Influence of Magnesium Additive on Mechanical Properties of Microbe Cementitious Material

The influence of magnesium additive concentrations(i.e.,0.5,1.5,2.5,3.5 mol/L and 4.5 mol/L) on the mechanical properties of microbe cementitious material was investigated.In addition,the mineral composition produced by microbe and microstructure of microbe cementitious material was analyzed by X-ray diffraction and scanning electron microscopy.The results indicate that when the magnesium additive concentration is 2.5 mol/L,the microbe cementitious material has the denser microstructure with the lower porosity.The compressive strength could be superior.When the magnesium additive concentration was rather low,the precipitated minerals induced by microbe in the microbe cementitious material were mainly calcite and Mg-calcite,and the morphology of precipitated minerals appeared mainly cauliflower shape.However,the magnesium additive concentration is higher,the minerals were mainly monohydrocalcite and hydromagnesite,and the morphology was mainly ball cylindrical.