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.

Effect of High Volumes of Fly Ash on Flowability and Drying Shrinkage of Engineered Cementitious Composites

2011 ◽  
Vol 675-677 ◽  
pp. 61-64
Author(s):  
Yu Zhu ◽  
Ying Zi Yang ◽  
Yan Yao
Keyword(s):  
Fly Ash ◽  
Drying Shrinkage ◽  
Ash Content ◽  
Experimental Results ◽  
Replacement Ratio ◽  
Slump Flow ◽  
Binder Ratio ◽  
Deformation Test ◽  
Flow Deformation ◽  
Water Binder Ratio

In order to investigate flowability and drying shrinkage of ECC, mini-slump flow deformation test and drying shrinkage are employed to analyse the influence of fly ash on the flowability and shrinkage of ECC. The water-binder ratio is kept at 0.25. The replacement ratio of cement by fly ash is 50%, 60%, 70% and 80%, respectively. The experimental results show that fluidity of fresh cment paste increases obviously as the fly ash becomes larger. The drying shrinkage of ECC specimens is greatly reduced as the content of fly ash increases from 50% to 80%. The measured drying shrinkage strian of ECC specimens with 80% fly ash at 28 days is less than 1000×10-6. 25% reduction of drying shrinkage of ECC is found when the fly ash content increases from 50% to 80%.

Research on Improving the Durability of Fly Ash Concrete

2011 ◽  
Vol 250-253 ◽  
pp. 626-629
Author(s):  
Hong Zhu Quan
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Drying Shrinkage ◽  
Drying Process ◽  
Air Drying ◽  
Damage Resistance ◽  
Fly Ash Concrete ◽  
Air Content ◽  
Binder Ratio ◽  
Freeze Damage

The purpose of this study was to improve the durability of fly ash concrete. As a result, by making fly ash concrete into non-air-entraining type and using durability improving admixture, the compressive strength of fly ash concrete increases 10%~30%, reducing initial compressive strength defects; drying shrinkage is controlled at 60% compared to when the mixture is not added; carbonation of fly ash concrete can be considered roughly proportional to water-cement ratio regardless of water-binder ratio or fly ash replacementratio; the freeze damage resistance improves for 2 weeks curing in air (drying process). Finally, by making fly ash concrete from non-air entraining type and using durability improving admixture, the difficulty of controlling air content in fly ash concrete is reduced and quality management is simplified.

Research on Durability of High Volume Fly Ash Concrete

2012 ◽  
Vol 174-177 ◽  
pp. 380-383 ◽  
Author(s):  
Hong Zhu Quan
Keyword(s):  
Fly Ash ◽  
Portland Cement ◽  
Experimental Studies ◽  
High Volume ◽  
Portland Cement Concrete ◽  
Freezing And Thawing ◽  
Replacement Ratio ◽  
Rapid Reduction ◽  
Fly Ash Concrete

The paper presents the results of series of experimental studies on effects of the type and replacement ratio of fly ash to portland cement on durability of concrete. Specimens made from 28 mixes of fly ash concrete with water binder ratio of 38% to 60% and with replacement ratio of fly ash of 25% to 70% and 5 mixes of portland cement concrete with water cement ratio of 38% to 75% were tested for compressive strengths, drying shrinkage, carbonation and resistance to freezing and thawing. As a results, drying shringkage decreased with fly ash addition regardless of type and replacement ratio of fly ash. Carbonation increased with fly ash replacement ratio, and type 1 fly ash showed higher carbonation. Type 1 and tpye 2 fly ashes showed practically no change in durability factor after 300 cycles of freezing and thawing up to 55% replacement, while type 4 fly ash showed rapid reduction in durability factor up to 40% replacement ratio.

An Abrasion Damage of Fly Ash Concretes Previously Subjected to Scaling

2016 ◽  
Vol 258 ◽  
pp. 587-590
Author(s):  
Aneta Nowak-Michta
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Abrasion Resistance ◽  
Air Entrainment ◽  
Binder Ratio ◽  
Abrasion Damage ◽  
Water Binder Ratio ◽  
Class F

Effect of quantity and quality of fly ash and compressive strength of concretes with their addition on abrasion resistance previously subjected to scaling is analyzed in the paper. The abrasion resistance was measured in Böhme test according to EN 1338: 2005. The cement was replaced with 20, 35, and 50% of Class F siliceous fly ash in three categories of losses on ignition A, B and C by mass. The water-binder ratio, the air-entrainment and the workability of mixtures were maintained constant at 0.38, 4,5% and 150 mm respectively.Prior scaling causes a decrease in abrasion resistance of fly ash concretes. In addition, both quantitative and qualitative fly ash parameters and compressive strength have an influence on abrasion damage.

