Investigation of relations between porosity, pore structure, and C1− diffusion of fly ash and blended cement pastes

ABSTRACTPore structure development in portland/fly ash blends was investigated using mercury porosimetry and methanol exchange techniques. The progress of hydration was monitored using compressive strength tests. The specimens were made using four water-cement ratios and were hydrated over a one-year period in lime-saturated water. Mercury porosimetry results indicated that the blended cement pastes generally had higher total porosity than plain cement pastes. The major contribution to this increase in porosity was in the form of smaller pore sizes. With reactive fly ash at 20% replacement, the pore structure of mature paste consists mainly of pores nominally smaller than 0.05 μm in diameter. Diffusion parameters obtained from the methanol exchange results were found to be inversely related to the volume of large pores (nominally <0.05 μm) and also to the volume of small pores (nominally <0.05 μm). The effects of the physical and chemical properties of cements and fly ashes on pore structure development are discussed.

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Pore Structure Development in Portland Cement/Fly Ash Blends

MRS Proceedings ◽

10.1557/proc-86-209 ◽

1986 ◽

Vol 86 ◽

Cited By ~ 2

Author(s):

David J. Cook ◽

Huu T. Cao ◽

Everett P. Coan

Keyword(s):

Fly Ash ◽

Portland Cement ◽

Pore Structure ◽

Mercury Porosimetry ◽

Chemical Properties ◽

Blended Cement ◽

Total Porosity ◽

Structure Development ◽

Cement Pastes ◽

Diffusion Parameters

ABSTRACTPore structure development in portland cement/fly ash blends was investigated using mercury porosimetry and methanol exchange techniques. The progress of hydration was monitored using compressive strength tests. The specimens were made using four water-cement ratios and were hydrated over a one-year period in lime-saturated water. Mercury porosimetry results indicated that the blended cement pastes generally had higher total porosity than plain cement pastes. The major contribution to this increase in porosity was in the form of smaller pore sizes. With reactive fly ash at 20% replacement, the pore structure of mature paste consists mainly of pores nominally smaller than 0.05 μm in diameter. Diffusion parameters obtained from the methanol exchange results were found to be inversely related to the volume of large pores (nominally >0.05 μm) and also to the volume of small pores (nominally <0.05 μm). The effects of the physical and chemical properties of cements and fly ashes on pore structure development are discussed.

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Pore Structure Changes of Blended Cement Pastes Containing Fly Ash, Rice Husk Ash, and Palm Oil Fuel Ash Caused by Carbonation

Journal of Materials in Civil Engineering ◽

10.1061/(asce)0899-1561(2009)21:11(666) ◽

2009 ◽

Vol 21 (11) ◽

pp. 666-671 ◽

Cited By ~ 27

Author(s):

Prinya Chindaprasirt ◽

Sumrerng Rukzon

Keyword(s):

Fly Ash ◽

Pore Structure ◽

Palm Oil ◽

Rice Husk Ash ◽

Blended Cement ◽

Palm Oil Fuel Ash ◽

Cement Pastes ◽

Structure Changes ◽

Fuel Ash ◽

Oil Fuel

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

Cement and Concrete Research ◽

10.1016/j.cemconres.2011.09.012 ◽

2012 ◽

Vol 42 (1) ◽

pp. 194-204 ◽

Cited By ~ 193

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

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High Volume Slag and Slag-Fly Ash Blended Cement Pastes Containing Nano Silica

Materials Science Forum ◽

10.4028/www.scientific.net/msf.967.205 ◽

2019 ◽

Vol 967 ◽

pp. 205-213

Author(s):

Faiz U.A. Shaikh ◽

Anwar Hosan

Keyword(s):

Compressive Strength ◽

Fly Ash ◽

Cement Paste ◽

Ordinary Portland Cement ◽

Blended Cement ◽

High Volume ◽

Ash Content ◽

Partial Replacement ◽

Nano Silica ◽

Cement Pastes

This paper presents the effect of nanosilica (NS) on compressive strength and microstructure of cement paste containing high volume slag and high volume slag-fly ash blend as partial replacement of ordinary Portland cement (OPC). Results show that high volume slag (HVS) cement paste containing 60% slag exhibited about 4% higher compressive strength than control cement paste, while the HVS cement paste containing 70% slag maintained the similar compressive strength to control cement paste. However, about 9% and 37% reduction in compressive strength in HVS cement pastes is observed due to use of 80% and 90% slag, respectively. The high volume slag-fly ash (HVSFA) cement pastes containing total slag and fly ash content of 60% exhibited about 5%-16% higher compressive strength than control cement paste. However, significant reduction in compressive strength is observed in higher slag-fly ash blends with increasing in fly ash contents. Results also show that the addition of 1-4% NS improves the compressive strength of HVS cement paste containing 70% slag by about 9-24%. However, at higher slag contents of 80% and 90% this improvement is even higher e.g. 11-29% and 17-41%, respectively. The NS addition also improves the compressive strength by about 1-59% and 5-21% in high volume slag-fly ash cement pastes containing 21% fly ash+49%slag and 24% fly ash+56%slag, respectively. The thermogravimetric analysis (TGA) results confirm the reduction of calcium hydroxide (CH) in HVS/HVSFA pastes containing NS indicating the formation of additional calcium silicate hydrate (CSH) gels in the system. By combining slag, fly ash and NS in high volumes e.g. 70-80%, the carbon footprint of cement paste is reduced by 66-76% while maintains the similar compressive strength of control cement paste. Keywords: high volume slag, nanosilica, compressive strength, TGA, high volume slag-fly ash blend, CO2 emission.

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