Numerical simulation:

Material and structural behavior are simulated by means of a multiscale approach involving both microscopic and macroscopic scales. The goal is to integrate testing and simulations to develop computational models with predictive capabilities.

Mechanical testing:

Bending, tensile and fractural tests are conducted to study the mechanical behavior of FGMs. The measured parameters are used as input for special constitutive models of our finite element codes.

Rheology:

Rheological properties of the fresh cement-based composites are crucial to the successful extrusion processing. Extrusion of functionally graded fresh cement-based composites is far more difficult than extrusion of monolithic material. The relative rheological properties of different layers of paste need to be adjusted distinctively.

Microstructure:

Extrusion processing produces microstructural features with special characteristics, which in turn influence the material properties. In this study, a micro-CT is used to investigate the actual 3-D microstructure of novel fiber-reinforced cement-based FGMs. Thus real 3-D microstructural measurements (e.g. fiber distribution & orientation, porosity) are obtained from the image analysis.

Extrusion:

A lab-scale ram extruder was made to manufacture the functionally graded material. Connected to an Instron machine, the pressure and the extrusion speed can be well controlled giving more flexibility than a standard commercial extruder.

Other than single-run extrusion, re-extrusion and co-extrusion method will be used to exploit the full benefit of extrusion technique. It is expected that the FGM will be much denser in matrix and much stronger in interface between different layers.