Hydration Performance and Pore Structure of Fly Ash-Cement Pastes

2012 ◽  
Vol 204-208 ◽  
pp. 3867-3871 ◽  
Author(s):  
Xiang Li ◽  
Yun Dong ◽  
Hua Quan Yang
Keyword(s):  
Fly Ash ◽  
Pore Structure ◽  
Pore Solution ◽  
Ex Situ ◽  
Replacement Ratio ◽  
Cement Pastes ◽  
Binder Ratio ◽  
Very High ◽  
Reaction Degree ◽  
Curing Age

The hydration performance and pore structure of fly ash-cement (FC) pastes were investigated by means of XRD, TG, ex-situ leaching (ESL) and MIP. The results reveal that the influence of curing age to the kinds of hydration products of FC pastes is unconspicuous. As the content of fly ash increase, the Ca(OH)2 content decrease gradually. However, the content of Ca(OH)2 left in every paste is almost constant after 28d, regardless of the replacement ratio of fly ash and water-binder ratio. The decline of alkalinity of pore solution is not endless, even though the contents of fly ash in FC pastes is very high(65%).The incorporation of fly ash in proper ratios could increase the ratio of harmless pores and improve the microstructure of the FC pastes. Ca(OH)2 was not consumed heavily or exhausted when cementitious material was hydrated due to the low reaction degree of fly ash.

Influence of Fly Ash on Alkalinity of Pore Solution and Microstructure Characteristics of Hardened Cement Pastes

2012 ◽  
Vol 253-255 ◽  
pp. 322-325 ◽  
Author(s):  
Jian Jun Yan ◽  
Xiang Li ◽  
Hua Quan Yang
Keyword(s):  
Fly Ash ◽  
Pore Solution ◽  
Cementitious Material ◽  
Ex Situ ◽  
Hardened Cement ◽  
Cement Pastes ◽  
Microstructure Characteristics ◽  
Hardened Cement Pastes ◽  
Very High ◽  
Reaction Degree

Influence of fly ash on alkalinity of pore solution and microstructure characteristics of hardened cement pastes were investigated by means of ex-situ leaching (ESL), MIP and SEM. The results reveal that the decline of alkalinity of pore solution is not endless, even though the contents of fly ash in fly ash-cement(FC) pastes is very high(65%).The incorporation of fly ash in proper ratios could increase the ratio of harmless pores and improve the microstructure of the FC pastes. Ca(OH)2 was not consumed heavily or exhausted when cementitious material was hydrated due to the low reaction degree of fly ash.

Pore structure characterization of cement pastes blended with high-volume fly-ash

2012 ◽  
Vol 42 (1) ◽  
pp. 194-204 ◽  
Author(s):  
Qiang Zeng ◽  
Kefei Li ◽  
Teddy Fen-chong ◽  
Patrick Dangla
Keyword(s):  
Fly Ash ◽  
Pore Structure ◽  
High Volume ◽  
Structure Characterization ◽  
Cement Pastes ◽  
High Volume Fly Ash

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.

Modification of water absorption and pore structure of high-volume fly ash cement pastes by incorporating nanosilica

2021 ◽  
Vol 33 ◽  
pp. 101638 ◽  
Author(s):  
Qian Huang ◽  
Xiaohong Zhu ◽  
Dongsheng Liu ◽  
Liang Zhao ◽  
Min Zhao
Keyword(s):  
Fly Ash ◽  
Pore Structure ◽  
Water Absorption ◽  
High Volume ◽  
Cement Pastes ◽  
High Volume Fly Ash

Surface fractal analysis of pore structure of high-volume fly-ash cement pastes

2010 ◽  
Vol 257 (3) ◽  
pp. 762-768 ◽  
Author(s):  
Qiang Zeng ◽  
Kefei Li ◽  
Teddy Fen-Chong ◽  
Patrick Dangla
Keyword(s):  
Fly Ash ◽  
Pore Structure ◽  
Fractal Analysis ◽  
High Volume ◽  
Cement Pastes ◽  
Surface Fractal ◽  
High Volume Fly Ash

Size Effect on Compressive Strength and Modulus of Elasticity in High Performance Concrete

2013 ◽  
Vol 634-638 ◽  
pp. 2742-2745 ◽  
Author(s):  
Jeong Eun Kim ◽  
Wan Shin Park ◽  
Nam Yong Eom ◽  
Do Gyeum Kim ◽  
Jea Myoung Noh
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Size Effect ◽  
Modulus Of Elasticity ◽  
High Performance ◽  
High Performance Concrete ◽  
Type A ◽  
Type B ◽  
Replacement Ratio ◽  
Curing Age

This study undertook the research of size effect on compressive strength and modulus of elasticity, respectively. The parameters of this study are curing age and fly ash replacement ratio to investigate size effect of Type A (100mm x 200mm) and Type B (150mm x 300mm) specimens in high performance concrete. On this study, high performance concrete was fabricated with different FA contents of 10%, 20% and 30%. The measurements were performed on days 28 and 91.

Changes of pore structure and chloride content in cement pastes after pore solution expression

2020 ◽  
Vol 106 ◽  
pp. 103465 ◽  
Author(s):  
Xiang Hu ◽  
Caijun Shi ◽  
Qiang Yuan ◽  
Jian Zhang ◽  
Geert De Schutter
Keyword(s):  
Pore Structure ◽  
Pore Solution ◽  
Chloride Content ◽  
Cement Pastes

Bound Water in Cement Pastes and its Significance for Pore Solution Compositions

1986 ◽  
Vol 85 ◽  
Author(s):  
H. F. W. Taylor
Keyword(s):  
Fly Ash ◽  
Pore Solution ◽  
Bound Water ◽  
Free Water ◽  
Adsorbed Water ◽  
Interlayer Water ◽  
Structural Water ◽  
Cement Pastes ◽  
Evaporable Water ◽  
Definition Of

ABSTRACTThe problem of defining bound water in a cement paste is discussed; a reasonable definition is one that includes interlayer water in C-S-H and AFm phases, structural water in ettringite, and adsorbed water, but not water in micropores or in larger pores. On this basis, structural considerations indicate a value of around 32% on the ignited weight for a fully hydrated paste. ‘Non-evaporable’ water, typically around 22% on the ignited weight at full hydration, cannot be identified with bound water, because dehydration to the state in which only non-evaporable water remains causes major loss of interlayer water and destruction of ettringite. In the interpretation of pore solution data, the definition of bound water, and the value assumed for this quantity, are important, because the ionic concentrations in the pore solution are greatly affected by the volume of free water available to dissolve them. If cement is partially replaced by low calcium fly ash, the quantity of bound water at any given age is substantially reduced. This effect contributes to the relatively low concentrations of alkali metal and hydroxyl ions that are observed in the pore solutions of many portland-fly ash cement pastes.

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%.

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