Experimental Study on the Properties of Expansive Slurry after Adding Sodium Silicate

Adding expansion agent to ordinary slurry can make the volume of the slurry expand, but makes the setting time of the slurry long. Conversely, adding sodium silicate will shorten the setting time of the slurry. By means of the setting time test, expansion evolution monitoring, uniaxial compression, XRD and SEM, the changes in setting time, expansion performance and UCS of expansive slurry with different sodium silicate contents were explored. The results of the tests show that: (1) Sodium silicate can effectively shorten the setting time of the expansive slurry, and the higher the sodium silicate content, the shorter the setting time of slurry. With 25% content of sodium silicate, the initial setting time of the slurry with 10% and 20% contents of expansion agent decreased from 630min and 740min to 50min and 35min respectively, which decreased by 92.6% and 95.27%, (2) Sodium silicate does not affect the time of expansion evolution of the expansive slurry, but has a certain impact on the final expansion ratio of the slurry. With the increase in sodium silicate content, the final expansion ratio of the slurry increased slightly at first and then decreased at last. With 25% content of sodium silicate, the final expansion ratios of the slurry with 10% and 20% contents of expansion agent decreased from 0.39% and 1.66% to 0.27% and 1.24% respectively, which decreased by 30.77% and 25.30%, (3) Sodium silicate can significantly improve the UCS of expansive slurry. The inflection points of UCS of the slurry with 10% and 20% expansion agent contents are 15% and 20% sodium silicate contents respectively, and the strength increased from 4.98MPa and 4.44MPa to 17.85MPa and 17.99MPa respectively, which also increased by 258.43% and 305.18%.