Effects of Pumping on the Quality of the Concrete Air Void

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  • Air Entrainment - an overview | ScienceDirect Topics

    Air entrainment is usually specified by the percentage of air in the mix but may also be specified by air void characteristics of spacing factor or specific surface of the air in the hardened concrete. Dosage is typically 0.2–0.4% on cement weight unless they are supplied as a multifunctional product, usually with a dispersing admixture.

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  • Concrete Pumping Effects on Air-Entrained Voids in

    UNDERSTANDING THE PUMPABILITY OF CONCRETE

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  • Research - Concrete Pumping Effects on Entrained Air-Voids

    UNDERSTANDING THE PUMPABILITY OF CONCRETE

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  • Air Entrainment - an overview | ScienceDirect Topics

    Air entrainment is usually specified by the percentage of air in the mix but may also be specified by air void characteristics of spacing factor or specific surface of the air in the hardened concrete. Dosage is typically 0.2–0.4% on cement weight unless they are supplied as a multifunctional product, usually with a dispersing admixture.

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  • Admixture Basics: An Overview

    Air Void Systems • Discovered in the 1930's and is still considered one of the most significant improvements in concrete technology. • Most standard specifications require that concrete be air entrained if exposed to freeze thaw cycles. • Uses air entraining admixtures to create a network of small disconnected air voids

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  • US-23 Aggregate Test Road Long-Term Performance Evaluation

    Excellent frost resistance is attributed to a well-draining OGDC and concrete air-void system with an average of 5.4% total air and air-void spacing factor well within the range recommended by American Concrete Institute (0.004 to 0.008 in.) for frost protection. …

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  • Effect of paste-to-voids volume ratio on the performance

    "Effect of Paste-to-Voids Volume Ratio on the Performance of Concrete Mixtures," ASCE Journal of Materials in Civil Engineering. DOI: 10.1061/(ASCE)MT.1943-5533.0000728, Vol. 25, No. 12, pp. 1840-1851. This paper discusses an approach to achieve a concrete mixture quality minimum with impact whilst meeting specifications.

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  • Air Entrainment versus Air Entrapment - NPCA

    Dec 20, 2012 · 3. Loss of entrained air in air-entrained concrete. And ACI 309R-05 Guide for Consolidation of Concrete, Section 7.7.8, "Over Vibration Effects," states, "Loss of entrained air in air-entrained concrete—This can reduce the concrete's resistance to cycles of freezing and thawing. The problem generally occurs in mixtures with excessive

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  • PROPERTIES AND MIX DESIGNATIONS - MnDOT

    A good air void system is also essential to having a durable concrete when the concrete is exposed to freeze-thaw conditions. Concrete having a total air void content of about 6.5% seems optimal. A mix having 6.5% total air voids will have approximately 1.5% entrapped air voids and 5.0% entrained air voids.

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  • Concrete pumping and its effect on the air void system

    The laboratory tests conducted show a significant amount of air volume was lost in the fresh concrete as a result of pumping. In many cases, the quality of the air void system in the fresh concrete would predict the concrete would have poor performance in freeze-thaw testing; however, all mixtures showed satisfactory performance in ASTM C666 freeze-thaw testing.

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  • I. RESEARCH PROJECT TITLE: Best Practices for Concrete

    air systems. The project will also go to concrete field placements with pumping to determine how different concrete mixtures and pumping conditions affect air void systems and slump. Task 1: A literature review will be performed on the factors that affect concrete pumpability and rheology, air entrainment loss during pumping, and concrete

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  • A Professional's Handbook on Grouting and Concrete Repair

    FIVE STAR PRODUCTS, INC. 750 Commerce Drive Fairfield, CT 06825 Support: (800) 243.2206 Fax: (203) 336.7930 FiveStarProducts.com A Professional's

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  • Research - Concrete Pumping Effects on Entrained Air-Voids

    Jul 05, 2018 · Up to12%cash back · The particular effect of pumping on changes in the concrete air void system has been investigated in the past [5,6,7,8,9,10]. The general belief within the North American concrete industry is that pumping reduces air content by two or three percent . However, numerous studies have shown that the behavior of the air void system is not easily predicted and pumping can increase, decrease, or have no effect on the air content or the air void system (in terms of air void …

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  • Effect of atmospheric pressure on air content and air void

    The effects of atmospheric pressure changes on the air-entraining capability of air-entraining admixtures and the air void parameters of hardened concrete are studied using a low-pressure test

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  • Major Problems in Concrete Pumping Works: How to Avoid

    Major Problems in Concrete Pumping Works. 1. Blockage of Concrete Pump. Blockage can occur due to numerous bends in the pipeline, too sharp or too wide turns, gap-graded aggregate, and failure to clean and maintain the pipeline after each concreting work. High water-cement ratio and long waiting-time at construction site during which concrete

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  • News Detail - American Concrete Institute

    Jun 12, 2017 · The main goal of the research is to understand which parameters of pumping and concrete mix design have the largest effect on the workability and air-void systems and apply the results to improved guidelines for concrete producers and contractors to assure the quality of the concrete placed in the formworks by pumping.

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  • Tips on how to prevent surface voids in your concrete

    Air does not mix with water and is not able to get out of the concrete mix, resulting in voids on your concrete surface. Concrete release agents are also a cause for surface voids. When release agents are not applied correctly, the lower ends of the moulds may fill with puddles of oil or the release agent is not designed for the application.

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  • Five Reasons To Buy A Self-Loading Concrete Mixer In

    Apr 24, 2021 · You'll find five reasons to buy a self-loading concrete mixer in Nigeria below. 1. A Self-Loading Mixer Can Save You Time. It can take time to produce the concrete that you need. Time is something that is often in short supply on job sites. When you invest in a self-loading mixer, you'll have less work to do, which means you'll be able to

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  • Period #10 Notes: ADMIXTURES & CEMENT REPLACEMENT

    • Water reducers are mostly used for hot weather concrete placing and to aid pumping. A water-reducer plasticizer, however, is a hygroscopic powder, which can entrain air into the concrete mix via its effect on water's surface tension, thereby also, obtaining some of the benefits of air-entrainment (see below). 2.

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  • Entrained Concrete - an overview | ScienceDirect Topics

    Tony Binns, in Advanced Concrete Technology, 2003. Air-entraining agents. The small air bubbles in air-entrained concrete behave like fine fines and can, accordingly, compensate for the lack of this size of material in coarse sand.The ability of air-entrainment to increase cohesion is well-established. Concrete that would normally be unpumpable due to low cohesion may be improved by the

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