scholarly journals Effects of Parameters of Air-Avid Structure on the Salt-Frost Durability of Hardened Concrete

2020 ◽  
Vol 10 (2) ◽  
pp. 632 ◽  
Author(s):  
Hui Zhang ◽  
Peiwei Gao ◽  
Zhixiang Zhang ◽  
Youqiang Pan ◽  
Weiguang Zhang
Keyword(s):  
Frost Resistance ◽  
Fresh Concrete ◽  
Close Correlation ◽  
Hardened Concrete ◽  
Air Content ◽  
Spacing Factor ◽  
Void Structure ◽  
Air Void ◽  
Frost Durability ◽  
Air Void Structure

Through laboratory testing, this research studied the connection between air-void structures of hardened concrete and fresh concrete and discussed the effects of the air-void structure on the salt-frost durability of the concrete. The results demonstrate that, in comparison with fresh concrete, the air-void spacing factor shows a close correlation with hardened concrete air-content and decreases in the form of a power function as the air-content increases. When the fresh concrete air-content is more than 6% and the hardened concrete air-void spacing factor is less than 0.18 mm, the influence of parameters of air-void structure on the salt-frost resistance of the concrete reduces. The air-void spacing factor more significantly affects the salt-frost resistance of the concrete compared with air content and the correlation reaches 0.93. Therefore, air-content and air-void spacing factor are recommended for dual control.

Influence of Air Content and Vibration Time on Frost Resistance of Air Entrained Concrete

2013 ◽  
Vol 857 ◽  
pp. 110-115 ◽  
Author(s):  
Xiu Hua Zheng ◽  
Yong Ge ◽  
Jie Yuan
Keyword(s):  
Frost Resistance ◽  
Hardened Concrete ◽  
Air Voids ◽  
Air Content ◽  
High Durability ◽  
Void Structure ◽  
Vibration Time ◽  
Air Void ◽  
Air Void Structure ◽  
Air Entrained Concrete

Air-entraining agent turely is one of the necessary compositions of the high durability concrete. The influence of air content and vibration time on the frost resistance of concrete was researched, and air void characteristics of hardened concrete was analysed. The results showed that the air contents could reduce the compressive strengthof hardened concrete excessively, but it made the spacing factor reduce obviously and significantly improve the frost resistance of concrete.The air voids with different structure in concrete were realized by vibration time. It was found that the air void structure and the frost resistance properties were influenced by the vibration time largely. The optimized vibration time is 30s, the appropriate vibration time is 20s~30s, no more than 35s.

scholarly journals The Flexural Strength and Frost Resistance of Air Entrained Concrete

2012 ◽  
Vol 5 ◽  
pp. 364-369 ◽  
Author(s):  
Xiu Hua Zheng ◽  
Qin Fei Li ◽  
Jie Yuan ◽  
Yong Ge
Keyword(s):  
Flexural Strength ◽  
Frost Resistance ◽  
Test Results ◽  
Key Factors ◽  
Air Content ◽  
Void Structure ◽  
Vibration Time ◽  
Air Void ◽  
Air Void Structure ◽  
Air Entrained Concrete

The flexural strength and frost resistance properties of air entrained concrete were tested in this study. Although the flexural strength of concrete does not change largely with increasing of air content, it still has a maximum value with air content of 4%. The test results show that the frost resistance increase with increasing of air content. In air entrained concrete, the total air content is not the only factor that affect the final properties of the concrete, the air void structure parameters, including void size, shape, and distribution, are key factors as well. It was found that the air void structure and the frost resistance properties were influenced by the vibration time largely. The optimized vibration time is 30s.

Quality Evaluation of Air Entraining Agent Based on Air Void Parameters of Fresh Concrete

2014 ◽  
Vol 629-630 ◽  
pp. 593-599
Author(s):  
Lu Yang ◽  
Yong Jiang Xie ◽  
Hua Jian Li
Keyword(s):  
Surface Tension ◽  
Frost Resistance ◽  
Fresh Concrete ◽  
Diameter Distribution ◽  
Hardened Concrete ◽  
Air Bubbles ◽  
Spacing Factor ◽  
Durability Index ◽  
Air Void

In order to evaluate the quality of air entraining agent quickly and effectively. Air void parameters of fresh concrete with different air entraining agents were studied by Air Void Analyzer (AVA). The spacing factor and durability index of hardened concrete were tested and the relationship between the surface tension of air entraining agent and frost resistance of concrete was compared. The results showed that, the quality of air entraining agent can be evaluated quickly and effectively by diameter distribution of air bubbles in fresh concrete and spacing factor of fresh concrete. AEA2 introduced much more big air bubbles into concrete which is bad for the frost resistance of concrete. The quality of AEA2 was the worst, so the durability index of hardened concrete was 58.7%. Quality of air entraining agent cannot be characterized by properties of air entraining agent, but air entraining ability can be characterized by surface tension of air entraining agent. Keywords: air entraining agent (AEA), air void parameter, fresh concrete

Precision of the air void characteristics measurement by ASTM C 457: results of an interlaboratory test program

1996 ◽  
Vol 23 (5) ◽  
pp. 1118-1128 ◽  
Author(s):  
François Saucier ◽  
Richard Pleau ◽  
Daniel Vézina
Keyword(s):  
Test Method ◽  
Interlaboratory Study ◽  
Hardened Concrete ◽  
Probability Of Error ◽  
Air Content ◽  
Spacing Factor ◽  
Interlaboratory Test ◽  
Void System ◽  
Concrete Production ◽  
Air Void

