Air Entrained Voids
Air Entrained Voids - Related Videos
01:27
Air-entraining Agents
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2024
Air-entraining agents improve the durability and workability of concrete in climates with frequent freezing and thawing. These agents prevent cracks by introducing small air bubbles into the mix, creating spaces accommodating water expansion when temperatures drop. The air-entraining agents lower the surface tension of water, forming stable, small air bubbles. This method is more effective than having accidental large voids, as the intentional, smaller, and evenly distributed air voids improve...
01:28
Effects of Air-entrainment in Concrete
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2024
Air entrainment in concrete significantly enhances the material's durability, especially in environments subjected to freeze-thaw cycles. Introducing small air bubbles into the concrete mix acts as internal voids that accommodate the expansion of water when it freezes, thereby alleviating internal stress and preventing structural cracks. This function is crucial in climates with significant freezing and thawing, as it protects the concrete from repeated stresses that could lead to premature...
01:12
Total Voids in Concrete
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2024
Total voids in concrete encompass gel water volume, capillary pores, and entrapped air. Gel water (retained within the cement hydration products) and physically entrapped or adsorbed water are significant for the hydration process. For complete hydration, it's estimated that the space needed for the products of a cubic centimeter of cement doubles. Capillary pores constitute the unoccupied space within the hydrated cement paste, with their size largely influenced by the water-to-cement ratio...
07:12
Circadian Entrainment of Drosophila Melanogaster
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Cited by 1 •
2020
Here, we detail how to synchronize Drosophila to a circadian day. This is the first, and most important step necessary for studying biological rhythms and chronobiology.
06:39
Real-Time Void Spot Assay
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Cited by 14 •
2023
This article describes a new method to study mouse voiding behavior by incorporating video monitoring in the conventional void spot assay. This approach provides temporal, spatial, and volumetric information on the voiding events and details of mouse behavior during the light and dark phases of the day.
FAQs
Protection comes from pressure relief during freezing. When water in hardened concrete expands as it freezes, the closely spaced voids provide nearby space that can accommodate this expansion. By reducing the pressure imposed on the surrounding cement paste, the void network helps limit freeze-thaw damage and surface scaling. This mechanism also explains why spacing, not merely total air content, matters.
Air-entraining admixtures stabilize bubbles during mixing, allowing a distributed void network to remain in the cement paste. Bubble distribution and spacing determine how effectively the system can provide pressure-relief locations throughout the concrete. The admixture therefore influences both durability-related performance and fresh-concrete behavior, including cohesion and ease of placement.
More air is not automatically better. Engineers must balance the durability benefits of an appropriate void system against the possibility that excessive void volume will reduce compressive strength. Air content and bubble spacing are therefore mixture-design variables rather than incidental observations. Controlling both helps align resistance to freezing and scaling with the concrete’s required structural performance.
Analysis connects the concrete’s internal void system with expected performance. By examining air content and bubble spacing, engineers can evaluate whether mixture design and production provide the intended balance of freeze-thaw protection, deicing-salt resistance, workability, and compressive strength. The results support quality control, mixture design decisions, and assessment of long-term concrete performance.
The air-entraining admixture is incorporated during mixing, where it stabilizes bubbles in the cement paste. Engineers then control the resulting air content and bubble spacing as part of mixture design and quality control. This workflow links the mixing stage to fresh-concrete placement and to durability evaluation after hardening, helping maintain the intended balance of properties.
They are especially relevant when concrete must withstand freezing, thawing, or exposure to deicing salts, because the void system supports pressure relief and scaling resistance. The same design is useful when improved cohesion and easier placement are needed in fresh concrete. Engineering teams also assess the system when investigating strength tradeoffs or verifying long-term performance.