Measurements of laboratory rates of concrete expansion and their comparisons with field rates

Abstract

The R.H. Saunders dam is one of over one hundred concrete dams, worldwide, suffering from structural and operational problems due to the expansion of concrete resulting from alkali–aggregate reaction. A laboratory test methodology for measuring the residual expansion rate in these dams with simulation of field environment has been developed. This paper describes the test principles and method of interpretation of the different tests developed. Results of various expansion tests performed on samples recovered from the R.H Saunders dam (Canada) are presented. Results showed that the expansion rates measured in laboratory are consistent with those measured by extensive instrumentation in the field (in situ rebar tests, levelling data, stress meters, and in situ overcoring data). It is believed that the test methodology developed provides the necessary and inexpensive tools for measuring the stress-dependent residual expansion potentials in concrete dams. It would also have an impact on the design of remedial measures and the prediction of future performance because of the reliability and versatility of the test method.Key words: dams, concrete, expansion, alkalis, aggregate, reaction, cement.