Use of Seawater as an Accelerator in 3D Printed Concrete (2024-11)¶

Seawater (SW) is one of the viable alternatives to replace freshwater (FW) for producing concrete in regions facing extremely severe water stress. Seawater has high potential to be used as a set-on-demand accelerator among the other expensive materials being widely researched in additive manufacturing. The current study evaluated the progress of heat of hydration in 3DPC-FW and 3DPC-SW mixes using isothermal calorimetry. Furthermore, fresh and early-age properties of these mixes were studied using a flow table, manual shear vane, uniaxial unconfined compressive strength tests, and dynamic elastic modulus development. Strength development and shrinkage progress up to 28 days were evaluated. A detailed investigation reveals that an increase in compressive strength from the very first hours of hydration, a reduction in workability which could be compensated by modifying SP, and higher shrinkage were observed in SW-mixed 3DPC compared to the FW-mixed counterpart. Furthermore, the potential improvement in the speed of printing is highlighted in this study with 3DPC-SW mix demonstrating acceleration in early strength.