STP ShaliPlast AE
Modified-resin air-entraining admixture that locks a stable micro air-void system into concrete — freeze-thaw durability, better cohesion and watertightness to ASTM C260 and IS 9103.
What is it?
A brown, aqueous modified-resin air-entraining admixture from STP Limited (formerly AirMix 200) that deliberately infuses microscopic air bubbles into concrete, mortar and plaster. Chloride-free, conforming to ASTM C260, AASHTO M154 and IS 9103-1979.
Where is it used?
Ready-mix plants, marine structural concrete, mass raft pours, dams and reservoirs, underground water tanks, and any exterior concrete facing freeze-thaw cycling in cold or high-altitude regions.
Why use it?
A controlled air-void system protects concrete from freeze-thaw damage and de-icing salts while cutting bleeding, segregation and permeability — with water reduction and no chloride added to the mix.
How is it applied?
Dispensed into the gauging water — never onto dry cement — at 0.7–1.0% by weight of cement per the STP data sheet, with trial mixes to fix the exact dose for your cement, sand and temperature.
About STP ShaliPlast AE
ShaliPlast AE is STP Limited’s air-entraining admixture, sold for years as AirMix 200 before joining the ShaliPlast family. It is an aqueous solution of modified resins that generates millions of microscopic, uniformly spaced air bubbles inside the concrete body as it mixes. Unlike accidental entrapped air, this engineered air-void system is stable across a wide temperature band — which is exactly what ready-mix producers need when the same mix design has to perform in a Delhi summer and a Himalayan winter. The product is manufactured under tight factory control and conforms to ASTM C260, AASHTO M154 and IS 9103-1979.
For Indian infrastructure work, its real value shows in two places: cold-region concrete, where the air voids absorb the expansion of freezing pore water, and water-retaining or marine structures, where reduced bleeding and lower permeability translate into tighter, more durable concrete. Space Arc Engineering supplies genuine STP stock in 20 kg and 200 kg drums across Delhi NCR and pan-India, with dosing support for trial mixes.
The technical insight
The modified resin works as a surfactant at the water-cement interface. During mixing it stabilises tiny air bubbles — typically far smaller than entrapped air voids — and holds them uniformly dispersed with controlled size and spacing. When hardened concrete freezes, water in the capillary pores expands roughly 9% in volume; without relief, that hydraulic pressure cracks the paste a little more with every cycle. Each entrained void acts as a pressure-relief chamber the freezing water can escape into, which is why bubble spacing matters more than total air content. In the fresh state, the same bubbles behave like ball bearings between aggregate particles — improving plasticity and cohesion, reducing bleed water channels, and allowing the mix water to be cut without losing workability.
Where it is used
- Ready-mixed concrete needing consistent air content across seasons and hauls
- Pavements, bridge decks and exterior concrete exposed to freeze-thaw cycles
- Structural concrete in marine and coastal environments
- Mass concrete construction such as rafts and large foundation pours
- Water-retaining structures — dams, reservoirs and spillways
- Underground water tanks and other buried water-holding concrete
- Mortars and plasters where added cohesion and workability are wanted
- Mixes with harsh or poorly graded sands that tend to bleed and segregate
Key advantages
- Builds a stable air-void system with controlled bubble size and spacing for reliable freeze-thaw protection
- Improves resistance to de-icing salts, sulphate attack and corrosive water
- Allows water reduction without any loss of workability
- Cuts bleeding and segregation for a more cohesive, easier-to-finish mix
- Reduces permeability and improves watertightness of the hardened concrete
- Chloride content nil — no added corrosion risk for reinforced or prestressed work
- Performs consistently over a wide range of ambient temperatures
- Compatible with all Portland cements including sulphate-resisting cement (SRC)
Limitations & considerations
- Not compatible with high-alumina cement
- Entrained air trades away some compressive strength, so the mix must be redesigned around the target air content
- A small amount of air is lost during pumping — dose and verify accordingly at the point of placement
- Effective dosage shifts with cement type, sand fineness, temperature and mix design; trial mixes are essential and overdosing must be avoided
- Must be dosed into the gauging water separately from other admixtures — never pre-blended or added to dry cement
- Excessive vibration drives entrained air back out; the near self-compacting mix needs only light compaction
Selection & best practice
Dose ShaliPlast AE through a calibrated dispenser into the gauging water only — it must never touch dry cement, and it should enter the mixer independently of any other admixture. STP’s recommended sequence: charge all materials with about 70% of the mixing water and mix for three minutes, then add the remaining water carrying the admixture and mix a further three minutes to reach the required slump. Because air content responds to cement brand, sand grading and ambient temperature, run site trial mixes to lock the dose within the 0.7–1.0% by weight of cement range and check air content at the delivery point, not just the plant. Compact lightly, then cure thoroughly with a curing compound or wet hessian.
Specifications
| Composition | Aqueous solution of modified resins |
| Appearance | Brown liquid |
| Density | 1.00–1.05 g/cc |
| pH value | 7–8 |
| Chloride content | Nil |
| Standards compliance | ASTM C260, AASHTO M154, IS 9103-1979 |
| Dosage | 0.7–1.0% by weight of cement (establish by trial mix) |
| Packing | 20 kg and 200 kg drums |
| Shelf life | 12 months in original unopened packing, stored cool and dry under shed |
Industry use cases
Ready-Mix Concrete
RMC plants use ShaliPlast AE to hold a consistent air content across seasonal temperature swings and long hauls, keeping every truckload of a durability-specified mix within tolerance.
Cold-Region Infrastructure
Roads, pavements and bridge decks in Himalayan and high-altitude projects rely on entrained air to survive daily freeze-thaw cycling and de-icing salt exposure.
Marine & Coastal Works
Structural concrete for jetties, sea-facing frames and coastal foundations gains sulphate and corrosive-water resistance along with lower permeability.
Water Infrastructure
Dams, reservoirs and underground water tanks benefit from reduced bleeding and improved watertightness in large water-retaining pours.
Mass Concrete & Rafts
Large raft foundations use the improved cohesion and reduced segregation to place big volumes cleanly with less compaction effort.
Frequently asked questions
What dosage of ShaliPlast AE should I use?
Will entrained air reduce my concrete strength?
How is entrained air different from entrapped air?
Can I use ShaliPlast AE with a superplasticizer?
Is it safe for reinforced and prestressed concrete?
What pack sizes are available, and is this the same product as AirMix 200?
How we position STP ShaliPlast AE
ShaliPlast AE fills the air-entrainment slot in STP’s GARA admixture range. On projects that also need slump retention or high water reduction, pair it with an STP ShaliPlast plasticiser dosed separately, and protect the finished pour with an STP curing compound. For water-retaining structures where integral waterproofing is specified alongside air entrainment, STP’s Shalicrete line is the natural companion. Where the project specification names Fosroc or calls for a neutralised vinsol-resin air entrainer, Fosroc Conplast AE300 is the direct equivalent we stock and can supply against the same enquiry.
Fosroc Conplast AE300 — Specifiers who need a neutralised vinsol-resin air entrainer or whose tender documents name Fosroc typically choose Conplast AE300 for the same freeze-thaw durability role.
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