Fosroc Conplast 316 AEA 1:5
Chloride-free, vinsol-resin air-entraining admixture that builds a stable microscopic bubble structure into concrete for freeze-thaw and de-icing-salt durability.
What is it?
A chloride-free liquid air-entraining admixture (AEA) for concrete, based on neutralised vinsol resin and surfactants (tensides), supplied as a brown solution that disperses instantly in the mixing water.
Where is it used?
Durability-critical and exposure-class concrete: pavements, bridge decks, parking structures, water-retaining works, marine and high-altitude jobs in India where freeze-thaw, de-icing salts or harsh exposure apply.
Why use it?
Entrained micro-air bubbles relieve internal freeze-thaw pressure, cut surface scaling, improve cohesion and workability, and reduce bleeding and segregation in pumped or transported mixes.
How is it applied?
Dosed with the mixing water (never onto dry cement) at the batching plant via a calibrated dispenser; air content is verified on site by the pressure-pot test and the dosage trimmed by trial mix.
About Fosroc Conplast 316 AEA 1:5
Fosroc Conplast 316 AEA 1:5 is an air-entraining admixture (AEA) from Fosroc’s long-established Conplast range of concrete admixtures. Confirmed on Fosroc’s official product pages, it is described as a chloride-free air-entraining admixture based on neutralised vinsol resin and tensides (surfactants), supplied as a brown solution that instantly disperses in water. The “1:5” suffix denotes the supply concentration/dilution variant of the 316 AEA chemistry, so the working dosage is read against that strength rather than against a neat concentrate. The job of an AEA is fundamentally different from a plasticiser or waterproofer: instead of reducing water or blocking pores, it deliberately builds millions of tiny, stable, disconnected air bubbles into the cement paste. Those bubbles act as internal pressure-relief chambers. When pore water freezes and expands, the surrounding micro-bubbles give it somewhere to go, so the concrete is not torn apart from within. The same bubble system is what protects pavements and decks from surface scaling under de-icing salts and rapid temperature swings. For Indian contractors and consultants, this matters most on high-altitude and Himalayan infrastructure (Ladakh, Himachal, Uttarakhand, Sikkim, the North-East), cold-region airfields and highways, marine and splash-zone structures, and any project written to a freeze-thaw or severe-exposure durability clause. Because air entrainment also improves the cohesion and “creaminess” of a mix, the admixture additionally helps lean or harsh aggregate gradings pump and finish better, and reduces bleed and segregation during long transit in transit mixers. Space Arc Engineering, an authorised Fosroc distributor and applicator across Delhi NCR and Pan-India, positions Conplast 316 AEA 1:5 for clients who need verified, standards-grade air entrainment rather than an unbranded “aerating” liquid, and who want it backed by mix-design support and site QA. It is a specialist durability tool — most ordinary Indian RCC does not need it — but where the specification calls for entrained air, getting the chemistry, dosage and quality control right is what separates a 50-year deck from one that scales in five winters.
The technical insight
Air entrainment is controlled by what engineers call the air-void system, not just the headline air percentage. What protects concrete from freeze-thaw is a fine, closely-spaced bubble network — typically a spacing factor below about 0.20 mm and a high specific surface — rather than a few large voids. Vinsol-resin AEAs like Conplast 316 AEA generate exactly this fine, well-distributed micro-bubble structure at the cement-paste/aggregate interface, and a useful field property of this product is that the entrained air stays stable during transport in rotary (transit) trucks, so the air you batch is close to the air you place. Two design rules follow. First, every 1% of entrained air costs roughly 5% of compressive strength, so air content must be specified as a target band (commonly 4–7% depending on aggregate size and exposure) and not maximised. Second, dosage is sensitive: cement fineness, fly ash or slag, sand fines, mix temperature, slump and even mixing time all shift the air yield, which is why an AEA must always be dialled in by trial mix and then verified on site with the pressure-air meter, not assumed from a fixed dose. Air entrainment and water reduction also interact — when used alongside a Conplast plasticiser or superplasticiser, the AEA dose usually needs trimming because the dispersing chemistry changes the bubble yield. Practically, the admixture is added into the gauging water for uniform dispersion; dosing it onto dry cement or as a late addition gives erratic, unreliable air.
