The study of the structure rebuilding and yield stress of 3D printing geopolymer pastes

For 3D printing construction materials, workability and interlayer force of fresh printing pastes were necessary to ensured extrudability and buildability in the period from extrude to hardened of pastes. The workability and interlayer force of 3 Dimensional printing geopolymer pastes related to its rheological property and more particularly to its structure rebuilding and yield stress. The present study is aimed at investigating structure rebuilding and yield stress of 3 Dimensional printing geopolymer pastes at different Si/Na ratio of alkali activator by rheology method. Results revealed that rheology is an important research method for the extrudability and buildability of 3D printing geopolymer pastes. Structure rebuilding ability (SRE) and fast-growing yield stress of 3 Dimensional printing geopolymer ensured the stability of structure in the period from extrude to hardened of paste. Si/Na ratio of alkali activator has significantly influences on extrudability and buildability of 3D printing geopolymer pastes. High Si/Na ratio of alkali activator decreases the viscosity, yield stress and development rate of fresh pastes. Si/Na ratio of alkali activation significantly influences rate of structure rebuilding of pastes, and low Si/Na ratio of alkali activator exhibited high ability of recovery of pastes.