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Home > Publications > International Concrete Abstracts Portal
Showing 1-5 of 211 Abstracts search results
Document:
SP-354_25
Date:
July 1, 2022
Author(s):
Marina Licht, Ida Ros, Roberta Magarotto
Publication:
Symposium Papers
Volume:
354
Abstract:
Air-entraining agents have had years of success in improving resistance to freezing and thawing damage (due to both internal distress and salt scaling). However, this success has not come without some troubles as even today concrete producers wrestle with controlling air content in concrete. As well-known and reported in literature, the ability to consistently obtain target air-void systems in concrete is not trivial, and changes in raw materials, processing, or construction methods may significantly impact air entrainment. The present study investigates how the mixing procedure of concrete can affect air content and air void distribution. In addition, chemical parameters like air-entraining agent (AEA) and defoamer (DF) chemistries are examined. Mixing procedure parameters as mixing time and addition of the air entrainer before or after the defoamer-containing superplasticizer impact air stability and quality in a different way depending on the AEA type and on the interaction between the AEA and the DF. Mortar samples produced by different mixing procedures and mixing times with two different AEA and defoamer chemistries were tested. Air void diameter distribution of mortar samples was measured at fresh stage with an air-void analyzer (AVA). The interaction effects of the mixing procedure with the AEA and DF chemistries were quantified by the Design of Experiment (DoE).
DOI:
10.14359/51736081
CI4101Moffatt
January 1, 2019
Edward (Ted) G. Moffatt and Michael D.A. Thomas
Concrete International
41
Issue:
1
Issues with providing an optimum air entrainment in concrete can be eliminated using dimensionally stable particles known as microspheres. In this article, performance test data for concretes produced with polymeric microspheres are compared against test data for concrete produced with a conventional air-entraining admixture. While wider use of microspheres in concrete has been hindered by production and logistics costs, the authors believe they could be cost effective for applications that require highly reliable protection against freezing-and-thawing damage.
SP326-16
August 10, 2018
O. I. Matveeva and G. D. Fedorova
326
According to GOST 26633-2015 the air entrainment content in the concrete mix has to be not less than 4% for concretes with mark on frost resistance F1200 (F2100) and above. The standard places particularly high demands on this indicator to the concrete of the structural layers of roads and airfields, where the volume of air entrainment in a concrete mix for a single layer or upper layer of the duplex coating shall be 5-7% and for the bottom layer of the duplex coating is about 4-6%. Thus, due to the introduction of the updated normative document outside of the application were of a concrete mix with a volume of air involved 3-4%, which previously was widely used. At the same time according to different researching the amount of air involved from 2.8 to 3.7% provided by mark on frost resistance of concrete F1300 above. The article presents experimental data confirming the validity of using concrete mixtures with lower air contents involved (2-4%) than it is accepted the standard. The volume of air entrainment of concrete mix is necessary to expand from 2 to 7%. This will save the cement consumption.
According to GOST 26633-2015 the air entrainment content in the concrete mix has to be not less than 4% for concretes with mark on frost resistance F1200 (F2100) and above. The standard places particularly high demands on this indicator to the concrete of the structural layers of roads and airfields, where the volume of air entrainment in a concrete mix for a single layer or upper layer of the duplex coating shall be 5-7% and for the bottom layer of the duplex coating is about 4-6%.
Thus, due to the introduction of the updated normative document outside of the application were of a concrete mix with a volume of air involved 3-4%, which previously was widely used. At the same time according to different researching the amount of air involved from 2.8 to 3.7% provided by mark on frost resistance of concrete F1300 above.
The article presents experimental data confirming the validity of using concrete mixtures with lower air contents involved (2-4%) than it is accepted the standard. The volume of air entrainment of concrete mix is necessary to expand from 2 to 7%. This will save the cement consumption.
10.14359/51710986
CI4008Q&A
August 1, 2018
40
8
I’m designing two concrete slabs: one interior for a freezer and one exterior. Since both slabs will be exposed to freezing, should I specify entrained air for both concrete mixtures?
SP303-18
June 1, 2015
Frank Shaode Ong, Charles K. Nmai, James Curtis Smith, and John Luciano
303
The focus of this paper is a new liquid microspheres-based admixture that has been developed to provide freezing and thawing protection of cementitious-based materials under cyclic, saturated conditions, while addressing and eliminating issues typically associated with the use of surfactant-based admixtures for air entrainment. Consequently, this microspheres-based admixture provides unique opportunities and flexibility in reproportioning or optimizing current air-entrained concrete mixtures with respect to using increased levels of supplementary cementitious materials. It is also shown in the paper that the microspheres-based admixture will facilitate the use of materials that typically hinder air entrainment. A microspheres recovery test method that has been developed to measure the microspheres content of fresh content for quality assurance purposes is also presented and discussed.
10.14359/51688138
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