Experimental study on real-time control of roller compacted concrete dam compaction quality using unit compaction energy indices

• The UCE indices can be used to evaluate compaction quality of RCC dams.
• Quantitative relation between UCE and RCC compaction quality is established.
• A real-time UCE monitoring system is presented in RCC compaction quality control.

Vibrating compaction is a marked feature distinguishing roller compacted concrete (RCC) from conventional concrete and is the key factor influencing RCC construction quality. The compaction of RCC results from the comprehensive effect of all compaction parameters. Considering every construction parameter separately would increase the difficulty of construction control and not guarantee construction quality. Therefore, real-time monitoring quality indices—namely, unit compaction energy (UCE), including unit volume compaction energy (UVCE) and unit area compaction energy (UACE), which reflect the comprehensive effect of compaction parameters—were proposed to evaluate the compaction quality of RCC matrix and interface, respectively. To investigate the UCE for predicting the compaction quality of an RCC dam, a three-part laboratory compaction experiment was conducted using a hand vibratory roller. Data on compaction parameters, UVCE/UACE and in situ measurements (e.g., nuclear moisture density, shear strength) were collected to perform statistical regression analyses. A density regression model of RCC matrix and a shear strength regression model of RCC interface were established to determine the control criteria of UVCE and UACE, respectively. Furthermore, a UCE-based real-time monitoring system was developed for field quality control, which is the subsequent practical application of the laboratory experimental study and will result in RCC construction quality assurance.