Conditions of DEF Development in Various Climatic Conditions: Laboratory and Field Investigation

Occurrence of Delayed Ettringite Formation (DEF) is highly dependent on climatic conditions (e.g. temperature, moisture, rainfall, etc.). Consequently, the induced degradation may develop with various features, depending on the exposure conditions. Moreover, the effect of climate on DEF in concretes using different types of cement still remains unclear. In this context, a joint French-Japanese research program was developed. For three different concrete mixes produced with different cements, material specimens were exposed in the laboratory to different temperatures (from 8 ℃ to 38 ℃): by monitoring expansion in these conditions, the objective was to understand the effect of temperature in simple and controlled conditions. In addition, 30cm-cube specimens were cast and distributed in various field-exposure sites in France and in Japan: this allowed to monitor DEF development in different climatic conditions and thus better understand the influence of complex exposure conditions on the expansion. This paper presents the design of the program (concrete mixes, laboratory and field test setups, exposure site characteristics, etc.). Laboratory test results are presented to illustrate the material characteristics and provide comprehensive details about the effect of temperature on DEF. The DEF potential of each mix has been confirmed. Moreover, for the cements considered in this research, DEF has been influenced in different ways by the temperature.