An Evaluation Method for the Skeleton Structure of Cement-Stabilized Crushed Rock Material Using X-Ray CT Images

Abstract

Abstract No appropriate or accurate skeleton evaluation indexes currently exist for cement-stabilized crushed rock materials (CCRMs). To establish new skeleton evaluation indexes for a CCRM, different skeleton tightness–influenced regions of coarse aggregates were defined and compared to accurately capture the degree of tightness of a skeleton based on computed tomography images. The skeleton denseness index (φ¯) and skeleton stability index (φ¯) were proposed. Moreover, φ¯ was used to evaluate a CCRM that was compacted using the vertical vibration compaction method (VVCM) with different gradations to verify its feasibility. The meso-skeleton and macroscopic indexes (maximum dry density and compressive strength) of a CCRM with different compaction methods and vibration times, along with a field CCRM, were measured and compared. The results show that a range with twice the equivalent radius is rational as the influenced region. The φ¯ of a CCRM compacted using VVCM decreases as the gradation becomes finer, revealing that φ¯ can capture a CCRM skeleton. A CCRM compacted using a quasistatic compaction method has smaller meso-skeleton and macroscopic indexes than a CCRM using VVCM or a field CCRM; all indexes of the CCRM applying VVCM increase as the vibration time increases, whereas the growth rate slows. The results of vibration compaction (90 s) for CCRM match the common outdoor compaction results when constructing semirigid bases (common gradation and cement dosage) in Guangdong Province, China. Moreover, a strong correlation exists between meso-skeleton evaluation indexes and the compressive strength for a 7-day period.