Crack Resistance Evaluating of HSC Based on Thermal Stress Testing

2010 ◽  
Vol 168-170 ◽  
pp. 716-720 ◽  
Author(s):  
Bo Chen ◽  
Yue Bo Cai ◽  
Jian Tong Ding ◽  
Yao Jian
Keyword(s):  
Fly Ash ◽  
Crack Resistance ◽  
Silica Fume ◽  
Stress Testing ◽  
Testing Machine ◽  
Drying Shrinkage ◽  
High Strength ◽  
Fly Ash Concrete ◽  
Binder Ratio ◽  
Complex Crack

In order to evaluate the crack resistance of high strength fly ash concrete, concretes with different contents of silica fume and fly ash were compared with same strength grade by adjusting water to binder ratio. Compared with the concrete with 5% silica fume plus 35% fly ash，concrete with 40% fly ash has same mechanical properties and tensile strain as well as lower drying shrinkage. Complex crack resistance of high strength fly ash concretes were evaluated by Temperature Stress Testing Machine (TSTM). The results show that fly ash concretes have outstanding crack resistance because of higher allowable temperature differential and lower cracking temperature.

scholarly journals Mechanical Properties of Basalt-Based Recycled Aggregate Concrete for Jeju Island

Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5429
Author(s):  
Hong-Beom Choi ◽  
Jin-O Park ◽  
Tae-Hyun Kim ◽  
Kyeo-Re Lee
Keyword(s):  
Mechanical Performance ◽  
Drying Shrinkage ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Superior Performance ◽  
Recycled Aggregates ◽  
Replacement Ratio ◽  
Volume Percentage ◽  
Air Content

Recycled aggregate is essential to protect Jeju Island’s natural environment, but waste concrete, including porous basalt, is a factor that lowers the quality of recycled aggregate. Therefore, an experiment was conducted to analyze the properties of concrete application of basalt-based recycled aggregate (B-RA) through quality improvement. The absorption of the B-RA ranged from 3–5%; restricting its absorption to less than 3% was challenging owing to its porosity and irregular shape. However, the increase in the solid volume percentage of the concrete when replacing 25 or 50% of fresh basalt aggregate with recycled basalt aggregate improved the mechanical performance of the concrete, especially at 25%, for which a compressive strength of 55.9 MPa and modulus of elasticity of 25.9 GPa exceeded those of concrete with fresh basalt aggregate. Moreover, increasing the replacement ratio of the fresh basalt with recycled aggregate reduced the slump and decreased the air content, consequently increasing the concrete drying shrinkage. However, the replacement of fresh basalt aggregate with recycled basalt aggregate unaltered the mechanical performance of the concrete. The results indicate that efficient use of recycled aggregates can yield superior performance to that of fresh basalt, irrespective of aggregate quality.

Influence of Mineral Admixtures on early Shrinkage of Ordinary Concrete

2012 ◽  
Vol 450-451 ◽  
pp. 135-139 ◽  
Author(s):  
Li Feng Zhang ◽  
Jun Ying Lai ◽  
Xiao Qian Qian ◽  
De Long Hu
Keyword(s):  
Fly Ash ◽  
Mineral Admixtures ◽  
Plastic Film ◽  
Replacement Ratio ◽  
Building Research ◽  
Ordinary Concrete ◽  
Building Research Institute ◽  
China Academy ◽  
Binder Ratio ◽  
Water Binder Ratio

In this paper the influence of mineral admixtures on early shrinkage of ordinary concrete with the same water-binder ratio is studied by self-made equipment and CABR-NES deformation instrument developed by China Academy of Building Research Institute. All concrete specimens are cured with one surface exposed to air and others are covered with plastic film. The replacement ratio of mineral admixtures is 10%, 20% and 30%, respectively, and a mixture of a combination of both fly ash and slag is also studied. The results indicate fly ash reducing the early shrinkage of ordinary concrete, and the shrinkage decreases with the increasing of replacement ratio, but the effect is not so significant when the replacement ratio is above 20%. Slag also reduces the early shrinkage of ordinary concrete, and the shrinkage decreases with the increasing of replacement ratio, but the effect is not so significant when the replacement ratio is below 20%. Mixture with a combination of both fly ash and slag has lower shrinkage than mixture with fly ash.

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.

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.

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%.

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