Behavior of Geopolymer Concrete Confined with Circular Hoops

This paper discusses the behavior of geopolymer concrete subjected
to passive confinement under compression loads. The confinement is induced by
the use of lateral hoops, assembled from un-deformed reinforcing bars. To
compare the effect of confinement, identical specimens were produced using
conventional concrete with the similar concrete compressive strength. The
cylinder specimens were 100 mm in diameter and 200 mm in height, and the
hoops were placed on the outer most fibers of the cylinders, perpendicular to the
line of loading, with no concrete cover. The parameters analyzed in this study
were the steel bar to concrete volumetric ratio, the hoop spacings and the steel
yield stresses. The experimental results show that unconfined geopolymer
concrete were very brittle compared to the unconfined Portland cement concrete.
The strength enhancement (K value) of the confined geopolymer concrete was
higher than K value of Portland cement concrete. Confined geopolymer concrete
also has better deformability compared to the confined Portland cement concrete.
The average confinement effectiveness of geopolymer concrete also has a higher
value than that commonly used in the Indonesian Concrete Standard (SNI), that
is 4.1. The results were further assessed to the most recent experimental test
results conducted in this area.