Fosroc Conplast 316 AEA
A chloride-free, vinsol-resin air-entraining admixture that builds a stable microscopic air-void system into concrete for frost, freeze-thaw and de-icing-salt durability.
What is it?
Conplast 316 AEA is Fosroc’s chloride-free air-entraining admixture (AEA) based on neutralised vinsol resin. It generates a controlled system of microscopic, evenly distributed air bubbles in the concrete to improve frost resistance, cohesion and workability.
Where is it used?
Pavement-quality and exposed concrete: roads, bridge decks, airport runways and taxiways, hardstandings, canal linings and any large area at risk of frost or de-icing-salt damage. Also used to improve cohesion in mixes made with poorly graded aggregates.
Why use it?
Entrained air gives concrete a pressure-relief network that resists freeze-thaw and de-icing-salt scaling, while simultaneously cutting bleeding and segregation and improving finishability and pumpability.
How is it applied?
Added to the mixing water or with the final part of the gauging water at a typical dosage of 0.05-0.10 litres per 100 kg of cement, then trial-tested on site to dial in the target air content (commonly 4-6%).
About Fosroc Conplast 316 AEA
Conplast 316 AEA is the air-entraining admixture in Fosroc’s Conplast concrete-admixture range, supplied to the Indian market by Space Arc Engineering as an authorised Fosroc distributor and applicator. Chemically it is a chloride-free liquid based on neutralised vinsol resin (a rosin-derived surfactant) and supplied as a ready-to-use solution that disperses instantly in the mixing water. Unlike superplasticisers or water-reducers, an AEA is not added to make concrete flow or gain strength; its single job is to build a deliberate, stable system of microscopic air voids into the hardened paste. Those voids are the difference between a slab that survives repeated freezing winters and one that scales and spalls within a few seasons. Conplast 316 AEA works at the interface between the mixing water and the cement and aggregate particles, where its surfactant action stabilises tiny air bubbles, typically 10 to 300 microns across, and holds them evenly dispersed through the mix until the concrete sets. In Indian practice the product is most relevant to infrastructure exposed to genuine frost cycles, such as Himalayan and high-altitude roads, hill-station structures, cold-store and refrigerated floors, and projects built to international highway or airfield specifications where an air-entrained mix is mandated. Just as usefully in plains conditions, the same air voids act as internal ball bearings that improve cohesion and pumpability and suppress bleeding and segregation, which is why it is also specified for lean and harsh mixes made with marginal or poorly graded sand. The admixture is compatible with all ordinary Portland and blended cements and can be used alongside other compatible Fosroc Conplast admixtures, such as a superplasticiser, as part of a combined system, provided each is dispensed separately and trial-checked.
The technical insight
The performance of an air-entrained mix is governed less by total air content than by the air-void spacing factor, the average distance water in the paste has to travel to reach an escape void when it freezes and expands by roughly 9 percent. A well-distributed Conplast 316 AEA void system keeps that spacing factor low (broadly below 0.20 mm) so internal pressure is relieved before it cracks the paste. The single most important field point is that entrained air is sensitive to the whole mix and process, not just the dose. Air content rises with higher sand content (a sand increase from 35 to 45 percent can lift air from about 4.5 to 6.0 percent), and it falls with rising concrete temperature, very fine cements, high fly-ash (PFA) content, some pigments, over-mixing, prolonged transit, pumping and vibration. Because each percentage point of entrained air costs roughly 5 to 6 percent of compressive strength, the dose must be tuned to hit the specified air band and no more, then verified with a pressure air meter at the point of placing, not just at the batching plant.
Where it is used
- Concrete roads, highways and pavement-quality concrete (PQC) exposed to frost and de-icing salts
- Bridge decks, parapets and exposed structural slabs in cold and high-altitude regions
- Airport runways, taxiways, aprons and other extensive exposed concrete areas
- Himalayan and hill-region infrastructure subject to repeated freeze-thaw cycles
- Cold-store, freezer and refrigerated-warehouse floor slabs
- Canal linings, dam facings and hydraulic structures needing frost and scaling resistance
- Lean, harsh or low-cement mixes where improved cohesion and reduced bleeding are required
- Ready-mixed concrete and retarded mortar, as part of a combined admixture system
Key advantages
- Substantially improves resistance to freeze-thaw damage and de-icing-salt scaling, extending the service life of exposed concrete
- Chloride-free, so it is safe for reinforced and prestressed concrete with no added risk of reinforcement corrosion
- Stable, evenly distributed air-void system that performs across a wide range of aggregate qualities and mix conditions
- Improves cohesion and workability, producing a dense, close-textured finish free from gravel nests and sand runs
- Reduces bleeding and segregation, which improves pumpability and surface quality
- Disperses instantly in the mixing water and is compatible with OPC, PPC and blended cements
- Complies with recognised international standards (BS 5075 Part 2, BS 4887 Part 1, ASTM C260) for air-entraining admixtures
Limitations & considerations
- Entrained air reduces compressive strength by roughly 5-6 percent for every 1 percent of air, so mix design must compensate
- Air content is highly sensitive to sand content, cement fineness, temperature, mixing time, transit, pumping and vibration, demanding on-site control
- High fly-ash (PFA) content and certain pigments can interfere with air entrainment, and may need an alternative admixture or adjusted dosing
- Over-dosing produces excessive air and a sharp strength loss; the dose must always be established by site trials with an air meter
- It is an air-entrainer only, not a water-reducer or strength-gaining superplasticiser, and is not an integral waterproofer
- Not required for, and generally not specified in, ordinary plains concrete that never sees genuine freezing conditions
- Air content must be verified at the point of placing, as significant air can be lost in transit, pumping and compaction
Selection & best practice
Always establish the dose by site trial rather than copying a generic figure: start near 0.08 litres per 100 kg of cement, then adjust to hit the specified air band (typically 4-6 percent). Add Conplast 316 AEA to the mixing water or the final portion of gauging water, never to the dry cement, and keep it in a separate dispenser from any superplasticiser. Measure air content with a pressure air meter on fresh concrete at the point of discharge or placing, not just at the plant, because air is lost during transit, pumping and vibration. Hold the mix proportions, sand content, cement source and admixture batch as constant as possible once a satisfactory air content is proven, and re-check whenever materials, ambient temperature or transit time change. Avoid over-vibration and over-mixing, which collapse the void system. Do not store the drums in direct sun; keep them shaded and within their shelf life, and run a fresh trial if stock is old. For combined systems, confirm compatibility and dispense each admixture independently.
