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Loss of Air Content in Pumped Concrete

Air Entrainment and the Properties of Concrete | Concrete

The entrainment of air in fresh concrete improves its workability. The place-ability of an air entrained concrete having 7.5 cm slump was found better than a non-air entrained concrete having a slump of 12.5 cms. Better place-ability of air entrained concrete results in more homogeneous concrete with least segregation, bleeding and honeycombing.

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Mix Design and Pumped Concrete - Civil Engineering Portal

A loss of slump during pumping is normal and should be taken into consideration when proportioning the concrete mixes. A slump loss of 25 mm per 300 meters of conduit length is not unusual, the amount depending upon ambient temperature, length of line, pressure used to move the concrete, moisture content of aggregate at the time of mixing

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CONCRETE 101

specification requirements which require a specific amount of air content at the point of placement or at the discharge end of the pumping. Air loss can be minimized when pumping by slowing down the "free-fall" of the concrete and minimizing the pumping pressure. 2. What is slump? (Why/what/how it effects concrete and us)

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CIP 21 Loss of Air Content in Pumped Concrete

Oct 01, 1992 · Describes an investigation of the phenomenon of loss of entrained air in pumped concrete. Conclusions and recommendations include: 1) With long vertically downward boom or pipe sections, half the air can be lost; 2) Do some sampling at the …

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"Controlling Air Content in Concrete That is Being Pumped

Changes in the air content of fresh concrete that is being pumped can occur at a number of places. These locations include the initial loading of the concrete into the pump hopper, as it passes through the pump line, and when it exits the line. This synthesis reviews the findings of recent research studies which deal with air content change in pumped concrete and summarizes methods of reducing

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"Controlling Air Content in Concrete That is Being Pumped

Changes in the air content of fresh concrete that is being pumped can occur at a number of places. These locations include the initial loading of the concrete into the pump hopper, as it passes through the pump line, and when it exits the line. This synthesis reviews the findings of recent research studies which deal with air content change in pumped concrete and summarizes methods of reducing

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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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CIP 21 - Loss of Air Content in Pumped Concrete

Loss of air content in pumped concrete will not reduce freeze thaw durability of concrete as long as the air void system is not compromised. The air loss due to pumping can be determined by measuring the air content of samples discharged from the ready mixed concrete truck and at discharge from the pump. Testing concrete as discharged from the pump alongside the pump will require the most critical boom …

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Air and pumping of concrete - Concrete Engineering general

Aug 16, 2011 · also there can be air content loss if a porous aggregate (for lightweight concrete) is used that was not properly saturated and the pumping process causes a slump loss. also, many pumped mixes will go to elevated decks where the weight of the concrete requires a lighter mix so concrete supply companies will entrain air for this reason.

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Loss of Air Content in Pumped Concrete - Atlantic Concrete

Keep concrete from sliding down the line under its own weight. Where possit;>le, avoid vertical or steep downward boom sections. Be cautious with higslumps, particularly with 3 high cement content mixes and mixes containing silica fume. Steady pumping may help …

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

generally is no significant loss of air. There is some controversy over how frequently air loss is a problem in pumped concrete. Certainly, it doesn't occur every time, or even most times. However, it does occur of-ten enough to be considered seriously until better solu-tions are developed. There are several mechanisms involved, but air loss will occur if the weight of concrete in a vertical or

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Loss of Air Content in Pumped Concrete

The air loss due to pumping can be determined by measuring the air content of samples discharged from the ready mixed concrete truck and at discharge from . CIP 21 - Loss of Air Content in Pumped Concrete. Loss of air content in pumped concrete will not reduce freeze thaw durability of concrete as long as the air void system is not compromised. The air

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Re-Examining air content testing for pumped concrete

Oct 17, 2020 · The pressures from pumping seem to cause air to dissolve. This air then returns to the concrete over time. This can cause the concrete producer to introduce air contents that are much higher than needed. This causes a loss of strength and an increase in porosity. Concrete may also be wrongly rejected. 1. Sample concrete before and after the

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Testing Fresh Concrete at Point of Delivery

Aug 16, 2011 · also there can be air content loss if a porous aggregate (for lightweight concrete) is used that was not properly saturated and the pumping process causes a slump loss. also, many pumped mixes will go to elevated decks where the weight of the concrete requires a lighter mix so concrete supply companies will entrain air for this reason.

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Concrete In Practice (CIP) - NRMCA

Concrete In Practice is a series of one-page information sheets on important Testing Concrete Series (10 topics: Jobsite Addition of Water, Discrepancies in Yield, Loss of Air Content In Pumped Concrete, Acceptance Testing of Concrete, Making Concrete Cylinders in the Field, Testing Compressive Strength of Concrete, Low Concrete

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Mix Design and Pumped Concrete - Civil Engineering Portal

A loss of slump during pumping is normal and should be taken into consideration when proportioning the concrete mixes. A slump loss of 25 mm per 300 meters of conduit length is not unusual, the amount depending upon ambient temperature, length of line, pressure used to move the concrete, moisture content of aggregate at the time of mixing

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

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 …

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CIP 21 - Loss of Air Content in Pumped Concrete

Field experience indicates that air loss through a pump is greatest in concrete with higher cementitious material content and flowable concrete mixtures. Air loss is also experienced in mixtures with a moderate cement factor around 500 lb/yd3 (300 kg/m3) of total cementitious material and medium slump. The air loss due to pumping should be determined

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Slump adjustment is a fact of life for concrete

the water content can va r y by about 1 gallon, the water- c e m e n t ratio can va r y by about 0.02, and the slump can change by 1 inch per cubic yard of concre t e . Most batch plant operators work BY BRUCE A. SUPRENANT Slump adjustment is a fact of life for concrete contractors, but they should follow these guidelines for its use

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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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