Deep Cement Mixing (DCM) Quality Assessment using Real-Time Operational Parameters Data-PPT Presentation

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The study proposes using real-time construction data to assess the quality of Deep Cement Mixing (DCM) columns earlier than conventional post-curing coring tests, which typically occur after 28 or 91 days. Early assessment could help identify construction problems, guide remediation, and target coring toward potentially problematic areas.<br /><br />Researchers examined operational records from 300 pairs of double-shaft DCM columns. They separated the data into plots of depth, grout flow, water flow, and drilling rotation speed, then classified columns based on these patterns: Category I (normal construction), Category II (normal construction with delayed toe grouting), and Category III (abnormal construction).<br /><br />Overall, 97% of columns were classified as Category I (77%) or Category II (20%); only 3% were abnormal. Category II columns had longer water injection durations and received about three times as much water as Category I columns, despite having similar depths. The pattern was attributed to harder soil near the column toe. Analysis also found that water-to-soil and cement-to-cement-soil ratios varied by site zone and were related to unconfined compressive strength (qu). In zone P6, harder soil throughout the column and increased cement content were associated with strength higher than desired. In zone S6, harder soil near the toe meant a modest cement increase could bring strength closer to the target.<br /><br />The study concludes that operational data can provide a basis for proactive DCM quality assessment and for developing a combined quality index. It recommends setting limits on the proportion of Category III columns and requiring additional testing for them. While the work discusses assessing both strength and permeability, the reported results primarily concern strength.

Keywords

Deep Cement Mixing

DCM columns

real-time construction data

quality assessment

post-curing coring

operational records

grout flow

water-to-soil ratio

unconfined compressive strength

construction problems