Anti-foaming agents are specialized chemical additives incorporated into concrete mixes to suppress or eliminate foam and air bubbles that form during mixing, transportation, or placement. In concrete, foaming arises when surfactants, entrained air, or admixtures (especially high-range water reducers) stabilize small bubbles; these bubbles, if not controlled, can lead to defects such as voids, honeycombing, reduced strength, blemished surface finishes, and non-uniformity in color and texture.
ARIT's ART-DF concrete defoamer is one such product developed specifically to handle these issues. It reduces bubble formation during mixing and pouring, improving compactness and structural integrity without negatively affecting workability or final curing.
Defoamer antifoaming agents work by interfering with the lifecycle of bubbles. Chemically, they reduce surface tension or disrupt the stability of the bubble walls so bubbles merge and escape more easily, rather than being trapped in the fresh concrete. Common types include silicone-based compounds, mineral oils, non-silicone organic agents like polyethers or fatty alcohols, and powders. According to general industrial knowledge, insoluble oils, stearates, alcohols, silicones and glycols are regularly used as defoamer ingredients.
ART-DF demonstrates how modern defoamers are designed for compatibility and effectiveness: it's a semi-transparent liquid with high solid content (~97 %), neutral to slightly acidic pH in use, reasonably low viscosity, and stable in hot and humid environments. It's suited for high-performance concretes, precast components, decorative surfaces, self-compacting concrete, and large infrastructure works where both structural integrity and surface smoothness are important.
In essence, anti-foaming agents are essential tools in concrete admixture technology. They allow for the use of powerful water reducers and other admixtures without incurring the side effects of excessive foam. By carefully balancing the mix design, including the type and dosage, they help ensure that the concrete is dense, strong, visually acceptable, and durable.
Precast concrete yards (beams, girders): where finish, uniform color, and no surface defects are essential.
High-speed railway/bridge construction: large structural components, where large concrete pours are involved.
Architectural concrete, exposed surfaces, decorative facades.
Pumped concrete operations: foam causes pumping issues, pockets.
Mass concrete/large scale pours: ability to maintain workability and manage bubble escape.
Concrete in hot climates: rapid hydration tends to trap bubbles; defoamer helps maintain quality.
The Jinyi Railway Beam Yard, operated by China Railway Shanghai Engineering Group, produces precast C55T girders with strict requirements: no visible blowholes, uniform color, high finish. They require about 1 hour slump retention to allow handling of concrete with low water-binder ratio and high paste content in summer.
Under high paste systems with low water, air bubbles tend to persist or form during vibration. Rapid bubble release is needed so that surface finish is smooth and color uniform.
ARIT used two products: ART-DF (E) for eliminating small bubbles, and ART-DF (D) to accelerate discharge of bubbles. Together, they effectively meet aesthetic and functional requirements: concrete with no visible surface bubbles, good slump retention, even appearance.
Hefei West Station is a large high-speed rail hub with mixed uses. For the pier bodies (cast-in-place C50 concrete), demands include no obvious defects, uniform color, clear concrete finish, and slump retention of about 1 hour.
Air entrainment/bubbles must be carefully managed, color and finish appearance stringent. Mixes also need to maintain fluidity and appearance over time (during transport, vibration, placing). Defoaming and air-entraining agents must be balanced: first maintain workability, then eliminate bubbles just before finishing.
ARIT used two types of origin liquor admixtures: ART-M22 and ART-M15 to achieve slump retention, plus ART-Defoaming E to handle bubble elimination. Combination of three satisfied both slump time and visual quality requirements.
The defoamer should be added after slump retentive admixtures and before finishing stages so bubble formation is first managed, then eliminated.
Using just enough anti-foam: too little leaves bubbles; too much can interfere with air-entraining agents, reduce durability (air voids matter), alter setting.
Compatibility among anti-foam, air-entraining agents, water reducers, and cement type. Some defoamers may neutralize air-entraining agents or reduce retention of desired entrained air.
Summer vs winter: warm temperatures speed up hydration, foam can persist longer; heat may require more defoamer or different types; vibration and placement speed matter.
For projects where appearance is critical (station facades, visible structural elements), controlling foam is essential not just for strength but for visual quality. ARIT projects show that combining slump retention+defoamer+precise admixture recipe yields desirable result.
It reduces or removes entrained air or surface foam; helps bubbles escape; ensures better surface finish, reduces defects; improves color uniformity; avoids problems caused by trapped air.
No. They serve opposite roles in some respects: air-entraining agents introduce small stable bubbles for freeze-thaw durability; defoamers remove undesirable foam/large bubbles. The two must be balanced carefully.
Silicone-based defoamers; non-silicone oils/fatty acids; powders; origin liquor defoamers like ART-DF types; combinations; specialty types for color or appearance; also liquid vs powder etc.
Yes. If used improperly, defoamers may reduce needed air bubbles. The mix designer must use proper dosage, check compatibility, perform lab trials.
Yes. Many anti-foaming agents used in concrete and industrial processes can be safe when used correctly: using approved formulations, controlled dosages, proper handling and PPE, and complying with applicable regulations.
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