Fosroc Conplast AE316
A chloride-free air entraining admixture that builds a stable microscopic bubble structure into concrete for durable freeze-thaw and de-icing-salt resistance.
What is it?
Conplast AE316 is a ready-to-use, chloride-free air entraining admixture (AEA) from Fosroc, based on a synergistic blend of synthetic and naturally occurring surfactants and supplied as a light brown liquid that disperses instantly in mixing water.
Where is it used?
Used in air-entrained structural and pavement-quality concrete exposed to freeze-thaw cycling and de-icing salts, plus mixes where improved cohesion and reduced bleeding are required across varying batching temperatures.
Why use it?
It deliberately introduces 5% +/- 2% of evenly distributed microscopic air voids that relieve internal pressure during freezing, sharply improving durability while also improving workability and reducing segregation and bleed.
How is it applied?
Dosed by the ready-mix or site batching plant at 0.03 to 0.20 litres per 100 kg of cement, gauged into the mixing water; never added to dry cement, and air content is verified on site by pressure-meter testing.
About Fosroc Conplast AE316
Fosroc Conplast AE316 is a purpose-built air entraining admixture engineered for concrete that must survive repeated freezing and thawing or exposure to de-icing chemicals. It is supplied as a light brown liquid based on a synergistic blend of synthetic and naturally occurring surfactants, is entirely chloride-free, and disperses instantly the moment it meets the mixing water. Its job is not to plasticise or accelerate the mix but to deliberately and controllably build a network of microscopic, discrete air bubbles into the hardened cement paste.
The mechanism is straightforward but precise. The surfactants act at the interface between the mixing water and the cement and aggregate particles, stabilising tiny air bubbles that would otherwise coalesce and escape. These bubbles remain finely divided and uniformly spaced throughout the concrete. When water in the capillary pores later freezes and expands, the entrained voids act as relief chambers that accommodate the pressure instead of letting it crack the paste. This is the single most reliable way to make concrete frost-durable, and it is mandated in many cold-climate pavement and bridge specifications worldwide.
What distinguishes AE316 within the Conplast air entraining family is its formulation for consistency. Air entrainment is notoriously sensitive to concrete temperature, cement chemistry, fines content and mixing energy, and many entrainers swing wildly in yield when conditions change. AE316 is designed to deliver more stable, repeatable air content across varying concrete temperatures, which makes it easier for a ready-mix producer to hit a target air spec batch after batch rather than chasing the dosage. Alongside the durability benefit, the entrained air also improves workability and cohesion and reduces bleeding and segregation, so the fresh concrete places and finishes more predictably.
In the Indian context, AE316 sits in Fosroc’s admixture portfolio as a specialist product rather than an everyday water-reducer. It is the right choice when a specification explicitly calls for an air-entrained mix, a measured air percentage and freeze-thaw durability rather than just strength. For projects in genuinely cold zones such as Himalayan and high-altitude road and hydro works, or for any structure where an entrained air content is contractually required, it is a well-documented, standards-compliant option that Space Arc Engineering supplies as an authorised Fosroc distributor.
The technical insight
The value of an air entrainer is judged not by how much air it produces but by the quality of the void system, and this is where dosage discipline matters. The target with AE316 is typically 5% +/- 2% total air in a medium-workability mix at 300-350 kg/m3 cement content, but the durability benefit depends on a fine bubble spacing factor, not just the headline percentage. Over-dosing inflates the air figure and silently sacrifices compressive strength, because every additional 1% of air costs roughly 5% of strength. Under-dosing leaves the paste unprotected. Because air yield is genuinely sensitive to concrete temperature, sand grading and fines, supplementary materials such as fly ash, mixing time and even the order of addition, the correct dosage must be established by trial mixes that replicate site materials and ambient conditions, then verified on every delivery with a calibrated pressure air meter. AE316 should be batched into the mixing water and never onto dry cement; combining it with a separately added water-reducer or superplasticiser can shift the air yield, so any admixture combination must be trial-tested together rather than assumed compatible.
