Dataset supporting the paper: Sensing of damage and repair of cement mortar using electromechanical impedance

Data collection method:

Two identical mortar beams of 100 × 100 × 500 mm were used throughout the experimental program. One beam was used in the damage experiment, and the other on the repair experiment. The binder used was CEM I 52.5N and the sand was siliceous CEN Standard sand, with grains size distribution ranges between 0.08 and 2.00 mm conforming to BS EN 196-1. Mortars were casted with a sand/cement ratio of 3.0, and a water/cement ratio of 0.65. At 24 hours after casting, the samples were demoulded, and cured in a curing room of 21°C and 50% RH. The samples remained in the curing room for a minimum of 90 days before testing to ensure sufficient hydration. Lead zirconate titanate , PZT, disk was used to acquire the impedance signiture. The setup was composed of a soft PZT patch. A Cyanoacrylate CN-Y adhesive type was used to attach the PZT patch an aluminum plate as well as the aluminum plate to the beam. The PZT patch was connected through 50 Ω coaxial cables to a Newtons4th PSM 3750 frequency analyzer interfaced with an impedance analyzer . The frequency analyzer was controlled by a PC which was connected through a USB cable. The voltage amplitude used to collect the admittance response was 1 V, and the frequency range used was 15 kHz to 350 kHz. Through this frequency range, 1000 points were collected at 335 Hz intervals. In the damage experiment, the mortar beam was subjected to five different damage stages. In each damage stage 22 holes were drilled by an electric drill on the surface of the beam. The drilling started with hole number 1 at a distance of 220 mm away from the center of the beam, and along the center line of the beam. Additional holes were subsequently drilled in a line approaching and passing the center of the beam at 20 mm intervals which ended with hole number 22 .Hole diameters of 4 mm, 5 mm, 6 mm, 8 mm and 10 mm were used. The impedance signiture for the beam was collected before and after each hole was drilled. In the Repair stage experiment, damage was simulated by drilling 16 holes of 10 mm diameter and 5 mm depth at 15 mm spacing along the center line of the beam. The repair was simulated by filling the drilled holes with a cement paste (CEM 1 52.5N, water/cement ratio of 0.35). Theimpedance signature was obtained before and after drilling each hole. After filling the holes with the cement paste, the impedance signature was collected for a period of 60 hours to assess the repair effect on the EMI response. In order to minimize the effect of the ambient temperature and relative humidity, the admittance signatures for the sample were collected before and during the repair process, while the sample was in an environmental chamber of 21.8°C and 68% RH. These two values were specifically selected as they represent the average laboratory temperature and relative humidity during the drilling. The temperature variations during the repair process was recorded by a K type thermocouple which was attached to the center of the sample adjacent to the PZT patch. The thermocouple wires were connected to a PC controlled TC-08 data logger.

Additional information:

The row collected impedance signature, was then converted to an electrical admittance signature in order to allow for further comparison with other previous published studies.