Study on Frost-Salt Resistance of Fly Ash Concrete

2012 ◽  
Vol 598 ◽  
pp. 432-437 ◽  
Author(s):  
Cong Tao Sun ◽  
Wei Hua Li ◽  
Bao Rong Hou
Keyword(s):  
Weight Loss ◽  
Fly Ash ◽  
Dynamic Modulus ◽  
Surface Characteristics ◽  
Salt Resistance ◽  
Cycle Number ◽  
Fly Ash Concrete ◽  
Influence Of Water ◽  
Binder Ratio ◽  
Water Binder Ratio

Accelerated frost-salt tests of fly ash concrete were carried out, through which the influence of water-binder ratio, volume of fly ash, air-entraining content on the frost-salt resistance of concrete were discussed, and the variation of surface characteristics, weight loss rate, relative dynamic modulus of concrete elasticity with the number of freeze-thaw cycles were investigated. The weight loss of specimens is above 5 percent; Water-binder ratio has decisive influence on the frost-salt resistance of concrete; concrete with suitable volume of fly ash can also increase the standard of frost-salt resistance; there is a critical air-entraining content which can improve the frost-salt resistance by the greatest extent. The relationship between dynamic modulus of elasticity and compressive strength are established. And also, calculation formula for the cycle number of frost-salt resistance is proposed.

scholarly journals Experimental Study on Durability Improvement of Fly Ash Concrete with Durability Improving Admixture

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Hong-zhu Quan ◽  
Hideo Kasami
Keyword(s):  
Fly Ash ◽  
Experimental Studies ◽  
Drying Shrinkage ◽  
Replacement Ratio ◽  
Fly Ash Concrete ◽  
Air Content ◽  
Carbonation Resistance ◽  
Binder Ratio ◽  
Water Binder Ratio

In order to improve the durability of fly ash concrete, a series of experimental studies are carried out, where durability improving admixture is used to reduce drying shrinkage and improve freezing-thawing resistance. The effects of durability improving admixture, air content, water-binder ratio, and fly ash replacement ratio on the performance of fly ash concrete are discussed in this paper. The results show that by using durability improving admixture in nonair-entraining fly ash concrete, the compressive strength of fly ash concrete can be improved by 10%–20%, and the drying shrinkage is reduced by 60%. Carbonation resistance of concrete is roughly proportional to water-cement ratio regardless of water-binder ratio and fly ash replacement ratio. For the specimens cured in air for 2 weeks, the freezing-thawing resistance is improved. In addition, by making use of durability improving admixture, it is easier to control the air content and make fly ash concrete into nonair-entraining one. The quality of fly ash concrete is thereby optimized.

Influencing Factors of the Fluidity and Strength of Phosphate Concrete

2011 ◽  
Vol 250-253 ◽  
pp. 464-468
Author(s):  
Hong Tao Wang ◽  
Ju Hui Cao ◽  
Shuang Mei Li ◽  
Ming Xue
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Water Retention ◽  
Natural Conditions ◽  
Slump Flow ◽  
Influence Of Water ◽  
Binder Ratio ◽  
Curing Methods ◽  
Early Strength ◽  
Water Binder Ratio

The influence of water binder ratio, content of borax and fly ash on the fluidity and strength of phosphate concrete were investigated. Results showed that the slump and slump flow of phosphate concrete improved with content of water and borax increasing. But the strength decreased, especially early strength. While the mixing amount of borax was less than 1.5% of the magnesium phosphate cement, the influence on later strength was relatively less. The fluidity decreased significantly and the cohesiveness and water retention improved while the content of fly ash was between 10% and 30%.The compressive strength increased while the content of fly ash was 10%.The better curing methods was curing in the natural conditions, the compressive increased with the age prolonged.

