A comparative study on the pore structure of alkali-activated fly ash evaluated by mercury intrusion porosimetry, N2 adsorption and image analysis

2018 ◽  
Vol 53 (8) ◽  
pp. 5958-5972 ◽  
Author(s):  
Y. Ma ◽  
G. Wang ◽  
G. Ye ◽  
J. Hu
Keyword(s):  
Image Analysis ◽  
Fly Ash ◽  
Comparative Study ◽  
Pore Structure ◽  
Mercury Intrusion Porosimetry ◽  
N2 Adsorption ◽  
Mercury Intrusion ◽  
Alkali Activated

A Comparison of the Pore Structure of Cement and Fly Ash/Cement Mortars Made with Sea Water and Fresh Water

1986 ◽  
Vol 85 ◽  
Author(s):  
B. K. Marsh ◽  
R. C. Joshi ◽  
A. Balasundaram
Keyword(s):  
Fly Ash ◽  
Pore Structure ◽  
Fresh Water ◽  
Mercury Intrusion Porosimetry ◽  
Sea Water ◽  
Blended Cement ◽  
Fly Ashes ◽  
Mercury Intrusion ◽  
Pore Structures ◽  
Cement Mortars

ABSTRACTPore structures of portland and blended cement mortars prepared with sea water were assessed by mercury intrusion porosimetry. Comparison is made with similar mortars made with fresh water. Mortars were made using cement containing 0%, 25% or 50% (by volume) of one of two Alberta fly ashes. They were tested after 90 days of continuous immersion in sea water at 5°C or 20° C. Results show that the mortars made with sea water generally contained a much higher volume of fine pores although the porosity was, in some cases, greater than that of mortars made with fresh water. Nevertheless, the volume of larger pores was lower in the mortars made with sea water. The pore structure of the various mortars is discussed in relation to potential durability.

Porous Systems Based on Alkali-Activated Fly Ash

2018 ◽  
Vol 276 ◽  
pp. 179-184
Author(s):  
Pavel Kejík ◽  
Vlastimil Bílek Jr. ◽  
Pavel Bulejko ◽  
Jan Hajzler ◽  
Matěj Březina ◽  
...  
Keyword(s):  
Fly Ash ◽  
Mercury Intrusion Porosimetry ◽  
Capillary Flow ◽  
Coarse Fraction ◽  
Binder Phase ◽  
Sintering Process ◽  
Porosity Level ◽  
Mercury Intrusion ◽  
Alkali Activated ◽  
Different Doses

This paper studies possibilities of alkali-activated fly ash (AAFA) for the preparation of systems with preserved certain porosity level. Such systems would be used for example as filtration barriers, which are commonly prepared by both energetically and economically expensive sintering process at high temperatures. Porosity preservation was facilitated by the use of only coarse fraction from fly ash particles together with the use of low water to fly ash ratio and pressure compaction. Two different doses of sodium hydroxide were used to alkali activate fly ash. Prepared specimens were moist cured at 95 °C for 24 hours. Porosity and binder phase among the fly ash grains were investigated using scanning electron microscopy (SEM), mercury intrusion porosimetry (MIP) and capillary flow porosimetry (CFP). The results showed that it is possible to prepare AAFA-based porous systems and modify their properties by changing the activator dose.

The Influence of Moisture on the Expansion of Macro-Defect-Free Cements

1991 ◽  
Vol 245 ◽  
Author(s):  
H. Igarashi ◽  
T. Takahashi
Keyword(s):  
Image Analysis ◽  
Polyvinyl Alcohol ◽  
Portland Cement ◽  
Pore Structure ◽  
Calcium Hydroxide ◽  
Mercury Intrusion Porosimetry ◽  
Nitrogen Adsorption ◽  
Cement Pastes ◽  
Alcohol Acetate ◽  
Mercury Intrusion

ABSTRACTMDF(Macro-Defect-Free ) cement pastes, which consist of portland cement and polyvinyl alcohol/acetate, were prepared by varying the temperature during pressing and drying operations. We then examined the expansion of MDF cement pastes at various constant humidities. There was a large difference in expansion above 60%R.H. between samples prepared varying temperature at which samples were pressed. Samples pressed at 90 °C showed less expansion than samples pressed at 40 °C.The pore structure of MDF cement pastes before exposure to moisture was measured by nitrogen adsorption, mercury intrusion porosimetry and image analysis. The properties of a matrix containing polyvinyl alcohol/acetate and cemnt hydrates were also investigated by TEM, IR and XPS.There were not large differences in the result of IR and XPS measurement between the MDF cement pastes prepared at various temperatures. Calcium hydroxide crystal, lying perpendicular to cement particles, were often observed only in the MDF cement pastes pressed at 90 °C which occurs by water absorption, seems to be suppressed by calcium hydroxide crystal.

Microstructure of High Strength Concrete Mercury Intrusion Porosimetry and Thermogravimetry Analysis

2011 ◽  
Vol 243-249 ◽  
pp. 3781-3786 ◽  
Author(s):  
Iqbal Khan Mohammad
Keyword(s):  
Fly Ash ◽  
Pore Structure ◽  
Calcium Hydroxide ◽  
Silica Fume ◽  
High Strength Concrete ◽  
Mercury Intrusion Porosimetry ◽  
High Strength ◽  
Thermogravimetry Analysis ◽  
Mercury Intrusion ◽  
Strength Concrete

Microstructural properties such as pore structure and hydration play a decisive role in determining the properties of a concrete. This paper presents the investigation on pore structure and hydration process of high strength concrete. Pore structure study was conducted using mercury intrusion porosimetry and hydration progress was monitored using thermogravimetry analysis on various blended combinations of cementitious materials incorporating fly ash and silica fume as partial cement replacement. It was found that silica fume refined the pore structure efficiently and reduced the calcium hydroxide content as early as 1 day. All ternary blended systems containing fly ash and silica fume exhibited lower calcium hydroxide content and refined pore structure in comparison to their respective blended pastes.

scholarly journals Effect of CaSO4 Incorporation on Pore Structure and Drying Shrinkage of Alkali-Activated Binders

Materials ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1673 ◽  
Author(s):  
Hyeongmin Son ◽  
Sol Moi Park ◽  
Joon Ho Seo ◽  
Haeng Ki Lee
Keyword(s):  
Fly Ash ◽  
Pore Structure ◽  
Drying Shrinkage ◽  
Phase Changes ◽  
X Ray Diffraction ◽  
Activated Slag ◽  
Capillary Tension ◽  
Alkali Activated Binders ◽  
Internal Pore Structure ◽  
Alkali Activated

This present study investigates the effects of CaSO4 incorporation on the pore structure and drying shrinkage of alkali-activated slag and fly ash. The slag and fly ash were activated at a 5:5 ratio by weighing with a sodium silicate. Thereafter, 0%, 5%, 10%, and 15% of CaSO4 were incorporated to investigate the changes in phase formation and internal pore structure. X-Ray Diffraction (XRD), thermogravimetry (TG)/derivative thermogravimetry (DTG), mercury intrusion porosimetry (MIP), nuclear magnetic resonance (NMR), and drying shrinkage tests were carried out to find the correlation between the pore structure and drying shrinkage of the specimens. The results showed that CaSO4 incorporation increased the formation of thenardite, and these phase changes affected the pore structure of the activated fly ash and slag. The increase in the CaSO4 content increased the pore distribution in the mesopore. As a result, the capillary tension and drying shrinkage decreased.

Sign in / Sign up

Export Citation Format

Share Document