Preparation and properties of nano-SiO2 modified aluminum sulfate alkali-free liquid accelerator
Aluminum sulfate,fluosilicic acid,aluminum hydroxide and other raw materials were used to prepare alkali-free liquid accelerator mother liquor,and nano-SiO2 was used to modify it.The performance index of the modified alkali-free accelerator was tested with the reference cement,and XRD,SEM,TG-DTG and other means were used to test the cement samples mixed with accelerator.The results show that with the increase of nano-SiO2 content,the compressive strength of cement mixed with accelerator gradually increases,and the setting time first decreases and then increases.When the accelerator is mixed with 3％nano-SiO2,the setting time is the shortest.Adding accelerator containing 3％nano-SiO2,the initial setting time of cement is 195 s,and the final setting time is 345 s.The 1 d compressive strength can reach 10.2 MPa,and the 28 d compressive strength is 50.5 MPa.The introduction of nano-SiO2 in the accelerator can promote the hydration of cement,but when the content of nano-SiO2 in the accelerator is high,it will make the ettringite become fine needle-like and lead to the deterioration of the accelerator effect.
alkali-free liquid acceleratornano-silicasetting timecompressive strengthmechanism of action
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