A concrete performance test for delayed ettringite formation: Part II validation

Delayed ettringite formation (DEF) is a rare problem of concrete, whose reaction mechanisms have been investigated by a large number of studies. In order to develop a performance test, the authors have conducted a feasibility study and an optimization study followed by this validation study. A performance test was previously developed to evaluate the risk of expansion as a result of DEF for a given “concrete/heating” combination to be evaluated. This paper presents the results of the validation study and explains the necessary conditions that must be applied for this test to be used as part of a rigorous preventive procedure. Data has been collected to reproduce the heat development in concrete under actual conditions on site or in a prefabrication factory. Concrete/heating combinations were studied for which 10 or 20 years' experience of the use of the concrete in wet environments existed. After nearly 300 days of testing, all the laboratory results reproduced the behaviour observed in-situ. On the basis of these macroscopic measurements and microscopic observations, DEF susceptible concretes can be distinguished from concretes that have never caused problems, despite being heated to 80 °C in early age. This test program therefore, confirms the reliability of the proposed performance test.