Confinement of low-strength concrete with fiber reinforced cementitious matrix (FRCM) composites

This paper presents the results of an experimental campaign aimed at assessing the effect of varying influencing parameters on the behavior of low-strength concrete prisms confined with fiber reinforced cementitious matrix (FRCM) composites. For this scope, 60 specimens were casted and tested to derive experimental stress-strain curves under monotonic axial loading. The following test variables were adopted: two types of fibers, i.e. carbon and glass fibers; four section geometries, i.e. circular, square and intermediate with two corner radius values (22 and 38 mm); two specimen dimension values, maintaining the same slenderness h/d = 2, but with two height values, i.e. 200 and 300 mm; and lastly, the presence of a pre-existing damage, with two different levels. Stress vs. axial strain and fibers hoop strains were analyzed and results were then discussed in terms of strength gain and ductility, highlighting how carbon and glass fibers jackets improve the confinement of bare specimens. Experimental evidences show how the extent of strength and ductility gains depend on composite type, cross-section geometry and specimen dimension. Also, full strength recovery of damaged specimens was achieved by carbon-FRCM system, whereas this was not possible by means of glass fibers-based jackets.