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what is the effect of pumping on air entrained concrete

what is the effect of pumping on air entrained concrete

Research - Concrete Pumping Effects on Entrained Air-Voids ...

Jul 02, 1994  Concrete Pumping Effects on Entrained Air-Voids. Pumping is a frequently used method of efficiently transporting concrete from the delivery vehicles to the formwork. 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.

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Concrete Pumping Effects on Entrained Air-Voids

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

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Appendices: Concrete Pumping Effects on Entrained Air-Voids

Jul 02, 1994  Appendices: Concrete Pumping Effects on Entrained Air-Voids. Publication URL: Full Document (pdf 1.9 mb) Pumping is a frequently used method of efficiently transporting concrete from the delivery vehicles to the formwork. Unfortunately, pumping concrete can affect the air content of a concrete mix. This has caused concern about the possible ...

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Air entrainment and concrete - USDA

effects on the chara c t e r istics of both the plastic and the hard e n e d concrete. In fresh concre t e , the tiny air bub- ... we r e air entrained concrete speci-m e n s . After 5 years of exposure (663 f re e ze-thaw cycles) 26 percent of the columns had failed; again, no air en-

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Appendices: Concrete Pumping Effects on Entrained Air-Voids

Jul 02, 1994  Appendices: Concrete Pumping Effects on Entrained Air-Voids. Publication URL: Full Document (pdf 1.9 mb) Pumping is a frequently used method of efficiently transporting concrete from the delivery vehicles to the formwork. Unfortunately, pumping concrete can affect the air content of a concrete mix. This has caused concern about the possible ...

get price

Concrete Pumping Effects on Entrained Air-Voids

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

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Appendices: Concrete Pumping Effects on Entrained Air

Appendices: Concrete Pumping Effects on Entrained Air-Voids Author: William Elkey, Donald J. Janssen, Kenneth C. Hover ... Pumped concrete, Stability \(Mechanics\), Water reducing agents Keywords: concrete pumping, pressure, air voids, entrained air, freezing and thawing, spacing factor, specific surface, Philleo factor Created Date:

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The effects of pumping on the air content and void ...

Dec 01, 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

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Air entrainment and concrete - USDA

effects on the chara c t e r istics of both the plastic and the hard e n e d concrete. In fresh concre t e , the tiny air bub- ... we r e air entrained concrete speci-m e n s . After 5 years of exposure (663 f re e ze-thaw cycles) 26 percent of the columns had failed; again, no air en-

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CIP 21 - Loss of Air Content in Pumped Concrete

Queries on Concrete, Concrete International, August 1992, p. 71. 5. “Effects of Pumping Air Entrained Concrete,” Washington Ag-gregates and Concrete Association, March 20, 1991, 12 pp. 6. Dyer, R.M., “An Investigation of Concrete Pumping Pressure and the Effects on the Air Void System of Concrete,” Master’s

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Air-Entrained Concrete - Portland Cement Association

Air-entrained concrete is produced using air-entraining portland cement, or by the introduction of air-entraining agents, under careful engineering supervision, as the concrete is mixed on the job. The amount of entrained air is usually between four and seven percent of the volume of the concrete, but may be varied as required by special ...

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Air-Entrained Concrete Air Entraining Cement Air Concrete

Effect of Air Entrainment on Concrete Compressive Strength. Air entraining admixture commonly introduced to increase concrete workability without affecting the concrete strength very much. Form the study says that the air-entrained concrete having 7.5 cm slump is better than the slump of 12.5 cm of the non-air-entrained concrete.

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Effect of Fly Ash on the Durability of Air-Entrained Concrete

The effects of low temperature curing and moisture availability during curing were also evaluated. These tests indicated that the freeze-thaw resistance of air-entrained concrete was reduced by the use of certain fly ashes when cured at low temperature. For other conditions there was no

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Air Entrainment and the Properties of Concrete Concrete ...

Road research Laboratory U.K, it is found that 5% air entrainment increases the compacting factor by 0.07, which would be equal to an increase in slump from 1.2 cm to 5.0 cms. 3. Effect on Strength of Concrete: Generally it can be said that air entrainment in concrete reduces the compressive strength of concrete.

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Examination of Air Entrainment Stability Factors of Pumped ...

Nature of AEA Film Around the Entrained Air Void [22] . Interactions Between Cement, Air, Water and Molecules of Air Entraining Agent [17] Apparatus Used in the Linear Traverse Method [19] . Effect of Entrained Air Content on the 28-Day Compressive Strength of Concrete [22] . . . . . .

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Why is concrete air content important?

Apr 23, 2020  Air-entraining admixtures cause small stable bubbles of air to form uniformly through a concrete mix. The benefits of entraining air in the concrete include increased resistance to freeze-thaw degradation, increased cohesion (resulting in less bleed and segregation) and improved compaction in low-workability mixes.

