Corrugated tube protocol for autogenous shrinkage measurements: review and statistical assessment

Among different methods of measuring early age autogenous deformation of cementitious materials, the corrugated tube method described in the ASTMC1698-09 standard is one of the most commonly used. Despite the standardization and the common application of this method in the research community, only limited information has been published about the method's precision. This paper is dedicated to a review of this method, together with a statistical assessment of the results of an experimental study on three cement pastes. The autogenous deformation of cement pastes of water-to-cement ratio 0.30-0.36, with and without internal curing, was measured by different operators in a single laboratory following the standard ASTM procedure. In addition to determining the method's precision, key factors influencing the results (i.e., rotation, temperature, time-zero) were identified and their effects were quantified. It was found that the method is sensitive enough to resolve different levels of shrinkage and its evolution in time, and that the effect of the operator is not significant. However, considerably high scatter was found between replicate samples within a single operator. The major source of the scatter was due to the inaccuracies in the initial measurement after setting (time-zero), being the reference point for strain determination.