GGBFS, or Granulated ground blast furnace slab has most of the attributes of flyash, except for the enhanced early strength. It increases durability, reduces ASR, reduces permeability and enhances ultimate strength, but does have a slower strength gain than flyash. ACI recognizes it's benefits for increased durability through reduced ASR and increased ultimate strength. Here in the mid-Atlantic area, slag has almost entirely replaced flyash in ready mixed concrete, and slag cement blends are very common in low permeability grout mixes.
However, with the significant reduction in iron and virgin steel production in North America, slag's availability may be in jeopardy within a decade or so.
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Paul Blakita
QA/QC Engineer
Maryland
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Original Message:
Sent: 02-22-2017 11:38
From: Michael Elwardany
Subject: Type F Fly Ash
We have been using 25% Type F Fly Ash as a cementitious replacement factor for all concrete pavements in our area. The results have been great with respect to early strength development, ultimate strength achieved, mitigation of ASR and (we think) increased abrasion resistance. The industry is in a panic about future supplies. If anybody has direct experience with using slag cement, silica fume or metakaoline for any/all reasons listed, please share. - #SCM Seeker
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Michael Elwardany
Raleigh NC
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