Study on the performance of industrial fluorosilicic acid modified aluminum sulfate based alkali free liquid accelerator
The aluminum sulfate as the main material,compounded with materials such as triethanolamine and lithium carbonate,to prepare an alkali free liquid accelerator.Then,industrial fluorosilicic acid is used as a modified component to investigate the effect of aluminum sulfate alkali free accelerator on the setting time and compressive strength performance of P·O 42.5 ordinary portland cement at different in-dustrial fluorosilicic acid dosages.XRD,SEM,and TG-DTG were used to analyze the phase composition and microstructure of the hydration products of the sample,and further explore the process of cement hy-dration reaction with the addition of modified component aluminum sulfate accelerator and the mechanism of action of the modified component.The results show that the addition of industrial fluorosilicic acid into the accelerator can significantly shorten the setting time of cement.When the industrial fluorosilicic acid content in the accelerator is 10％,the cement setting time reaches the minimum value,with initial and fi-nal setting times of 1.67 min and 4.28 min,respectively.With the addition of different amounts of indus-trial fluorosilicic acid in the accelerator,the 1 d compressive strength and 28 d compressive strength of the mortar first increase and then decrease.The compressive strength reaches its maximum when the industrial fluorosilicic acid content is 6％,and the 1 d and 28 d strengths are 12.4 MPa and 48.4 MPa,respective-ly.Compared with the accelerator without industrial fluorosilicic acid,after adding industrial fluorosilicic acid,the cement slurry will consume CH into more needle bar AFt,and accelerate the hydration of C3S to form C—S—H gel.However,when the industrial fluorosilicic acid content is excessive,the generated CaF2 precipitate will inhibit the hydration reaction and affect the formation of the compressive strength of the mortar for 1 d.
accelerating agentmodified componentsindustrial fluorosilicic acidmechanism of action
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