3D printing of Geopolymer Concrete

3D printing of Geopolymer Concrete

Aldin, Zainab (TU Delft Civil Engineering and Geosciences)

Ye, Guang (mentor)
Schlangen, Erik (graduation committee)
Nugteren, Henk (graduation committee)

Delft University of Technology

Civil Engineering

2019-01-08

In spite of the fact that there are many advantages of alkali activated materials (also called geopolymers) over the cement-based materials, geopolymer concrete has been used in the past for construction purposes on a very limited level. Among the many advantages of geopolymers compared with the cement-based materials is less CO2 emission, it uses byproducts as a binder, less energy consumption during its production, more durable as a material, fast setting time and high strength development. This work is an attempt to exert some light on the usability and applicability of geopolymers in the field of construction with concentration on its use in the 3D printing. The main aim of this study is to propose a design methodology for geopolymer paste mixture to be used in 3D printing process. For achieving this goal, one paste mixture design was selected among six ones on the bases of longer workability/flowability, suitable extrudability and specific setting time. These six designs have different binder ratios. The selected mixture design, named S20, was tested further to find out its suitability for 3D printing process. This S20 mixture was tested on compressive strength, setting time, rheological properties, open time, buildability and 28 days tensile bonding strength of two layers. To find the best suitable design, modifications were done on the S20 mixture by changing the ratios between the used alkaline solutions Na2SiO3 and NaOH (0.25 was selected). These alkaline solutions played a major role in delaying the initial setting time for rheological tests (90 minutes were selected) and the extrudability for the 3D printing process. Another factor for the best design is the Acti-gel as an additive. This additive has a direct link with the buildability, extrudability and viscosity when added with different percentages. The best selected percentage of the Acti-gel was 0.75% for this mixture design. The open time and the 28 days tensile bonding strength tests were selected to be 33 minutes and 1.32 MPa respectively. Comparing the measured plastic viscosity to the open time test, the extrudability of the mixture is not anymore valid beyond 8.8 Pa.s plastic viscosity. This short open time of 33 minutes for such geopolymer mixture design needs a fast-performing 3D printer. This might help in achieving construction projects within short time.

3D Printing
Alkaline activated materials
geopolymers
Rheological properties
Mechanical properties
Setting time

http://resolver.tudelft.nl/uuid:7862fc20-7b66-40ca-957a-7bca1ec20e54

Student theses

master thesis

© 2019 Zainab Aldin