1/1/1996 · Concrete Pumping Effects on Entrained Air Voids. Final Report, Research Project T9233 Task 21, for the Washington State Transportation Commission, Washington State Transportation Center, University of Washington, Seattle, June 1994, 97 pp.
1/7/2016 · The number of air voids in air-entrained WMS before and after shotcreting is compared in Fig. 8. Note that the number of 10–100 μm entrained air voids was greatest for WMS with a 4.5% silica fume replacement both before and after shotcreting.
3/4/2019 · Intentionally entrained air voids improve the resistance of concrete to damage from cycles of freezing and thawing. Any air voids reduce the strength of concrete, with about a 5% reduction in strength for each 1% increase in the volume of air voids.
The actual effect of pumping on the air content measured for the concrete is not consistent; in some cases air content has increased, while in others it has decreased. Previous work has shown that pumping causes pressure in the concrete, and this pressure can alter the air-void system.
Effect of entrained air voids on the microstructure and
1/12/2019 · Yingling et al.  report that the air loss mechanism in pumped concrete may largely be due to the impact of rapidly moving concrete contacting stationary objects (such as shotcrete impacting the substrate at high velocity) thereby breaking the internal air voids
Title. Concrete Pumping Effects on Entrained Air-Voids. Author. William Elkey, Donald J. Janssen, Kenneth C. Hover. Subject. Admixtures, Air entraining agents, Air voids, Fly ash, Freeze thaw durability, Lignosulfonate, Mix design, Pressurization, Pumped concrete, Stability (Mechanics), Water reducing agents. Keywords. concrete pumping, pressure,
5/7/2018 · Dyer M (1991) An investigation of concrete pumping and effects of pressure on the air void system of concrete. Master Thesis, University of Washington, WA 17. Elkey W, Janssen DJ, Hover KC (1994) Concrete pumping effects on entrained air voids. Research
8/3/2021 · SF can influence the entrained air voids in concrete. Because of the high surface area of SF, it was reported that with the addition of condensed silica fume (CSF), the dosage of AEA to obtain required air content increased,, . In the presence of a high amount of.
8 The effects of entrained air on microstructure and transport properties of concrete with up to 11.5% air at different w/c 9 ratios, curing and conditioning regimes were investigated. It was found that air voids disrupt the packing of cement and
2/7/1994 · The actual effect of pumping on the air content measured for the concrete is not consistent; in some cases air content has increased, while in others it has decreased. Previous work has shown that pumping causes pressure in the concrete, and this pressure can alter the air-void system.
Civil Engineering: Air bubbles voids and Effects in Concrete
26/4/2021 · Enhanced Entrained Air Void System Characterization for Durable Highway Concrete Status: Active Introduction The impact of the air void system depends on the total volume, size, and dispersion of the air voids in the concrete system as well as their compatibility
Unfortunately, the pumping of air -entrained concrete is known to affect the fresh air content in the fresh concrete. This has caused concern about the durability of concrete in environments where the concrete will experience repeated freezing and thawing cycles.
Page 2 of 10 the art test method to study the entrained air void system in concrete is ASTM C457 – "Standard Test Method for Microscopical Determination of Parameters of the Air-Void System in Hardened Concrete"  originally proposed by Brown and Pierson
Air in concrete originates in four general ways, producing "entrapped" and "entrained" voids which are differentiated by their spatial and pressure rela-onships Title: Orgin, Evolution, and Effects of the Air Void System in Concrete.Part 1 - Etrained Air in Unhardend
9/1/2018 · Effects of air voids: When the air voids in hardened concrete are mostly in the form of large voids and pockets, the effects are generally detrimental. Failure to remove larger voids results in porous, poorly consolidated concrete in the forms and around re-bars and other inserts, with honeycombing and reduced in-place strength.