Fluidized solidification modification tests on expansive soil and its mixing proportions study

Fluidized solidification modification constitutes a new method for repurposing discarded materials, offering a solution to challenges associated with backfill compaction in irregular or constrained spaces within road engineering. Employing a distinct variety of medium expansive soil from the Nanning region, and amalgamating it with water, cement, and standardized sand, fluidized solidified soil specimens were developed and evaluated through laboratory-scale geotechnical examinations. The implications of diverse mixing proportions on swelling potential, strength, fluidity and bleeding rate of the specimens were comprehensively analyzed. Results show that the swelling characteristic of the specimens is largely contingent upon the cement-to-aggregate ratio and the sand-to-soil ratio, while the water-to-solid ratio exerts a minimal effect. The specimens manifest non-expansive characteristics when the cement-to-aggregate ratio exceeds 18% and the sand-to-soil ratio surpasses 6%. The unconfined compressive strength primarily emanates from the cement-to-aggregate ratio, exhibiting an initial increase followed by a decline with an augmented sand-to-soil ratio, necessitating sand-to-soil ratio control within 10%. An elevation in the water-to-solid ratio substantially attenuates the strength, with a ratio exceeding 80% markedly accelerating the strength degradation under cyclical wet-dry conditions. Initial fluidity is positively correlated with the water-to-solid ratio, sand-to-soil ratio and cement-to-aggregate ratio, and is least affected by the cement-to-aggregate ratio. The 90 min after the specimen finished mixing is the main stage of fluidity loss, with the rate of fluidity loss ranging from 23% to 32%, and then the change slows down. The bleeding rate is controlled by the water-to-solid ratio and is less affected by the cement-to-aggregate ratio. Based on the experimental pattern, the proportion design process for fluidized solidification modification of expansive soils was derived through data normalization analysis. © 2024 Zhejiang University. All rights reserved.