Toward sustainable construction 3D printing: limestone and non-calcined recycled marine clay as partial cement replacement

This study investigates the effects of partial substitution of Ordinary Portland Cement with different proportions of non-calcined marine clay and different grades (by particle size) of Ground Limestone to formulate 3D-printable concrete. Non-calcined clay was used because of its lower energy requirement than calcined clay. The rheology of the mixes was evaluated by extrudability, tack, Large Amplitude Oscillatory shear, and Logarithmic Stress Ramp tests. Their mechanical performance was evaluated with respect to compressive, splitting, shear, and three-point bending (flexural) strengths. Results show that adding only about 1 % of oven-dried (low temperature) marine clay and 19 % of limestone improve cohesion and build-up of static yield strength while ensuring extrudability. This study hopes to pave the way for more studies on using non-calcined marine clay as a more sustainable option for construction 3D printing.