plots UCS of the two types of fiber-reinforced cementeclay
with fiber content of 0, 0.5%, 1.0%, 1.5%, 2.5%. As evident, both
types of improved soil had relatively higher unconfined compression
strength. For specimens improved with polypropylene fibers
and fiber bundles, its strength increased when the fiber content
increased from 0 to 0.5% but decreased if the fiber content is further
increased. The fiber inclusion could be easily distributed in the
specimens and bear the pulling stress inside when the fiber content
is relatively low. But it would be hard to blend the fiber or strips
discretely if the fiber contents were excessive. Thus, excessive fiber
inclusion might tangle together in some parts of the specimens so
that the cementation and fiber bonds there were obstructed. It can
be concluded that both two types of improved soil reached their
peak strength at the fiber content of 0.5% and that, considering the
fiber content of 0.5% as a threshold, the strength had an overall
trend to decreas