The main goal of this work is the development of a computational program for the quantitative assessment of the effects of entrained air in pipeline systems with respect to their operational safety. Likewise, two specific problems are investigated. (1) The effect of entrained air in form of pockets on hydraulic transients, during pump shutdown. It can be considered the most dangerous maneuver
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 …
12/7/2010 · Uses and effects of air entrainment. Air entrainment is the process where many small air bubbles are distibuted into concrete and become part of the matrix that binds the aggregate together in the hardened concrete. These air bubbles are dispersed throughout the hardened cement paste but are not, by definition, part of the paste (Dolch 1984).
Unfortunately, pumping concrete can affect the air content of a concrete mix. This has caused concern about the possible loss of resistance of the concrete to freezing and thawing. 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.
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
Concrete Technology Today 2 Return To Index discrete air voids in concrete, termed "entrained air." Non-air-entrained (left side) and properly air-entrained concretes (right side) are shown in Fig. 2. Most of the entrained air bubbles are smaller than the head of a pin
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 10 increase the
2/7/1994 · Unfortunately, pumping concrete can affect the air content of a concrete mix. This has caused concern about the possible loss of resistance of the concrete to freezing and thawing. 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.
1992, 2005 PRECAUTIONS Conduct a pre-pour conference in accordance with the agenda outlined in CIP 32 with the contractor, pump operator, and ready mixed concrete supplier present. Discuss the necessity for care in pumping air entrained concrete, and list
16/8/2011 · Air is one more method used to change the viscosity of the mix. It makes it more fluid while maintaining the same water-cement ratio. RE: Air and pumping of concrete. JAE (Structural) 10 Aug 11 08:32. Agree - and I once had a contractor add air to a lightweight mix - …
•Air Content and SAM testing after pumping may not be representative of the hardened concrete. •If this is true then concrete should not be rejected for low air or high SAM Number after pumping. •It appears that sampling the concrete prior to pumping is a good
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.
10/7/2020 · Air entrainment seems to reduce the risk of concrete spalling. • Air entrainment decreases the compressive strength of concrete at high temperatures. • Air entrainment has no effect on the compressive strength of concrete at 800 C. • No internal autoclaving
Air entrainment and its effects in concrete • Aggregate Research
IMPLEMENTATION STATEMENT This report summarizes the findings pertaining to the effects of various factors on the pumping of air-entrained Portland Cement Concrete and the circumstances surrounding the loss of air that can occur during the
It is claimed that, the place-ability of an air entrained concrete having 7.5 cm slump is better than a non-air entrained concrete with a slump of 12.5 cm. By and large, the compressive strength of concrete is reduced by use of air entrained admixture, as shown in Fig. 1.
1/12/2019 · In particular, the effects of pumping air-entrained wet mix shotcrete on its air content and air void system are discussed, along with the possible ramifications of using different pump rates. 2. Equipment, materials, and procedure
"Effects of Pumping Air Entrained Concrete," Washington Aggregates and Concrete Association, March 20, 1991, 12 pp. Dyer, R.M., "An Investigation of Concrete Pumping Pressure and the Effects on the Air Void System of Concrete," Master's Thesis, Department of Civil Engineering, University of Washington, Seattle, Washington, 1991.
They believed that air bubbles entrained at low atmospheric pressure would be compressed when exposed to standard pressure. Therefore, this experimental condition might exert inevitable effects on the air content of concrete and features of air-voids structure