Permeability is defined as the property that governs the rate of fluid flow through a porous solid (Ref. 1). The porosity of cement paste determines the permeability of concrete (Ref. 2). The water-cement ratio is one of the largest contributors to porosity development, but, on the whole, porosity is determined through chemical interaction.
Woodcraft - Rochester
50 Spencerport Road Rochester, NY, 14606
HARMCO FASTENER CO INC
428 State Street Rochester, NY, 14608
Secor Do it Best Hardware
6260 Furnace Road
Avon True Value & Auto
275 E Main Street
Bristol Valley Hardwoods of Rochester
4054 Bristol Valley Road Route 64
Mayer Hardware, Inc
226 Winton Rd N
6280 Rt 96 Ste B Victor, NY, 14564
Lowe's of Macedon
1605 Macedon Parkway Macedon, NY, 14502
Abrasive Tool Corp
1555 Emerson Street
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Source: THE CONCRETE PRODUCER/CONCRETE JOURNAL MAGAZINE
Publication date: March 1, 2001
Question: A customer has asked us to include fibers in the mix design for a water retention tank. The idea is that the fibers will reduce the permeability of the concrete. Is that true?
Answer: There are really two responses here. The first defines permeability, and the second determines how fibers affect permeability.
Permeability is defined as the property that governs the rate of fluid flow through a porous solid (Ref. 1). The porosity of cement paste determines the permeability of concrete (Ref. 2). The water-cement ratio is one of the largest contributors to porosity development, but, on the whole, porosity is determined through chemical interaction. Since the fibers themselves are chemically inert and have no interaction with cementitious reactions, it is not possible for the fibers to decrease the permeability of concrete.
However, this is not to say that fluid will not flow through the concrete at a different rate when fibers are present. In a simple sense, fibers are small, flexible aggregates. As such, they create a small matrix of aggregates within the larger concrete matrix. If moisture flows through concrete via the cement paste, then the fibers create a more tortuous path. The more tortuous the path, the longer it takes the water takes to traverse it.
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