Compressive strength and curing mechanism of alkali-activated geopolymer curing marine silty soft soil
Marine silty soft soil is rich in all kinds of soluble salts and organic matter,and is prone to deterioration effect when cement is used for curing to solve the engineering problem of reinforcement failure that often occurs in traditional silicate cement curing.In order to solve the engineering problems of traditional silicate cement curing,which often lead to reinforcement failure,NaOH was used as alkali activation.The geopolymer-cement combination was used for curing marine silty soft soil to study the effects of cement and geopolymer mixing ratio,alkali activation content and curing age on the unconfined concrete,and curing age on the unconfined compressive strength of the cured soil.It was to analyze the micromorphology and hydration products of alkali activate geopolymer curing of marine silty soft soil by scanning electron microscope and X-ray diffraction tests.It was to reveal the mechanism of its curing.The results of the study show that the addition of NaOH alone does not significantly increase the strength of the hydraulic soil,and the strength of the hydraulic soil does not significantly increase with increasing alkali activation content.At the same time,the curing effect of different calcium geopolymers varies significantly.The early strength of slag geopolymer cured soil increases rapidly and the late strength increases slowly,and its unconfined compressive strength increases and then decreases with increasing NaOH content and improves with increasing slag dosage.Fly ash geopolymer cured soil strength growth is slower,the higher the NaOH content of its unconfined compressive strength is greater,and the strength with the increase in the dosage of fly ash and reduce.Half of the cement is replaced by slag.The 28 d strength of the cured soil is up to 6.19 MPa compared to that of the hydraulic soil,which is 107.5%higher.The same proportion of fly ash replacement,the maximum 28 d strength of only 3.012 MPa.microscopic analysis shows that the addition of alkali activation and geopolymer can promote the soluble salt hydration crystallization and degradation of organic matter alkaline environment,effectively increase the effective hydration products,improve the cohesion between particles to make the soil structure more compact,macroscopic manifestation of the strength of the cured soil to improve.The results can provide theoretical guidance for solving the practical engineering problems caused by cement reinforcement of marine silt soft soil.
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