Effects of micro-environmental climate on the carbonation depth and the pH value in fly ash concrete

2018 ◽  
Vol 181 ◽  
pp. 309-317 ◽  
Author(s):  
Cai-feng Lu ◽  
Wei Wang ◽  
Qing-tao Li ◽  
Ming Hao ◽  
Yuan Xu
Keyword(s):  
Fly Ash ◽  
Ph Value ◽  
Carbonation Depth ◽  
Fly Ash Concrete

Research on the Variation of pH Value of the Ordinary Concrete and Fly Ash Concrete in the Carbonation Process

2011 ◽  
Vol 374-377 ◽  
pp. 1934-1937 ◽  
Author(s):  
Guang Zheng Qi ◽  
Di Tao Niu ◽  
Cheng Fang Yuan ◽  
Fu Zhen Duan
Keyword(s):  
Fly Ash ◽  
High Performance ◽  
Ph Value ◽  
Economic Benefits ◽  
Carbonation Depth ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Ordinary Concrete ◽  
Fly Ash Concrete ◽  
Carbonation Process

The accelerated carbonation test was carried out for the ordinary concrete and fly ash concrete. Influences of water-cement ratio, carbonation age and fly ash content on pH value were researched. The results show that carbonation depth, including incomplete carbonized zone, can be effectively reduced by reducing water-cement ratio. So lower water-cement ratio means high performance of resistance of carbonate. The use of fly ash can optimize concrete pore morphology, it’s beneficial for anti-carbonation. However, It disadvantageous to anti-carbonation because of less carbonation material. By taking appropriate mixture of fly ash we can not only enhance the anti-carbonation ability of concrete, but also reduce the use of cement to get well economic benefits.

Study on the Influence of Freeze-Thaw on the Carbonation Property of Fly Ash Concrete

2013 ◽  
Vol 357-360 ◽  
pp. 939-943 ◽  
Author(s):  
Jian Gang Niu ◽  
Liang Yan ◽  
Hai Tao Zhai
Keyword(s):  
Fly Ash ◽  
Laboratory Simulation ◽  
Influence Coefficient ◽  
Carbonation Depth ◽  
Freeze Thaw ◽  
Fly Ash Concrete ◽  
Concrete Carbonation ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle

Based on the coupling testing program of freeze-thaw and carbonation, the laboratory simulation test is carried out. The laws of carbonation depth of the fly ash concrete suffered the freeze-thaw cycle in different test modes and the influence of fly ash dosage on concrete carbonation depth after the freeze-thaw cycle are studied. Defining the influence coefficient of the freeze-thaw cycles on carbonation depth of concrete, the mechanism of coupling of freeze-thaw and carbonation is analyzed,and the role of freeze-thaw and carbonation in the coupling process are obtained.

scholarly journals Carbonation Depth Model and Prediction of Hybrid Fiber Fly Ash Concrete

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Jing-shuang Zhang ◽  
Meng Cheng ◽  
Jian-hua Zhu
Keyword(s):  
Fly Ash ◽  
Polypropylene Fiber ◽  
Basalt Fiber ◽  
Ash Content ◽  
Prediction Formula ◽  
Hybrid Fiber ◽  
Carbonation Depth ◽  
Weakly Alkaline ◽  
Fly Ash Concrete ◽  
Steel Bar

The concrete is weakly alkaline, the alkalinity of the concrete will be reduced after being carbonized, and the protective effect of the concrete on the steel bar will be weakened, even leading to corrosion of the steel bar. In this paper, fly ash is used to replace cement in the same amount, and basalt fiber and polypropylene fiber are added in a certain amount to make hybrid fiber fly ash concrete. Through rapid carbonation test, the influence of carbonation time and fly ash content on carbonation performance of hybrid fiber fly ash concrete is studied. The curve is fitted according to a single factor carbonation model with fly ash content as the main parameter, and the fitting curve and prediction formula are obtained. The results show that, in the same carbonization time, compared with the concrete without fly ash, the concrete with fly ash content of 5%, 10%, 20%, and 30% has average carbonization depth promotion rates of 6.4%, 14.9%, 59.8%, and 73.5%. When the fly ash content varies in the range of 10%∼20%, the carbonation resistance of hybrid fiber concrete changes most sensitively. At the same fly ash content, with the increase of carbonization time, the carbonization depth of concrete increases by 41.7%∼62.3%; Through the verification of the fitting curve and fitting formula obtained after fitting, it is concluded that the error of the prediction formula of carbonation depth of hybrid fiber fly ash concrete is within 9.1%, and the error of carbonation depth of 14 d and 28 d is within 4.3%. Replacing cement with fly ash has certain engineering significance and can achieve the purpose of recycling waste materials.

Carbonation of Fly Ash Concrete and Micro-Hardness Analysis

2011 ◽  
Vol 378-379 ◽  
pp. 56-59 ◽  
Author(s):  
Liu Qing Tu ◽  
Wen Bing Xu ◽  
Wei Chen
Keyword(s):  
Fly Ash ◽  
Portland Cement ◽  
Transition Zone ◽  
Ash Content ◽  
Experimental Results ◽  
Micro Hardness ◽  
Carbonation Depth ◽  
Carbonation Reaction ◽  
Micromechanical Analysis ◽  
Fly Ash Concrete

The effects of carbonation age, fly ash content in the binder and the water to binder ratios on the carbonation depth of fly ash concrete is investigated and the micromechanical properties of the hardened paste and the inter facial transition zone is analyzed with the micro-hardness method. The experimental results show that replacing Portland cement in concrete with fly ash increases the carbonation rate at early ages, while the late age carbonation rate is lowered. Micromechanical analysis shows that the carbonation reaction increases the micro-hardness of the paste and the compactness of the ITZ. For the relative low replacement levels, the width of the ITZ is reduced if the concrete is carbonated.

