The effect of electrical stray current on material properties of mortar specimens

Well known is that stray electrical current i.e. current with a spatial distribution in any conductive environment, can affect civil structures, e.g. initiate or enhance steel corrosion or affect microstructural and mechanical properties of the cement-based bulk matrix. While the former is related to polarization effects in conditions of current flow, the latter is generally a consequence of leaching phenomena, which normally occurs due to concentration gradients. In the case of current flow, concentration gradients’ controlled diffusion is accompanied by migration i.e. ion and water transport in an electrical field. Although these conditions are not specifically and intentionally arranged, with regard to civil structures they would be inevitable for the underground or water submerged sections. Related to a study on the effect of stray currents on cement-based materials microstructure, leaching processes were observed, accompanied by alterations in pore network parameters (as porosity and pore size distribution) and mechanical properties (as compressive strength). Two current regimes were investigated i.e. 100mA/m2 and 1A/m2 as applied current densities and outcomes compared to properties of the investigated specimens in “natural leaching” conditions or control, no-current cases. The investigation shows indeed enhanced alterations of material properties for the “under current” conditions, substantiated by chemical analysis, mercury intrusion porosimetry and mechanical tests.Structural EngineeringCivil Engineering and Geoscience