Where it is used
- Freeze-thaw-exposed concrete: high-altitude and Himalayan roads, bridges, tunnels and buildings in Ladakh, Himachal, Uttarakhand, Sikkim and the North-East
- Highway and airfield pavements subject to de-icing salts and rapid temperature swings, where surface scaling must be prevented
- Bridge decks, parapets and approach slabs requiring severe-exposure durability
- Marine, coastal and splash-zone structures needing improved frost and cyclic-exposure resistance
- Water-retaining and hydraulic structures where a denser, more cohesive, lower-bleed concrete is wanted
- Lean, harsh or gap-graded mixes that need better cohesion, pumpability and finishability
- Ready-mix concrete transported long distances in transit mixers where mix stability and reduced segregation are required
Key advantages
- Chloride-free chemistry — safe for reinforced and prestressed concrete with no risk of admixture-induced corrosion
- Builds a fine, stable, evenly distributed micro-air-bubble structure for genuine freeze-thaw and de-icing-salt protection
- Air content remains stable during transport in rotary/transit trucks, so placed air matches batched air
- Reduces surface scaling, dusting and frost damage, extending the service life of pavements and decks
- Improves mix cohesion, workability and finish, and cuts bleeding and segregation in lean or harsh mixes
- Disperses instantly in the mixing water for uniform action across the batch
- Internationally classified as an air-entraining admixture (EN 934-2:T5), giving consultants a recognised specification reference
Limitations & considerations
- Each ~1% of entrained air reduces compressive strength by roughly 5%, so over-dosing directly weakens the concrete
- Dosage is highly sensitive to cement type, fly ash/slag, sand fines, temperature, slump and mixing time — it must be set by trial mix and confirmed on site, never fixed blindly
- Requires on-site air-content testing (pressure-pot meter); without QA the air-void system cannot be guaranteed
- Not a water-reducer, plasticiser or waterproofer — it does not increase strength or directly stop water ingress; use the correct Conplast product for those needs
- Most routine Indian RCC does not require air entrainment; it adds cost and QA only where freeze-thaw or severe exposure is specified
- Interacts with plasticisers/superplasticisers, so the dose needs re-balancing when admixtures are combined
- Must be added to the gauging water; adding onto dry cement or as a delayed dose gives erratic air content
Selection & best practice
Treat air content as a design target, not a fixed dose. Establish the admixture dosage by laboratory and site trial mixes using the actual project cement, aggregates and SCMs, aiming for the specified air band (commonly 4–7% by exposure class and aggregate size). Always add Conplast 316 AEA 1:5 into the mixing/gauging water through a calibrated dispenser — never onto dry cement and never as a late top-up. Verify air content on every shift, and after any change of materials or weather, with a pressure-type air meter, and re-trim the dose accordingly. When combining with a Conplast plasticiser or superplasticiser, re-balance the AEA dose by trial because the dispersant alters air yield. Account for the strength penalty of entrained air in the mix design, keep mixing time and slump consistent, and store the product in its original sealed containers, protected from frost and direct sun. For exposure-class projects, run the dosage and air-void targets past Space Arc Engineering’s technical team so the mix is both compliant and economical.
Specifications
| Product type | Chloride-free air-entraining admixture (AEA) for concrete |
| Chemical base | Neutralised vinsol resin and tensides (surfactants) |
| Appearance | Brown solution; disperses instantly in water |
| Chloride content | Chloride free (nil) |
| Primary function | Generates a stable microscopic air-bubble structure for freeze-thaw and de-icing-salt durability |
| International classification | Air-entraining additive to concrete, EN 934-2:T5 |
| Typical air content target | ~5% (project-specified, commonly 4–7% by exposure/aggregate) |
| Specific gravity (AE316-class AEA) | Typically ~1.02 at 25 deg C (confirm on supplied-batch TDS) |
| Indicative dosage (AE316-class AEA) | ~0.03–0.20 L per 100 kg cement, set by trial mix for the 1:5 strength |
| Compatibility | Compatible with ordinary Portland cement and other Conplast admixtures when dosed separately |
| Addition method | Added to the mixing/gauging water via calibrated dispenser |
| Air stability | Air content stable during transport in rotary/transit trucks |
| Pack / shelf life | Liquid in drums/pails; confirm exact pack size and shelf life on the regional Fosroc TDS |
Industry use cases
High-altitude & Himalayan infrastructure
Roads, bridges and buildings in Ladakh, Himachal, Uttarakhand and the North-East where concrete endures repeated freeze-thaw cycles use entrained air to prevent internal cracking and scaling.
Highways & airfields
Rigid pavements and runway/taxiway slabs exposed to de-icing salts and sharp temperature swings rely on a stable air-void system to resist surface scaling over decades.
Bridges & transport structures
Decks, parapets and approach slabs written to severe-exposure durability clauses specify air entrainment to meet design service-life requirements.
Marine & coastal works
Splash-zone and tidal structures use entrained air, alongside dense low-permeability mixes, to improve resistance to cyclic wetting, frost and aggressive exposure.
Ready-mix & long-haul concrete
RMC plants supplying distant sites use the admixture’s transit-stable air and improved cohesion to reduce bleeding and segregation during extended transport.
Water-retaining & hydraulic structures
Reservoirs, canals and treatment works benefit from the denser, more cohesive, lower-bleed concrete that controlled air entrainment helps produce.
Frequently asked questions
What exactly does Conplast 316 AEA 1:5 do to concrete?
What does the ‘1:5’ in the name mean?
How much should I dose, and how do I control the air content?
Will it reduce my concrete’s strength?
Is it safe for reinforced and prestressed concrete?
Do most projects in India actually need air entrainment?
How we position Fosroc Conplast 316 AEA 1:5
Within Fosroc’s Conplast admixture family, Conplast 316 AEA 1:5 is the dedicated air-entrainment specialist — it sits apart from the water-reducing and workability products such as Conplast SP430 (superplasticiser) and Conplast WP200 (integral waterproofer), and from companion air-entraining/aerating grades like Conplast AEA, Conplast AE316 and Conplast AE383. On many durability-driven jobs it is used together with a Conplast plasticiser or superplasticiser, with the AEA dose re-balanced by trial because the two chemistries interact. Among credible alternatives in the Indian market, comparable air-entraining admixtures include Sika AER / SikaAer-series products from Sika and air-entraining grades from BASF/Master Builders Solutions (MasterAir). Dr. Fixit and STP (Pidilite) are strong, widely-used names in India but are positioned primarily around waterproofing and repair systems rather than dedicated freeze-thaw air-entraining admixtures, so they are less of a like-for-like substitute here. Space Arc Engineering’s recommendation is straightforward: where a specification genuinely calls for entrained air for freeze-thaw or severe-exposure durability, choose a properly classified AEA such as Conplast 316 AEA 1:5 and back it with trial mixes and on-site air testing; where the real need is water reduction, workability or waterproofing, a different Conplast (or competitor) product will serve better. As an authorised Fosroc distributor and applicator in Delhi NCR and Pan-India, Space Arc can supply the correct grade, confirm the current regional technical data sheet, and provide mix-design and QA support so the air-void system performs as designed.
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