Improving the Compressive Strength and Stability of Steel Slag Cement-based Materials by Microbial Mineralization Technology
Using the microbial mineralization technology to improve the compressive strength and stability of steel slag cementitious materials was studied.The effect of microorganism on the compressive strength and linear expansion rate of steel slag cement-based material was studied,and the porosity,micro morphology and phase composition of mortar specimens were analyzed by automatic mercury porosimeter (MIP),field emission scanning electron microscope (SEM) and X-ray diffraction (XRD).The microbial modification mechanism of steel slag cement-based material was discussed in detail.The experiment test results showed that the optiaml addition amount of microbial spore was 2.0％ of the total mass of cement and steel slag.Microorganisms could promote the formation of carbonate precipitation of Ca(OH)2,free CaO and free MgO in steel slag cement-based material,reduce the porosity in the matrix and improve the compressive strength.The compressive strength of the steel slag cement-based material after adding microorganism was as high as 40.8 MPa,while the linear expansion rate was only 0.45‰.In the physical and chemical environment of steel slag cement-based material,microbial spores could germinate and grow into vegetative cells.Under the action of carbonic anhydrase,the content of free CaO and free MgO in steel slag cement-based material could be effectively reduced,so as to improve the stability.
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