Sustainable 3D printable concrete: a comprehensive study on nanoclay-modified mixtures incorporating seashells

The construction industry has been transformed by 3D printing technology, offering alternative method for fabricating complex structures.The key to this progress lies in the development of 3D printable concrete (3DCP) with optimal rheological and mechanical properties.This paper studies the effect of different dosages of nanoclay on 3DCP with crushed seashells (scallop shells) as partial replacement for sand.Traditional cast in situ concrete heavily relies on sand, prompting the exploration of sustainable alternatives due to resource concerns.Seashells, as abundant waste from marine ecosystems, emerge as a viable substitute to sand, leveraging their unique properties and sustainable sourcing.The materials used in this research are Portland cement, fly-ash, basalt fiber, polycarboxylate polymer-based superplasticizer and nanoclay.Nanoclay was used to improve rheology and workability during the fresh state, increase the concrete capacity to support the weight of upper layers and be easily extruded without cracking.The research methodology includes material characterization, and rheological property assessment.Seashell aggregates characterization was determined by particle size distribution, chemical composition, and physical attributes.Rheological properties were determined with flow table, cone penetrometer, and cylindrical slump tests to evaluate the printability.