Where it is used
- Pavement-quality concrete (PQC) for roads, highways and concrete carriageways exposed to frost
- Bridge decks, approach slabs and parapets in freeze-thaw and de-icing-salt environments
- Airport runways, taxiways and aprons requiring frost-durable concrete
- Hydraulic and water-retaining structures in cold and high-altitude regions
- Concrete in Himalayan, hill-station and high-altitude infrastructure subject to repeated freezing
- Any specification mandating a measured entrained air content for durability
- Mixes where improved cohesion and reduced bleeding or segregation are needed during placement and finishing
Key advantages
- Chloride-free, so it is safe for reinforced and prestressed concrete with no added risk of steel corrosion
- Produces a stable, evenly distributed microscopic air-void system for reliable freeze-thaw and de-icing-salt durability
- Formulated for more consistent air yield across varying concrete temperatures than conventional entrainers
- Improves workability and cohesion while reducing bleeding and segregation in the fresh mix
- Compatible with all types of ordinary Portland cement
- Ready-to-use liquid that disperses instantly in the mixing water with no pre-mixing
- Compliant with recognised standards including IS 9103, ASTM C260 and BS 5075 Part 2
- Long 12-month shelf life under normal storage, suiting project stockholding
Limitations & considerations
- Entrained air reduces compressive strength (roughly 5% loss per 1% added air), so mix design must compensate
- Air yield is sensitive to temperature, sand fines, fly ash, mixing time and dosage, demanding trial mixes and on-site pressure-meter verification
- Over-dosing easily pushes air content out of spec and erodes strength; it is not a forgiving forget-it admixture
- It is a specialist air entrainer only, not a water-reducer, plasticiser, accelerator or waterproofer
- Combining with other admixtures can alter air yield, so combinations must be trial-tested, not assumed
- Requires correct addition into the mixing water; adding to dry cement gives poor and erratic results
- Provides freeze-thaw durability but is unnecessary, and counterproductive, in non-frost mixes where strength is the priority
- Protect from freezing in storage; the product freezes near 0 degrees C
Selection & best practice
Establish the AE316 dosage by laboratory and field trial mixes using the actual project cement, sand, aggregates and any fly ash, batched at the expected site temperature, and confirm both the target air content and the resulting strength before production. Always gauge the admixture into the mixing water, never onto dry cement, and keep the dosage within 0.03-0.20 litres per 100 kg of cement. Verify air content on every load with a calibrated pressure-type air meter at the point of placement, since air can be lost during long haulage, pumping and over-vibration. Where AE316 is used with a Fosroc water-reducer or superplasticiser, trial the full admixture combination together because each can shift the air yield. Store drums sealed, out of direct sun and above freezing, and use within the 12-month shelf life.
Specifications
| Product type | Chloride-free air entraining admixture (AEA) |
| Chemical basis | Synergistic blend of synthetic and naturally occurring surfactants |
| Appearance | Light brown liquid, disperses instantly in water |
| Specific gravity | Typically 1.02 at 25 degrees C |
| Chloride content | Nil (to BS 5075) |
| Target air content | 5% +/- 2% in medium-workability concrete (300-350 kg/m3 cement) |
| Typical dosage | 0.03 to 0.20 litres per 100 kg of cement (established by trial) |
| Cement compatibility | All types of ordinary Portland cement |
| Standards | IS 9103, ASTM C260, BS 5075 Part 2 |
| Packaging | 210 litre drums and 25 litre pails |
| Shelf life | 12 months minimum under normal storage conditions |
| Storage | Keep sealed, protect from freezing (freezes near 0 degrees C) |
Industry use cases
Highways & roads
Air-entrained pavement-quality concrete for carriageways, bridge decks and approach slabs in frost-prone and de-icing-salt zones, where AE316 delivers the specified air content for long-term durability.
Aviation infrastructure
Runways, taxiways and aprons in cold-region airports that require frost-resistant concrete with a controlled, verified entrained air system.
Hydropower & water structures
Dams, spillways, canals and water-retaining structures in Himalayan and high-altitude projects subject to repeated freeze-thaw cycling.
Cold-region buildings
Structural concrete for buildings and external works in hill stations and high-altitude towns where winter freezing threatens durability.
Ready-mix production
RMC plants supplying air-entrained mixes that need a stable, repeatable air yield across changing ambient temperatures and batch conditions.
Frequently asked questions
What is Fosroc Conplast AE316 used for?
What is the recommended dosage of Conplast AE316?
Is Conplast AE316 chloride-free and safe for reinforced concrete?
Which standards does Conplast AE316 comply with?
Does air entrainment reduce concrete strength?
How is Conplast AE316 added to concrete?
What are the packaging sizes and shelf life?
How we position Fosroc Conplast AE316
Conplast AE316 is a specialist within Fosroc’s air entraining range, distinguished by its formulation for more stable air yield across changing concrete temperatures. It sits alongside Fosroc Conplast AEA (based on neutralised vinsol resin) and Conplast AE383 (based on synthetic surfactants), which cover similar frost-durability duties at different price and performance points; where a project also needs water reduction and entrained air together, a Fosroc plasticising-entrainer or a separate Conplast water-reducer such as Conplast SP430 paired with an AEA may be specified instead. Buyers should note AE316 is purely an air entrainer, not an all-in-one product, so it is usually combined with a water-reducer rather than replacing one. Credible alternative air entrainers in the Indian market include Sika AER and the BASF/Master Builders Solutions MasterAir range, with Dr. Fixit and STP (Pidilite/Bostik) more focused on waterproofing and general admixtures than on frost-grade air entrainment. As an authorised Fosroc distributor and applicator across Delhi NCR and Pan-India, Space Arc Engineering supplies genuine AE316 with TDS-backed dosage guidance and trial-mix support; for the exact air target and dosage on your mix, request a technical consultation rather than relying on a fixed figure.
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