Air Loss During Concrete Pumping

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  • Slump Loss in Pump Lines| Concrete Construction Magazine

    By Concrete Construction Staff. Please send information on slump loss in concrete pump lines and strength tests on pumped concrete. Slump loss generally does not occur in small line pump systems. If long lengths of flexible hose are used, a slump loss may occur because of the higher coefficient of friction in the hose line.

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  • Loss of Air Content in Pumped Concrete — What, why, & how

    Air Loss During Concrete Pumping. During the concrete pumping process, the tiny air entrainment bubbles that exist in the concrete can be compromised and the total air content by mass can be reduced from the designed and batched levels. Concrete air entrainment requirements ( which are for exterior concrete to increase freeze/thaw resistance) are usually based on samples taken from….

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  • PROPERTIES AND MIX DESIGNATIONS - MnDOT

    5-694.216 AIR ENTRAINMENT All concrete contains some entrapped air bubbles. Large entrapped air bubbles are undesirable. Air-entrained concrete has air, in a finely divided and dispersed form, purposely induced at the time of mixing. The air is produced in the concre te by the addition of an approved air-entraining admixture.

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  • Loss of Air Content in Pumped Concrete — What, why, & how

    Sep 03, 2020 · Pumping air entrained concrete is a significant challenge for the concrete industry. It is common to lose 1% to 3% volume of air during pumping. This loss

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  • Air Entrainment - Concrete Pumping

    Air loss can be minimized when pumping by slowing down the "free-fall" of the concrete and minimizing the pumping pressure.

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  • Surge Control in Pumping Stations | Pumps & Systems

    Dec 17, 2011 · The pump column refills with air after each pump stoppage. Air valves play an important roll in automatically venting the pump column air and controlling surges in pump columns. If the vertical turbine pump is started without an air valve, the air in the pump column would be pressurized and forced through the check valve into the pipeline

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  • Pumping Air Entrained Concrete

    various factors on the pumping of air-entrained Portland Cement Concrete and the circumstances surrounding the loss of air that can occur during the pumping of fresh concrete. The mechanism of entraining concrete with air is presented to focus on the instability of the air bubbles while

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  • Friction Loss - an overview | ScienceDirect Topics

    The pressure loss during each step is formulated with the equation of a straight line using equation 17. (17) Δ P L = 0.017 × 2 θ − 0.02 / iN The opening angle 2 θ is calculated by first estimating equivalent radius for diffuser inlet and outlet assuming the diffuser was a cone using equations 18 and 19 .

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  • Concrete Pouring Steps and Techniques - Structural Guide

    Concrete can be poured into the slab by using the pump car or manually concrete can be taken into the slab. Concrete Pouring in Piles. Concreting of piles is different from the other concreting methods. Special methods are used for concrete the piles. After the excavations are completed, the tremie pipe is inserted into the excavated pile.

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  • CIP 21 - Loss of Air Content in Pumped Concrete

    It is normal to find a loss of about 0.5 to 1.0 percent air as concrete is conveyed through a pump. However, with long boom pumps, having the boom in an orientation with a long, near-vertical downward section of pipe, the air content at discharge may be less than half of that of the concrete going into the pump …

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  • Air Loss in Fly Ash Concrete| Concrete Construction Magazine

    Jul 01, 1987 · Loss on ignition (LOI) is a measurement of unburned carbon remaining in the ash. Specifications of the American Society for Testing and Materials (ASTM C 618) for fly ash used in concrete limit the LOI to 6 percent. Values greater than 2 to 3 percent, however, will probably require you to significantly increase the air entraining agent dosage.

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  • Air Entrainment - an overview | ScienceDirect Topics

    M Richardson, in Durability of Concrete and Cement Composites, 2007. Allowance for strength loss. Air entrainment leads to a loss of concrete strength. Typically the direct strength loss is about 5.5% per percentage of air entrainment though this effect can be somewhat offset by the improved workability (reduced water demand) of air entrained concrete (Wright, 1953).

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  • ASTM C231: Testing Air Content of Concrete With a Type B

    Apr 04, 2021 · This guide will teach you how to test air content of concrete with a type B pressure meter. It covers the reasons you are performing this test, the equipment needed, and the procedure of ASTM C231. It is intended to be a supplement to reading the ASTM as well as a study tool for the ACI exam.

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  • Slump adjustment is a fact of life for concrete

    rises during the day and the aggre-gate dri e s, more water is absorbed, reducing concrete slump. To indicate changes in sand m o i s t u r e content, pro d u c e r s should use a properly maintained and calibrated sand moisture me-t e r. Mo i s t u r e-compensating equip-ment can be set to automatically re p ro p o r tion sand and water batch

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  • Examination of Air Entrainment Stability Factors of Pumped

    Aug 03, 2009 · To reduce the air loss when pumping you have to control the free fall either by reducing the hose to create back pressure or position the boom to reduce the free fall. Most state jobs that I have been on test concrete at point of placement not at the hopper.

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  • ASTM C231: Testing Air Content of Concrete With a Type B

    Apr 04, 2021 · This guide will teach you how to test air content of concrete with a type B pressure meter. It covers the reasons you are performing this test, the equipment needed, and the procedure of ASTM C231. It is intended to be a supplement to reading the ASTM as well as a study tool for the ACI exam.

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  • Preliminarily experimental research on local pressure loss

    The pressure of the fresh concrete during pumping in conveying pipes is critical in both concrete pump design and conveying pipes layout. The local pressure loss occurring at the connections between pipes, which often has been overlooked in the total pumping pressure research, is quite significant compared to the total pressure drop, especially for long conveying pipes.

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  • OVERVIEW OF CONSTRUCTION AND DESIGN OF AUGER …

    2005). After concrete or grout placement is completed, the reinforcement cage is inserted or vibrated down into the fresh concrete or grout mixture and tied off at the surface. The rate of withdrawal of the auger is important as well; it needs to be synchronized with the concrete or grout pumping rate. The average cross-sectional

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  • Curing of Concrete

    required of the concrete, the purpose for which it is to be used, and the ambient conditions, ie the temperature and relative humidity of the surrounding atmosphere. Curing is designed primarily to keep the concrete moist, by preventing the loss of moisture from the concrete during the period in which it is gaining strength. Curing may be applied

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  • The Do's And Dont's Of Concrete Pumping - Allied Insurance

    Concrete Pumping Insurance: Offers coverage for concrete pumpers rented including over-the-road liability, loss of income and extra expense, loss of rents, equipment in your care and more. Physical Damage & Auto Liability: Covers personal effects, towing and the physical damage of any rentals.

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