Çimento esaslı değişik türden killer içereren malzemelerin ekstrüzyon ve reolojik karakterizasyonu

Recently, digital manufacturing has been termed the fourth industrial revolution (Industry 4.0). Implementation of digital manufacturing revolutionizes the construction industry with the potential of freeform architecture, less raw material consumption, reduced construction costs, and increased worker safety. Thus, for the last decade methods on digital manufacturing of concrete gained a significant interest compared to conventional concrete. While the studies mainly focus on the development of specially designed 3-D printers, at this current technology readiness lever the main challenge is to design the highly thixotropic material and the software enabling heterogenous material flow. In terms of material design, the printable mortars must be extrudable through a nozzle without clogging and retain its shape right after the printing and when another layer is deposited, in short, it must be buildable. To be able to provide layer deposition on top of each other, the consistency of mortar should increase fast upon extrusion. The thixotropic nature of cement paste enables this rapid viscosity change. Time dependent viscosity and shear stress of the material limits the extrusion rate and the height of the construction, fast extrusion rates reduce the buildability, whereas slow extrusion rates create cold joints between the layers and decreases the interlayer bond strength, resulting the overall strength to decrease. These properties could be adjusted by using appropriate materials with appropriate mix design. This study aims to investigate the influence of 2 different clays, nano-montmorillonite and sepiolite, on rheological properties of fly-ash (FA) amended cement-based systems adapted for 3D printing. Herein, the clays were incorporated at 0.5 and 1% of the cement content. The effects of these clays on rheological properties such as static and dynamic yield stress, apparent viscosity and thixotropy were analysed. The performance of clays was compared to a commercially available viscosity modifying agents (VMA). Finally, selected mixes were printed through extrusion. The results showed that both clays were compatible with polycarboxylate ether based (PCE) superplasticizer and FA. In fact, the impact of clays on rheological properties were much more pronounced in samples containing 20% FA by weight of cement at a dosage of 0.5% of the cement weight.