Since 1993, the Quebec Department of Transportation requires all its concrete suppliers to demonstrate that their concrete satisfies the requirements of the CSA A23.1 standard as regards the maximum spacing factor of the air void system. This new requirement raises questions about the reproducibility of the ASTM C 457 test method. An interlaboratory study was carried out to verify if the variability of the test method is sufficiently low to allow reliable decisions on the acceptance or rejection of in-place hardened concrete. A total of 18 operators from 13 different laboratories microscopically examined the six concrete slabs used for the study. It is concluded that the average reproducibility coefficient of variation is 14.4% for the total air content measurement and 14.2% for the spacing factor measurement. Considering these results, the probability that the measured value of the spacing factor exceeds the mandatory limit of 230 μm on a concrete production containing an air void system with a spacing factor of 170 μm (the target value proposed in the CSA A23.1 M-94 standard) is less than 0.7% (a probability of error of about 1%, 5%, or 10% is typical of most quality control test methods). Key words: concrete, air content, air void measurement, spacing factor, ASTM C 457 standard, interlaboratory study, freeze–thaw durability.

Béton produit en bétonnière mobile et en usine conventionnelle : comparaison des caractéristiques du réseau de bulles d'air

1988 ◽  
Vol 15 (3) ◽  
pp. 306-314
Author(s):  
Gaston Larose ◽  
Michel Pigeon
Keyword(s):  
Key Words ◽  
Laboratory Tests ◽  
Fresh Concrete ◽  
Mobile Unit ◽  
Freeze Thaw ◽  
Air Content ◽  
Spacing Factor ◽  
Void System ◽  
Concrete Mixer ◽  
Air Void

The durability of concrete to freeze-thaw cycles is dependent upon the existence of an adequate air-void system. There are very few studies on the air-void system of field concretes. Laboratory tests have proven that the air content measurement on the fresh concrete is not sufficient to judge the aptitude of the air-void system to protect the concrete from frost damage.This paper is a comparison of the air-void systems of field concretes produced in either a conventional plant or a mobile unit the use of which is becoming more and more frequent. The concretes produced in the conventional plant generally had sufficient air-void systems for air contents in the usual range (5–7%). The mobile unit showed that a slightly higher air content (8%) was needed to produce an adequate air-void system. Key words: concrete, mobile concrete-mixer, air-void systems, air-entraining agent, spacing factor, surface area, air content.

A laboratory investigation for potential durability of ready-mixed concrete retempered for air content and workability

1976 ◽  
Vol 3 (4) ◽  
pp. 570-577 ◽  
Author(s):  
B. W. Langan ◽  
M. A. Ward
Keyword(s):  
Compressive Strength ◽  
Laboratory Investigation ◽  
Hardened Concrete ◽  
Air Content ◽  
Spacing Factor ◽  
Void System ◽  
Air Void ◽  
Ready Mixed Concrete ◽  
Mixed Concrete

The effects of agitation and retempering on some properties of fresh and hardened concrete are considered.Data are presented on the influence of agitation and retempering with an air-entraining agent on the workability, compressive strength, and air void system in hardened concrete.The results indicate that although agitation reduces air content and increases the spacing factor, the original parameters can be regained by proper retempering. It is shown that any loss in compressive strength due to retempering is accompanied by an increase in potential durability due to the improvement of the air void system.

Investigation on the Property and Air Void Structure of Foamed Cement-Fly Ash-Steel Slag Concrete

2010 ◽  
Vol 150-151 ◽  
pp. 1457-1461 ◽  
Author(s):  
Yong Hao Fang ◽  
Quan Wen ◽  
Pin Dai
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Bulk Density ◽  
Volume Fraction ◽  
Steel Slag ◽  
Close Correlation ◽  
Average Shape ◽  
Void Structure ◽  
Air Void ◽  
Air Void Structure

The properties and void structures of foamed concretes prepared from portland cement, fly ash, steel slag and foam agent were investigated. The results show that substituting cement by steel slag resulted in little change in dry bulk density, but reduced the compressive strength; on the other hand, when cement was substituted with fly ash, though the dry bulk density decreased, the compressive strength increased as the proportion of substitution increased from 30%to 45%. Increasing the volume fraction of the foam decreased greatly the dry bulk density and the compressive strength, and reduced the thermal conductivity as well. Image analysis on the air void structure shows that the larger air void fraction, the larger average void size and lower void roundness. There is a close correlation between the average mean Feret diameter and the average shape factor.

scholarly journals Scaling Resistance and Air Void Characteristics in Concrete Containing GGBS

2016 ◽  
Vol 62 (4) ◽  
pp. 181-192 ◽  
Author(s):  
J. Wawrzeńczyk ◽  
A. Molendowska ◽  
T. Juszczak
Keyword(s):  
Frost Resistance ◽  
Air Entrainment ◽  
Test Results ◽  
Fundamental Factor ◽  
Air Content ◽  
Concrete Mixtures ◽  
Spacing Factor ◽  
Void System ◽  
Surface Scaling ◽  
Air Void

AbstractIn this paper we discuss the test results for concretes containing various amounts of ggbs as compared to concretes made with Portland cement. The main objective of these tests is to evaluate the influence of varying air content in such mixtures on the structure and frost resistance of concrete. The authors suggest that the approach presented here allows for a safe design of concrete mixtures in terms of their frost resistance.The results indicate that concrete can be resistant to surface scaling even at the W/C ratio markedly higher than 0.45. Increased addition of ggbs leads to a decrease in concrete resistance to surface scaling. Proper air entrainment is the fundamental factor for frost-resistant concrete, and the air void system has to be assessed (micropore content A300, spacing factor $\overline L $). The addition of ggbs increases pore diameters, thus, to obtain the appropriate air pore spacing factor, micropore quantities introduced have to be increased.

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