floors and group-housing blocks — that versatility earns its keep on site. A contractor doesn’t need to source and cross-check compatibility between three separate chemicals; ShaliCrete’s bond-coat, waterproofing-coat and repair-mortar ratios are all built around the same base liquid. Space Arc supplies ShaliCrete as an authorised STP distributor, and where we’re engaged to apply it, we sequence it with the surface preparation, timed re-coating, moist curing and protective screed the TDS specifies — the steps that decide whether an acrylic-bonded waterproofing coat survives one monsoon or ten.
The technical insight
The number worth reading on the TDS is solid content — 30 ± 2%. That’s the actual polymer left behind once the water in the emulsion evaporates and cures into film; it’s what does the bonding and pore-sealing, which is why several application ratios in the TDS specify “no dilution.” A thinner, cheaper acrylic moves less polymer into the cement matrix at the same coverage rate, so coverage-per-kg comparisons across brands only mean something once solid content is matched like-for-like. Just as important: ShaliCrete is described as letting “trapped vapour escape” rather than sealing a fully impermeable membrane — it is a polymer-modified cementitious coating, not an elastomeric or crystalline waterproofing system. That makes it well suited to intermittently wetted areas like bathrooms, kitchens and terraces, and a poorer fit for sustained hydrostatic pressure below grade, where a dedicated membrane system is the safer specification.
Where it is used
- Waterproofing slurry coat under tile beds in sunken toilets, kitchens and utility areas
- Bonding coat between old and new concrete at construction joints, extensions and toppings
- Gauging liquid for polymer-modified repair mortar on spalled columns, beams, chajjas and balconies
- Waterproof lining for small sumps, water tanks, planters, aquariums and terrariums
- Bond coat under cement plaster for a durable, crack-resistant exterior wall finish
- Admixture (up to 10% by weight of cement) in cement-based paint for exterior coatings
- Repair patching for precast structural members, screed toppings and surface cracks
- General-purpose bonding agent wherever fresh mortar or concrete needs to key onto a hardened substrate
Key advantages
- Single product covers bonding, waterproofing and mortar modification — fewer materials to stock, order and match on site
- Improves bond strength between old and new work, cutting the risk of delamination and patch failure
- Vapour-permeable film lets trapped moisture escape, reducing blistering and peeling versus a fully sealed coating
- Higher flexural and tensile strength in the modified mortar means fewer shrinkage and hairline cracks
- Reduces mortar/concrete permeability, slowing water ingress through the treated layer
- Non-flammable and does not release toxic gases if exposed to fire
- Simple brush application — no spray rig, injection pump or specialist tooling required
- Reported non-toxic to workmen when handled per the manufacturer’s safety data sheet
Limitations & considerations
- Not a substitute for a dedicated membrane or crystalline system under sustained hydrostatic pressure (basements, below water table) — it’s a polymer-modified cementitious coating, not an elastomeric membrane
- The TDS explicitly calls for a 15-25 mm protective plaster/screed over the coating — leaving it exposed goes against the manufacturer’s own instructions
- Performance depends heavily on using the correct mixing ratio for each application; over-diluting to stretch coverage weakens the film
- Needs a genuine 24-hour moist cure — skipping this in Delhi’s dry summer heat is one of the most common causes of on-site failure we see
- Published coverage figures (2.25-2.5 sq.m per kg) are theoretical and drop on porous or uneven substrates, so site quantities should carry a margin
- No published chemical-resistance data — not the right choice where sustained acid, oil or aggressive chemical exposure is expected
Selection & best practice
Confirm the substrate is at least 3 days old, sound and free of dirt, oil, laitance and mould — scrape and clean chemically rather than acid-etch, which the TDS specifically warns against. Fill cracks, honeycombs or faulty construction joints first with a 1:2:3 ShaliCrete:cement:fine-sand mortar and let it touch-dry. Pre-wet the surface with no standing water, then brush on at least two ShaliCrete coats with a 5-6 hour gap between them — never over standing water. After the final coat, moist-cure for 24 hours by spraying water, without letting the surface dry out or go underwater, then allow a further 24 hours to dry before covering with the mandatory 15-25 mm protective plaster or screed. That last step is the one contractors skip most often on Delhi NCR sites — and it’s the one the manufacturer treats as non-negotiable for the membrane’s durability.
Specifications
| Chemistry / Type | Single-component, water-based acrylic polymer liquid |
| Appearance | Free-flowing white liquid; dries to a colourless film |
| Specific Gravity @ 27°C | 1.01 |
| Solid Content | 30 ± 2% |
| pH | > 7 |
| Coverage (waterproofing coat, 2 coats, ~1 mm) | 2.5 m²/kg |
| Compressive Strength (1:2 SC:cement bonding slurry) | 285 kg/cm² |
| Compressive Strength (polymer repair mortar, SC 5% bwt cement) | 405 kg/cm² |
| Pack Sizes | 1 kg, 5 kg, 20 kg, 50 kg, 200 kg |
Industry use cases
Residential bathroom & toilet re-waterproofing
Slurry-coated under the tile bed during sunken-slab waterproofing repairs in Delhi NCR apartments and builder floors.
RCC repair & rehabilitation
Bond coat plus polymer repair mortar (1:2:5 ratio) for patching spalled balconies, chajjas and columns in 15-40 year old structures.
Terrace and planter waterproofing
Brush-applied waterproofing coat under a protective screed ahead of monsoon, on terraces, planters and small concrete decks.
Construction joints & toppings
Bonding coat (1:2 ShaliCrete:cement) keying new screed or topping concrete onto an existing precast or cast slab.
Exterior wall finishing
Bond coat under cement plaster, or admixed into cement paint, for a durable exterior finish on masonry walls.
Frequently asked questions
Is ShaliCrete a complete waterproofing solution on its own?
How much ShaliCrete do I need for a sunken toilet slab?
Can it be used purely as a bonding coat, without the waterproofing step?
Does applying ShaliCrete need any special equipment?
What’s the shelf life, and how should leftover material be stored?
How is ShaliCrete different from a plain SBR bonding agent?
How we position STP ShaliCrete
ShaliCrete sits within STP Limited’s Waterproofing & Insulation range alongside the brand’s RestoFix repair/rehabilitation systems, and Space Arc supplies it as an authorised STP distributor across Delhi NCR and pan-India projects, sequencing it with compatible STP grouts and repair mortars where a job needs more than one product. Where a tender or consultant specifies an internationally referenced bonding-and-curing agent by name, or a project is already running a Fosroc-specified repair system, Fosroc Nitobond AR is the credible cross-brand alternative for the bonding/curing role — Space Arc stocks and supplies both, and can advise on which fits a given specification and budget.
Fosroc Nitobond AR — Specifiers who need an internationally referenced bonding-and-curing agent by name — or whose project is already running a Fosroc-specified repair system — often choose Nitobond AR over ShaliCrete for tender and system compatibility.
Related Waterproofing products
Source STP ShaliCrete for your project
Authorised distribution, technical advice & professional application across Delhi NCR and Pan-India.