Iranian Researchers Present Induction Bonding Technique in 3D-Printed Cementitious Binders

Sunday, June 21, 2020 - 13:03

Researchers of Iran University of Science and Technology in cooperation with Rice University in Houston, Texas and Monash University, in Melbourne, Australia could present “Induction Bonding” technique in 3D-Printed Cementitious Binders.

According to an ISCA report, 3D printing of cementitious materials holds a great promise for construction due to its rapid, consistent, modular and geometry-controlled ability.

In this study, researchers report a combined experimental and computational approach to understand and control fabrication of 3D-printed cementitious materials with significantly enhanced interlayer strength using multimaterial 3D printing, in which the composition, function, and structure of the materials are programmed.

“Results show that the intrinsic low interlayer cohesion is caused by excess moisture and time lag that block the majority of valuable interactions in the interlayer zone between the adjacent cement matrices. As a remedy, a thin epoxy layer is introduced as an intermediator between the adjacent extruded layers, both to improve the interlayer cohesion and to extend the possible time delay between printed adjacent layers.

“The ab initio calculations demonstrate that an orbital overlap between the calcium ions, as the main electrophilic part of the cement structure, and the hydroxyl groups, as the nucleophilic part of the epoxy, create strong interfacial absorption sites.

“These electronic absorptions lead to several iono-covalent bonds between the cement matrix and epoxy, leading to significant improvements in tensile, shear and compressive strengths as well as ductility of the 3D-printed composites. This is verified by the experimental data, which showed an average of 84% improvement in interlayer bonding.

“The upward augmentation of interlayer bonding helps 3D printing cementitious material to overcome their intrinsic limitation of weak interlayer cohesion, thereby mitigating/eliminating the key bottleneck of additive manufacturing in constructing materials.”

The research, published in ACS publication, was done by Ehsan Hosseini, Mohammad Zakertabrizi, Asghar Habibnejad Korayem, Zafar Zaker and Rouzbeh Shahsavari from Nanomaterials Research Center, School of Civil Engineering of Iran University of Science and Technology.

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