For air bubble entrainment in hydraulics, see air bubble entrainment (hydraulics).
Air entrainment in concrete is the intentional creation of tiny air bubbles in a batch by adding an air entraining agent during mixing. A form of surfactant (a surface-active substance that in the instance reduces the surface tension between water and solids) it allows bubbles of a desired size to form. These are created during concrete mixing (while the slurry is in its liquid state), with most surviving to remain part of it when hardened.
Air entrainment makes concrete more workable[1] during placement, and increases its durability when hardened, particularly in climates subject to freeze-thaw cycles.[2] It also improves the workability of concrete.[2]
In contrast to the foam concrete, that is made by introducing stable air bubbles through the use of a foam agent, which is lightweight (has lower density), and is commonly used for insulation or filling voids, air entrained concrete, has evenly distributed tiny air voids introduced through admixtures to enhance durability, workability, and resistance to freeze-thaw cycles without significantly reducing its overall density, and without negative impact on its mechanical properties, allowing to use it in objects such as bridges[3] or roads built using roller compacted concrete.[4] Another difference is manufacturing process: foam concrete involves the creation of a foam mixture separately, which is then mixed with cement, sand, and water to form the final product, while air entrained concrete is produced by adding specialized admixtures or additives directly into the concrete mix during mixing to create small air bubbles throughout the mixture.[5]
Approximately 85% of concrete manufacturing in the United States contains air-entraining agents, which are considered the fifth ingredient in concrete manufacturing technology.[6]
^Chia, K.-S.; Zhang, M.-H. (2007). "Workability of air-entrained lightweight concrete from rheology perspective". Magazine of Concrete Research. 59 (5): 367–375. doi:10.1680/macr.2007.59.5.367.
^ abDu, Lianxiang; Folliard, Kevin J. (2005). "Mechanisms of air entrainment in concrete". Cement and Concrete Research. 35 (8): 1463–1471. doi:10.1016/j.cemconres.2004.07.026.
^Zhang, Peng; Li, Dan; Qiao, Yun; Zhang, Sulei; Sun, Congtao; Zhao, Tiejun (2018). "Effect of Air Entrainment on the Mechanical Properties, Chloride Migration, and Microstructure of Ordinary Concrete and Fly Ash Concrete". Journal of Materials in Civil Engineering. 30 (10). doi:10.1061/(ASCE)MT.1943-5533.0002456. S2CID 139634425.
^Wu, Zemei; Libre, Nicolas A.; Khayat, Kamal H. (2020). "Factors affecting air-entrainment and performance of roller compacted concrete". Construction and Building Materials. 259. doi:10.1016/j.conbuildmat.2020.120413. S2CID 224900303.
^Raj, Amritha; Sathyan, Dhanya; Mini, K.M. (2019). "Physical and functional characteristics of foam concrete: A review". Construction and Building Materials. 221: 787–799. doi:10.1016/j.conbuildmat.2019.06.052. S2CID 197616669.
^Mohammed AS, Pandey RK (2015). "Effect of Air Entrainment on Compressive Strength, Density, and Ingredients of Concrete" (PDF). International Journal of Modern Engineering Research (IJMER). 5 (1): 77–78. ISSN 2249-6645.
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happens, the jump can be accompanied by violent turbulence, eddying, airentrainment, and surface undulations, or waves. There are two main manifestations...
difference is that in Ia, IIa, and IIIa, an air-entraining agent is ground into the mix. The air-entrainment must meet the minimum and maximum optional...
interconnected air voids totaling approximately 15 to 25 percent. Water runs through the voids in the pavement to the soil underneath. Airentrainment admixtures...
and cured for 24 hours in a 66 °C steam bath, then toughened with an airentrainment agent, the bricks can last for more than 100 freeze-thaw cycles. Owing...
installed for some years, the mechanisms of airentrainment at the aerators and the slow movement of the air away from the spillway surface are still challenging...
incorporates stable air bubbles to create a lightweight and highly insulating product. Unlike air-entrained concrete, which introduces tiny air bubbles through...
Machine Wüthrich, Davide; Chanson, Hubert (September 2014). "Hydraulics, AirEntrainment, and Energy Dissipation on a Gabion Stepped Weir". Journal of Hydraulic...
west-northwest, a nearby upper-level low imparted high wind shear and dry airentrainment, and the depression degenerated into a remnant low twelve hours later...
bubbles, which continue to be a benefit during paint application. Airentrainment during mixing is not unique to PVA—in fact hardly a formula for paint...
levels of AirEntraining Agent (AEA) needed during concrete mixing, with or without mineral additives like combustion fly ash, that control air void volumes...
later in the day. As the hurricane pushed northward, continued drier airentrainment and increasingly strong southerly wind shear displaced Lee's convection...
the air-liquid surface where it destabilizes the foam lamellas. This causes rupture of the air bubbles and breakdown of surface foam. Entrainedair bubbles...
was developed additionally as a measure of fire resistance. Later airentrainment technology made boards lighter and less brittle, and joint treatment...
Center) for a new deep underground C2 center with >3 mi (4.8 km) of airentrainment tunnels (cancelled in 1979.)[citation needed] After the 2001 September...
northern coast of the peninsula on October 27. After weakening due to dry airentrainment, Zeta reorganized and became a hurricane again, and eventually a Category 2...
eye becoming cloud-filled and the deep convection eroding due to dry airentrainment. Jasper managed to maintain its intensity while battling unfavorable...
van Heerwaarden, C. C.; et al. (2009). "Interactions between dry-airentrainment, surface evaporation and convective boundary layer development". Quarterly...
environmental conditions became adverse. Strong vertical wind shear and dry airentrainment quickly stripped the storm of its convection, and it became a remnant...
exceeded, cracks appear. Adding an airentrainment agent during the mixing of fresh concrete induces the formation of tiny air bubbles in the fresh concrete...
early on September 13, about 415 mi (670 km) southeast of Bermuda. Dry airentrainment gave the storm a somewhat ragged appearance, but Paulette continued...
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