Surface Treatment of 3DPC Interlayers with Silicate-Based Solution for Enhanced Interfacial Bonding (2025-05)¶

The unavoidable challenge of weakened interlayers in 3D Concrete Printing yields diminished mechanical performance due to compromised micro- and macrostructural properties that are a culmination of the material and process parameters, in conjunction with ambient environmental conditions. A bond enhancement technique is proposed that is characterised by the surface treatment of interlayer surfaces with a silicate-based solution with the intention of densifying and improving the cementitious matrix in the interlayer region. After applying the surface treatment, the mechanical properties were assessed through compression and direct tensile tests. For microstructural characterisation, SEM/EDS analysis was performed to quantify the hydration products and their morphology in tandem with XCT analysis to assess the pore structure of the interlayer region. The surface treatment technique strengthened the interfaces, yielding up to 126 % bond strength improvement. Furthermore, the interlayer region is densified, with a marked decrease in total pore volume, as well as largest pore size observed. Moreover, the pore structure is more homogenous after the application of surface treatment.