Experimental study on the mechanical properties of geopolymer solidified clay based on response surface method
Geopolymer is a kind of green cementing material with fast hardening,high strength and good durability.In this study,the experimen on clay solidification was carried out by adding such geopolymer cementing materials as slag,calcium carbide slag and alkali activators CaO and NaHCO3.With the influencing factors of slag content,calcium carbide slag content and alkali initiator content,and with the response values of 7 and 28 days of so-lidified soil compressive strength,the optimal mix ratio was obtained through Box-Behnken test.The results showed that the slag dosage had the greatest effect at 7 days of maintenance age,and the alkali stimulant dosage had the greatest effect at 28 days of maintenance age.The predicted compressive strength of the solidified soil was close to the actual compressive strength,and the reliability of the model was high.When the slag content was 17.37％,the calcium carbide slag content was 9.31％and the alkali activator content was 6.51％,the tar-get value of the compressive strength reached 612.97 kPa at the 7 days and 875.69 kPa at the 28 days.According to SEM analysis,the main hydration product for 7 days was flocculent C-S-H gel,and with the increase of curing age,the flocculent C-S-H gel gradually formed a three-dimensional network C-S-H gel.With the formation of ettringite,acicular ettringite and C-S-H gel filled the intergranular pores of solidified soil,which improved the mechanical properties of solidified soil.
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