On the expansive cracking of a cement matrix containing atomized basic oxygen furnace slag with a metallic iron

Abstract

A series of experiments was conducted to investigate the crack-expansion of a cement matrix containing atomized basic oxygen furnace slag with a metallic iron. The BOF slag particles were dispersed in supersaturated Ca(OH)2 solution mimicking the pore solution in a cement matrix and the changes in these particles were visually observed. X-ray diffraction, thermogravimetry, and X-ray photoelectron spectroscopy were conducted on different slag powders and cement paste in the slag. Our major observations indicated that 1) cracks in the BOF slag-containing cement matrix were initiated from the slag particles, 2) the BOF slag contained metallic Fe and free MgO, and 3) Fe oxides, portlandite, and brucite were formed at slag crack points. Therefore, corrosion of metallic Fe is proposed as the main reason for the cracking of a cement matrix with atomized BOF slag; further, hydration of free MgO helps in crack growth and propagation. © 2020 Elsevier Ltd