Laboratory accelerated and outdoor durability testing of concrete with supplementary cementitious materials

Abstract

This paper aims to clarify the differences in durability test results of concrete containing supplementary cementitious materials (SCMs) for both laboratory-accelerated and outdoor exposure conditions. Twenty-six types of concrete specimens fabricated with and without SCMs were used for laboratoryaccelerated and outdoor exposure tests to measure the resistance to carbonation and chloride ingress. An accelerated carbonation test and an immersion test were conducted in accordance with Japanese standard testing procedures, and outdoor exposure tests were performed at three test sites in Japan over 20 months. Although the testing conditions between these two approaches were substantially different, both results exhibited the same trend: the use of SCMs impaired the resistance to carbonation but improved that to chloride ingress. The carbonation depths estimated by the accelerated carbonation test were, however, slightly greater than those measured in the exposed specimens. This conservative estimation for the carbonation depth was assumed to be a result of overly severe testing conditions of the accelerated carbonation test. Additionally, differences in the chloride profiles of the specimens were found between those soaked in a NaCl solution and those exposed to outdoor conditions. These differences were prominent in the specimens containing highvolume SCMs because their chloride profiles were affected by carbonation observed at the concrete surface layer of the specimens. It should be emphasized that the chloride penetration resistance improved by the use of SCMs for the laboratory-accelerated condition was, on the other hand, relatively reduced for the outdoor exposure conditions where carbonation and chloride ingress progressed simultaneously in concrete.