Novel approach to detect encasement failures in the anchorage system of guyed transmission towers by distribution of relaxation times

[Display omitted] •Identification of time constants of cement paste by EIS/DRT.•Characterization of the pore structure of cement paste by EIS/DRT.•Detection of simulated failures in the cement paste encasement in soils of 4.0–200 Ω.m.•Novel approach to develop an NDT methodology to inspecting guyed transmission towers. Anchor rods of guyed transmission towers encapsulated in Portland cement pastes and mortar are usually affected by corrosion processes when buried in soils with chemical aggressiveness. Encasement failures, such as cracks and leaks, cause preferential points of degradation of the inner metal bar, affecting its mechanical integrity over the years and causing, in many cases, the collapse of the transmission tower. However, the nondestructive testing (NDT) used for diagnosis has not shown conclusive results. In this study, a methodology to detect failures in the cement paste encasement was developed using electrochemical impedance spectroscopy (EIS) by evaluating the distribution of relaxation time constants (DRT) to identify different time constants of water in the pore structure of cement paste. These parameters were typically determined by the nuclear magnetic resonance (NMR) relaxometry technique, which was not correctly applied to the field tests. From the results, it was possible to detect the presence of cement paste in soils with electrical resistivities varying from 4.0 to 200.0 Ω.m by identifying their time constant at 0.10 ms, which was attributed to the water present in the hydrated calcium silicate gel (C-S-H) interlayers.