Effects of Compressive Strength and Carbonation of HCSA Amount on High Volume Fly Ash Concrete

2011 ◽  
Vol 261-263 ◽  
pp. 333-337
Author(s):  
Juan Hong Liu ◽  
Fang Fang Hou ◽  
Shao Min Song ◽  
Bo Ya Jia
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Internal Structure ◽  
High Volume ◽  
Carbonation Depth ◽  
Fly Ash Concrete ◽  
Resistance Increase ◽  
Expansive Concrete ◽  
High Volume Fly Ash ◽  
Carbonation Resistance

In this article, the effects of compressive strength and carbonation depth of HCSA mixing amount on high volume fly ash concrete have been investigated. Besides, the effects of compressive strength and carbonation depth of the fly ash amount on HCSA expansive concrete have been also analyzed. The results show that proper HCSA mixing amount can improve the compressive strength and anti-carbonation resistance. On the condition of 55% mixing amount of fly ash and 6% HCSA, the compressive strength for 28 days enhanced 8MPa, the carbonation depth decreased by 0.7mm, at the age of 70, the strength increased by 12MPa and the depth reduced 1.7mm; when the mixing amount of HCSA reaches 10%, the internal structure of concrete would be destroyed; In the case of 6% HCSA amount, the compressive strength and anti-carbonation resistance decreases with the increase of fly ash mixing amount. While comparing to the concrete without HCSA, the compressive strength and anti-carbonation resistance increase obviously.

A study on carbonation depth prediction for fly ash concrete

2006 ◽  
Vol 20 (9) ◽  
pp. 744-753 ◽  
Author(s):  
J. Khunthongkeaw ◽  
S. Tangtermsirikul ◽  
T. Leelawat
Keyword(s):  
Fly Ash ◽  
Carbonation Depth ◽  
Fly Ash Concrete ◽  
Depth Prediction

High Performance Concrete with High Volume Fly Ash

2006 ◽  
Vol 302-303 ◽  
pp. 470-478 ◽  
Author(s):  
Jian Hua Wu ◽  
Xin Cheng Pu ◽  
Fang Liu ◽  
Chong Wang
Keyword(s):  
Fly Ash ◽  
High Performance ◽  
High Performance Concrete ◽  
Ph Value ◽  
High Volume ◽  
Volume Stability ◽  
Fly Ash Concrete ◽  
High Volume Fly Ash ◽  
Large Dosage ◽  
Technical Measures

The emphasis of this paper is how to increase the 3-day and 28-day strength of high volume fly ash concrete. By some technical measures, such as improving the initial pozzolanic activity (3 day) of fly ash and decreasing the ratio of water to binding material and increasing the total dosage of binding materials, a concrete with the ratio of fly ash to binding materials between 50 %-70 % can be made. The fluidity of the concrete mix with large dosage of fly ash is very good and the strength at 3 day and 28 day are more than 42.5 MPa and 85 MPa respectively. By determining the pH value and the calcium hydrate content of the paste with large dosage of fly ash and accelerated carbonation test, it is shown that the resistance of the concrete to carbonization has been improved. The concrete with large dosage fly ash has good volume stability.

scholarly journals Influence of Potassium-Based Alkaline Electrolyzed Water on Hydration Process and the Properties of Cement-Based Materials with Fly Ash

Materials ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 6956
Author(s):  
Zexin Yu ◽  
Zixi Xie ◽  
Tianyu Zhang ◽  
Gongbing Yue ◽  
Haibao Liu ◽  
...  
Keyword(s):  
Fly Ash ◽  
Cement Hydration ◽  
Ph Value ◽  
Hydration Process ◽  
Hydration Reaction ◽  
Electrolyzed Water ◽  
Ordinary Water ◽  
Fly Ash Concrete ◽  
Cement Based Materials ◽  
Alkaline Electrolyzed Water

Alkaline electrolyzed water, a kind of clean green water with excellent characteristics such as high activity, strong alkalinity, high ion penetrating ability, electrical charge, and good molecule adsorption, was significant to the resource utilization of industrial fly ash waste. This paper studies highly active potassium-based alkaline electrolyzed water′s impact, compared with ordinary water, on the cement hydration process using microstructural methods such as a hydration heat test, differential thermal analysis, X-ray diffraction (XRD) pattern, and Scanning electron microscope (SEM) image analysis. Fly ash cement-based materials were first prepared with alkaline electrolyzed water as the mixing water. The alkaline electrolyzed water’s influence on fly ash paste workability and the mechanical properties of fly ash mortar for varying fly ash proportions were ratified. Then alkaline electrolyzed water with the best pH value was selected to prepare fly ash concrete, and its durability was studied. The test results showed that it is feasible to increase the utilization rate of fly ash by using alkaline electrolyzed water. Furthermore, it promoted the process of cement hydration, increased the rate of the hydration reaction, and the promotion effect increased with the increase in pH value of the alkaline electrolyzed water, and also promoted the effective decomposition of the vitreous shell of fly ash to stimulate its early activity. Concurrent tests with ordinary water paste showed that the water requirement for normal consistency and setting time with alkaline electrolyzed water paste were significantly less. Alkaline electrolyzed water also solved the problem related to the low early strength of fly ash mortar. Furthermore, using alkaline electrolyzed water with an optimum pH value of 11.5 to prepare fly ash concrete effectively reduced concrete′s carbonation depth and carbonation rate and lessened the chloride ion migration coefficient.

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