Self-Sensing Capabilities of Cement Pastes Treated by Direct Current Curing Technique

Abstract

In this study, an innovative curing technique, that is able to polarize the ions inside cement pastes is investigated. This technique is curing the cement paste while applying a direct current (DC). A total of 6 cement paste cubes were casted, 3 of them were not treated so it will serve as a reference and other 3 were cured while applying 25 V DC on two opposite sides of the specimen. All specimens were tested under different amplitude cyclic loading and the produced piezoelectric voltage was recorded. The results show that this technique was able to increase the produced piezoelectric voltage of the treated cement paste specimens when compared to the reference ones. In addition, the produced piezoelectricity showed a proportional behavior to the applied loads, which indicates the capabilities of self-sensing of the treated specimens. The voltage sensitivity values of the both the reference specimens and the treated ones are 0.34 and 1.77 mV/kN, respectively. The effect of the trapped moisture inside the specimens was also investigated, and the results show that the piezoelectricity greatly depends on the existence of moisture inside the specimens.

Electromechanical properties of self-sensing cement pastes polarized while fresh

“…Utilizing the DC electrical field to polarize cement pastes while fresh has been previously presented by the author [28][29][30]. This polarization can enhance the intrinsic self-sensing properties of the cement pastes.…”

“…The effect of polarizing of hardened cement pastes on its electrical properties will vanish after disconnecting the polarizing current. Polarization can be achieved by applying a uniform electrical field on the fresh cement paste specimen while curing [28,29]. This technique has multiple advantages when compared to the others mentioned before.…”

“…The results showed that changing the w/c ratio had negligible effect on the piezoelectric behavior of the tested specimens. Another study by the author [28] tested the relationship between the amplitude of the applied load on the treated specimens and their piezoelectric response. The results showed that the specimens produced a piezoelectric voltage that is directly related to the amplitude of the loading when tested parallel to the polarizing axis.…”