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Is entrained air required in wet-mix shotcrete? Concrete ...

Aug 01, 1992  The ACI 506 "Guide to Shotcrete" recommends entraining air in wet-mix shotcrete. Section 2.7.2 of that document says: "Wet-mix shotcrete that will be exposed to freeze-thaw cycles should be air entrained. Air entrainment tends to make some mixes more workable and may reduce rebound. Data are available to show that a significant quantity of the ...

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Concrete Pumping Effects on Air-Entrained Voids in ...

Placing concrete using a concrete pump has placement advantages due to the increased speed, accessibility, and convenience of operation. Unfortunately, the pumping of air-entrained concrete is known to affect the fresh air content in the fresh concrete.

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Appendices: Concrete Pumping Effects on Entrained Air

Appendices: Concrete Pumping Effects on Entrained Air-Voids Author: William Elkey, Donald J. Janssen, Kenneth C. Hover ... Pumped concrete, Stability \(Mechanics\), Water reducing agents Keywords: concrete pumping, pressure, air voids, entrained air, freezing and thawing, spacing factor, specific surface, Philleo factor Created Date:

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CONCRETE PUMPING EFFECTS ON ENTRAINED AIR-VOIDS. FINAL REPORT

CONCRETE PUMPING EFFECTS ON ENTRAINED AIR-VOIDS. FINAL REPORT. Pumping is a frequently used method of efficiently transporting concrete from the delivery vehicles to the formwork. Unfortunately, pumping concrete can affect the air content of a concrete mix.

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Air entrainment and its effects in concrete • Aggregate ...

Jul 12, 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).

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Examination of Air Entrainment Stability Factors of Pumped ...

Nature of AEA Film Around the Entrained Air Void [22] . Interactions Between Cement, Air, Water and Molecules of Air Entraining Agent [17] Apparatus Used in the Linear Traverse Method [19] . Effect of Entrained Air Content on the 28-Day Compressive Strength of Concrete [22] . . . . . .

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Air-Entrained Concrete - Portland Cement Association

Air-entrained concrete is produced using air-entraining portland cement, or by the introduction of air-entraining agents, under careful engineering supervision, as the concrete is mixed on the job. The amount of entrained air is usually between four and seven percent of the volume of the concrete, but may be varied as required by special ...

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Investigating Effects of Concrete Handling on Air Content ...

Sep 01, 1995  A 1994 study examined the effects of concrete handling methods on normal air-entrained concrete. Concrete for a large parking lot and driveway project was placed by pump, crane and bucket, truck-mounted conveyer, and directly from the chutes of ready mix trucks. The primary goal of the test program was to determine how air content, air-void system parameters, and freeze-thaw durability of air ...

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Factors Which May Influence Air Content - RussTech

Pumping Concrete – May result in air content reductions of 2%-3% at the discharge end of the pump boom. Higher air losses usually are the result of boom configuration causing free fall of the concrete and will sometimes actually create a vacuum in the pump boom. Finishing – If concrete surfaces are excessively finished air content at the ...

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Air Entrainers - an overview ScienceDirect Topics

Nov 06, 2010  Air entrainers may also reduce water loss in pumping, and make a mix easier to pump. 24.4.3 Effect of PFA on air entrainment. Residual part-burnt carbon in PFA seriously affects the performance of some air entrainers. It increases the dose required by a factor of between 2 and 5, it can lead to additional air loss on extended mixing, and if the ...

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Why is concrete air content important?

Apr 23, 2020  Air-entraining admixtures cause small stable bubbles of air to form uniformly through a concrete mix. The benefits of entraining air in the concrete include increased resistance to freeze-thaw degradation, increased cohesion (resulting in less bleed and segregation) and improved compaction in low-workability mixes.

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What is air entrained concrete? - Quora

Air entrained concrete is a type of concrete generally used in colder climes to negate the possible effects of freezing on concrete. Without adequate air entrainment concrete will have serious durability and performance issues in freezing/subfreez...

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Air entrainment in fresh concrete and its effects on ...

The effect of low atmospheric pressure of the environment on the air content and bubble stability of air-entrained concrete was investigated in Beijing and Lhasa.

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Is entrained air required in wet-mix shotcrete? Concrete ...

Aug 01, 1992  The ACI 506 "Guide to Shotcrete" recommends entraining air in wet-mix shotcrete. Section 2.7.2 of that document says: "Wet-mix shotcrete that will be exposed to freeze-thaw cycles should be air entrained. Air entrainment tends to make some mixes more workable and may reduce rebound. Data are available to show that a significant quantity of the ...

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Understanding Wet-Mix Shotcrete: Mix Design ...

Initial Air Content concept. This concept is a . clever and simple system by which the workability of the fresh concrete is increased to meet the pump-ability requirement by introducing a large amount of entrained air bubbles into the mix, instead of relying on water-reducing admixtures to increase workability. The trick is that during pumping and

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