Functionally-graded fiber-reinforced cement composite: Processing, microstructure, and properties

A functionally-graded material system has been developed with a spatially tailored fiber distribution to produce a four-layered, functionally-graded fiber-reinforced cement composite (FGFRCC). Fiber volume fractions were increased linearly from 0% in the compression zone to 2% in the tensile zone so that more fibers were available to carry tensile stress in a bending beam experiment. Extrusion was used to produce single homogeneous layers of constant fiber volume fraction and highly oriented fibers. The FRCC layers with different fiber volume fractions were stacked according to the desired configuration and then pressed to produce an integrated FGFRCC. Polished cross-sections of the FGFRCC were examined using a scanning electron microscope (SEM) to measure the fiber distribution. Flexural tests were carried out to characterize the mechanical behavior and to evaluate the effectiveness of the designed fiber distribution. No delamination between layers was observed in the fractured specimens. Compared to homogeneous FRCC with the same overall fiber volume fraction, the FGFRCC exhibited about 50% higher strength and comparable work of fracture.