Study on Microstructure of Long-Age Concrete with HCSA Expansive Agent

2017 ◽  
Vol 744 ◽  
pp. 40-44 ◽  
Author(s):  
Fang Fang Hou
Keyword(s):  
Fly Ash ◽  
High Volume ◽  
Hydration Product ◽  
Curing Time ◽  
Average Ratio ◽  
Expansive Agent ◽  
Binding Material ◽  
High Volume Fly Ash ◽  
Energy Dispersion Spectrum ◽  
Scanning Electron

The microstructure of high-volume fly ash and long-age concrete with HCSA expansive agent at different curing time is studied by means of scanning electron microscope and energy dispersion spectrum analysis. The result shows that wet curing is benefit to the generation of ettringite which is the hydration product of HCSA expansive agent, and also is benefit to the hydration of cement and fly ash, which can fundamentally improve compactness of concrete. For the concrete which mix 6% amount of HCSA expansive agent a 60% amount of fly ash, when it is not cured, the average ratio of Ca to Si is 1.8, and the value is 0.36 after 28d curing. Since the ration of Ca to Si is lower, the hydration rate of binding material is faster.

Effects of Curing Time on Micro Properties of High-Volume Fly Ash Concrete with HCSA Expansive Agent

2017 ◽  
Vol 744 ◽  
pp. 87-91
Author(s):  
Xiao Jie Geng ◽  
Fang Fang Hou
Keyword(s):  
Fly Ash ◽  
Internal Structure ◽  
High Volume ◽  
Curing Time ◽  
Fly Ash Concrete ◽  
Internal Porosity ◽  
Expansive Agent ◽  
High Volume Fly Ash ◽  
Strength And Durability ◽  
Better Than

The effect of different curing time on internal structure of high-volume fly ash concrete with HCSA expansive agent is studied, and the analysis of that compactness and endurance of concrete could be improved by HCSA expansive agent which could fundamentally compact the internal structure of high-volume fly ash concrete is performed. The result shows that curing is beneficial to generation of ettringite and could accelerate hydration of concrete with expansive agent; the compactness of cured concrete with HCSA is better than which was not cured. The internal porosity was filled by expansive agent after hydration expansion, and concrete was more dense, leading to that the strength and durability of concrete improved.

scholarly journals Effect of Copolymer Latexes on Physicomechanical Properties of Mortar Containing High Volume Fly Ash as a Replacement Material of Cement

2014 ◽  
Vol 2014 ◽  
pp. 1-11
Author(s):  
El-Sayed Negim ◽  
Latipa Kozhamzharova ◽  
Yeligbayeva Gulzhakhan ◽  
Jamal Khatib ◽  
Lyazzat Bekbayeva ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Compressive Strength ◽  
Fly Ash ◽  
Setting Time ◽  
High Volume ◽  
Physicomechanical Properties ◽  
Partial Replacement ◽  
Setting Times ◽  
High Volume Fly Ash ◽  
Scanning Electron

This paper investigates the physicomechanical properties of mortar containing high volume of fly ash (FA) as partial replacement of cement in presence of copolymer latexes. Portland cement (PC) was partially replaced with 0, 10, 20, 30 50, and 60% FA. Copolymer latexes were used based on 2-hydroxyethyl acrylate (2-HEA) and 2-hydroxymethylacrylate (2-HEMA). Testing included workability, setting time, absorption, chemically combined water content, compressive strength, and scanning electron microscopy (SEM). The addition of FA to mortar as replacement of PC affected the physicomechanical properties of mortar. As the content of FA in the concrete increased, the setting times (initial and final) were elongated. The results obtained at 28 days of curing indicate that the maximum properties of mortar occur at around 30% FA. Beyond 30% FA the properties of mortar reduce and at 60% FA the properties of mortar are lower than those of the reference mortar without FA. However, the addition of polymer latexes into mortar containing FA improved most of the physicomechanical properties of mortar at all curing times. Compressive strength, combined water, and workability of mortar containing FA premixed with latexes are higher than those of mortar containing FA without latexes.

scholarly journals Fineness of Coal Fly Ash for Use in Cement and Concrete

Fuels ◽  
2021 ◽  
Vol 2 (4) ◽  
pp. 471-486
Author(s):  
Miguel Ángel Sanjuán ◽  
Cristina Argiz
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Coal Fly Ash ◽  
High Volume ◽  
Generation Process ◽  
Self Compacting Concrete ◽  
Roller Compacted Concrete ◽  
Binding Material ◽  
High Volume Fly Ash ◽  
Indirect Indicator

Nowadays, coal is increasingly being used as an energy source in some countries. This coal-fired generation process, however, has the disadvantage that produces large quantities of coal fly ash. Its characteristics differ depending on the combustion conditions and the coal source. Fineness will influence early compressive strength in cement-based materials. The finer the binding material, the higher the early compressive strength. They can be used to produce high-volume fly ash (HVFA) concrete, self-compacting concrete (SCC), concrete for marine infrastructures, pervious concrete, roller compacted concrete (RCC) and so on.More than seven hundred samples of coal fly ash were collected from a coal-fired power plant for a period of ten years, and their fineness were characterized by sieving. The average fineness on 45 µm, 63 µm, 90 µm and 200 µm mesh sieves were 22.5%, 15.5%, 9.1% and 2.0%, respectively. Then, most of the coal fly ash particles were lower than 45 µm, i.e., from 15 to 30% were retained on the 45 µm sieve, and from 10 to 20% by mass of coal fly ash particles were retained on a 63 µm sieve. Fineness on a 45 µm sieve is a good indirect indicator of the residues on the 63 µm, 90 µm and 200 µm mesh sieves. Accordingly, it is suggested to broaden the range from ±5% to as high as ±7% regarding the fineness variation requirement. Finally, the tested coal fly ash can be applied as cement constituent.

scholarly journals Compressive Strength of High-Volume Fly Ash (HVFA) Concrete as a Function of Lime Water and Curing Time

2021 ◽  
Author(s):  
Chin Mei Yun ◽  
Md. Rezaur Rahman ◽  
Kuok King Kuok ◽  
Mohd Elfy Mersal ◽  
Colin Ngu Ker Liing ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Portland Cement ◽  
High Volume ◽  
Partial Replacement ◽  
Curing Time ◽  
Additional Information ◽  
Lime Water ◽  
High Volume Fly Ash

Abstract The compressive strength of high-volume fly ash (HVFA) concrete with varied volume percentages of 40%, 50%, and 60% was examined utilizing low calcium fly ash (Class-F) as a partial replacement for regular Portland cement in this study. On the 7th, 28th, and 56th days, the compressive strength is tested. At the 7th and 28th days, the influence of saturated lime water on the compressive strength of HVFA concrete is evaluated. The inclusion of fly ash as a replacement for Portland cement reduces the compressive strength of the HVFA concrete, according to the findings. At the 56th day, the HVFA concrete with 40% fly ash substitution has a compressive strength equivalent to the regular weight concrete. At the 28th day, it was discovered that saturated lime water was helpful in maximizing the strength of HVFA concrete with 50% fly ash substitution. There was additional information about the characterization of HVFA concrete.

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