Evaluation of Cone-Penetration Test as a Rheology Quality-Control Field-Oriented Test for 3D Printing Cement-Based...

Area of Science:

• Construction Materials Science
• Additive Manufacturing Technologies
• Geotechnical Engineering

Background:

• 3D printing of cement-based systems (3DP CBSs) requires precise material properties for successful construction.
• On-site construction necessitates field-oriented testing for real-time quality control and process monitoring.
• Understanding the evolution of mechanical properties is crucial for governing construction speed and ensuring structural integrity.

Purpose of the Study:

• To evaluate the cone penetration test (CPT) as a field-oriented method for assessing the mechanical properties of 3DP CBSs over time.
• To compare CPT results with established laboratory tests like the squeeze test (SQT) and vane test (VT).
• To establish a correlation between CPT measurements and the fresh compressive strength and shear yield stress of 3DP CBSs.

Main Methods:

• Utilized the cone penetration test (CPT) to measure penetration depth in 3DP CBSs over 90 minutes.
• Calculated shear yield stress and fresh compressive strength from CPT data.
• Compared CPT results with laboratory-based squeeze tests (SQT) and vane tests (VT) on various CBS formulations.

Main Results:

• CPT measurements are significantly influenced by the paste's stiffness (Young's Modulus, E), potentially leading to overestimated strength.
• An inflection point in stiffness increase (at 130 kPa) indicates a transition from plastic to pseudo-rigid behavior in the pastes.
• A linear adjustment was defined for CPT-derived average strength based on SQT and VT results, correlating with the evolution of mechanical properties.

Conclusions:

• The cone penetration test (CPT) shows potential as a field-based method for monitoring the mechanical evolution of 3D printed cement-based systems.
• CPT's accuracy in strength estimation is dependent on accounting for the material's stiffness and transitional behavior.
• The study provides a method to adjust CPT data for more reliable strength assessment in real-time construction monitoring.