Potential of Weathered Blast Furnace Slag for use as an Addition in Concrete

Thomas D. Dyer, Michael J. McCarthy (Lead / Corresponding author), Laszlo J. Csetenyi

Research output: Contribution to journalArticle

Abstract

The paper investigates the potential for recovering granulated blast furnace slag after four years storage in a stockpile (weathered) for use as an addition in concrete. The initial research physically and chemically characterized fresh and weathered granulated slag. Thereafter, studies on ground materials, including their use in paste and mortar were carried out. The weathered granulated slag was similar to fresh slag in terms of particle size, shape and elemental composition. However, there was greater roughening of particle surfaces, with various weathering products forming. Following grinding, fresh slag comprised angular particles covering a range of sizes, while finer particles in weathered slag included fragmented reaction products. In cement paste, weathered slag gave reductions in chemically bound water. In mortar, this showed little difference in flow properties compared to fresh slag, with reductions in compressive strength and increases in porosity also noted. Further analyses suggest that, at equal Blaine fineness, weathered slag (i) is actually coarser than fresh material, affecting particle packing and giving larger capillary pores, and (ii) has lower reactivity due to reduced surface area. The practical implications are examined and approaches to using weathered slag in concrete suggested.
Original languageEnglish
Number of pages38
JournalMagazine of Concrete Research
Early online date27 Aug 2019
DOIs
Publication statusE-pub ahead of print - 27 Aug 2019

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Slags
Concretes
Ointments
Mortar
Weathering
Reaction products
Compressive strength
Cements
Porosity
Particle size
Water
Chemical analysis

Keywords

  • Cement/cementitious materials
  • Chemical properties
  • Sustainability

Cite this

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title = "Potential of Weathered Blast Furnace Slag for use as an Addition in Concrete",
abstract = "The paper investigates the potential for recovering granulated blast furnace slag after four years storage in a stockpile (weathered) for use as an addition in concrete. The initial research physically and chemically characterized fresh and weathered granulated slag. Thereafter, studies on ground materials, including their use in paste and mortar were carried out. The weathered granulated slag was similar to fresh slag in terms of particle size, shape and elemental composition. However, there was greater roughening of particle surfaces, with various weathering products forming. Following grinding, fresh slag comprised angular particles covering a range of sizes, while finer particles in weathered slag included fragmented reaction products. In cement paste, weathered slag gave reductions in chemically bound water. In mortar, this showed little difference in flow properties compared to fresh slag, with reductions in compressive strength and increases in porosity also noted. Further analyses suggest that, at equal Blaine fineness, weathered slag (i) is actually coarser than fresh material, affecting particle packing and giving larger capillary pores, and (ii) has lower reactivity due to reduced surface area. The practical implications are examined and approaches to using weathered slag in concrete suggested.",
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AU - McCarthy, Michael J.

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N2 - The paper investigates the potential for recovering granulated blast furnace slag after four years storage in a stockpile (weathered) for use as an addition in concrete. The initial research physically and chemically characterized fresh and weathered granulated slag. Thereafter, studies on ground materials, including their use in paste and mortar were carried out. The weathered granulated slag was similar to fresh slag in terms of particle size, shape and elemental composition. However, there was greater roughening of particle surfaces, with various weathering products forming. Following grinding, fresh slag comprised angular particles covering a range of sizes, while finer particles in weathered slag included fragmented reaction products. In cement paste, weathered slag gave reductions in chemically bound water. In mortar, this showed little difference in flow properties compared to fresh slag, with reductions in compressive strength and increases in porosity also noted. Further analyses suggest that, at equal Blaine fineness, weathered slag (i) is actually coarser than fresh material, affecting particle packing and giving larger capillary pores, and (ii) has lower reactivity due to reduced surface area. The practical implications are examined and approaches to using weathered slag in concrete suggested.

AB - The paper investigates the potential for recovering granulated blast furnace slag after four years storage in a stockpile (weathered) for use as an addition in concrete. The initial research physically and chemically characterized fresh and weathered granulated slag. Thereafter, studies on ground materials, including their use in paste and mortar were carried out. The weathered granulated slag was similar to fresh slag in terms of particle size, shape and elemental composition. However, there was greater roughening of particle surfaces, with various weathering products forming. Following grinding, fresh slag comprised angular particles covering a range of sizes, while finer particles in weathered slag included fragmented reaction products. In cement paste, weathered slag gave reductions in chemically bound water. In mortar, this showed little difference in flow properties compared to fresh slag, with reductions in compressive strength and increases in porosity also noted. Further analyses suggest that, at equal Blaine fineness, weathered slag (i) is actually coarser than fresh material, affecting particle packing and giving larger capillary pores, and (ii) has lower reactivity due to reduced surface area. The practical implications are examined and approaches to using weathered slag in concrete suggested.

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