Mechanical Performance and Solidification Mechanism of Fluidized Solidified Soil of Slag Calcium Sulfoaluminate Cement
The large amount of sludge generated by dredging projects has high moisture content and heavy metals,posing a serious threat to the environment.The preparation of fluidized solidified soil by solidifying agents to solidify sludge is an effective method for resource utilization of sludge.The commonly used ordinary Portland cement(OPC)for solidification of sludge has problems such as low strength,high energy consumption,and high carbon emissions.However,slag calcium sulfoaluminate cement(G-CSA)is a new type of cementitious material with low carbon and high strength,which has potential application prospects in solidification of sludge.G-CSA was applied to prepare fluidized solidified soil and OPC fluidized solidified soil group was set.The effect of high belite sulfoaluminate cement(HB-CSA)clinker on the mechanical properties on G-CSA fluidized solidified soil was studied,and hydration products and pore structure were characterized to further analyze the solidification mechanism of G-CSA.The results show that the strength of G-CSA fluidized solidified soil increases first and then decreases with the increase of HB-CSA clinker content.When the content is 10％,the mechanical properties of G-CSA fluidized solidified soil reach the optimal level,with its 28 d compressive strength and flexural strength being 2.35 and 2.06 times that of OPC fluidized solidified soil respectively;The columnar AFt in G-CSA forms a skeleton structure,while the C-S-H gel binds the soil particles into a whole,thus effectively filling the internal pores of G-CSA fluidized solidified soil;An appropriate amount of HB-CSA clinker can reduce the porosity of G-CSA fluidized solidified soil and refine the pore structure to improve its mechanical properties.
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