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

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This study proposes using real-time construction data to assess deep cement mixing (DCM) column quality earlier than conventional post-curing coring tests allow. The approach analyzes operational records for each column, separating data into synchronized depth–time, grout-flow, water-flow, and rotation-speed graphs. These support evaluation of injection volumes, water-to-soil and cement-to-cement-plus-soil ratios, and mixing performance, with the aim of developing quality indicators and focusing coring on potentially problematic columns.<br /><br />The method was applied to more than 300 pairs of double-shaft DCM columns in a coastal seepage cut-off project. Columns were classified by operational patterns: 77% were typical (Category I), 20% showed delayed toe grouting, often associated with hard soil near the column toe (Category II), and 3% had anomalous patterns or missing data (Category III). The latter were treated as outliers and subjected to post-curing coring.<br /><br />Water-to-soil and cement ratios varied between zones, reflecting differences in soil conditions and construction response. Core tests showed median unconfined compressive strength of 1.38 MPa overall, with higher strength in zone P6 than S6. A blade rotational number of 400 revolutions per metre was consistent across the project and was considered adequate for the site’s sandy silt.<br /><br />Overall, operational data indicated that most columns followed the design approach and met or exceeded strength expectations. The authors recommend using real-time records for early warning and acceptance decisions, setting limits for anomalous columns, and requiring additional testing where operational data are irregular.

Keywords

deep cement mixing

DCM columns

real-time construction data

quality assessment

operational records

grout flow

water flow

rotation speed

unconfined compressive strength

post-curing coring