ABSTRACT
Ground Support in Mining and Underground Construction-Villaescusa & Potvin (eds.) © 2004 Taylor & Francis Group, London, ISBN 90 5809 640 8
ABSTRACT: In this paper laboratory corrosion tests and their results made on rebars and steel strands are presented. The aims of corrosion research were to determine the differences in corrosion rate between solid rebar and cable, to determine the effectiveness of corrosion prevention methods in relation to cable operating time and to find a corrosivity classification method, which could be used in estimating the corrosivity of the environment, where rock bolts are used. The results include weight loss tests, strand structure tests and stress corrosion cracking tests. The effect of the corrosion protection, like epoxy-coating and hot dip galvanizing, on the axial behavior of the steel strands are also discussed on the basis of the laboratory pull out tests made on test samples. The research work was done at the Helsinki University of Technology. The axial load displacement behavior of test bolts was tested by double pipe pull tests with different embedment lenghts. Five different bolt types were tested: rebar, black steel strand, hot dip galvanized steel strand, epoxy coated steel strand and bulbed strand. All the strands were seven-wired steel strand. The rebars were tested as a reference test bolt of the bolt type most used in civil rock engineering.
