Title:
Chlorides in Concrete: Science-Based Exposure Classifications and Allowable Limits
Author(s):
David Trejo and Gokul Dev Vasudevan
Publication:
Materials Journal
Volume:
121
Issue:
1
Appears on pages(s):
5-16
Keywords:
admixed chloride; allowable chloride concentration; corrosion; critical chloride concentration; exposure classification; limit state design; probability of corrosion
DOI:
10.14359/51739198
Date:
1/1/2024
Abstract:
Inconsistencies in standards and codes result in confusion,
increased costs, and do not promote the efficient use of concrete. In
addition to inconsistencies, the lack of science-based approaches
and data used for defining criteria in these standards and codes
can limit the reliability and trust of these requirements. A review
of industry documents indicates that inconsistencies and lack of
science-based approaches exist across many documents, both
throughout the industry and within ACI, relating to the corrosion
of steel reinforcement embedded in concrete. This paper proposes
to address five key issues to promote science-based standardization
of requirements necessary for reinforced concrete systems exposed
to corrosive conditions. These five issues include the need for: 1)
standardization of chloride testing methods and requirements; 2)
standardization of chloride reporting units; 3) standardization of
terminology for specifying chlorides in cementitious systems; 4)
standardization of exposure classifications for corrosive conditions;
and 5) standardization of allowable chloride limits.
This paper presents current inconsistencies in guide documents
and codes for each of the items listed previously and then proposes
an approach to standardize each using either available data and/
or a scientifically based approach. Recommendations for testing,
reporting, definition of exposure classifications, and allowable
chloride limits are then proposed. It is hoped that the systematic
approach used herein will lead to standardization and consistency,
less confusion, and will promote the efficient use of durable and
economical concrete.
Related References:
ACI Committee 201, 2016, “Guide to Durable Concrete (ACI 201.2R-16),” American Concrete Institute, Farmington Hills, MI, 84 pp.
ACI Committee 222, 2019, “Guide to Protection of Reinforcing Steel in Concrete Against Corrosion (ACI 222R-19),” American Concrete Institute, Farmington Hills, MI, 60 pp.
ACI Committee 301, 2020, “Specifications for Concrete Construction (ACI SPEC-301-20),” American Concrete Institute, Farmington Hills, MI, 69 pp.
ACI Committee 318, 2019, “Building Code Requirements for Structural Concrete (ACI 318-19) and Commentary (ACI 318R-19) (Reapproved 2022),” American Concrete Institute, Farmington Hills, MI, 624 pp.
ACI Committee 329, 2014, “Report on Performance-Based Requirements for Concrete (ACI 329R-14),” American Concrete Institute, Farmington Hills, MI, 46 pp.
ACI Committee 350, 2020, “Code Requirements for Environmental Engineering Concrete Structures (ACI 350-20) and Commentary (ACI 350R-20),” American Concrete Institute, Farmington Hills, MI. 553 pp.
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ASTM C1524/C1524M-20, 2020, “Standard Test Method for Water-Extractable Chloride in Aggregate (Soxhlet Method),” ASTM International, West Conshohocken, PA, 5 pp.
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