Freeze Thaw Durability of Steel and Polypropylene Reinforced Shotcretes: A Review

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Title: Freeze Thaw Durability of Steel and Polypropylene Reinforced Shotcretes: A Review

Author(s): D. R. Morgna

Publication: Special Publication

Volume: 126

Issue:

Appears on pages(s): 901-918

Keywords: durability; fibers; freeze-thaw durability; metal fibers; reinforcing steels; shotcrete; synthetic fibers; Materials Research

Date: 8/1/1991

Abstract:
Fiber reinforced shotcretes have been used in numerous external exposure applications where the shotcrete is subjected to cycles of freezing and thawing, often in a saturated condition. This paper summarizes the results of several laboratory studies in which both wet and dry-mix fiber reinforced shotcretes have been tested to ASTM C 666 Procedure A (Freezing and Thawing in Water). It is shown that both steel and high-volume polypropylene fiber reinforced wet-mix shotcretes can be made freeze-thaw durable, provided the shotcrete is properly air entrained. Nonair-entrained fiber reinforced wet-mix shotcrete deteriorates very rapidly in the ASTM C 666 Procedure A test. In the dry-mix shotcrete process, it does not appear possible to effectively use air-entraining admixtures; in spite of this, it is shown that properly designed and applied steel fiber reinforced dry-mix shotcrete can be made freeze-thaw durable. The important criteria for making such steel fiber reinforced dry-mix shotcretes freeze-thaw durable are discussed. It is currently not possible to practically produce high-volume polypropylene fiber reinforced shotcrete using the dry-mix process, and so the inherent freeze-thaw durability of such a system is not known.