Experimental Study on Engineering Characteristics of Fluidized Solidified Soil Containing Collapsible Loess and Gravel

To eliminate the defects of traditional backfilling methods and materials, combined with the characteristics of collapsible loess area, the premixed fluidized solidified soil with collapsible loess and gravel as aggregate was prepared. The influence of different loess-to-gravel (L/G), water-to-solid (W/S) and binder-to-aggregate (B/A) ratios on the workability and mechanical properties of the premixed fluid solidified soil was analyzed by carrying out flowability and unconfined compressive strength tests. The permeability test and collapsibility test were conducted to discuss the performance change of the proposed material after solidification and water exposure. The main conclusions are as follows: (1) For certain fixed cementitious material content, with the increase of collapsible loess content, the amount of water required to meet the flowability requirements of the mixture also increases, but the strength of the sample decreases as a whole. (2) The increase of the content of cementitious materials improves the strength of the sample, but reduces the flowability of the mixture, especially for the mixture with large L/G ratio and relatively low W/S ratio. (3) Premixed fluidized solidified soil made with collapsible loess and gravel which meets the requirements of flowability and minimum strength also meets the requirements of impermeability and collapsibility in the relevant specifications. (4) According to the test results, after W/S ratio is adjusted to meet the flowability requirement, the fluidized premixed solidified soil with L/G ratio between 1.50 and 1.86 and B/A ratio not less than 0.06 has good workability and mechanical properties.