Capillary Water Intake by 3D-Printed Concrete Visualised and Quantified by Neutron Radiography
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Water uptake into two formulations of 3D-printed concrete via capillary suction was assessed by neutron radiography. The samples varied in their layer-to-layer deposition time intervals (TI) and the use of different binders. TI of two and 13 min were short enough to avoid preferential capillary suction at interlayer bonding areas in the fine-grained printable concretes containing supplementary cementitious materials. An increase in the time interval to 24 h gave rise to quick capillary suction through the layer-to-layer interfaces. However, moisture did not redistribute into the matrix regions from the interfaces. For mixture with Portland cement as sole binder and addition of a superabsorbent polymer (SAP), the short layer-to-layer deposition interval of two minutes resulted in tight interlayer bonds with quasi-null capillary suction. Intervals of 13 and 36 min, however, resulted in partially quick and intense absorption of water and immediate absorption by adjacent SAP particles.
KeywordsExtrusion-based additive manufacturing Transport properties Neutron radiography imaging Superabsorbent polymers
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