Title:
Hydrogen Embrittlement Testing of Concrete Screws
Author(s):
Anthony J. Lamanna
Publication:
Materials Journal
Volume:
114
Issue:
1
Appears on pages(s):
15-19
Keywords:
anchors; concrete screws; durability; hydrogen embrittlement; induced cracking
DOI:
10.14359/51689470
Date:
1/1/2017
Abstract:
Concrete screw anchors can be susceptible to stress-induced hydrogen embrittlement cracking because they are case hardened and often coated. Hydrogen attack can result in decreased tensile ductility and decreased fracture stress at the root, which is where the threads meet the core. Currently, Acceptance Criteria 193 (AC 193) requires that two types of tests are conducted to qualify screw fasteners for stress-induced hydrogen embrittlement cracking under service conditions: 1) Method A, which is a test subjecting a concrete screw installed in concrete to a sustained tensile load while in an aggressive environment; and 2) Method B, which is a bending test on the threaded portion of the fastener while in an aggressive environment. This study examines Method A and Method B qualification test data obtained from three manufacturers for five different diameters and 11 different lengths. The comparison of the test results for the two methods shows that Method B is a redundant test, resulting in no additional safety or information beyond that gained from Method A.
Related References:
AC 193, 2012, “Acceptance Criteria for Mechanical Anchors in Concrete Elements,” International Code Council Evaluation Service, approved June 2012, editorially revised May 2013.
ACI Committee 355, 2007, “Qualification of Post-Installed Mechanical Anchors in Concrete (ACI 355.2-07) and Commentary,” American Concrete Institute, Farmington Hills, MI, 35 pp.
ASTM F1624-12, 2012, “Standard Test Method for Measurement of Hydrogen Embrittlement Threshold in Steel by the Incremental Step Loading Technique,” ASTM International, West Conshohocken, PA, 12 pp.
Gerber, B., 2006, “Proposed Revisions to the Acceptance Criteria for Mechanical Anchors in Concrete Elements, Subject AC193-0606-R3 (BG/KS),” ICC-ES Evaluation Service, Inc., 2006.
Herring, D. H., and Sisson, R. D., 2008, “The Heat Treatment of Fasteners—Embrittlement Issues,” Fastener Technology International, V. 31, No. 6, Dec., pp. 32-34.
IBC, 2015, “2015 International Building Code,” International Code Council, Washington, DC.
Interrante, C. G., and Raymond, L., 1995, “Hydrogen Damage,” ASTM Manual Series MNL No. 20, pp. 272-288.
Menzel, K., and Fuchs, W., 2006, “Concrete Screws—Suitability in Respect to Brittle Fracture,” Otto-Graf Institute, Institute of Construction Materials, University of Stuttgart, Stuttgart, Germany, 2006.