Effect of Water-Binder Ratio and Mineral Admixture on Frost Scaling Resistance of Concrete

2014 ◽  
Vol 881-883 ◽  
pp. 1212-1215 ◽  
Author(s):  
Zhong Hua Li ◽  
Hui Xu ◽  
Chao Su ◽  
Duo Zheng ◽  
Jia Liang Yang
Keyword(s):  
Fly Ash ◽  
Modulus Of Elasticity ◽  
Dynamic Modulus ◽  
Loss Rate ◽  
Elasticity Modulus ◽  
Mineral Admixture ◽  
Salt Scaling ◽  
Binder Ratio ◽  
Scaling Resistance ◽  
Water Binder Ratio

In order to increase freeze-salt scaling resistance of concrete, effect of water-binder ratio, fly ash, slag and silica fume on freeze-salt scaling resistance are researched according to the CDF method. The results show that the scaled mass and the dynamic modulus of elasticity loss rate of the concrete are reduced with decreasement of water-binder ratio. When mineral admixture compound is added into concrete the scaled mass and the dynamic modulus of elasticity loss rate are also reduced. Compared with fly ash and slag the trend is more obvious as result of fume and slag added. The scaled mass and the loss rate of dynamic elasticity modulus are slightly reduced with decreasement of fly ash and slag. But the scaled mass and the loss rate of dynamic elasticity modulus are obviously reduced with increasement of silica fume and slag.

Frost Scaling Resistance and Improvement of Concrete

2014 ◽  
Vol 507 ◽  
pp. 368-372
Author(s):  
Zhong Hua Li ◽  
Chao Su ◽  
Duo Deng ◽  
Jia Liang Yang ◽  
Heng Jiung Ba
Keyword(s):  
Fly Ash ◽  
Modulus Of Elasticity ◽  
Dynamic Modulus ◽  
Loss Rate ◽  
Salt Resistance ◽  
Mineral Admixture ◽  
Fly Ash Concrete ◽  
Salt Scaling ◽  
Dynamic Modulus Of Elasticity ◽  
Scaling Resistance

In order to increase freeze-salt scaling resistance of concrete, improvement of fly ash, slag and air entraining agent on freeze-salt scaling resistance are researched according to the CDF method. The results show that the scaled mass and the dynamic modulus of elasticity loss rate of concrete are reduced by 20% to 36 % and 4 % to 55 %. The microstructure was more denser compared with the control concrete after 28 cycles as a result of adding mineral admixture and air entraining agent into concrete. The freeze-salt scaling resistance of concrete is improved. The freeze-salt resistance of concrete mixed with ground slag is superior to fly ash concrete. The damage of concrete is mainly surface scaling during salts frost.

scholarly journals Experimental Investigation and Analytical Modeling of Chloride Diffusivity of Fly Ash Concrete

Materials ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 862 ◽  
Author(s):  
Jian Zhang ◽  
Xin-Zhu Zhou ◽  
Jian-Jun Zheng ◽  
Hai-Long Ye ◽  
Jin Yang
Keyword(s):  
Fly Ash ◽  
Analytical Modeling ◽  
Volume Fraction ◽  
Ash Content ◽  
Aggregate Model ◽  
Fly Ash Concrete ◽  
Chloride Diffusivity ◽  
Binder Ratio ◽  
Water Binder Ratio ◽  
Curing Age

Owing to its importance in the assessment of reinforced concrete structures, it is essential to determine the chloride diffusivity of fly ash concrete. This paper presents an investigation into the diffusion characteristics of chloride ions in fly ash concrete. Through experiment, the relationship between chloride diffusivity and curing age up to 1800 days is measured and the effects of curing age, water/binder ratio, aggregate volume fraction, and fly ash content (i.e., percentage of total cementitious material by mass) on chloride diffusivity are evaluated. It is found that the chloride diffusivity decreases with the increase of curing age, aggregate volume fraction, and fly ash content, but increases with the increase of water/binder ratio. In analytical modeling, an equivalent aggregate model is constructed and the equivalent interfacial transition zone (ITZ) thickness is derived analytically. With the equivalent aggregate model, three-phase fly ash concrete reduces to a two-phase composite material. By extending the Maxwell method, the chloride diffusivity of fly ash concrete is formulated. Finally, the validity of the analytical method is verified by experimental results.

