Topology-Driven Compression and Energy Absorption of PLA-Lattice-Reinforced Mortar

The design of cellular architectures based on topology offers a promising strategy for tailoring the mechanical performance of cementitious composites without altering the matrix composition. However, the influence of the topological transition from re-entrant auxetic structures to conventional honeycomb structures on the compressive response of mortar is not yet fully understood. In this study, a family of polylactic acid (PLA) cellular architectures was systematically designed using fused deposition modeling (FDM), varying the strut angle from −70∘ to +70∘ and thereby generating a transition from auxetic to honeycomb topologies, with the cubic configuration serving as the intermediate topology. Quasi-static compression tests were conducted on standalone lattices, lattice-reinforced mortar composites, and unreinforced mortar specimens. The response was characterized in terms of apparent compressive modulus, apparent yield stress, energy absorption density, and specific energy absorption. Embedding the PLA lattices in mortar changed the macroscopic post-yield response, with the reinforced specimens sustaining deformation over a larger strain interval than the corresponding isolated lattices. This behavior is consistent with a constraint effect imposed by the surrounding matrix; however, the post-test PLA–mortar interface condition, possible debonding or delamination, and internal crack distribution were not directly characterized. Accordingly, the compressive response of these structured composites is governed by the combined effects of cellular topology and matrix–lattice interaction, while the specific microscale mechanisms underlying this interaction require direct experimental validation. These findings establish topological transition as a design strategy for developing cementitious composites with tailored quasi-static mechanical performance.