Specifications
| Product type | Air-entraining admixture (AEA) for concrete |
| Chemical base | Chloride-free, neutralised vinsol resin (surfactant) |
| Appearance | Liquid that disperses instantly in water (regional grades supplied translucent water-white or brown) |
| Specific gravity | Approx. 1.01 at 27 deg C |
| Chloride content | Nil (to BS 5075) |
| Alkali content | Typically less than 14.0 g Na2O equivalent per litre of admixture |
| pH | Minimum 6 |
| Typical dosage | 0.05 – 0.10 litres per 100 kg of cement (approx. 0.08 L gives ~5% air) |
| Typical air content | 5% +/- 1.5% at typical dosage in medium-workability concrete |
| Standards compliance | BS 5075 Part 2; BS 4887 Part 1; ASTM C260; EN 934-2 (air-entraining); DoT Specification for Highway Works |
| Cement compatibility | OPC, PPC and blended cements |
| Shelf life | Approx. 12 months in unopened containers stored in shade |
Industry use cases
Roads & Highways
Pavement-quality concrete for roads and bridge decks in frost-prone and high-altitude corridors, where an air-entrained mix is specified for freeze-thaw and de-icing-salt durability.
Airports & Aviation
Runways, taxiways and aprons built to international airfield specifications that mandate a controlled entrained-air system in the exposed slab.
Hill & High-Altitude Infrastructure
Himalayan roads, tunnels portals, retaining structures and hill-station buildings subjected to repeated overnight freezing and daytime thaw cycles.
Cold Storage & Industrial Floors
Freezer rooms, cold-store and refrigerated-warehouse floor slabs that cycle below freezing and need scaling resistance.
Water & Hydraulic Structures
Canal linings, dam facings and spillways where frost resistance and reduced bleeding improve surface durability and watertightness of the cover concrete.
Ready-Mixed Concrete
RMC producers improving cohesion, pumpability and finish in lean or harsh mixes made with poorly graded sand, dosing AEA at the plant under air-meter control.
Frequently asked questions
Is Fosroc Conplast 316 AEA a real product?
What does Conplast 316 AEA actually do to concrete?
What is the correct dosage?
Will it reduce the strength of my concrete?
Does it contain chloride or affect reinforcement?
Do I need air entrainment for normal construction in the plains?
How is it supplied and stored?
How we position Fosroc Conplast 316 AEA
Within the Fosroc Conplast family, Conplast 316 AEA is the specialist air-entrainer and should not be confused with the water-reducing superplasticisers in the same range. If your goal is workability, water reduction or strength rather than frost resistance, the right choice is a superplasticiser such as Fosroc Conplast SP430 or the PCE-based Auramix admixtures (for example Auramix 300 or Auramix 400); if it is integral waterproofing, the Conplast WP and Conplast Crystalline products apply. Conplast 316 AEA is what you specify when a project genuinely needs freeze-thaw and de-icing-salt durability, and it can be run alongside one of those superplasticisers as a combined system. Among credible alternatives, Sika offers Sika AER and the Sika AEA-series air-entrainers, MBS (Master Builders Solutions, formerly BASF) offers MasterAir, and Dr. Fixit and STP (Pidilite) supply admixture ranges to the Indian market; an architect or consultant may legitimately compare these on availability, technical support and project approvals. For frost-exposed infrastructure built to BS, ASTM or EN air-entrainment requirements, Conplast 316 AEA’s vinsol-resin chemistry, chloride-free formulation and documented standards compliance make it a well-established and specifiable option, and Space Arc Engineering supports its use in India with verified supply and on-site dosing and air-content guidance.
Related Concrete Admixtures products
Source Fosroc Conplast 316 AEA for your project
Authorised distribution, technical advice & professional application across Delhi NCR and Pan-India.