Frost-Resisting Property of Bridge Concrete in Alpine Frigid Region

2013 ◽  
Vol 857 ◽  
pp. 239-247
Author(s):  
Yin Chuan Guo ◽  
Ai Qin Shen ◽  
Jian Wang ◽  
Hong Ji Zhao
Keyword(s):  
Fly Ash ◽  
Water Consumption ◽  
Reference Value ◽  
Ash Content ◽  
Impact Mechanism ◽  
Air Content ◽  
Influence Of Water ◽  
Binder Ratio ◽  
The Impact ◽  
Water Binder Ratio

Supported by the Guozigou-bridge, the paper studied the Frost-resisting property of bridge concrete in alpine frigid region. Researched the effect of water-binder ratio, fly-ash content, water consumption and air-entraining agent consumption, and reveals the impact mechanism of frost-resisting property of bridge concrete in alpine frigid region. Analyzed the influence rule of frost-resisting property and showed reference value of concrete's ingredient rate in alpine frigid region. The result showed that low water-binder ratio and water consumption can effectively improve the deicer-frost resistance of concrete and the influence of water consumption is more significant. Best air content between 4.5% ~ 4.5%.

Prediction Model for Cementing Efficiency of Fly Ash Concrete by Statistical Analyses

2011 ◽  
Vol 250-253 ◽  
pp. 1293-1296 ◽  
Author(s):  
Hong Bum Cho ◽  
Nam Yong Jee
Keyword(s):  
Fly Ash ◽  
Prediction Model ◽  
Statistical Analyses ◽  
Test Results ◽  
Construction Sites ◽  
K Value ◽  
Fly Ash Concrete ◽  
Mix Proportion ◽  
Wide Range ◽  
Binder Ratio

This paper offers the model that can estimate the cementing efficiency of fly ash (k value) based on a mix proportion of concrete containing fly ash (FA). The prediction model was derived using various statistical analyses, based on a wide range of mix proportions and a number of strength test results of ready mixed concretes used in eight construction sites. The k value increases with increasing water-binder ratio. As the FA replacement ratios increase, the k value increases at FA replacement ratios of less than 15%, but decreases at ratios of 15% or more. The k values obtained from the cementing efficiency estimate model range from 0.1 to 2.1.

Influence of the Fly-Ash Content of Concrete at Low Water-Binder Ratio on Hydration Degree of Binders and Cement

2011 ◽  
Vol 250-253 ◽  
pp. 445-449
Author(s):  
Li Wei Xu ◽  
Jian Lan Zheng
Keyword(s):  
Fly Ash ◽  
Temperature Rise ◽  
High Performance Concrete ◽  
Ash Content ◽  
Adiabatic Temperature ◽  
Mineral Admixture ◽  
Hydration Degree ◽  
Adiabatic Temperature Rise ◽  
Binder Ratio ◽  
Water Binder Ratio

The hydration degree of binders and cement is investigated by measuring the adiabatic- temperature rise of concrete at low water-binder ratio with different fly-ash content. The results denote that, with a constant water-binder ratio, both of the hydration degree of binders and that of cement decrease with the increasing fly-ash content in the early stage. In a later stage, however, the hydration degree of cement increases with the increasing fly-ash content and the hydration degree of binders peaks when the fly-ash content is 35%. Fly ash is one of the mineral admixture of which high-performance concrete is made up. It brings down the rise of concrete temperature significantly and helps solve the problems of shrinkage and crack of concrete structure. Because the hydration mechanism in common concrete is different from that in concrete with low water-binder ratio, and the hydration environment is different between concrete and cement pastes, to determine the adiabatic-temperature rise of concrete directly conforms to the actual situation. The adiabatic-temperature rise, adiabatic-temperature-rise rate, hydration degree of both binders and cement are investigated by measuring adiabatic-temperature rise of concrete with different fly-ash content.

Sign in / Sign up

Export Citation Format

Share Document