Experimental study on leaching-abrasion behavior of concrete in flowing solution with low velocity

摘要

In order to study the influence of flowing velocity of solution on the leaching-abrasion behavior of concrete, this paper conducts a series of accelerated corrosion experiments on specimens in 1 M ammonium chloride solution with 0.0, 0.5,1.0 and 2.5 m/s. The leaching-abrasion behavior of the specimens, characterized by the leaching depth, porosity, phase composition, microstructure morphology and hydration product of its surface, was investigated by using the phenolphthalein indicator, saturation-drying weighing, X-ray diffraction (XRD), thermogravimetric analysis (TG) and scanning electron microscopy (SEM). Additionally, the boundary movement of specimen caused by the abrasion of flowing solution was also studied. Results showed that, higher flowing velocity of solution results in higher leaching depth and porosity in specimen. With the increase in flowing velocity of solution, the compactness of microstructure and the content of cement-hydrated products on the surface of specimen decrease first and then increase, but at a certain flowing velocity, the content of C-S-H gel is basically constant at its surface when the boundary of specimen moves. Finally, the boundary movement condition of specimen in flowing solution was proposed. (C) 2019 Elsevier Ltd. All rights reserved.