Measurement of the Hygric Resistance of Concrete Blocks with Perfect Contact Interface: Influence of the Contact Area – Complementary Comments

In March 2021, this journal published the paper “Measurement of the Hygric Resistance of Concrete Blocks with Perfect Contact Interface: Influence of the Contact Area”. This commentary aims to provide readers with a set of complementary comments that seek to clarify a few issues that can be raised.

The analysis was done based on the original paper “Measurement of the Hygric Resistance of Concrete Blocks with Perfect Contact Interface: Influence of the Contact Area”. The purpose was to complete and comment on the work developed in the original paper, and to clarify some points that might be less understood.

Some interesting questions are presented, and the analysis results intend to clarify them, namely: (1) the magnitude of the quantified post-interface flows; (2) the distinguishability of the moisture absorption in the monolithic and perfect contact samples; (3) the robustness of the knee-point identification algorithm; (4) the dependability of the capillary absorption measurements; (5) the consistency of the capillary absorption processing; (6) the number and “quality” of samples that should be used.

The conclusions to highlight are the following: the hygric resistance results would be different as they consider different methodologies for the knee point detection and a different number of data points after the knee (different ones) to calculate the slope; the monolithic samples reached the highest moisture masses, Mw, and the Mw values became lower with the interface occurrence; for the knee-point identification, it was only considered valid the use of the third of the three algorithms described in Section 2.3; the taping of the samples was carefully done, and absorption tests using epoxy resin is considered a better solution; the C calculation was made for all monolithic samples, but only the 3 more representative experimental results for each contact area were represented (as mentioned) and the A_w of the 10x10 cm² cross-section should be 0.1013 kg/m²s^0.5, which does not influence the conclusions/findings.