Microbial induced carbonate precipitation modified steel slag: Mechanical improvement and erosion resistance to sulfate attack

This present study discussed the mechanical improvement and erosion resistance property of steel slag (SS) modified by microbial induced carbonate precipitation (MICP). SS aggregates, a waste product obtained from iron and steel industry was firstly treated by MICP. For the strength and structural purpose, eight kinds of SS-sand mixtures were designed at different contents of Part I SS and Part II SS. The maximum UCS of bio-modified SS was 2453.8 kPa which is about 3 times to that of sand-only sample, while the maximum flexural strength of bio-modified SS was 551.2 kPa which is lower than that achieved by sand-only sample (771.8 kPa). There is a strong relationship between CaCO3 content and UCS. Microscope structure was illustrated through scanning electron microscope (SEM). Combining with the results from SEM, X-Ray Diffraction (XRD) test and Fourier Transform Infrared Spectroscopy (FTIR), it is confirmed that SS particles were wrapped with calcite, vaterite, and amorphous CaCO3 minerals. Lower calcium leaching concentration was observed in sulfate-bearing solution compared to that in tap water condition. Improved mechanical performance and prominent erosion resistance properties light up the application of MICP-treated SS.