Title:
Cyclic Damage to PVA Microfibre Embedded in Cementitious Matrix in Alternating Tension-Compression Regime
Author(s):
Ranjbarian, M.; Mechtcherine, V.
Publication:
Symposium Paper
Volume:
343
Issue:
Appears on pages(s):
321-329
Keywords:
SHCC, cement-based composites, PVA microfibre, fibre pull-out test, fatigue, cyclic tension-compression loading regime, cyclic damage
DOI:
Date:
10/1/2020
Abstract:
The structures subject to dynamic loading demand more ductile materials to prevent
catastrophic failure. The results of investigations on strain-hardening cement-based
composites (SHCCs) distinguished this group of materials – due to their highly ductile
behaviour – as a suitable alternative for structures with high resistance against seismic, impact
and cyclic loadings. While mechanical properties of SHCC are determined mostly by bridging
behaviour of dispersed fibres crossing cracks and properties of fibre-matrix interface, the
dependency of these mechanisms on the loading regime is pronounced. Specifically, under
cyclic loading, the number of cycles to failure decreases dramatically when SHCC is subject
to alternating tension-compression regime. Degradation of fibres compressed between the
crack faces and deterioration of their bridging capacity are responsible for such early failure
and necessitate further investigations at the micro level. The article at hand presents the
influence of loading history in cyclic tension-compression regime on the bridging capacity of
the single PVA microfibre embedded in cementitious matrix. A novel double-sided single
fibre pull-out setup is used for the experimental investigations. First the test setup, material
composition and testing procedure are explained. Next, the results of double-sided pull-out
specimens, tested under monotonic and cyclic tension-compression regimes, are discussed. It
is shown that the deterioration of fibre bridging capacity can be assessed by applying cyclic
loading in post-cracking stage, followed by pulling the fibre out of the matrix. Possibility of a
change in pull-out behaviour of PVA microfibre from “fibre rupture” to “fibre pullout”, also a
change of behaviour in post debonding regime from “hardening” to “softening” are also
observed. Eventually, the results of microscopic analysis are presented and discussed, which
show the specific phenomena responsible for changes in pull-out behaviour.